Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

 

PART THREE – Clinical Management of Special Surgical Problems

Chapter 27 – Anesthesia for Pediatric Same-Day Procedures

David M. Polaner

  

 

Procedures and Patients Amenable to Outpatient Surgery and Anesthesia, 874

  

 

Contraindications for Outpatient Anesthesia, 875

  

 

Ex-premies and Apnea, 875

  

 

Obstructive Sleep Apnea,876

  

 

Preoperative Evaluation and Planning, 876

  

 

Preoperative Testing,877

  

 

Underlying Illnesses and Complicating Factors, 878

  

 

Upper Respiratory Tract Infections,879

  

 

Asthma, 880

  

 

Diabetes, 880

  

 

Malignant Hyperthermia, 881

  

 

Sickle Cell Anemia, 881

  

 

Preoperative Preparation of the Child and Family, 881

  

 

Family-Centered Care, 881

  

 

Preoperative Teaching and Parental Presence,881

  

 

Preoperative Fasting, 882

  

 

Premedication, 882

  

 

Anesthetic Techniques, 883

  

 

Induction, 883

  

 

Airway Management, 883

  

 

Anesthetic Maintenance, 884

  

 

Neuromuscular Blockade,886

  

 

Fluids, 887

  

 

Emergence, 887

  

 

Postoperative Analgesia, 887

  

 

Regional and Local Anesthesia,887

  

 

Caudal Anesthesia, 888

  

 

Intravenous Agents, 888

  

 

Pediatric Acute Care Unit/Recovery/Discharge Issues, 889

  

 

Nausea and Vomiting, 889

  

 

Inadequate Analgesia, 889

  

 

Excessive Somnolence,889

  

 

Complications and Unanticipated Admission, 890

  

 

Facility Design and Patient Throughput, 890

  

 

Summary, 890

Outpatient procedures continue to constitute the majority of anesthetic procedures performed in children in the United States. It is estimated that more than 60% of anesthetic procedures in children are performed on outpatients, and this number is considerably higher in some practice settings. Although the practice of outpatient anesthesia and surgery for children is not new—reports in the medical literature have documented the practice for nearly 100 years—advances in drugs and techniques are transforming how we care for our day surgery patients. Procedures that previously required overnight stays can often be performed on a same-day basis. We are able to reduce the incidence of troubling side effects of anesthetics that may have prevented the discharge of patients in the past, and better postoperative analgesic regimens may allow earlier discharge. Changes in facility designs have improved our ability to provide outpatient care in an efficient and cost-effective manner, while simultaneously enhancing and simplifying the perioperative experience for our patients and their families. Nevertheless, along with these advances have come new challenges. The envelope of what patient and procedure are appropriate for same-day surgery has continued to stretch, while resources may be shrinking under the managed care environment in North America. The pressure to increase performance and throughput places greater stresses on the perioperative system, and great care must be taken to avoid cutting corners for the illusionary benefits of efficiency and cost containment alone.

Historical reports of outpatient surgery date back to the early twentieth century, when Nicholl reported nearly 9000 operations on ambulatory children at Glasgow's Royal Hospital for Sick Children (Nicholl, 1909 ). Other early reports from the United States soon followed, but it was not until the 1970s that studies were published looking at same-day surgery from a systems perspective. In addition to examining the patient population, complication rates, and surgical procedures, these reports began to look at issues such as cost and delivery of care, as well as the optimization of the nursing and support staff, organization, and physical plant for outpatient surgery. Attention to these details continues to play a central role in the increased utilization and success of outpatient surgery. In the current economic climate of health care in the United States, there is and will continue to be a major emphasis on cost savings. In addition to the economic advantages of savings on hospital resources, a primary driving force in the popularity of pediatric outpatient surgery is satisfaction of the patients and their parents. There are obvious advantages for many parents and children to avoid even overnight hospitalization and to have the child back in his or her familiar home environment on the same day. The decisions that are made in planning the outpatient system will have a major impact on how parents perceive ease of use and quality of care of the entire system and, as a result, its success. Factors that are not medical (ease of parking, efficiency of check-in, waiting time, parental presence during induction of anesthesia, and early admission to the postanesthetic care unit [PACU]) may make impressions on the parent that are equal to the obvious medical issues, such as complication rates, postoperative analgesia, nausea and vomiting, and rapid return to the preoperative mental state.

▪ PROCEDURES AND PATIENTS AMENABLE TO OUTPATIENT SURGERY AND ANESTHESIA

Many operative procedures are well suited to be performed on pediatric outpatients, and all share several common characteristics. They all are peripheral procedures that do not involve violation of a body cavity. They all have a limited duration, generally less than 2 hours, and have minimal or moderate amounts of postoperative pain that can easily be managed with oral analgesics or the one-time administration of a regional block. They do not result in major physiologic perturbations or blood loss, nor do they disturb the ability to take oral fluids and nutrition in the immediate postoperative period. They do not require postoperative monitoring beyond the capability of the parents and home. Commonly performed outpatient procedures are listed and categorized in Box 27-1 .

BOX 27-1 

Operations Commonly Performed as Outpatient Surgical Procedures by Specialty

Otolaryngology

Myringotomy and ventilating tubes, adenoidectomy (see text), tonsillectomy (see text), frenulectomy, branchial cleft cysts, endoscopic sinus surgery, examinations under anesthesia including some bronchoscopy

Ophthalmology

Examination under anesthesia, strabismus repair, nasolacrimal duct probe, intraocular lens implantation, trabeculectomy

General pediatric surgery and urology

Herniorrhaphy and hydrocelectomy, orchiopexy, uncomplicated hypospadias, cystoscopy and cystoscopic surgery, circumcision, esophagoscopy, lumps and bumps

Gastroenterology

Endoscopy

Plastic surgery

Cleft lip and some cleft palate repairs, placement of tissue expanders, scar revisions, minor reconstructive procedures (otoplasty, septorhinoplasty, etc.)

Orthopedics

Hardware removal, casting, percutaneous tenotomies, arthrograms

Radiology

Imaging studies, radiation therapy

Dentistry

 

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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

Copyright © 2005 Mosby, An Imprint of Elsevier

▪ CONTRAINDICATIONS FOR OUTPATIENT ANESTHESIA

There are few firm contraindications to outpatient surgery for amenable procedures, but there are some patients who have medical issues that make it advisable to consider an overnight (“23-hour”) admission rather than a discharge on the day of surgery. In the majority of these cases, monitoring is required because of anesthetic-related risks, or because of exceptional risks related to the operative procedure or postoperative care in susceptible individuals.

▪ EX-PREMIES AND APNEA

The risk of postanesthetic apnea in former premature infants has been well described since the early 1980s, when Liu and others (1983) published the first prospective study of premature infants anesthetized between 41 and 46 weeks postconceptual age (postconceptual age = gestational age at birth + current age in weeks). In this report, a group of premature infants was compared with a control group of term infants of similar ages. The incidence of apnea, defined as pauses in breathing lasting longer than 15 seconds, was 20%. Subsequent studies have approximated this incidence, although some have placed the at-risk period as far out as 60 weeks postconceptual age ( Welborn et al., 1986 ; Kurth et al., 1987 ; Warner et al., 1992 ). It is now established that infants born before 36 weeks of conception are at risk of apnea after general anesthesia. It appears that this is due to immaturity in control of breathing by the brainstem after exposure to general anesthetics, and there may be similar risks after exposure to sedative-hypnotic agents and neuroleptic agents such as ketamine. Numerous studies have tried to define the period of susceptibility in the at-risk population. Several investigators have stratified the risk depending on postconceptual age and gestational age at birth, and a meta-analysis of eight studies has reported that the postconceptual age required to reduce the risk to less than 1% with 95% confidence was 54 weeks in infants born at 35 weeks gestational age and 56 weeks in those born before 32 weeks ( Malviya et al., 1993 ; Coté et al., 1995 ). In this meta-analysis, anemia was also associated with increased apnea risk, even in infants older than 42 weeks postconceptual age. The patients in the numerous studies that were included in this meta-analysis may not have all been comparable in terms of underlying state of health, so one must approach these data (as in all meta-analyses) with some caution. Several investigators have suggested that the use of regional anesthesia may eliminate the risk, and a few even advocate discharge of these patients on the day of surgery if no other agents have been administered ( Veverka et al., 1991 ; Webster et al., 1991 ; Sartorelli et al., 1992 ; Krane et al., 1995 ). However, uncontrolled case reports of apnea after spinal anesthesia have been published ( Watcha et al., 1989 ; Tobias et al., 1998 ). Because these are case reports and there were no control pneumograms, it is unknown if the apnea was related to the anesthetic, but these reports have still prompted most clinicians and consultants to continue to recommend admission and monitoring of these patients for 24 hours after any anesthetic. Caffeine, which has a long history of effective use in apnea of prematurity, has also been suggested to increase central respiratory drive after anesthesia in these patients, although this is still not commonly used (Welborn et al., 1988, 1989 [215] [216]).

▪ OBSTRUCTIVE SLEEP APNEA

One of the most common indications for tonsillectomy is upper airway obstruction during sleep. In many centers, obstructive sleep apnea (OSA) accounts for 50% or more of all children presenting for tonsillectomy and adenoidectomy ( Messner, 2003 ). These children may have abnormal ventilatory responses to both hypoxia and hypercarbia due to the chronic exposure to hypoxic and hypercarbic conditions during sleep ( Strauss et al., 1999 ; Kerbl et al., 2001 ). These responses can take up to several weeks to revert to normal after resolution of the obstruction. There are concerns, therefore, about the ability to maintain adequate breathing and oxygenation after the exposure to general anesthetics and to opioids given for postoperative analgesia. A study of 15 otherwise normal children, aged 1 to 18, with mild OSA used preoperative and postoperative pneumograms to assess respiratory status on the night after adenotonsillectomy. Nine of these children received a halothane-based anesthetic, and six received a fentanyl-based technique. The number of obstructive events decreased and the nadir of oxygen saturation improved from 78% to 92% with fentanyl-based technique. The authors concluded that in cases of mild OSA without other underlying disorders, intensive postoperative monitoring is not necessary ( Helfaer et al., 1996 ). In a group of 134 children selected for outpatient tonsillectomy, of whom 83% carried the diagnosis and indication for surgery of OSA, 11 (8.2%) were admitted for overnight observation after experiencing respiratory problems in the postanesthetic care unit ( Lalakea et al., 1999 ). These patients as a group were significantly younger than those discharged home (average age, 4 versus 6.3 years). Preoperative evaluation and assessment of OSA were not described. Most otolaryngologists consider significant (as opposed to mild) OSA to be a contraindication to outpatient management of adenotonsillectomy, especially in children younger than 3 years, although in one small study the postoperative complications in these younger children were not related to obstructive events ( Slovik et al., 2003 ). Those investigators suggested that the severity of OSA, rather than patient age, may be a more predictive factor, but this is in conflict with other reports, which recommend that age of less than 3 years should be considered an independent discriminator ( Shott et al., 1987 ; Biavati et al., 1997 ). The only criterion that appears to be accurate in the diagnosis and stratification of severity in OSA is polysomnography; the history or pulse oximetry alone is neither specific nor sensitive enough (American Thoracic Society, 1996 ; Schechter, 2002 ; Subcommittee on Obstructive Sleep Apnea American Academy of Pediatrics, 2002 ).

