Etsuro K. Motoyama
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Anesthesia-Related Mortality, 1155
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Anesthesia-Related Morbidity in Infants and Children, 1158
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Common Causes of Anesthesia-Related Mishaps, 1166
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Prevention of Anesthesia-Related Mishaps, 1168
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Summary, 1170 |
The safety of infants and children undergoing general anesthesia has improved considerably since the 1970s, as evidenced by significant decreases in anesthesia mortality despite the fact that more complicated surgical procedures have been performed on sicker children and more premature infants.
Since the 1980s, anesthesiologists' awareness of and interest in the subject of patient safety have reached a new peak ( Smith and Norman, 1987 ; Runciman, 1988a ; Runciman et al., 1988b) , and a number of new steps have been taken to ensure perioperative patient safety ( Keats and Siker, 1985 ). In addition to advanced technology for patient monitoring, standards for basic patient monitoring have been implemented ( American Society of Anesthesiologists, 1986 ; Eichhorn et al., 1986 ). Documentation of the quality assurance (QA) process has been emphasized as an integral and essential component for hospital accreditation by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) in the United States. To further improve the quality of patient care, a number of national and international organizations have been created, including the International Committee on Prevention of Anesthesia Mortality and Morbidity ( Cooper, 1988 ), the Anesthesia Patient Safety Foundation (Cooper and Pierce, 1986 ), and the Australian Patient Safety Foundation ( Pierce, 1988 ; Runciman, 1988b ).
Nevertheless, anesthesia-related morbidity and mortality still do occur during the administration of anesthesia, and can happen with any anesthesiologist under various situations. An analysis of anesthetic mishaps from U.S. closed anesthesia malpractice claims, before the new patient monitoring standards with pulse oximetry and capnography were instituted, indicated that at least 80% of the claims consist of preventable hypoxic damage caused by human errors rather than mechanical failures ( Davis, 1984 ).
Allnutt (1987) , a member of the British Army Personnel Research Establishment, examined human factors in anesthesia-related mishaps in comparison with those in military aviation accidents. He stresses that “both pilots and doctors make many errors” (that is, performance that deviates from the ideal). “Usually there is sufficient slack in the system for the error to be… noticed and corrected, but some apparently innocuous errors are not noticed and some systems are not so forgiving as others” (such as a high performance aircraft in flight). “Thus recovery from a control error when flying at high speed, low level may not be possible, whereas the same error in the cruise [at high altitude] might barely occasion comment.” A basic tenet of Allnutt's theory is that “all human beings, without any exception whatsoever, make errors and that such errors are a completely normal and necessary part of human cognitive function.” He goes on to state that “to claim exemption on the grounds of being a senior professor [or a] test pilot … or of having 30 years' experience or 3000 accident-free hours, is the first step on the road to disaster.” The first step toward the prevention of catastrophe is for the pilot or the anesthetist to accept that he or she is as likely as anyone else to make an error ( Pierce, 1988 ).
In this chapter, some of the important aspects of patient safety'the incidence and causes of mortality and morbidity and measures for the prevention of anesthesia-related mishaps'are discussed.
▪ ANESTHESIA-RELATED MORTALITY
▪ OVERALL ANESTHESIA-RELATED MORTALITY
The number of deaths associated with general anesthesia has declined steadily over the past several decades as the standard of anesthesia practice has improved and as advances have been made in instrumentation, anesthetic and adjuvant drugs, and safety monitors and standards. The extensive survey of 10 university hospitals by Beecher and Todd (1954) involving nearly 600,000 anesthetic cases between 1948 and 1952 suggested that mortality primarily attributable to anesthesia occurred in 1:2680 anesthetic cases (3.7:10,000), whereas the overall anesthesia-associated mortality was 1:1580 (6.3:10,000) anesthetics ( Graff et al., 1964 ). A survey by Dornette and Orth (1956) showed similar mortality rates. The data from the Baltimore Anesthesia Study Committee (1953 to 1963) showed an anesthesia-related death rate of 2.7:10,000 cases. During the 1970s and 1980s, statistics on anesthesia-related mortality in the United States were scarce, apparently because of medicolegal concerns. The anesthesia-related mortality from Canadian, British, and European sources during this period ranged from 0.7 to 2.2:10,000 anesthetic procedures ( Bodlander, 1975 ; Harrison, 1978 ; Hovi-Viander, 1980 ;Turnbull et al., 1980 ; Lunn and Mushin, 1982 ; Hatton et al., 1983 ; Vickers and Lunn, 1983 ).
