Handbook of Clinical Anesthesia
The field of office-based anesthesia (OBA) has become an intrinsic and vital component within the field of anesthesiology (Hausman LM, Rosenblatt MA: Office-based anesthesia. InClinical Anesthesia. Edited by Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC. Philadelphia: Lippincott Williams & Wilkins, 2009, pp 847–860). An office-based anesthetic is one that is performed in a location, usually an office or procedure room, that is not accredited by a state agency as an ambulatory surgery center (ASC) or as a hospital and may, in some states, have no accreditation at all. It was estimated that by 2005, approximately 82% of all procedures were outpatient and of these, 24% were office based. A challenge to office-based practitioners is that presently there is little or no training in OBA within the standard anesthesia residency program.
- Advantages and Disadvantages
- Office Safety
Injuries and deaths occurring in offices are often multifactorial in their causation (including overdosages of local anesthetics, prolonged surgery with occult blood loss, accumulation of multiple anesthetics, hypovolemia, hypoxemia, and the use of reversal drugs with short half-lives). Both the Anesthesia Patient Safety Foundation and the American Society of Anesthesiologists (ASA) have emerged as leaders in the field of OBA safety and have advocated that the quality of care in an office-based practice be no less than that of a hospital or ASC. Reports of morbidity and mortality within office-based practices vary dramatically. The challenge of acquiring accurate morbidity and mortality data for OBA is complicated by the fact that many offices
are not required to report adverse events. There are reported cases of injuries to patients in offices resulting from obsolete and malfunctioning anesthesia machines, as well as resulting from alarms that have not been serviced or are not functioning properly (Table 33-2). The ASA has created guidelines for defining obsolete anesthesia machines.
Table 33-1 Advantages and Disadvantages of Office-Based Anesthesia
Advantages Cost containment (facility fee)
Ease of scheduling
Patient and surgeon convenience
Decreased patient exposure to nosocomial infections
Improved patient privacy
Continuity of care
Issues of patient safety and peer review
May be an absence of regulations regarding certification of the surgeon or anesthesiologist
May be an absence of documentation, policies, and procedures and reporting of adverse outcomes
III. Patient Selection
Before presenting for an office-based procedure, the patient must be medically optimized. The patient should have a preoperative history and physical examination recorded within 30 days, all pertinent laboratory tests performed, and any medically indicated specialist consultation(s) done.
The ideal patient for an office-based procedure has an ASA physical status of 1 or 2. The ASA also has developed recommendations regarding patient selection. When determining whether a patient is suitable for OBA, it is important to realize that the location is often remote and the anesthesiologist may be unable to get assistance if it is required. Anticipated anesthetic problems must be avoided (Table 33-3).
Table 33-2 Causes of Injury in the Office
Inadequate resuscitation equipment
Inadequate monitoring (most commonly, no pulse oximetry)
Inadequate preoperative or postoperative evaluation
Slow recognition of an event
Slow response to an event
Lack of experience
Table 33-3 Characteristics of Patients Who May Not be Good Candidates for Office-Based Procedures
Poorly controlled diabetes mellitus
Expected significant blood loss or postoperative pain
History of substance abuse
Susceptibility to malignant hyperthermia
Potential difficult airway
Obstructive sleep apnea syndrome
NPO less than 8 hours
Previous adverse outcome from anesthesia
Significant drug allergies
Pulmonary aspiration risk
- Obesity and Obstructive Sleep Apnea. It is estimated that 60% to 90% of all patients with obstructive sleep apnea (OSA) are obese. The majority of the patients with OSA have not been formally diagnosed. There may be failure to intubate the trachea or ventilate the lungs, they may have respiratory distress soon after tracheal extubation, or they may suffer from respiratory arrest with preoperative sedation or postoperative analgesia. These patients tend to be exquisitely sensitive to the respiratory depressant effects of even small dosages of sedation or analgesics.
- Pulmonary embolism from deep vein thrombosis is a significant cause of perioperative morbidity and mortality from office-based surgical procedures.
- Surgeon Selection
The relationship between the surgeon and anesthesiologist must be one of mutual trust and understanding. There have been cases reported of surgeons performing procedures for
which they have little or no training. A system should be in place for monitoring continuing medical education as well as peer review and performance improvement, for both surgeons and anesthesiologists (Table 33-4).