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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

Copyright © 2005 Mosby, An Imprint of Elsevier

▪ PREOPERATIVE EVALUATION AND PLANNING

The evaluation of outpatients for surgical procedures presents a significant organizational challenge to the anesthesiologist. Because one of the primary goals of outpatient surgery is both efficiency and rapid throughput, there is a great disincentive to require preoperative visits before the day of surgery. At the same time, an efficient system demands an absolute minimum of cancellations on the day of surgery. Such pressures put both the anesthesiologist and the system as a whole at increased risk of proceeding with cases in which the patient may not be optimally prepared for surgery and anesthesia. There is also a stress of “production pressure”—the urgency to move patients rapidly through the preoperative queue and into the operating room on schedule. This, too, is in competition with the need to provide the best and most complete evaluation and care of the patient. To avoid these situations, a system of preoperative screening must be instituted that provides the most accurate, up-to-date, and complete information to the anesthesiologist so that he or she may make well-informed decisions about patient management. Fortunately, both technological and nontechnological aids exist to streamline this process.

The implications of cancellation, particularly on the day of surgery, go far beyond the efficiency of the operating room. A survey by Tait and others (1997) found that nearly half of parents whose children's operations were cancelled on the day of scheduled surgery missed a day of work and that about half of these parents went unpaid as a result. Many drove long distances to get to the hospital, and nearly 25% were frustrated or angry as a result of the cancellation. A small number of dissatisfied or angry parents can have an adverse impact on the success of an outpatient surgery program well out of proportion to their numbers, and great attention must be paid to minimize these events by using systems that work effectively.

In many cases, a preoperative visit to the anesthesiologist is neither practical nor necessary. Because the majority of children presenting for same-day surgery are relatively healthy, screening tools such as telephone interviews and self-reporting can be implemented. Coordination with the surgeon's office may reduce both redundancy in paperwork and repeated questioning of the patient's family. The efficiency in combining surgical, anesthetic, and nursing evaluation can be greatly enhanced if a computerized record is used. With these systems, which are finally maturing after years of development, data from one evaluation can automatically populate another linked database. This can greatly streamline the evaluation process. Even in the majority of institutions where paper records remain the standard, systems using secure e-mail, facsimile, or even common forms can be designed to eliminate redundancy. The elimination of needless paperwork can be a great aid in increasing patient throughput, as well as in reducing the frustration of staff and parents alike.

The initial step in preoperative planning and evaluation begins when the surgeon books the case. This is the first opportunity for the system to alert the anesthesiologist of any unusual conditions or underlying illnesses that the patient may have. A short list of check boxes on the booking form suffices and need not involve great detail. This information can be reviewed by an anesthesiologist to detect any cases that might benefit from especially extensive consultation or planning before the day of surgery.

Because the surgeon's office is the initial contact point of the patient's family with the perioperative system, it also provides an excellent opportunity to present the parents with introductory information about the anesthetic. A pamphlet describing generalities such as the role of the pediatric anesthesiologist in caring for the child, NPO instructions, contact telephone numbers, and other information specific to the hospital or outpatient surgical center can be a useful reference for the family. Having a written reference for NPO guidelines is especially helpful, because lack of adherence to these instructions is a common cause of case delay or cancellation. Parents should be given a telephone number to call both for questions about the anesthetic agent that they feel cannot wait until the preoperative assessment and for consultation with an anesthesiologist should an intercurrent illness develop between the time of the visit to the surgeon and the day of surgery.

A preoperative visit to the surgeon alone, however, does not optimize the preoperative evaluation process for the anesthesiologist or for the same-day surgery process as a whole. A case-control study of pediatric outpatient cancellations found that 10% of same-day surgery patients at a children's hospital were cancelled on the day of surgery, and half of those were for preventable reasons. Cancelled patients who had inadequate preoperative preparation were more likely to have been seen only in the surgeon's office and not in the hospital's preoperative program ( MacArthur et al., 1995 ). It is clear that further screening is necessary to address general medical and anesthetic concerns.

A short telephone interview with the patient's parent before scheduled surgery, whether conducted by the anesthesiologist or a nurse practitioner, not only can be a source of clinical information about the patient and about the parent's concerns but also can forestall unanticipated problems that can cause delays, cancellations, or complications on the day of surgery. Knowing in advance, for example, that an asthmatic child had a mild upper respiratory tract infection (URI) the week before allows the anesthesiologist to prescribe a short course of steroids with ample time for the drug to take effect. The child who has sickle cell disease with an active URI, on the other hand, might have his or her operation postponed, thus saving the parents a trip to the hospital and allowing the schedule to be rearranged before the day begins. A well-organized system for conducting these calls should be established so that patients are not missed and communication with the anesthesiologists scheduled to care for them can be easily accomplished. It is important to organize the system so that the calls are most effective. As could be expected, a study of over 5000 patients conducted at National Children's Hospital in 1992 found that calls made during the evening were far more likely to successfully reach the parents ( Patel and Hannallah, 1992 ). In the United Kingdom and in some hospitals in the United States, preoperative clinics, rather than telephone screening, are used, but this may necessitate an additional visit by the family. The inconvenience may outweigh the advantages of a face-to-face visit for some families, and success may be predicated upon ease of use of the system. Preoperative screening and evaluation can also improve throughput on the day of surgery, particularly if there is a long list of very short-duration cases, such as myringotomy and tube placement. The duration of those cases is so short that the time it takes to do a preoperative evaluation may be longer than the operative time. Saving even 10 or 15 minutes per hour might allow the team to perform an additional operative procedure each hour.

Other methods of communication, including secure Web sites and e-mail, have been used for similar purposes. The ability of a family to access a secure server and enter preoperative interview information will likely become increasingly attractive in coming years. Although the personal interaction with a knowledgeable professional can never be replaced, certain standard data can be entered with great efficiency in this manner. Intranet-based kiosks at the hospital, where patients' families can use either keyboard or touch screen technology to enter information that is now entered on paper questionnaires at the time of admission, will become increasingly important modalities as hospitals move from paper-based records to digital ones.

It is particularly important that reports of previous operative procedures or consultations by specialists be available to the anesthesiologist during the preoperative assessment. A computerized repository of this information is the best solution, as it allows immediate access from any location, but many institutions have not yet migrated to completely digital medical records. A day surgery coordinator should have the responsibility of ensuring that necessary outside and internal records are readily available the day before surgery, to avoid delays. Such information also must be immediately accessible to the anesthesiologist on the day of surgery.

In some locations, it is common for a child's pediatrician to be responsible for “clearing” the child for surgery. This can be a considerable help, as the pediatrician often has the best knowledge of the child's underlying illnesses and conditions. The pediatrician, however, often has little understanding of the issues that are of greatest concern to the anesthesiologist and may actually miss or ignore problems that can affect anesthetic management, to the detriment of the preoperative evaluation process. The anesthetic implications and preoperative optimization of airway anatomy and function, gastroesophageal reflux, upper respiratory illness, and asthma, as well as of syndromes and chronic conditions such as trisomy 21 and the former premature infant, all may be underappreciated by pediatricians who do not work in the operating room or administer anesthesia and who usually have had little or no training in perioperative medicine ( Fisher, 1991 ). Several reviews by pediatric anesthesiologists in the pediatric literature have discussed the preoperative screening process and what the pediatrician needs to know about preparing the child for anesthesia ( Fisher, 1991 ; Fisher et al., 1994 ; Maxwell et al., 1994 ;Section on Anesthesiology, 1996 ). If a hospital or surgicenter relies on pediatricians as a major link in the preoperative assessment chain, the pediatricians must be familiar with this literature and should have ongoing communication with their anesthesiologist colleagues.

▪ PREOPERATIVE TESTING

Policies on preoperative testing have been completely reassessed, and abandonment of the routine use of tests has become the norm. This is driven by both the growing number of studies that demonstrated little or no value in such testing and economic concerns that mandate the elimination of unnecessary expenditures.

Urinalysis

A 1990 study of nearly 500 children scheduled for elective surgery found abnormalities in 15%; however, more than 80% of those were historically known, clinically insignificant, or false-positive results. The authors concluded that preoperative urinalysis should not be routinely performed on healthy children for preoperative assessment ( O'Conner and Drasner, 1990 ).

Pregnancy Testing

Sexual activity in adolescence is increasingly common, and, as a result, the risk of undiagnosed first trimester pregnancy may be increased in adolescents undergoing elective surgery. A survey of members of the Society for Pediatric Anesthesia found that nearly half of the respondents routinely test for pregnancy in postpubertal patients ( Patel et al., 1997 ). Other investigators have found a low yield of positive results, especially in girls under 15 years of age, but their study had a relatively small number of subjects, and some investigators who care for patients in different geographical regions have reported far higher rates of pregnancy in very young adolescents ( Kempen, 1997 ; Kempen et al., 1997 ; Wheeler and Coté, 1999 ). All of these investigators determined that history is an unreliable indicator of pregnancy, so that despite the small number of positive pregnancy test results, there is no reasonable alternative to testing. Pregnancy testing, which in most institutions is performed using urinary β-human chorionic gonadotropin (β-hCG), is reliable, inexpensive, and quick. Elective procedures should be cancelled if the result of the test indicates pregnancy, and appropriate referral and consultation should be obtained. With these facts in mind, routine testing for pregnancy in postpubertal girls is likely warranted. The ethical, legal, and criminal implications of positive findings are beyond the scope of this chapter but are discussed in the cited references.

Hematocrit/Complete Blood Cell Count

Unless an operation is expected to result in significant blood loss (highly unlikely for outpatient surgery), the screening complete blood cell count (CBC) has little or no value ( Roy et al., 1990 ; Hackmann et al., 1991 ; Roy et al., 1991 ). These studies have demonstrated that the presence of mild to moderate anemia has little to no effect on the conduct of anesthesia or outcome of children undergoing same-day surgical procedures. The presence of anemia in former premature infants under 54 weeks of postconceptual age has been found to correlate with an increased risk of postanesthetic apnea, and it is possible that screening for anemia in this population may detect those at increased risk ( Welborn et al., 1991 ). It is not known, however, if the anemia is the cause of increased apnea or only an associated finding. The neonatal literature is in conflict regarding the effect of transfusion on apnea of prematurity, with several studies demonstrating decreased apnea after transfusion, and several reporting no change ( Joshi et al., 1987 ; Hume, 1997 ). Of additional interest is the finding by Poets and others (1997) that there was a 3% increase in oxygen saturation after transfusion, although the frequency of apneic events did not diminish. Bifano and others (1992) found fewer apneic events both in the transfusion-treated group and in the control group who received volume expansion with 5% albumin, suggesting that improved cerebral circulation on the basis of hemodynamic effects, not increased oxygen carrying capacity, may be the benefit of this intervention. It must be recognized that these studies looked specifically at apnea of prematurity, not postanesthetic apnea in premature infants, and it may not be accurate to generalize their findings to the perioperative population. All at-risk former premature infants should be admitted for postoperative monitoring in any case; thus, screening may not alter clinical practice. Children with sickle cell disease (not trait) need to have a hemoglobin level measured, as both management and outcome of these patients are dependent on an adequate level of hemoglobin A or F (see later).