In the 1980s, European and Australian studies had shown much lower rates of operative mortality that were directly attributed to anesthesia. The report from the British Confidential Enquiry into Perioperative Deaths (CEPOD), a survey that was jointly organized by the Associations of Anaesthetists and Surgeons of Great Britain and Ireland during 1985 to 1986 and included more than 480,000 general anesthetic procedures, indicated the mortality attributable to anesthesia alone was 1:185,000 (0.054:10,000) anesthetics ( Buck et al., 1987 ). However, anesthesia, along with other causes, was thought to be a contributory factor in the death of between 1.4 (surgeons' estimate) and 9.8 (anesthetists' estimate) per 10,000 cases. A prospective survey of anesthesia outcome by the French Health Ministry during the 1978-1982 period, in which nearly 200,000 general anesthetic cases were documented, revealed an intraoperative and early postoperative death rate solely attributable to anesthesia to be 0.76:10,000 anesthetics, and an intraoperative death rate of 0.44:10,000 anesthetics ( Tiret et al., 1986 , 1988) ( Table 34-1 ).
TABLE 34-1 -- Historical changes in anesthesiarelated mortality (all ages)
|
Authors (Country) |
Study Years |
Incidence per 10,000 |
|
Beecher and Todd (United States) |
1948 to 1952 |
3.7 |
|
Graff et al. (United States) |
1953 to 1963 |
2.7 |
|
Hovi-Viander (Finland) |
1975 |
2.0 |
|
Lunn and Mushin (United Kingdom) |
1978 to 1979 |
1.0 |
|
Tikkanen (Finland) |
1986 |
0.6 |
|
Tiret and others (France) |
1978 to 1982 |
0.76[*] |
|
Buck and others, CEPOD (United Kingdom) |
1985 to 1986 |
0.05[*] |
|
Eichhorn (United States) |
1976 to 1988 (ASA PS 1 or 2) |
0.05[*] |
|
Lagasse (United States) |
1995 to 1999 |
0.75 |
|
Fasting and Gisvold (Canada) |
1996 to 2000 |
0.12 |
|
ASA PS, American Society of Anesthesiologists physical status; CEPOD, Confidential Enquiry into Perioperative Death. |
|
* |
Anesthesia primarily responsible only. |
Clearly, it is difficult to compare the incidence of anesthesia-related death among reports from different parts of the world because the definition and inclusion criteria (all inclusive versus American Society of Anesthesiologists [ASA] physical status [PS] 1 and 2), duration (perioperative, 48 hours versus 30 days), and the definition of anesthetic contributions (anesthesia contributory versus primary cause) to mortality may differ markedly.
A longitudinal comprehensive anesthesia-related mortality study from New South Wales, Australia, which has been continuous by the same author using the same criteria since 1960 (interrupted between 1980 and 1983 because of the temporary loss of legal confidentiality), has indeed shown a steady decline in anesthetic mortality from 1.8:10,000 cases in 1960 to 0.38:10,000 cases by 1984 (Holland, 1984, 1987 [58] [59]). Similarly, a longitudinal study from South Africa has also shown the trend of decreases in anesthesia-related mortality from 3.3:10,000 in 1956-1965 to 0.7:10,000 in 1983-1987 (Harrison, 1978, 1990 [55] [56]) ( Table 34-2 ).