Table 33-4 Sentinel Events That Should Trigger a Chart Review and Be Presented at a Performance Improvement Quality Assurance Meeting
Perioperative myocardial infarction or stroke
Reintubation of the trachea
Return to the operating room
Peripheral nerve injury
Adverse drug reaction
Uncontrolled pain, nausea, or vomiting
Unexpected hospital admission
Controlled substance discrepancy
- Office Selection
The office needs to be appropriately equipped and stocked to perform general anesthesia (Table 33-5). All equipment described in the ASA algorithm for management of the difficult airway should be present. Perioperative monitoring must adhere to the ASA standards for basic anesthetic monitoring. The office-based anesthesiologist should be prepared to begin the initial treatment of malignant hyperthermia, which requires having at least 12 bottles of dantrolene. Drug accounting must be performed in accordance with state and federal regulations. A medical director who is responsible for overall operations should be identified for every office.
- Emergenciescan occur in an office-based setting (Table 33-6). Destinations for a patient in need of hospital admission must be identified with a formal written arrangement with a nearby hospital. Contingency plans must be in place in the event of a power supply interruption or electrical failure.
Table 33-5 Equipment Needed for Safe Delivery of Office-Based Anesthesia
Noninvasive blood pressure with an assortment of cuff sizes
Heart rate and electrocardiography monitors
Self-inflating bag-mask ventilation device
Laryngoscopes (multiple sizes and styles)
Tracheal tubes (various sizes)
Emergency airway equipment (LMAs, cricothyrotomy kit, means for transtracheal jet ventilation)
Suction catheters and suction equipment
Dantrolene and malignant hyperthermia supplies
Vascular cannulation equipment
Table 33-6 Emergencies That May Occur Within an Office That Require Contingency Plans
Bomb or bomb threat
Loss of oxygen supply pressure
Cardiac or respiratory arrest in the waiting room, operating room, or PACU
External disturbance such as a riot
Massive blood loss
Emergency transfer of the patient to a hospital
PACU = postanesthesia care unit.
Table 33-7 American Society of Anesthesiologists' Classification of Surgical Offices According to the Anesthesia and Surgical Procedures Performed
Minor surgical procedures
Local, topical, or infiltration of local anesthetic
No sedation preoperatively or intraoperatively
Minor or major surgical procedures
Sedation via oral, rectal, or intravenous sedation
Analgesic or dissociative drugs
Minor or major surgical procedures
Major conduction block anesthesia
- Accreditation(Tables 33-7 and 33-8). The actual improvement in safety conferred by performing surgery in an accredited office has yet to be determined, and as long as there is no mandatory reporting system in place, it will be impossible to determine true morbidity rates associated with an office-based practice.
- Procedure Selection
Suitable office-based procedures range from incision and drainage of abscesses to micro-laparoscopies. Very few data are available regarding procedure length and suitability for office-based procedures, but it has been recommended that procedures not exceed 6 hours in duration and be completed by 3 p.m. to allow for recovery time. In addition, when determining the suitability of a procedure, one must consider the possibility of hypothermia, blood loss, and significant fluid shifts.
- Specific Procedures
- Liposuctionis the most commonly performed plastic surgery procedure and is accomplished by placing hollow rods into small incisions in the skin and suctioning subcutaneous fat into an aspiration canister. Superwet and tumescent techniques use large volumes (1–4 mL) of infiltrate solution that consists of 0.9%
saline or Ringer's lactate with epinephrine 1:1,000,000 and lidocaine 0.025% to 0.1%. Blood loss is generally 1% of the aspirate with these techniques. The peak serum levels of lidocaine occur 12 to 14 hours after injection. Liposuction is not a benign procedure and may be associated with morbidity and mortality caused by pulmonary embolism, anesthesia, myocardial infarction, infection, and hemorrhage. Risk factors include the use of multi-liter wetting solution infiltrations, large-volume aspiration causing massive third spacing, multiple concurrent procedures, anesthetic sedative effects yielding hypoventilation, and permissive discharge policies.
Table 33-8 Factors Considered by Accrediting Agencies
Physical layout of the office
Environmental safety and infection control
Patient and personnel records
Local hospital privileges (surgical and admission)
Intraoperative and postoperative staffing
Intraoperative and postoperative monitoring capabilities
Drugs (emergency, controlled substances, routine medications)
BLS or ACLS/PALS certification
Pre- and postanesthesia care and documentation
Quality assurance and peer review
Emergency procedure (fire, admission, and transfer)
- Aesthetics.Many facial aesthetic procedures, such as blepharoplasty, rhinoplasty, and meloplasty, are routinely performed in the office setting, usually under varying depths of monitored anesthesia care (MAC), but occasionally under general anesthesia.