Sickle Cell Testing

In many states, newborns in at-risk populations are screened for sickle cell disease, so the sickle cell status of all infants and children in those locations is known. In locations where such newborn screening is not universal, it is prudent to obtain sickle cell testing in any infant of at-risk ethnicity whose status is unknown, at least under the age of 3 years. Children older than this are likely to have had symptoms if affected. In children who do have sickle cell disease, a preoperative hemoglobin level is mandated to determine the need for preoperative transfusion. A large multicenter trial found that simple transfusion, if the hemoglobin was less than 10 g/dL, is as effective as exchange transfusion in these patients ( Vichinsky et al., 1995 ). Although one study has found that minor surgical procedures could be performed in sickle cell patients without preoperative transfusion, complication rates were significantly higher in those undergoing abdominal, thoracic, or airway procedures ( Griffin and Buchanan, 1993 ). Sickle cell trait, which usually does not cause any symptoms or illness, has rarely been associated with complications of surgery and anesthesia ( Konotey-Ahulu, 1969 ; McGarry and Duncan, 1973 ; Atlas, 1974 ; Gibson and Love, 1974 ), but hemoglobin determination in these patients is unnecessary (also see Chapter 32 , Systemic Disorders in Infants and Children).

Heart Murmurs and Cardiology Consultation

At least 25% of healthy children have an audible heart murmur at some time during childhood, and the question of when to refer a child to a pediatric cardiologist for the evaluation of a new murmur is often raised during the preoperative evaluation. The vast majority of these are functional “innocent” murmurs, not associated with any structural heart disease. Innocent murmurs are soft (less than grade 3), blowing, and loudest along the left sternal border. They tend to decrease or disappear during inspiration. Most congenital heart lesions present before the first several months of life, so in the absence of symptoms a murmur in an older child is less likely (but not entirely unlikely) to be significant. Exceptions include atrial septal defects, small ventricular septal defects, some cases of coarctation of the aorta, some hemodynamically insignificant valvular lesions that are still endocarditis risks, and, in rare instances, other lesions. The ability of a pediatric cardiologist to distinguish between a functional murmur and one caused by a structural heart lesion by examination alone was evaluated and found to be high, so more extensive (and expensive) evaluation, such as echocardiography, is rarely necessary (Newburger et al., 1983 ). If the child is older than 6 months, without any symptoms referable to the cardiac system, most skilled clinicians should be able to evaluate these murmurs and rule out hemodynamically significant congenital heart disease. Cardiomyopathy can also present with a new murmur, so a previously undetected murmur accompanied by symptoms suggestive of impaired myocardial performance or irritability, such as dysrhythmias, especially if they follow a viral illness, should be evaluated by a cardiologist.

Many children with congenital heart lesions require antibiotic prophylaxis for the prevention of endocarditis when undergoing at-risk operations. The American Heart Association recommendations are available at http://www.americanheart.org/presenter.jhtml?identifier=1745. One should note that for optimal treatment, the intravenous antibiotic should be administered at least 30 minutes before the procedure's start, which can pose a considerable problem in day surgery when an intravenous catheter is not present before induction. For procedures on the respiratory tract, intraoral procedures, or moderate risk patients for genitourinary procedures, oral antibiotics can be given 1 hour before the procedure, thereby eliminating the problem of timing in these cases. For genitourinary procedures in high-risk patients, this timing is more problematic, because there are no good oral alternatives. A reasonable approach is to begin to administer the antibiotics as soon as intravenous access is obtained but to be mindful of the need to administer gentamicin over a minimum of 10 to 15 minutes (also see Chapter 32 , Systemic Disorders in Infants and Children).

Copyright © 2008 Elsevier Inc. All rights reserved. - www.mdconsult.com

Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

Copyright © 2005 Mosby, An Imprint of Elsevier

▪ UNDERLYING ILLNESSES AND COMPLICATING FACTORS

There are numerous underlying conditions that exist commonly in relatively healthy children that do not preclude outpatient surgery but that have implications regarding the preoperative preparation and anesthetic management.

▪ UPPER RESPIRATORY TRACT INFECTIONS

Probably the most common problem to confront the anesthesiologist caring for children in outpatient surgery is the child with a URI and has been reviewed by Tait and Malviya (2005) . Viral respiratory tract illness is virtually ubiquitous in children, particularly during the winter months when close indoor contact in school and daycare with other children with colds is impossible to avoid. The average preschool child contracts between six and eight URIs per year. Both upper and lower respiratory tract viral infections can increase airway inflammation, irritability, and respiratory tract secretions via mechanisms as diverse as increased production and decreased degradation of tachykinins and other neuropeptides, virus-induced damage to M2 muscarinic receptors in the airways leading to vagal-mediated hyperreactivity, and increased volume and viscidity of airway secretions causing subsegmental atelectasis ( Empey et al., 1976 ; Dusser et al., 1989 ; Barclay et al., 1992 ). Increased airway reactivity and hyperresponsiveness occur in the lower airways even in patients with respiratory viral illness clinically limited to the upper airway and even in those with no history of asthma ( de Kluijver et al., 2002 ). After the apparent resolution of the URI, increased airway hyperresponsiveness and irritability may persist for as long as 6 to 8 weeks ( Empey et al., 1976 ; Empey, 1983 ). In children with underlying respiratory disease, such as asthma, bronchopulmonary dysplasia, or other chronic lung diseases, these responses may be further exaggerated. Other risk factors that may be associated with more serious or frequent complications are age of less than 1 year and sickle cell disease ( Cohen and Cameron, 1991 ). In what is perhaps one of the most comprehensive investigations of URI and anesthesia, 1078 infants and children were prospectively studied ( Tait et al., 2001 ). Independent risk factors for respiratory complications were endotracheal intubation, history of prematurity, reactive airways disease, parental smoking, airway surgery, nasal congestion and the presence of copious secretions. Of interest is that the history of prematurity was a risk factor even in children who were several years old and no longer had ongoing problems referable to their premature birth.

Numerous studies have documented that children who either have URIs or have recently recovered from one have more minor airway complications during or after anesthesia compared with healthy children. Mild oxygen desaturation and coughing, as well as more potentially serious complications such as bronchospasm, laryngospasm, and respiratory failure, are particularly likely to occur if the airway is stimulated. Tait and Knight (1987) prospectively studied a large cohort of children undergoing myringotomy and ventilating tube placement for chronic or recurrent otitis media. There was no significant increase in respiratory problems in the children with intercurrent URIs, and the severity of respiratory illness, as well as the duration of URI symptoms, actually decreased in the group receiving halothane anesthesia by mask without instrumentation of the airway. These beneficial results may have been influenced by the effects of myringotomy and drainage on the course of the infection. Coté and colleagues ( Coté et al., 1991 ; Rolf and Coté, 1992 ), in their investigation of the utility of capnometry and pulse oximetry in detecting adverse events during anesthesia and in a subsequent report further analyzing these data, found that children with URIs commonly had mild oxygen desaturation both during surgery and in recovery. Others have noted that postoperative oxygen requirements in these children are commonly but transiently increased ( Levy et al., 1992 ). It is possible that the cause is related to subsegmental atelectasis from increased quantity and viscidity of secretions, and that with deep breathing and coughing after emergence, reexpansion of these segments occurs. In the prospective study cited earlier, patients with current or recent URI had a greater incidence of respiratory complications, including breath-holding and desaturation of less than 90%, although none of the complications were associated with long-term sequelae. Both the authors and an accompanying editorial concluded that most children with URIs who were not overtly ill and had no other complicating medical issues could, with judicious attention to anesthetic technique, be safely anesthetized with increased risk for only mild transient sequelae ( Coté, 2001 ; Tait et al., 2001 ).

The potential for more serious complications in children with URI should not be overlooked. A prospective study of over 15,000 children found that children who developed laryngospasm were twice as likely to have a URI ( Schreiner et al., 1996 ). The investigators found that the incidence of laryngospasm was most clearly related to the parent's subjective assessment of a URI, and that younger age and surgeries involving the airway were additive risk factors. A prospective case-control study of 1283 children with URI who underwent general anesthesia found a 2- to 7-fold increase in respiratory complications during the perioperative course compared with their counterparts without URI ( Cohen and Cameron, 1991 ). The incidence was 11-fold higher if the patient was intubated. A very small minority of children with URI who do not appear to be very ill during the preoperative examination develop acute respiratory failure after the induction of anesthesia or sometime during the anesthetic course. Severe hypoxia, bronchospasm, ventilatory insufficiency, and diminution of compliance may occur, requiring postoperative ventilatory support and critical care management. Some of these children have underlying lower respiratory tract disease, such as pneumonia, and others may experience shunt and ventilation/perfusion mismatch from atelectasis and pulmonary collapse due to inspissation of secretions and mucus plugging ( Campbell, 1990 ; Barclay et al., 1992 ). In rare instances, cardiomyopathy follows viral illness. There are several reports of cardiac dysrhythmias after induction of general anesthesia in patients thought to have postviral myocarditis. The onset of abnormal rhythms on the electrocardiograph tracing or sudden deterioration of blood pressure or perfusion should alert the anesthesiologist to this possibility ( Brampton and Jago, 1990 ; Terasaki et al., 1990 ).

It should be borne in mind that all of the ill patients who are included in these studies had mild to moderate URIs—children who were more severely ill were cancelled by the clinicians responsible for their care and were never enrolled in the study. Thus, clinical judgment remains crucial in deciding whether to cancel a case. Firm criteria for when to proceed and when to cancel are hard to discern, but the following can be used as guidelines.

  

   

Laboratory tests are usually not useful; clinical impression is more reliable, such as the presence of toxicity, fever, purulent nasal discharge, productive cough, or wheezing. If physical examination suggests pneumonia, a chest radiograph may be confirmatory.

  

   

Ex-premature infants, infants with pulmonary disease (asthma, bronchopulmonary dysplasia, etc.), infants under 1 year of age, and children with sickle cell disease are more at risk.

  

   

Patients undergoing airway surgery are more at risk.

  

   

Endotracheal intubation increases the risk of complications. Data suggest that the risk of airway complications in children with URI is lowest with a conventional facemask, intermediate with a laryngeal mask airway (LMA), and greatest with an endotracheal tube (Tait et al., 1998, 2001 [198] [197]).

  

   

Airway hyperresponsiveness exists for 3 to 4 weeks after the resolution of the URI.

  

   

Transient oxygen requirements or other mild respiratory symptoms frequently occur and PACU discharge time may be delayed.

▪ ASTHMA

The prevalence and severity of asthma continue to increase in the United States and other industrialized countries. As of 1998, 6.4% of the U.S. population carried the diagnosis of asthma, and two thirds of those cases are children. Nearly one-half million patients are hospitalized yearly with exacerbations of asthma, and almost half of those are children. The prevalence has increased by about 60% since the 1980s. The death rate, although low, more than doubled from 1975 to 1995 ( Molfino and Slutsky, 1994 ; Sears, 1995 ). Children with a history of asthma can be safely and effectively anesthetized for same-day surgery, but careful preoperative preparation and evaluation, and intraoperative management, are crucial to avoid exacerbations and complications. Although it is common to think of asthma in terms of bronchospasm, current definitions of the disease emphasize the role or airway inflammation in pathogenesis, progression, and management. A consensus conference of the National Institutes of HealthNational Heart, Lung, and Blood Institute (2002) defined asthma as a chronic inflammatory disorder of the airways that involved many cell types beyond those structural elements of the airways themselves, including mast cells, eosinophils, and T lymphocytes. The inflammatory processes that are involved in both the pathogenesis of the disorder and the progression of disease are now addressed much more effectively in therapy for all asthmatics, not only those with severe disease. The mainstay of therapy in the past was the chronic use of bronchodilator therapy, with anti-inflammatory drugs reserved for the more severe cases; current thinking is that first-line treatment should target inflammation ( Spahn and Szefler, 2002 ; Kemp, 2003 ; Liu and Szefler, 2003 ).