TABLE 34-2 -- Anesthesia-related mortality: Longitudinal study at the same institution
|
Authors (Country) |
Study Years |
Incidence per 10,000 |
|
Holland (Australia) |
1960 to 1969 |
1.8 |
|
1970 to 1980 |
0.97 |
|
|
1983 to 1985 |
0.38 |
|
|
Harrison (South Africa) |
1956 to 1965 |
3.3 |
|
1967 to 1976 |
2.2 |
|
|
1983 to 1985 |
0.7 |
In the United States, Eichhorn (1989) analyzed the data from nine Harvard University-affiliated hospitals between 1976 and 1988. He reported 11 major anesthesia-related intraoperative accidents, including five deaths based on more than 1 million anesthetic procedures in relatively healthy patients (ASA PS 1 and 2); the anesthetic mortality was 0.05:10,000 cases; postoperative mortality, including two deaths from halothane hepatitis, was excluded from these statistics. After implementation of the patient monitoring standards in 1985 ( Eichhorn et al., 1986 ), there was only one serious accident (no mortality) in 319,000 general anesthetic procedures. Of the 11 major accidents, eight cases were considered preventable with proper monitoring, especially with capnography. Unrecognized hypoventilation was the most common cause (seven cases) of major mishaps. Inadequate supervision of residents and nurse anesthetists was also contributory. Although Eichhorn's statistics were based on a malpractice insurance database and are likely different and considerably lower than the data based on a peer review process, anesthetic safety appears to have improved significantly.
Anesthesiology was the first medical specialty to consider patient safety as an independent problem and has institutionalized patient safety in its scientific and governing bodies (such as the ASA Anesthesia Patient Safety Foundation and similar organizations in other countries) ( Cooper and Gaba, 2002 ). In 1999, the Committee on Quality of Health Care in America for the Institute of Medicine published a report entitled To Err Is Human: Building a Safer Health Care System ( Kohn et al., 1999) . The report stated: “Anesthesia is an area in which very impressive improvements in safety have been made.” This statement was based on the statistics that anesthesia-related mortality rates have decreased from two deaths per 10,000 anesthetic procedures in the 1980s to about one death per 200,000 to 300,000 anesthetic procedures administered today (probably quoting the report by Eichhorn et al. [1989 ]). Such dramatic decreases in anesthetic mortality have been attributed to a variety of mechanisms, including the wide acceptance of new monitoring guidelines, the improvement in monitoring techniques, safer anesthetic drugs, and the adoption of QA mechanisms and other systematic approaches for reducing human and systemic errors ( Gaba, 2000 ; Stoelting, 2000 ; Lagasse, 2002 ).
Based on the extensive analyses of 23 publications by 21 different investigators on anesthesia-related deaths between 1955 and 1999, Lagasse (2002) challenged the assertion of “impressive” gains in anesthesia patient safety published by the Institute of Medicine ( Kohn et al., 1999) . Lagasse's analyses demonstrated that the anesthesia-related mortality rate ranged between 1:1388 (7.2:10,000) and 1:85,708 (0.12:10,000) (mean, 2.17:10,000), a majority of which could have been preventable. The mortality in which anesthesia was considered solely responsible ranged between 1:6795 and 1:200,200 (1.47 to 0.05:10,000). However, he found no statistically significant decrease in mortality rates since the 1970s ( Lagasse, 2002 ).
Furthermore, Lagasse (2002) pointed out the inaccuracy of estimating the anesthesia-related mortality rates based on malpractice insurance claim statistics. Data from two (urban and suburban) university hospitals between 1992 and 1999 revealed 17 anesthesia-related deaths (N = 184,472). Most of these deaths occurred in sick patients (ASA PS 5) and there was no trend of improved mortality with time (Lagasse, 2002 ). Four out of these 17 patients (0.22:10,000) died as the result of major anesthetic mishaps and three of these four cases resulted in legal action; only one (0.08:10,000) occurred in a patient whose ASA PS was in the 1 or 2 category ( Lagasse, 2002 ). Thus, the mortality rate reported by Einhorn and others (1989) could have been underestimated.
One major drawback of Lagasse's assertion challenging the commonly held belief of marked improvement in anesthesia safety in recent years (2002) may be that his data base included disproportionately few reports after the 1990s when, in part as the result of the new perioperative monitoring guidelines (including pulse oximeter and capnography), the anesthesia-related morbidity and mortality rates have declined considerably.
In the editorial accompanying the article by Lagasse (2002) , Cooper and Gaba (2002) refuted Lagasse's conclusion by quoting more recent studies demonstrating that anesthesia has indeed become much safer in recent years. “Has anesthesia safety reached a plateau? Lagasse's data from hospitals in the 1990s contain too few patients for a definite conclusion but such a plateau is possible” ( Cooper and Gaba, 2002 ). On the other hand, if the low probability of anesthetic mortality in healthy patients is taken for granted, the goal of anesthesia patient safety may compete inappropriately against the economical pressure of efficiency and cost containment ( Cooper and Gaba, 2002 ).