- Facial plastic procedures that require the use of a laser pose a problem for the use of supplemental nasal oxygen to maintain adequate SpO2. Any supplemental oxygen must be turned off during periods of laser or electrocautery use about the face.
- The avoidance of supplemental oxygen when medically appropriate is ideal.
- Breast.Procedures such as breast biopsy or augmentation, implant exchanges, and completion of transverse rectus abdominal muscle (TRAM) flaps may be performed in office settings. It is likely that patients undergoing breast surgery will require antiemetic medication and postoperative analgesics.
- Gastrointestinal endoscopyincludes esophageal, gastric, and duodenal endoscopies (EGD) and colonoscopies. This patient population tends to be older, with significant comorbid conditions. Insertion of the endoscope can usually be accomplished with sedation using small doses of propofol with or without midazolam.
- Colonoscopy is painful secondary to the insertion and manipulation of the endoscope and may be associated with cardiovascular effects, including dysrhythmias, bradycardia, hypotension, hypertension, myocardial infarction, and death.
- The gastroenterology community has sought to be able to provide moderate or even deep sedation with propofol without the assistance of an anesthesia professional. (Propofol's package insert states that it may only be administered by individuals who are trained in the administration of drugs that cause deep sedation and general anesthesia.)
- Dentistry and Oral and Maxillofacial Surgery.Nitrous oxide has been used for most of the world's office-based dental anesthetics since 1884, when Horace Wells, himself a dentist, had nitrous oxide administered for a wisdom tooth extraction by a colleague. A high level of safety is attributed to the use of pulse oximetry, blood pressure, and ventilation monitoring, as well as administration of supplemental oxygen.
- Orthopedics and Podiatry.The orthopedic office provides an excellent location for an anesthesiologist who
practices regional anesthesia (intra-articular local anesthesia and MAC, three-in-one block of the lumbar plexus, brachial plexus block, ankle block). Spinal anesthetics in the office-based setting must be of short duration. Lidocaine, which provides reliable short-acting analgesia, may be associated with an increased risk of transient neurologic symptoms in the ambulatory patient population.
- Gynecology and Genitourinary.Many procedures, such as dilation and curettage, vasectomy, and cystoscopy have been performed in the office setting for many years, and recently there has been an increase in more invasive procedures such as mini-laparoscopies, ovum retrieval, prostate biopsies, and lithotripsy, necessitating an anesthesiologist's expertise.
- Ophthalmology and Otolaryngology.Topical anesthesia or periorbital and retrobulbar blocks are frequently used to provide analgesia. Supplemental sedation may be required.
- Pediatrics.Although no minimum age requirement for a child to undergo an office-based anesthetic has been established, patients older than 6 months of age and with an ASA physical status of 1 or 2 may be reasonable candidates for OBA (dental surgery, lacrimal duct probing, myringotomy) (Table 33-9).
VII. Anesthetic Techniques
The ASA recommends that anesthetics be provided or supervised by an anesthesiologist. The ASA has developed definitions regarding depths of anesthesia (Table 33-10). When formulating an anesthetic plan, one must consider that all agents and techniques used should be short acting, and the patient should be ready for discharge home soon after the completion of the procedure.
- Anesthetic Agents.Intravenous sedation (propofol, barbiturates, midazolam, fentanyl, meperidine) is the most commonly used anesthetic technique in the OBA setting. Drugs should have a short half-life, be inexpensive, and not be associated with undesirable side effects such as nausea and vomiting.
- Remifentanilis an ultra-short-acting opioid that, in combination with propofol for conscious sedation, provides discharge readiness within 15 minutes after
colonoscopy (48–80 minutes after meperidine or midazolam administration).
Table 33-9 Guidelines for the Pediatric Perioperative Anesthesia Environment
Patient Care Facility and Medical Staff Policies
Designation of operative procedures
Categorization of pediatric patients undergoing anesthesia
Annual minimal case volume to maintain clinical competence
Clinical Privileges of Anesthesiologists
Special clinical privileges
Patient Care Units
Preoperative evaluation and preparation units
Other health care providers involved in perioperative care
Availability and capabilities of clinical laboratory and radiologic services
Pediatric anesthesia equipment and drugs, including resuscitation cart
Anesthesiologist and physician staff
Postoperative Intensive Care Units
- Remifentanil is an ideal drug for use during many office-based procedures (e.g., facial cosmetic surgery) that may be painful during injection of the local anesthetic.