Anesthetizing the child with a history of asthma for outpatient surgery involves the same general principles as for inpatient procedures ( Pradal et al., 1995 ). It is critical for the asthmatic patient to closely adhere to his or her medication regimen before surgery. Inhaled steroids and agents such as leukotriene inhibitors and cromolyn all require chronic use for efficacy. The patient must use these medicines regularly and faithfully in the days and weeks before anesthesia. For those who have required systemic steroids in the past, a short course of steroids, beginning 24 hours before the induction of anesthesia, may be advisable, particularly if intubation of the trachea is required. Preoperative and intraoperative treatment with a short-acting β-agonist such as nebulized albuterol may be helpful as well, even if the patient is not symptomatic, because events may occur during surgery that are likely to provoke airway irritability, especially intubation ( Maslow et al., 2000 ). Much like the child with a URI, avoidance of intubation and airway stimulation, if possible, reduces the potential for exacerbation of airway irritability.

Volatile anesthetics, which have bronchodilatory properties, have obvious advantages in the asthmatic child. Propofol, which has been shown to relax tracheal smooth muscle in vitro and to decrease airway resistance in both healthy and asthmatic subjects during induction of anesthesia, is an excellent choice when an intravenous induction is used ( Pizov et al., 1995 ; Eames et al., 1996 ). This effect on airway smooth muscle has been shown to be even greater than that of ketamine ( Pedersen et al., 1993 ) and was also demonstrated during maintenance when an infusion was continued during the anesthetic. A propofol-based anesthetic, combined with either regional anesthesia or a non–histamine-releasing opioid, is a good alternative to volatile anesthesia when a total intravenous technique is indicated or desired. Caution must be taken with the sulfite-containing preparation of propofol—one study in adults demonstrated a significant increase in airway resistance with this formulation compared with the non–sulfite-containing drug ( Rieschke et al., 2003 ).

Emergence from anesthesia is perhaps the most vulnerable period. Although the stimulation of intubation at induction is unquestionably a time of increased risk, the ability to treat bronchospasm by deepening the anesthetic in response to airway hyperreactivity is not present at emergence. There is, therefore, an advantage to deep extubation when a volatile technique is used, because the patient can awaken without the endotracheal tube (a highly potent stimulus to the airway) in place. Judicious timing of extubation during emergence from total intravenous anesthesia can accomplish the same goal (also see Chapter 11 , Intraoperative and Postoperative Management; and Chapter 32 , Systemic Disorders).

The risk of anesthesia in a child with an active exacerbation of asthma is certainly increased, and careful attention must be given to postponing procedures in these patients until baseline control of the disease is regained. The child with severe asthma who is never fully “clear” can still be a suitable candidate for outpatient surgery if (1) his or her clinical management is optimized; (2) aggressive preoperative treatment, such as a short course of systemic steroids, increased bronchodilator therapy, and strict avoidance of airway irritants like tobacco smoke, is instituted; and (3) contingency plans for admission are made in the event of an exacerbation.

▪ DIABETES

Type 1 diabetes in children is not uncommon, occurring in approximately 1 in 500 school-aged children, but data on the optimal intraoperative management of children with this disease are scant. Perianesthetic management of diabetes mellitus in children has been reviewed ( Chadwick and Wilkinson, 2004 ; Ahmed et al., 2005 ). Although many of the problems involved in anesthetizing adults relate to the late complications of this condition (damage to many end-organ systems, autonomic dysfunction), these problems are less prevalent in children, and the most common issue is that of glucose control. Children with diabetes can be safely anesthetized as outpatients if great care is taken to maintain good glucose homeostasis. In the recent past, it was often recommended to administer half of the usual insulin dose on the morning of surgery and to begin a glucose-containing intravenous solution soon thereafter. Better options, however, are now the norm for management ( McAnulty et al., 2000 ;McAnulty and Hall, 2003 ; Chadwick and Wilkinson, 2004 ; Ahmed et al., 2005 ). In most patients, it is easiest to schedule their surgery early in the day and to administer no insulin at all on the morning of surgery, with the exception of insulin glargine. It is a recombinant human insulin analogue for basal control with no true peak and a very long duration of action of about 24 hours, which can be administered in the usual dose.

The blood glucose level should be obtained under general anesthesia, once intravenous access has been established, and upon awakening and again 2 to 3 hours later. Intravenous infusions containing 5% glucose have often been recommended for intraoperative fluid management, but it is easier to use a non–glucose-containing intravenous fluid into which a glucose-containing intravenous catheter is “piggybacked.” In this manner, the patient's fluid requirements and glucose requirements can be independently regulated. Because the most potentially catastrophic complication of diabetes during surgery is unrecognized hypoglycemia, blood glucose levels should be measured periodically during the procedure. Hypoglycemia should be treated promptly by reducing or stopping any insulin administration and increasing the intravenous glucose rate, and hyperglycemia treated with a continuous insulin infusion titrated to effect, usually beginning at a rate of 0.05 unit/kg per hour. The very short duration of action of intravenous regular insulin (about 5 minutes) makes glucose control much easier with this method ( Barnett et al., 1980 ). The same management scheme is continued in the PACU until the patient is awake and taking oral fluids without difficulty. At that time, a dose of subcutaneous regular insulin can be administered, and an oral diet begun. Blood glucose levels should be measured frequently during the postoperative day, because the stress of surgery often alters insulin requirements, and adjust the dose accordingly. The usual insulin regimen can often be restarted on the day after surgery (see Chapter 32 , Systemic Disorders).

▪ MALIGNANT HYPERTHERMIA

The advent of improved and short-acting intravenous anesthetics has made the management of patients with malignant hyperthermia (MH) considerably simpler. Current recommendations for the care of MH patients no longer includes prophylactic therapy with dantrolene, and the use of nontriggering techniques coupled with proper preparation of the anesthesia machine can ensure that these patients are not exposed to triggering agents. A 10-year review of 303 patients with the diagnosis of MH who underwent trigger-free anesthesia found that none developed fever in the perioperative period that was attributable to an MH crisis, and none required treatment with dantrolene ( Yentis et al., 1992 ). The authors concluded that MH-susceptible patients are suitable candidates for outpatient anesthesia (seeChapter 31 , Malignant Hyperthermia).

▪ SICKLE CELL ANEMIA

Children with sickle cell disease have increased risks in the perioperative period. Preoperative testing and management of transfusion were discussed earlier. The major risk factors for inducing a crisis in the perioperative period are dehydration, hypoxia, diminished perfusion, and acidosis. If close attention is paid to avoiding these, most sickle cell patients can be managed as outpatients for suitable operations. In particular, good hydration and analgesia are important for stable recovery. One must be more strict than usual in ensuring that the child can take oral fluids without difficulty before discharge home. The use of surgical tourniquets for orthopedic surgery in sickle cell patients is controversial ( Adu-Gyamfi et al., 1993 ) but should probably be avoided in outpatient surgery where postoperative acid-base status, perfusion, and the development of late-onset complications cannot be closely followed. Tonsillectomy and adenoidectomy in sickle cell patients with obstructive sleep apnea appear to entail increased risks and should not be performed on an outpatient basis ( Sidman and Fry, 1988 ; Derkay et al., 1991 ; Halvorson et al., 1997 ) (see Chapter 32 , Systemic Disorders).

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▪ PREOPERATIVE PREPARATION OF THE CHILD AND FAMILY

▪ FAMILY-CENTERED CARE

There is an increasing emphasis in pediatric care on the care of the child within the context of the family. This is in part behind the current vogue for including the parents of the patient in the experience of induction of anesthesia and early parental admission to the PACU. When one considers outpatient surgery, however, this concept is extended even further, because the family is more intimately involved in the postoperative care of the child than ever before. The parent or primary caregiver becomes the surrogate nurse once the child is discharged home and therefore must be involved to a greater degree in the postoperative experience even before discharge from the day surgery unit. It has become the norm in most pediatric institutions and general hospitals that have sizable pediatric surgical programs for parental involvement to include preoperative tours of the operating room and PACU, parental presence during induction of anesthesia, and admission of the parents to the PACU very soon after the child's arrival and emergence from anesthesia. In most cases, experience with these programs has found them to ease, not complicate, the care of the child, and disruptive parents are the rare exception ( Schofield and White, 1989 ).

▪ PREOPERATIVE TEACHING AND PARENTAL PRESENCE

Outpatient surgery is an intense experience for both parents and children. Many things happen in a very short time span, and the emphasis on efficiency and throughput can limit the time that staff can spend in preparing parent and child for all that will occur. Preoperative teaching programs have become common methods of education to help families understand what to expect on the day of surgery. These programs include preoperative tours of the outpatient surgery center, preoperative telephone calls, written brochures, and videotapes ( Karl et al., 1990 ; Kleinfeldt, 1990 ; O'Byrne et al., 1997 ; Cassady et al., 1999 ; Bellew et al., 2002 ; Koinig, 2002 ). While the explicit goal of these programs is education and the efficient transmission of information, an implicit goal is the reduction in anxiety of patients as well as their parents and undesirable behavioral consequences of the stress of the perioperative experience ( Margolis et al., 1998 ). The first objective of education and transmission of information can be met by many, if not all, of these programs, but teaching and tour programs may not be as effective in reducing anxiety and improving behavior as commonly thought. A study of 143 children aged 2 to 6 years who were randomized to receive either an interactive teaching book or no intervention found more, not less, preoperative anxiety in the children who had received the book but less aggression during induction and fewer behavioral changes 2 weeks after surgery ( Margolis et al., 1998 ). A well-controlled and designed study found that preoperative teaching programs of various modalities had an effect of anxiolysis only in the holding area on the day of surgery; that effect did not extend effectively to the induction period itself ( Kain et al., 1998 ) (see Chapter 7 , Psychological Aspects of Pediatric Anesthesia).

Although parental satisfaction was clearly increased by parental presence during induction and highly anxious children benefited from presence of a parent during induction, children's anxiety and behavior were more effectively modulated by the use of premedication ( Kain et al., 1996 , 1998). While these data might suggest that the expense and effort of elaborate teaching programs, when examined in a critical and rigorous manner, may not be as cost-effective as more modest programs combined with premedication, one must recognize that limited benefits have value as well. For the parent and child who are waiting for an hour in the preoperative area, a reduction in stress for that period alone is meaningful.