▪ MORTALITY IN INFANTS AND CHILDREN
Among the pediatric age group, the anesthesia-related mortality has been reported to be disproportionately high in the literature. In the 1950s, Beecher and Todd (1954) and Stevenson and others (1953)found that accidental deaths resulting from anesthesia were disproportionately high during the first decade of life. Between 1947 and 1956 at the Babies Hospital/Columbia-Presbyterian Medical Center,Rackow, Salanitre, and Green (1961) found that the frequency of cardiac arrest associated with anesthesia in infants less than 1 year of age (1 in 617 cases, or 16.2:10,000) was higher than in children aged 1 to 12 years (1 in 1678, or 6.0:10,000) and in adults (1 in 2580, or 3.9:10,000) ( Beecher and Todd, 1954 ). Hypoventilation and hypoxia from ether overdosage were among the common causes of death.Smith (1956) emphasized the importance of certain factors contributing to the high anesthetic mortality in pediatric anesthesia. These factors included lack of proper equipment, improper preoperative rehydration and stabilization, inadequate intraoperative monitoring, error in fluid replacement, and aspiration of vomitus. Today, half a century later, some of these factors are still applicable.
In the report by the Baltimore Anesthesia Study Committee ( Phillips and Frazier, 1957 ; Graff et al., 1964 ), anesthesia-related mortality for children less than 15 years of age was found to be 3.3:10,000 cases (versus 0.6:10,000 for the 15- to 24-year-old group). These authors also found that the ratio of anesthesia deaths to total surgical deaths was higher in the neonatal period than in any other age group. Furthermore, 57% of the deaths related to anesthesia occurred in healthy children (ASA PS 1 and 2). Respiratory problems were implicated in 83% of the anesthesia-related deaths ( Graff et al., 1964 ) (Table 34-3 ).
TABLE 34-3 -- Anesthesia-related mortality in children (N > 10,000)
|
Authors (City) |
Study Years |
Age (yr) |
Incidence per 10,000 |
|
Rackow (New York City) |
1947 to 1956 |
<1.0 |
16.2 |
|
|
|
1 to 12 |
6.0 |
|
Graffdanez others (Baltimore) |
1957 to 1964 |
<15 15 to 24 |
3.3 0.6 |
|
Smith (Boston) |
1957 to 1966 |
<10 |
1.9 |
|
|
1969 to 1978 |
<10 |
0.64 |
|
Elwyn (Salt Lake City) |
1970 to 1975 |
<11 |
0.34 |
|
Morray and others (POCA Registry) |
1994 to 1997 |
<18 |
0.34[*] |
|
Tay and others (Singapore) |
1997 to 1999 |
<18 |
0 |
|
Murat and others (Paris) |
2000 to 2002 |
<16 |
0 |
|
POCA, Pediatric Perioperative Cardiac Arrest. |
|
* |
Estimated. |
In contrast, in a review of 73 anesthesia-related cardiac arrests in children between 1960 and 1972 (33% resulted in death), Salem and others (1975) found that both respiratory (airway obstruction) and cardiovascular causes (blood loss, preoperative anemia, inappropriate injection of succinylcholine and potassium) were equally responsible. In retrospect, most of these accidents were preventable.
In an attempt to improve anesthesia patient safety in infants and children, a number of important innovations and improvements in perioperative management and monitoring had been made by the pioneering pediatric anesthesiologists in the 1950s and 1960s. These innovations included homemade pediatric blood pressure cuffs and precordial stethoscopes (by Robert Smith in Boston) and endotracheal intubation (by Margo Demming in Philadelphia). Fellowship training in pediatric anesthesia also began in several cities in North America and in the United Kingdom in the 1950s and spread across the continent by the early 1970s (see Chapter 35 , History of Pediatric Anesthesia).