- Disadvantages of remifentanil are possible nausea and vomiting, risk of drug-induced apnea, and the need for an infusion pump.
- Ketaminefunctions as both an anesthetic and an analgesic. It is particularly useful because it does not depress respirations and is not associated with nausea and vomiting. Ketamine may cause an increase in secretions as well as cause hallucinations. Another advantage of ketamine is that it is relatively inexpensive.
- Clonidinefacilitates blood pressure control throughout the perioperative period and may decrease the total propofol usage.
Table 33-10 Definitions of Levels of Sedation/Analgesia by the American Society of Anesthesiologists (October 13, 1999, by the House of Delegates)
Minimal Sedation (Anxiolysis)
The patient responds normally to verbal commands
Cognitive and motor function may be impaired
Ventilatory and cardiovascular function are maintained normally
Moderate Sedation/Analgesia (Conscious Sedation)
The patient responds purposefully to verbal commands either alone or with light tactile stimulation
The patient maintains a patent airway and spontaneous ventilation
Cardiovascular function is maintained
The patient cannot be easily aroused but can respond purposefully to repeated or painful stimulation
Ventilatory function may be impaired, requiring assistance in maintaining a patent airway, and spontaneous ventilation may be inadequate
Cardiovascular function is usually maintained
Drug-induced loss of consciousness
The patient is not arousable by painful stimulation
Ventilatory function is often impaired; the patient may require assistance in maintaining a patent airway
Spontaneous ventilation and neuromuscular functioning may be impaired
Positive-pressure ventilation is often required
Cardiovascular function may be impaired
- It is vital that the office be adequately equipped and staffed to rescue patients from a deeper stage of anesthesia. (MAC is planned, but general anesthesia must be anticipated.)
- Depth of anesthesia monitoring during MAC procedures has been shown to decrease the total propofol usage.
VIII. Postanesthesia Care Unit (PACU)
After an office-based procedure, it is expected that the patient will be able to sit in a chair or ambulate to an
examination room to dress almost immediately. A formal PACU may not be present, and the patient may recover in the surgical suite. Regardless of where the patient recovers, it is important to adhere to all ASA standards for monitoring and documentation throughout the postoperative period. Problems of postoperative nausea and vomiting (PONV) and pain may become particularly troublesome. It is imperative that every anesthetic administered is designed to maximize patient alertness and mobility and minimize the risks of the need for a prolonged PACU stay.
- Pain Management.Local anesthesia and conscious sedation supplemented by wound infiltration with local anesthetics or nerve blocks often form the basis for a multimodal strategy for postoperative pain management. Non-opioid analgesics (acetaminophen) and nonsteroidal antiinflammatory drugs (ketorolac) are routinely used. To minimize the potential for postoperative bleeding and risk of gastrointestinal complications, more specific cyclo-oxygenase-2 inhibitors are being increasingly used as non-opioid adjuvants for minimizing postoperative pain.
- Postoperative Nausea and Vomiting.An optimal antiemetic regimen for OBA has yet to be established, but because the causes of PONV are multifactorial, combination therapies may be more beneficial in high-risk patients. Many of the traditional first-line therapies are associated with sedation. Serotonin receptor antagonists and dexamethasone may be valuable.
Governmental oversight of office-based surgery varies among states; regulations currently exist in many states, and others are following. It is imperative that the anesthesiologist act as a patient advocate and help educate the surgeon as to what constitutes a safe anesthetizing location.
- Business and Legal Aspects
It is in the anesthesia provider's best interest to seek legal counsel and create a valid business plan before embarking
on a career in OBA. Billing strategies must be legal. In this complex environment of third-party payers, it is quite easy to make errors.
OBA continues to rapidly expand and pose unique challenges to anesthesiologists. Decisions about appropriate patient and procedure selection and equipping anesthetizing locations must be made in conjunction with the surgeon.
Editors: Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K.; Cahalan, Michael K.; Stock, M. Christine
Title: Handbook of Clinical Anesthesia, 6th Edition
Copyright ©2009 Lippincott Williams & Wilkins
> Table of Contents > Section VI - Anesthetic Management > Chapter 34 - Anesthesia Provided at Alternate Sites