Part of the art of pediatric anesthesia, of course, is the ability to rapidly establish effective and reassuring communication with parent and child. The rapport and trust that the anesthesiologist create during the preoperative interview also provides an important and effective method of reassurance and anxiolysis that can enhance the transition to the operating room. In the outpatient setting, where time is more constrained, the value of a quick game, magic trick, kind word, or even brief induction of hypnotic suggestion should not be underestimated. The child may be additionally comforted by bringing a security item, such as a blanket or favorite toy, into the operating room. Having this item immediately available at the time of emergence may also be helpful (also see Chapter 7 , Psychological Aspects of Pediatric Anesthesia, and Chapter 10 , Induction of Anesthesia and Maintenance of the Airway).

▪ PREOPERATIVE FASTING

In preparation of a child for anesthesia and surgery, it is extremely important to properly instruct the parents in regard to food and fluid intake. A number of studies in the 1990s demonstrated that clear fluids with or without sugar are rapidly cleared from the stomach and that the gastric fluid pH and volume are independent of the duration of fasting beyond 2 hours, provided that only clear fluids are consumed on the day of surgery ( Schreiner et al., 1990 ; Splinter and Schaefer, 1990 , Litman et al., 1994 ). The liberalization of guidelines for preoperative fluid administration offers the benefit of improved patient comfort. It also means that fewer infants and children demonstrate signs of hypoglycemia or dehydration at the time of anesthetic induction ( Welborn et al., 1993 ). Over the last decade, most pediatric institutions have altered and shortened the fasting period for clear liquids to 2 to 3 hours prior to induction of anesthesia for all ages, although approaches to infants on breastfeeding tend to vary among different institutions ( Ferrari et al., 1999 ).

Infants less than 6 months of age on breast milk require 4 hours of fasting. Breast milk or infant formula should be considered as solid food because the fat is the main determinant delaying gastric emptying ( Litman et al., 1994 ). Older infants over 6 months of age on milk or infant formula should be fasted for 6 hours; children on solid food, including cereal, toast, and juice with pulp (e.g., orange juice), are usually fasted for 8 hours (or NPO after midnight) prior to induction of anesthesia.

▪ PREMEDICATION

As was noted earlier, the use of sedative premedication has been shown to be the most effective means of reducing preoperative anxiety, postoperative recall, and maladaptive behavior in children undergoing outpatient surgery. Oral midazolam has become the most commonly used premedicant in the United States since the 1990s. Significant reduction in postoperative recall and establishment of anterograde amnesia has been demonstrated with 0.5 mg/kg of midazolam administered orally as soon as 10 minutes before induction ( Kain et al., 2000 ). Oral doses as low as 0.25 mg/kg have been demonstrated to be as effective as larger doses with only a slightly slower time of onset ( Coté et al., 2002 ). Of particular concern in the outpatient setting, however, is the problem of delayed emergence. Several studies using 0.5 mg/kg of oral midazolam have found that the drug delayed recovery ( Bevan et al., 1997 ; Viitanen et al., 1999a , 1999b), but the actual time of discharge from the hospital was not prolonged. In institutions where the PACU is divided into phase I (initial recovery from the operating room until the child has reached an awake state, with stable vital signs and is ready to take oral fluids) and phase II (less intensive observation and readying for discharge home) areas, this translates to a longer stay in phase I recovery only. Such delays have the potential to affect throughput and cause bottlenecks for patients arriving from the operating room but do not affect total hospital time. The use of lower doses may reduce this problem, but data are not yet available.

The benefits of oral administration, fairly rapid onset, and reliability of effect give midazolam considerable advantage over other agents. It does have several disadvantages, however, that must be considered. Midazolam has an extremely bitter and unpleasant taste. Although both the commercially available oral product and products compounded by the hospital mask the flavor to some degree, acceptance by some children remains poor. Alternative nonparenteral routes of administration have been studied, including nasal (0.2 to 0.3 mg/kg), transmucosal (0.2 mg/kg), and rectal (0.3 mg/kg), but each of these also has disadvantages, so that the oral administration remains the most commonly used and best tolerated for the majority of children ( Saint-Maurice et al., 1986 ; Karl et al., 1993 ; Pandit et al., 2001 ).

Other agents and routes of administration, although less commonly used, have a place in the armamentarium. Other medications have been used in conjunction with midazolam, notably ketamine ( Funk et al., 2000 ). Its advantage over a single-drug regimen appears to be in the child who is exceptionally uncooperative and requires a deeper level of sedation resulting from a dissociative state. Oral and transmucosal fentanyl have been used with success as well. Both the oral administration of the intravenous preparation and the commercially available oral transmucosal fentanyl “lollypop” have been shown to be effective, but postoperative nausea may be increased compared with other agents, limiting its usefulness in the outpatient setting ( Howell et al., 2002 ; Tamura et al., 2003 ). Similar results have been seen with nasally administered sufentanil, which also may cause nasal burning and chest wall rigidity. This agent appears to be less useful than others for these reasons and has largely fallen out of favor with most pediatric anesthesiologists. Intramuscular administration of premedication is uncommonly used in children for obvious reasons—children have an intense dislike of needles. In some cases, however, when a child is exceedingly uncooperative and unmanageable, there may be no better alternative, and it is safer and more humane to administer a quick intramuscular injection with a small needle than to force the anesthesia mask on the face of an awake, struggling child for what will surely appear to be a very long 60 seconds. Ketamine, often in combination with midazolam and glycopyrrolate, is the most commonly used agent. The usual doses range from 2 to 3 mg/kg; lower doses are administered in combination with 0.1 mg/kg of midazolam. A high concentration (100 mg/mL) of ketamine should be used to minimize the injected volume (see Chapter 8 , Preoperative Preparation).

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Copyright © 2005 Mosby, An Imprint of Elsevier

▪ ANESTHETIC TECHNIQUES

The operative procedure and underlying condition of the patient remain the primary decisive factors when choosing an anesthetic plan, but the disposition of the patient, that is, discharge on the day of surgery, is an important consideration as well. An outpatient anesthetic has, in addition to all of the other usual goals, the priority of rapid return to baseline function with minimal untoward effects. It is only with these objectives in mind that patients can be effectively discharged home in a timely fashion.

▪ INDUCTION

Although clinical indications may on occasion dictate the safest induction technique, in many instances the older child may be given a choice, usually between inhalation and intravenous induction. Most children prefer an inhalation induction, but there are some who find the mask intolerable and prefer to have an intravenous catheter started with EMLA cream or local anesthetic. In cooperative school-aged children, this can often be accomplished without difficulty and may be offered to appropriate children as an option (also see Chapter 10 , Induction of Anesthesia and Maintenance of the Airway in Infants and Children).

The vast majority of children in the United States have an inhalation induction of anesthesia for outpatient procedures. The advantages are obvious—relatively rapid induction without any painful stimulus. Most children are needle-phobic and are quite relieved when informed that they need not have anything painful done to them while conscious. The technique of inhalation induction is described in detail inChapter 10 (Induction of Anesthesia). If the child uses a pacifier, it may be kept in his or her mouth until consciousness is lost, and the facemask placed over it. Scented oils such as bubble gum or fruit flavors may be added to the facemask to disguise the odor of the volatile agent. The room should be otherwise quiet and free from conversation or other distractions; the anesthesiologist should maintain continuous verbal contact with the child, telling a story in a soft, soothing modulated voice until the child falls asleep.

Sevoflurane has largely supplanted halothane as the agent of choice for induction. It has several advantages over halothane as an induction agent. Primary among these is the far greater hemodynamic stability of this agent. Sevoflurane induces far fewer problems with hypotension and diminished cardiac output than halothane does, even in the child who has a relatively long fasting period. Although some of this is due to the properties of the drug, some is also due to the construction of the vaporizer, because fewer minimum alveolar concentration (MAC) multiples can be given, preventing the anesthesiologist from delivering as deep an anesthetic. Dysrhythmias are also less common, because the drug does not cause the same degree of sensitization of the myocardium to catecholamines. Induction is rapid, and because sevoflurane is nonpungent, it causes very little airway irritation and coughing. It is possible to quickly increase the inspired concentration of sevoflurane or even begin with the vaporizer set at 8% and still avoid coughing. Sevoflurane does have a mildly unpleasant odor, but it is still easier to breathe than halothane, the only other agent suitable for inhalation induction. Sevoflurane does have several disadvantages as an induction agent compared with halothane. It causes more interference with ventilatory drive and respiratory muscle function, reducing the effectiveness of spontaneous ventilation ( Brown et al., 1998 ). Because the vaporizers are calibrated to give fewer MAC multiples than halothane vaporizers, overpressure to achieve rapid depth of anesthesia is more difficult. There is a considerable economic penalty as well—sevoflurane is more than 20 times as expensive as halothane. In many cases, even if a total intravenous anesthetic is planned, an inhalation induction with sevoflurane is performed until intravenous access can be established.

In the United States, intravenous induction is a less commonly used technique for children. Propofol (3.5 mg/kg) has many attributes that make it an ideal intravenous induction agent for outpatient anesthesia. Not only does it have a very rapid onset of action, but its termination of action is similarly fast, with a characteristic rapid return to baseline function. The drug has antiemetic properties, a highly desirable asset in outpatient anesthesia. Its only drawback is pain on injection. Although this may be moderated with lidocaine (1 to 2 mg/kg), injected before or mixed with the propofol, it can be quite painful, especially if injected into a small vein.

Rectal induction with a barbiturate such as methohexital, thiopental, or thiamylal has the advantage of being able to be performed in an induction area outside of the operating room. This allows the parents to be present without having to actually enter the operating room itself and can be administered easily to most toddlers. Rectal induction with barbiturates in general has a significant disadvantage in outpatient anesthesia'a very prolonged elimination half-life. Because of this, this technique is infrequently used in this setting.

▪ AIRWAY MANAGEMENT

There are numerous options for management of the airway in outpatient anesthesia. In many cases, a conventional anesthesia mask is used, such as during myringotomy and tube placement. This minimizes the risk of airway irritation but requires that at least one of the anesthesiologist's hands be occupied. It is contraindicated in the event of a full stomach and may be problematic in cases of easy airway obstruction, such as adenotonsillar hypertrophy.

The endotracheal tube remains the gold standard for the secured airway, although other devices are also commonly used. Many pediatric anesthesiologists intubate their patients “deep”'without the use of neuromuscular relaxants. This eliminates the need for reversal or for concerns of residual neuromuscular blockade postoperatively but mandates skillful judgment of anesthetic depth to avoid cord injury or laryngospasm. Just as with any anesthetic, one must choose the endotracheal tube size carefully so as to avoid producing injury or irritation to the vocal cords and trachea. It is particularly important to avoid any degree of postextubation croup in a patient who is going to be discharged home the same day. Certain outpatient surgery cases may still benefit from the placement of an endotracheal tube, such as herniorrhaphy, when the contralateral side is examined laparoscopically.