By the mid-1970s, anesthesia-related morbidity and mortality decreased considerably. Management of known hazards, such as the full stomach, preoperative fever, and hypovolemia, was greatly improved by increased experience and knowledge ( Smith, 1975 ). Smith (1980) reported the anesthesia-related mortality rate of 2.0:10,000 general anesthetic cases in children (0 to 10 years old) during the decade ending in 1966 at the Children's Hospital in Boston; the mortality rate decreased to 0.6:10,000 anesthetic cases in the decade ending in 1978. Furthermore, there was a series of 35,710 consecutive tonsillectomies and adenoidectomies, mostly in children, without a single death at the Eye and Ear Hospital of Pittsburgh ( Petruscak et al., 1974 ). There were 7500 consecutive anesthetics for cleft lip and cleft palate repairs without a death at the Children's Hospital in Boston ( Smith, 1975 ). Elwyn, in his 5-year study between 1970 and 1975 at the Primary Children's Hospital in Salt Lake City, reported one anesthetic death in 29,101 anesthetic procedures (0.34:10,000) in children under 11 years of age ( Smith, 1980 ). Downes and Raphaelly (1979) reported an anesthetic mortality of 0.2:10,000 cases (from a total of 50,000 patients) at Children's Hospital of Philadelphia. Most fatalities occur during the first year of life, beyond which the risk of mortality is no higher than that in teenagers and young adults (Smith, 1975 ) (see Table 34-3 ).
Despite advances in pediatric anesthesia, statistics in the 1980s still show anesthesia-related mortality rates in children that are three to four times higher than in the general patient population, although the mortality rates in children have decreased considerably and appeared to have reached a plateau ( Keenan and Boyan, 1985 ; Gibbs, 1986 ; Olsson and Hallen, 1988 ).
As part of a closed anesthesia malpractice claims study by the Committee on Professional Liability of ASA, Morray and others (1993) compared pediatric and adult closed claims and found a different distribution of serious outcomes in children compared with those in adults. Of 2400 closed malpractice claims, 238 (10%) were in the pediatric age group (≤15 years old). A majority of cases involved children less than 3 years of age, and 28% of all pediatric cases involved infants less than 1 year of age. Respiratory events (mostly inadequate ventilation) were more common than among adult claims (43% versus 30%) and mortality was higher (50% versus 35%), mostly attributable to inadequate ventilation. Anesthesia care was judged inadequate more often. The authors concluded that 89% of the pediatric claims that were related to inadequate ventilation could have been prevented with proper monitoring using pulse oximetry and capnography ( Morray et al., 1993 ).
Analysis of anesthesia-related incidents reported to the Australian Incident Monitoring Study (AIMS) showed almost identical characteristics among pediatric age groups ( van der Walt et al., 1993 ). Of the first 2000 cases reported, 10% involved infants and children. Incidents involving respiratory and breathing circuit systems accounted for nearly half of the adverse incidents. As with the ASA closed claims study, the Australian reviewers estimated that 89% of all applicable problems in AIMS could have been detected and potentially prevented by the combination of pulse oximetry and capnography ( van der Walt et al., 1993 ).
Has anesthesia-related mortality in pediatric patients decreased over the past decade, or has it reached the plateau as Lagasse's (2002) controversial analysis concluded? A study from Singapore based on the QA database reports no fatalities among 10,000 consecutive general pediatric anesthetic procedures from 1997 to 1999 ( Tay et al., 2001 ). A 2004 QA database study from Hopital d'Enfants Armand Trousseau in Paris also reports zero mortality among 24,165 general anesthetic procedures in children between 2000 and 2002 ( Murat et al., 2004 ). On the other hand, from the Pediatric Perioperative Cardiac Arrest (POCA) Registry in the United States (see later) between 1994 and 1997, the anesthesia-related mortality rate was estimated to be 0.36:10,000 ( Morray et al., 2000 ). Obviously, a large-scale prospective and longitudinal study is needed to determine the overall pediatric anesthesia-related mortality in the early 21st century.
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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.