Supraglottic airway devices cause less laryngeal irritation than an endotracheal tube, and can be placed without visualization of the airway ( Brimacombe, 1995 ). The laryngeal mask airway (LMA), developed by Brain, is the first of these devices and is available in multiple pediatric sizes. Several competitors, including the Cobra perilaryngeal airway (PLA; Engineered Medical Systems, Tri-Anim Corp.) ( Fig. 27-1A to C ) and the cuffed oropharyngeal airway (COPA; Mallinckrodt, Inc.) ( Fig. 27-2A and B ), are now marketed ( Robbins and Connelly, 2000 ; Bussolin and Busoni, 2002 ). All of these devices offer a less stimulating means of maintaining the airway while freeing the hands of the anesthesiologist for other tasks (see Chapter 9 , Anesthetic Equipment and Monitoring). As was mentioned, a number of studies have demonstrated that the ability to maintain a stable airway without stimulating the larynx and trachea can decrease the incidence of adverse respiratory events in children with active or recent URIs ( Tait et al., 1998 ). The same is likely to be true for patients with asthma. Although the LMA may diminish lower respiratory tract stimulation, it does not appear to decrease the incidence of postoperative sore throat ( Splinter et al., 1994 ). There are no data that compare the different supraglottic devices. The findings by Tait and others (1998) that endotracheal tubes are more stimulating than LMAs, which are in turn more stimulating than a facemask, may serve to guide the decision of how to manage the airway if all other factors are equal (see Chapter 10 , Induction of Anesthesia and Maintenance of the Airways in Infant and Children).

 
 

FIGURE 27-1  Cobra perilaryngeal airway (PLA). (A) The device with the cuff deflated ready for insertion. (B) A view of the laryngeal surface of the device. (C) The inflated cuff, which fills and conforms to the pharynx when in place.

 

 

 
 

FIGURE 27-2  Cuffed oropharyngeal airway (COPA). The device is sized and inserted like a conventional oropharyngeal airway with the cuff deflated (A) and the cuff inflated (B). The end of the device has a standard 15-mm connector to attach to the breathing circuit.

 

 

▪ ANESTHETIC MAINTENANCE

The ideal maintenance regimen for outpatient anesthesia would have three defining characteristics: ease of titration, rapid offset, and minimal residual side effects. While it can be argued that several techniques or contemporary agents fit this definition, none are entirely free of all side effects or are ideal agents in every situation.

Inhalation anesthesia is still the most commonly used maintenance technique and has numerous advantages to commend it. No organ or enzymatic metabolism is necessary for its elimination; it is simply breathed away. Volatile agents are easily titrated to effect, and anesthetic depth can be adjusted with relative rapidity. They are relatively economical, especially compared with newer intravenous agents, and they have beneficial effects on reactive airways, a common problem in children. There are several significant disadvantages that may diminish the claim for volatile agents as the ideal agents for outpatient anesthesia.

Halothane has in many places been replaced by sevoflurane as the primary volatile anesthetic in children. It has been claimed that the lower blood-gas solubility coefficient of sevoflurane gives it significant advantage over halothane for emergence, where a more rapid return to consciousness is desired in the outpatient setting. Data, however, do not confirm this contention and may actually give halothane several advantages over sevoflurane as a maintenance agent ( Bacher et al., 1997 ). While return to wakefulness may indeed be quicker with sevoflurane when both agents are discontinued simultaneously, the speed to awakening can be adjusted by merely turning off the halothane sooner. Perhaps more important, time to awakening has no relationship to time to discharge from the hospital ( Lerman et al., 1996 ; Sury et al., 1996 ; Welborn et al., 1996 ). The latter is the metric that reflects both day surgery unit efficiency and cost savings, and anesthesia with sevoflurane has not been shown to produce shorter discharge times, which is generally related to other factors, including premedication, complications of recovery such as postoperative nausea and vomiting (PONV), and analgesic needs ( Bacher et al., 1997).

Sevoflurane has one additional characteristic that limits its effectiveness as a maintenance agent in outpatient anesthesia—the problem of emergence agitation. Several investigators have studied this problem, which can be exceedingly disruptive and disturbing for PACU caregivers and parents. With the increased use of sevoflurane, it became apparent that there was an increase in emergence agitation or delirium in the PACU ( Rieger et al., 1996 ; Beskow and Westrin, 1999 ; Cravero et al., 2000 ). The child with emergence agitation appears wild and incoherent; he is inconsolable and does not appear to recognize familiar people. This phenomenon has clearly been distinguished from inadequate analgesia. Cravero and others (2000) compared emergence characteristics of sevoflurane anesthesia with those of halothane anesthesia in children undergoing magnetic resonance imaging. This prospective randomized study design effectively eliminated pain or dysphoria of neural blockade as potential confounding variables, leaving only the choice of volatile agent as a factor ( Cravero et al., 2000 ). Using either low- or high-threshold criteria to define agitation and delirium, the investigators found much higher rates (33% versus 0% with high-threshold criteria and 88% versus 12% with low-threshold criteria) with sevoflurane than with halothane. Any time advantage due to more rapid emergence was eliminated by the difficulty in caring for the agitated child in the PACU, and hospital discharge times were not different.

Another study of sevoflurane in 100 children undergoing myringotomy and tube placement found that even with very short anesthetics, the incidence of emergence agitation was unacceptably high ( Lapin et al., 1999 ). Although discharge times in this study were faster in the sevoflurane group, 67% demonstrated emergence agitation, leading them to conclude that sevoflurane was unsuitable for use as a sole agent for this procedure. They found that the addition of midazolam reduced this problem while lengthening recovery but not discharge times. The use of an opioid may have a similar or even more beneficial effect. It is possible that the cause is related to the different effects of these agents on brain function that has been noted on electroencephalography ( Constant et al., 1999 ).

Desflurane is another new volatile agent with rapid onset and offset characteristics due to an exceptionally low blood-gas partition coefficient and solubility. It, too, appears to have a higher incidence of emergence agitation than older agents ( Davis et al., 1994 ; Welborn et al., 1996 ; Valley et al., 2003 ). Emergence is significantly faster than with sevoflurane, however, due to its low solubility in tissues such as muscle and brain. Because sevoflurane is similar to halothane in its solubility in vessel-rich tissue groups, after discontinuance of the agent, significant blood concentrations are maintained as the agent returns from these depot storage sites to the bloodstream along its concentration gradient. This does not occur to a significant degree with desflurane because of its low tissue solubility, thereby speeding emergence time. Desflurane has also been found to decrease the ability to maintain spontaneous ventilation at concentrations greater than 1 MAC ( Behforouz et al., 1998 ). Although desflurane is a potent airway irritant and is contraindicated for inhalation induction due to a very high incidence of severe laryngospasm, it does not appear to cause problems with deep extubation ( Zwass et al., 1992 ;Sneyd et al., 1998 ; Valley et al., 2003 ) (see Chapter 11 , Intraoperative and Postoperative Management).

Nitrous oxide continues to be used as an adjunctive agent for outpatient anesthesia in combination with both volatile and intravenous agents. It is useful as a sedative while placing intravenous cannulas in situations where a pure intravenous technique is used, and it can ease the introduction of more pungent volatile agents when performing inhalation induction. Its use as an agent for maintenance, however, is limited by its capacity to increase the incidence of PONV. For this reason, its use in the outpatient setting has been debated ( Divatia et al., 1996 ).

The development of propofol heralded a new era in the maintenance of anesthesia in the same-day surgery setting. It is not hyperbole to suggest that it thrust total intravenous anesthesia (TIVA) into the mainstream of anesthetic techniques, allowing rapid titration of anesthetic depth and prompt emergence without the use of volatile agents. Propofol is a potent antiemetic, and it can reduce the incidence of nausea and vomiting when used in combination with both other anesthetic agents and other antiemetics ( Sneyd et al., 1998 ; Barst et al., 1999 ). Despite the rapid emergence characteristics, the incidence of delirium and agitation is very low compared with sevoflurane or desflurane. The major limitation of propofol is its limited analgesic properties, and it must be used with an opioid or a regional technique to provide adequate depth of anesthesia for most painful procedures. It is an excellent and perhaps the ideal agent for use in imaging, radiation treatment, or invasive radiologic procedures where there is a minimum or absence of stimulation ( Aldridge and Gordon, 1992 ; Martin et al., 1992 ; Vangerven et al., 1992 ; Frankville et al., 1993 ). It is particularly attractive for anesthesia for radiation therapy, where children require daily repeated general anesthetics for up to 6 consecutive weeks. In this situation, children are able to be ready for discharge home within 20 minutes of the end of the treatment session and, in contrast to the use of other agents such as barbiturates, have no evidence of either drug accumulation or development of tolerance and dose escalation ( Glauber and Audenaert, 1987 ; Mills and Lord, 1992 ; Fassoulaki et al., 1994 ).

Remifentanil is a unique intravenous opioid with very rapid onset and elimination. In contrast to other opioids, its degradation is independent of organ metabolism, instead relying on hydrolysis by plasma esterases. The drug permits the anesthesiologist to provide intense intraoperative levels of opioid analgesia with no residual respiratory depression after emergence ( Roulleau et al., 2003 ). Other postoperative side effects usually associated with opioids, such as nausea and vomiting, excessive sedation, and respiratory depression, are absent ( Pinsker and Carroll, 1999 ). Intraoperative conditions are notable for hemodynamic stability, although both bradycardia and hypotension can occur at higher infusion rates. The most significant caveat to the use of remifentanil is that its rapid degradation provides no postoperative analgesia ( Davis et al., 2000 ). It is essential, therefore, to use another agent or technique for this purpose, such as a long-acting opioid, regional block, or a nonsteroidal anti-inflammatory drug (NSAID) such as ketorolac, and to administer it with adequate time for action before dissipation of the effect of remifentanil (see Chapter 11 , Intraoperative and Postoperative Management).

Perhaps the most effective manner in which to use remifentanil is to combine it with propofol. The combination of the two agents provides a balanced anesthetic that is easily titratable and results in significant reductions in the dose of both ( Grundmann et al., 1998 ; Keidan et al., 2001 ). The two drugs can be mixed in the same syringe and administered via syringe pump. Because remifentanil degrades in propofol over time, aliquots small enough to be infused within 1 hour should be used ( Stewart et al., 2000 ). For procedures of mild to moderate noxious stimulation, 10 mcg of remifentanil/mL in 1 mL (10 mg) of propofol is used, with infusion rates beginning at 100 mcg of propofol/kg per minute (0.1 mcg of remifentanil/kg per minute). This concentration permits the maintenance of spontaneous ventilation in most patients ( Peacock et al., 1998 ; Reyle-Hahn et al., 2000 ). For more stimulating or painful procedures, the remifentanil concentration is doubled to 20 mcg per 1 mL of propofol, and the infusion begun at the same rate of 100 mcg of propofol per minute (0.2 mcg of remifentanil/kg per minute). Many patients breathe spontaneously with this concentration as well, although slow respiratory rates are common, and one must be vigilant to avoid hypoventilation. This technique provides a very stable intraoperative course, combined with an exceptionally smooth emergence and very rapid return to baseline function.

Regional anesthesia (usually in combination with a general anesthetic) can be used to great advantage in same-day surgery. The prime advantage and reason for its use is the provision of postoperative analgesia, but the modest reduction in the depth of general anesthesia can speed recovery and reduce the incidence of opioid-related untoward effects. Partial motor blockade is a not uncommon side effect of regional blocks, but, in most cases, it is not a contraindication to discharge home and can be reduced or eliminated by the use of low-concentration local anesthetics, and most children have their motor block resolved before discharge from the PACU ( Burns et al., 1990 ). Other reported advantages of regional blockade include decreased intraoperative blood loss and improved operating conditions during hypospadias repair ( Gunter et al., 1990 ). For operations less than 1 hour in duration, preoperative blockade did not affect the duration of postoperative analgesia compared with blockade administered at the end of the procedure ( Rice et al., 1990 ).

Nearly all regional anesthetics in children are administered after the induction of general anesthesia. The reader is referred to Chapter 14 (Pediatric Regional Anesthesia) for details on performing the various regional blocks. In most cases, regional blockade for ambulatory surgery is performed with local anesthetics only, omitting opioids and adjuvant agents, such as clonidine and ketamine. This eliminates the risks of respiratory depression that can occur with those additives, an important safety consideration in the patient who will not be monitored after discharge from the PACU.

▪ NEUROMUSCULAR BLOCKADE

In most outpatient procedures in infants and children, neuromuscular blockade is not necessary. The majority of surgical procedures that are performed in this setting can be performed without it, and intubation can most commonly be achieved with inhalation anesthesia with or without topical lidocaine, perhaps combined with a single dose of propofol in older children. When muscle relaxants are used, one should best avoid any of the longer-acting nondepolarizers and rely on intermediate-acting drugs such as mivacurium, cisatracurium, and vecuronium. These agents are discussed in detail in Chapter 6(Pharmacology for Pediatric Anesthesia). When used, adequacy of reversal must be ensured. An investigation in adults found that incomplete reversal and mild degrees of residual neuromuscular blockade were common ( Debaene et al., 2003 ). At least with some agents, children are less prone to inadequate spontaneous reversal. In children receiving mivacurium, residual weakness was not observed, whereas the finding was present in the adults ( Bevan et al., 1996 ). Nevertheless, stringent criteria for adequacy of spontaneous reversal must be sought, and reversal agents administered if necessary ( Baurain et al., 1998 ; Ali, 2003 ).

▪ FLUIDS

As the allowable NPO times for clear liquid become shorter, the consequences of preoperative fasting are less problematic, but there remain occasional patients who come to surgery with varying degrees of dehydration ( Coté, 1990 ; Cook-Sather et al., 2003 ). Additionally, the patient who is to be discharged home may not be interested in drinking large amounts of fluids in the hours immediately after surgery. It is useful, therefore, to provide adequate intravenous hydration not only to correct the fluid deficit but also to provide a cushion for the postoperative period. This is particularly the case for operations that may disrupt the ability to drink easily, such as tonsillectomy. Isotonic fluids should be administered, and the intravenous catheter may be kept in place until just before discharge. It is rarely necessary to provide glucose supplementation in the intravenous fluids ( Sandstrom et al., 1993 ). One should try to replete the deficit plus current maintenance requirements within 2 to 3 hours. In some cases, children are discharged home before that, but those are generally the ones at least risk for inadequate intake.

▪ EMERGENCE

The management of patients during emergence and the techniques of awake versus deep extubation and their comparison are detailed elsewhere (see Chapter 11 , Intraoperative and Postoperative Management). The management of emergence from anesthesia in the outpatient setting is largely a question about the intubated child and whether the endotracheal tube should be removed when the patient is deep or awake. Certainly the contraindications to deep extubation (full stomach, difficult airway, blood in the pharynx) are no different in the outpatient or inpatient setting. Those who prefer awake extubation are primarily concerned about the loss of airway and of the development of laryngospasm. There are certain advantages of deep extubation in the same-day surgery settings provided that the PACU staff is adept and experienced at dealing with the patient who has been extubated deep. The patient awakens from anesthesia in the PACU without the noxious stimulus of an endotracheal tube in place and may have a smoother emergence. The child with reactive airways disease does not have the airway stimulation that may precipitate a potentially severe episode of bronchospasm. Operating room efficiency is enhanced, because the patient is able to leave the operating room within a minute of the end of the surgery, and room turnover can proceed at a more rapid pace. Several caveats, in addition to the contraindications mentioned, are crucial to increase the safety of this practice. The tube should not be withdrawn unless the patient is breathing spontaneously and has been demonstrated to have no alteration in breathing pattern with stimulation of the trachea (usually accomplished by gently moving the endotracheal tube). In most cases, this requires at least a 2 MAC value of inhaled anesthetic. The patient should be placed on his or her side after extubation to prevent oropharyngeal secretions from collecting in the hypopharynx either stimulating the larynx or causing aspiration. Supplemental oxygen and close attention to airway patency are necessary during transport to the PACU. It is best to leave the child undisturbed in the PACU until he awakens on his own.

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▪ POSTOPERATIVE ANALGESIA

No child can be discharged to home if the pain cannot be adequately managed by the parents using simple interventions. Inadequate analgesia has been identified in several studies as one of the most common causes for unanticipated admission to the hospital after surgery ( Grenier et al., 1998 ). In another study, postoperative pain was identified by parents as the major problem they encountered after discharge home ( Kokinsky et al., 1999 ). Only 28% of the patients in this study had received regional blocks.

▪ REGIONAL AND LOCAL ANESTHESIA

Regional and local anesthesia has become one of the key modalities for postoperative analgesia for amenable procedures (see Chapter 14 , Pediatric Regional Anesthesia). Among the commonly performed operations in pediatric outpatient surgery that are associated with significant postoperative pain, only adenotonsillectomy is not suitable for local or regional anesthesia. A prospective randomized study in children of glossopharyngeal nerve block, previously reported as an effective technique in adults, was stopped before its completion due to a 50% incidence of upper airway obstruction in the treatment group. The authors terminated the study and concluded that glossopharyngeal block is dangerous in children after tonsillectomy due to the common occurrence of inadvertent blockade of the vagus and recurrent laryngeal nerves ( Bean-Lijewski, 1997 ).

Strict attention to the limits of local anesthetic dose must be observed with any regional block, and aspiration should precede any injection. When large volumes of local anesthetic are injected for any regional block, both a test dose and incremental injection technique should be used to minimize the risk of intravascular injection. A maximum of 2.5 mg/kg of bupivacaine can be administered to children over 6 months of age; younger infants should have the dose reduced by 30% (1.8 mg/kg) due to decreased levels of plasma binding proteins ( Lerman et al., 1989 ; Luz et al., 1998 ). In addition, there appears to be an increased toxicity risk during general anesthesia with volatile agents ( Badgwell et al., 1990 ). In these younger infants, an additional margin of safety may be gained by the use of levo-bupivacaine or ropivacaine, which appears to have less toxic potential ( Bardsley et al., 1998 ; Kohane et al., 1998 ; Gunter et al., 1999 ; Morrison et al., 2000 ).

Although usually performed by the surgeon, the value of wound infiltration with local anesthetic should not be underestimated. There are numerous minor procedures for which a regional nerve block would be more intervention than necessary, such as simple hardware removals in orthopedics, excisional biopsies of small lesions, etc., where infiltration of the wound can be used to great advantage. Blood levels with this technique have been found to be low when dose limits are adhered to ( Mobley et al., 1991 ). When a peripheral nerve or regional block can be performed, however, those techniques may offer superior analgesia. A study of caudal analgesia compared with wound infiltration for analgesia after inguinal herniorrhaphy found not only better analgesia but also quicker emergence times, fewer pain-related behaviors, and earlier hospital discharge times with the caudal block. Less supplementation with systemic analgesics was required with caudal block than with local infiltration ( Conroy et al., 1993).

▪ CAUDAL ANESTHESIA

Caudal anesthesia is probably the most commonly performed block in pediatric anesthesia practice. It is usually easy to administer, has an acceptably low incidence of complications, and is highly effective for surgical procedures below the level of the umbilicus ( Dalens and Hasnaoui, 1989 ). The duration of effective analgesia is considerably longer than one would expect based on the usual length of action of the local anesthetic alone. A study that compared 0.25% bupivacaine with and without epinephrine found that the addition of epinephrine markedly prolonged the analgesia and that prolonged duration of analgesia was correlated with both younger age and lower surgical site (penoscrotal versus inguinal) ( Warner et al., 1987 ). Duration of analgesia ranged from as short as 5 hours (inguinal surgery, older than 11 years) to as long as 23 hours (penoscrotal operation, 1 to 5 years old) as judged by the time to first requirement for supplemental analgesia. In a study of caudal blockade for analgesia after clubfoot repair, analgesia lasted at least 8 hours ( Foulk et al., 1995 ).

Side effects of caudal block in children are unusual. Multiple studies have confirmed that urinary retention does not occur after caudal block using local anesthetic without central neuraxis opioids ( Warner et al., 1987 ; Fisher et al., 1993 ). No differences in side effects were seen between caudal block and ilioinguinal-iliohypogastric nerve block; PACU stays were longer by less than 5 minutes and hospital stay by less than 10 minutes with the caudal blockade ( Splinter et al., 1995 ). Motor function is not significantly impaired at the time of discharge and does not preclude or delay discharge ( Burns et al., 1990 ).

Although one study found that placing the block at the end of the case resulted in better analgesia ( Holthusen et al., 1994 ), other well-controlled studies have shown that there is no decrement in the duration of analgesia with caudal blocks administered at the beginning or end of surgery for procedures lasting less than 1 hour ( Rice et al., 1990 ). A study of 0.5 mL/kg versus 1 mL/kg of 0.125% bupivacaine with epinephrine for penile and scrotal surgery found no difference in the duration of analgesia up to 8 hours postoperatively ( Malviya et al., 1992 ).

Peripheral nerve blocks can be used with considerable efficacy for outpatient surgery in children and can be administered either by the anesthesiologist or by the surgeon on the operative field. Ilioinguinal-iliohypogastric nerve block combined with wound infiltration showed similar efficacy to a caudal block for analgesia after inguinal herniorrhaphy in two randomized studies ( Schindler et al., 1991 ;Splinter et al., 1995 ). Paraumbilical block was shown to provide excellent analgesia for umbilical herniorrhaphy, although the duration of analgesia was less than 8 hours in 3 of 11 subjects ( Courreges et al., 1997 ). Fascia iliaca block is a very effective and easy-to-place block for surgery of the leg above the level of the knee ( Dalens et al., 1989) . Ophthalmic surgery is often associated with considerable postoperative pain. Placement of a peribulbar block ( Coppens et al., 2002 ; Subramaniam et al., 2003 ) or a subconjunctival injection ( Ates et al., 1998 ) has been shown to provide long-lasting analgesia with a minimum of side effects in pediatric patients. Peripheral nerve blocks are often used in older patients undergoing distal hypospadias repairs or for circumcision. The dorsal nerve block has been shown to result in better postoperative analgesia than a penile ring block ( Holder et al., 1997 ). Greater auricular nerve block has been shown to be efficacious after tympanomastoid surgery ( Suresh et al., 2002 ).

▪ INTRAVENOUS AGENTS

The development of parenterally administered NSAIDs, principally ketorolac, has allowed the anesthesiologist to administer nonopioid analgesics of equipotency to opioid analgesia. There is a sizable literature on the use of ketorolac in pediatric patients over the age of 1 year. The use of a cycloxygenase-2 (COX-2) inhibitor for analgesia in pediatric surgical patients has been reviewed ( Farrar and Lerman, 2002 ; Kokki, 2003 ; Morris et al., 2003 ). However, clinical studies to date of COX-2 inhibitors in pediatric patients have been limited. Many of these studies have specifically examined the role of ketorolac in outpatient surgery. Ketorolac has been shown to have several advantages over opioid analgesics for postoperative analgesia in pediatric outpatients. There is a significant reduction in nausea and vomiting in patients receiving ketorolac compared with morphine, fentanyl, or other opioids ( Mendel et al., 1995 ; Purday et al., 1996 ). The duration of a single dose of ketorolac is longer (6 hours) than that of most of the commonly used opioid analgesics ( Dsida et al., 2002 ). Lack of respiratory depression is one of ketorolac's major advantages over opioids. A major problem with the use of ketorolac in outpatient analgesia is that it causes reversible dysfunction of platelet adhesion, and bleeding problems have been noted to be more common in children undergoing adenotonsillectomy ( Gallagher et al., 1995 ; Judkins et al., 1996 ; Splinter et al., 1996 ; Splinter and Roberts, 1996 ). Bleeding problems have not been reported in other types of surgery, but one should use caution in administering ketorolac after other oral surgical procedures. Ketorolac appears to offer significant benefits to the pediatric outpatient after selected operations.

Opioids remain the gold standard for postoperative analgesia for moderate to severe pain, and they are still commonly prescribed for pediatric outpatients, both parenterally during anesthesia and via oral, transmucosal, and other routes for postoperative analgesia. Their principal disadvantages are the side effects of nausea, vomiting, and respiratory depression; at the doses prescribed for outpatients, ileus is rarely a problem. Even a single dose of morphine administered for postoperative analgesia after inguinal surgery has been reported to increase the incidence of postoperative nausea and vomiting (PONV) (Weinstein et al., 1994 ). For this reason, the author recommends that when opioids are used in outpatient surgery, multimodal prophylactic antiemetic therapy should be administered.

Intranasal fentanyl (2 mcg/kg, administered intraoperatively) has been used primarily for analgesia after myringotomy and tube surgery. Because these procedures are commonly performed without obtaining intravenous access, this provides an easy route for the administration of a potent analgesic. In a study comparing intranasal fentanyl with placebo, postoperative conditions were superior with fentanyl ( Henderson et al., 1988 ). Children who received intranasal fentanyl not only were more comfortable and less agitated but also did not have an increase in PONV, a problem that has been noted with intranasal sufentanil ( Henderson et al., 1988 ; Galinkin et al., 2000 ).

Numerous oral opioid analgesics are used for postoperative analgesia in children. In the majority of cases, these drugs are prescribed by the surgeon, not the anesthesiologist. Commonly used agents include oxycodone (0.1 to 0.2 mg/kg PO every 3 to 4 hours), hydrocodone (0.5 mg/kg PO every 3 to 4 hours), and codeine (1 mg/kg PO every 3 to 4 hours). All of these agents can be given in combination with acetaminophen and/or NSAIDs for added efficacy. These agents are generally administered for 1 to 3 days.

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▪ PEDIATRIC ACUTE CARE UNIT/RECOVERY/DISCHARGE ISSUES

▪ NAUSEA AND VOMITING

Postoperative nausea and vomiting (PONV) is perhaps the most common complication after anesthesia, although the reported incidence varies widely from approximately 8% to 50% ( Heyland et al., 1997 ;Villeret et al., 2002 ). The variance is most likely due to study methodology and definitions. It is usually not an intractable problem but certainly is the cause of considerable distress and, if not well controlled, may be a cause of unanticipated overnight admission ( Patel et al., 1997 ; Rose and Watcha, 1999 ). Numerous factors have been identified as increasing the risk of vomiting after anesthesia and surgery—some related to the surgical procedure, and some related to the anesthetic. The most common of these are listed in Table 27-1 . Because discharge home is so dependent on the child returning to a baseline condition that allows the intake of fluids and nutrients, it is essential that nausea and vomiting be kept to a minimum for outpatient surgeries.

TABLE 27-1   -- Common causes of postoperative nausea and vomiting in outpatients

Surgical Factors

Anesthetic Factors

Patient Factors

Adenotonsillectomy

Use of volatile agents

Prior history of postoperative nausea and vomiting

Middle ear surgery

Use of nitrous oxide

Testicular surgery

Use of opioids

Laparoscopie surgery

Insufflation of the stomach (difficult mask ventilation)

History of motion sickness

Insufflation of the bowel (endoscopy)

Reversal of neuromuscular blockade (cholinergics) Unrelieved pain

Age >2 years Girls > boys

 

 

Anesthetic technique has been correlated with the incidence of PONV, with propofol-based techniques having the lowest incidence ( Sneyd et al., 1998 ; Barst et al., 1999 ; Gurkan et al., 1999 ). The use of volatile agents, opioids, nitrous oxide, and cholinergic drugs for the reversal of neuromuscular blockade all increase the risk, although one study found that desflurane had less PONV than reported with other volatile anesthetics ( Mendel et al., 1995 ; Divatia et al., 1996 ; Kuhn et al., 1999 ). Remifentanil, in contrast with other opioids, did not increase PONV ( Pinsker and Carroll, 1999 ).

There have been studies of both treatment and prophylaxis of PONV in children undergoing outpatient surgery and anesthesia. One of the drugs commonly studied, droperidol, is no longer commonly used because of a rare association with cardiac dysrhythmias, so it is not discussed here. The most commonly used drugs for treatment and prophylaxis are the 5-HT3 antagonists (ondansetron, granisetron), dexamethasone, and metoclopramide. All have been shown to be effective for both prophylaxis and treatment in at least one study.

Dose-response studies of ondansetron suggest that for maximal efficacy, prophylactic doses of 0.1 to 0.15 mg/kg up to 4 mg should be administered ( Rose et al., 1996 ; Patel et al., 1997 ; Sadhasivam et al., 2000 ). Lower doses were either not as effective or no more effective than placebo. Timing the dose before or after manipulation of the extraocular muscles in strabismus surgery (one of the most “emetogenic” operations) did not appear to make a difference ( Madan et al., 2000 ). Another HT-3 antagonist, granisetron, was effective when 0.2 mg/kg was administered orally before the induction of anesthesia ( Munro et al., 1999 ). When a single dose is not adequate, controversy exists as to whether a second dose is efficacious ( Rose and Martin, 1996 ; Kovac et al., 1999 ). Dexamethasone is effective at preventing PONV and has the additional advantage of costing a very small fraction of the price of the HT-3 antagonists ( Splinter and Roberts, 1996 ; Subramaniam et al., 2001 ). Dosing recommendations vary widely, but most studies recommend between 0.2 and 1.0 mg/kg, to not exceed 20 mg. Metoclopramide acts by increasing gastric emptying. Although it appears to be effective, some investigators have found it to be less so than ondansetron. It has a higher incidence of side effects, primarily sleepiness and occasional extrapyramidal effects, than either of the other agents ( Broadman et al., 1990 ; Furst and Rodarte, 1994 ). Cisapride, which also is a prokinetic agent, was found to be ineffective in treating PONV ( Cook-Sather et al., 2002 ).

The use of multiple agents in combination for those at greatest risk of PONV is recommended by several investigators. It appears that combining multiple drugs with different mechanisms of action yields the best results ( Rose and Watcha, 1999 ). Similarly, the use of a low-risk anesthetic, especially propofol, which appears to have antiemetic properties of its own, in combination with prophylaxis, may result in the lowest incidence of all ( Barst et al., 1999 ).

An additional factor that has been found to promote PONV is the insistence on oral intake in the PACU before discharge. While it appears sensible to want to demonstrate that a child is able to take and retain oral intake before discharge home, investigators found that insistence on oral intake before discharge increased the incidence of PONV and lengthened hospital stay ( Schreiner et al., 1992 ; Schreiner and Nicolson, 1995 ). This common practice probably deserves a critical reexamination (see Chapter 11 , Intraoperative and Postoperative Management).

▪ INADEQUATE ANALGESIA

One of the common reasons for unanticipated admission, acceptable levels of analgesia are a necessity before discharge. No child can leave the hospital unless one is sure that the caregivers at home will be able to manage postoperative pain. More potent oral analgesics are often adequate to enable discharge, but in the event that it is not the case, admission and parenteral medications may be necessary. When the level of pain seems out of proportion to either the procedure performed or the experience of the clinicians, causes other than the obvious ones should be sought, although it must also be remembered that pain is a subjective experience and pain thresholds can vary widely.

▪ EXCESSIVE SOMNOLENCE

This is rarely a cause for admission but may be a cause for a prolonged PACU stay. Common reasons include excessive narcosis, sedative or opioid drug errors (unintentional or patient sensitivity), unusual sensitivity to inhaled anesthetics, and drug interactions.

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▪ COMPLICATIONS AND UNANTICIPATED ADMISSION

Even when all care issues have been optimized, there inevitably are patients who develop complications that prevent discharge home and require hospitalization. Inadequate analgesia, inability to take adequate oral fluids, PONV, excessive somnolence, respiratory deterioration in children with URI or occult lower tract disease, or surgical complications all occur at some point. What is most important is that there is a system in place to streamline these admissions. In some institutions, this may be overnight admission to a short-stay unit, which may be on the ward, in the PACU, or in the emergency department. In others, it will mean a bed on the regular ward. In all cases, it is essential that adequate follow-up be maintained by both the surgical and anesthetic team so that the issues that mandated admission are properly and adequately addressed.

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▪ FACILITY DESIGN AND PATIENT THROUGHPUT

Because such a large percentage of children undergoing surgery are cared for as outpatients, it is very common that their surgery takes place not in a separate outpatient facility but in the main operating room. Even though these facilities are not usually designed with outpatients in mind, and using them in this manner may be awkward at times, there are still numerous changes in organization that can reap benefits both in parent and patient satisfaction and in efficiency and throughput.

Patient throughput can be improved through the design of separate intake and discharge areas—one for inpatient and same-day admissions and a second for day surgery patients. In this manner, the routing through the admissions process could be streamlined, with optimized procedures for each. The two facilities enable staff to work more efficiently, as they can each focus on only a single function. All patients who are operated on in the main operating room are still routed through the same PACU, but same-day surgery patients are sent to the phase II recovery area in the same-day surgery area as soon as they are ready. This enables “fast tracking” and more rapid discharge of these patients. The same concept can be used for anesthesia for outpatient imaging, with those patients discharged home directly from a recovery area in the radiology department. Focusing on these systems issues can enable more patients to be cared for in a smoother and more professional manner.

Copyright © 2008 Elsevier Inc. All rights reserved. - www.mdconsult.com

Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

Copyright © 2005 Mosby, An Imprint of Elsevier

▪ SUMMARY

The number of children in the United States undergoing outpatient anesthesia has surpassed the number of inpatient cases. Many of the considerations for the care of these patients are identical to that of inpatients, but there are unique issues that must be addressed to enable children to go home on the day of surgery and anesthesia. Careful case selection, both on the basis of the child's underlying condition and for the planned surgical procedure, is critical in ensuring the success of an outpatient program. Whether these procedures are performed in the day surgery unit of a hospital or in a freestanding surgical center, the same level of same-day perioperative services for children should be available. One must have a well-designed systematic approach to organization, throughput, and clinical care to achieve both efficiency and safety.

Copyright © 2008 Elsevier Inc. All rights reserved. - www.mdconsult.com

Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.

Copyright © 2005 Mosby, An Imprint of Elsevier

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