Copyright © 2005 Mosby, An Imprint of Elsevier
▪ ANESTHESIA-RELATED MORBIDITY IN INFANTS AND CHILDREN
▪ PERIOPERATIVE CARDIAC ARRESTS
Incidences of perioperative cardiac arrests have been reported from North America, Europe, and Australia. Estimated incidence of cardiac arrests ranged 17 to 24:10,000, and, as with the mortality rates, the rates are 3 to 10 times higher in infants than in older children ( Olsson and Hallen, 1988 ; Tiret et al., 1988 ; Cohen et al., 1990 ). Studies by Keenan and Boyan (1985) and by Morgan and others (1993) also showed higher incidences of cardiac arrest in younger (<10 to 12 years) than in older children. Most frequent causes leading to cardiac arrest involved respiratory and cardiovascular systems and included relative drug overdosage, vagal stimulation, hypoventilation, and succinylcholine-induced asystole.
Keenan and others (1991) reported the effect of specialty training in pediatric anesthesia on the safety of children, especially in infants. In a single university hospital setting, the incidence of perioperative cardiac arrest in infants less than 1 year of age was 19:10,000 with mortality, when residents were supervised by nonpediatric attending anesthesiologists, whereas no arrest occurred when pediatric anesthesiologists were in charge.
Pediatric Perioperative Cardiac Arrest (Poca) Registry
In order to accurately estimate the incidence of cardiac arrests and adverse outcomes, the POCA Registry was formed in 1994 under the combined auspices of the ASA Committee on Professional Liability, the Quality Assurance Committee of the Section on Anesthesiology of the American Academy of Pediatrics ( Morray, 2004 ). The registry included 63 institutions, of which 75% were university hospitals and 40% were children's hospitals. All cardiac arrests requiring cardiopulmonary resuscitation during the immediate perioperative period are eligible for inclusion. During the first 4 years of the registry (1994-1997), participating institutions administered an estimated total of 1,089,200 cases of anesthesia in children younger than 18 years ( Morray et al., 2000 ). A total of 289 cardiac arrests were registered, of which 150 cases were considered as anesthesia contributory. The mean overall incidence of anesthesia-related cardiac arrest was 1.4:10,000 with a mortality rate of 26% (0.36:10,000). Of the total anesthesia-related cardiac arrests, 55% occurred in infants less than 11 months of age ( Morray et al., 2000 ).
Of the major causes of anesthesia-related cardiac arrests, medication-related (37%) and cardiovascular causes (32%) were most common, together accounting for 69% ( Table 34-4 ). In contrast, the respiratory causes represented only 20%, a marked reduction from the incidence of 43% reported by the ASA closed malpractice claim study ( Morray et al., 2000 ). Equipment-related causes comprised 7% of the total ( Morray et al., 2000 ). Of the patients' physical status, 33% were those with ASA PS 1 and 2, a significant decrease from earlier studies of pediatric mortality (57% of deaths) ( Graff et al., 1964), a significant improvement, and a move in the right direction, although it is still too high. Of medication-related cardiac arrests, cardiovascular depression with halothane alone, or in combination with other drugs (mostly opioids), accounted for 66% of all medication-related arrests. In healthy children with ASA PS 1 and 2, 64% of arrests were medication related in comparison with 23% in those with ASA PS 3 to 5 ( Morray et al., 2000 ; Mason, 2004 ) ( Fig. 34-1 ). Among the patients who sustained anesthesia-related cardiac arrest in the POCA Registry, death was associated most strongly with ASA PS 3 to 4 and emergency surgery ( Morray et al., 2000 ). Similar correlations between cardiac arrest or death and ASA PS 3 to 4 were found in the earlier study by Keenan and Boyan (1985) .
TABLE 34-4 -- Mechanism of cardiac arrest
|
Mechanism |
No. of Arrests |
|
Medication Related Inhalation Agents |
55 (37%) |
|
Halothane alone |
26 (46%) |
|
Halothane plus an intravenous medication |
11 (20%) |
|
Sevoflurane alone |
2 (4%) |
|
Intravenous Medications |
|
|
Single |
5 (9%) |
|
Combination |
5 (9%) |
|
Intravenous injection of local anesthetic |
5 (9%) |
|
Succinylcholine-induced hyperkalemia |
1 (2%) |
|
Cardiovascular |
48 (32%) |
|
Presumed cardiovascular, unclear etiology |
18 (38%) |
|
Hemorrhage, transfusion related |
8 (17%) |
|
Inadequate/inappropriate fluid therapy |
6 (13%) |
|
Arrhythmia |
5 (10%) |
|
Hyperkalemia |
4 (8%) |
|
Air embolism |
2 (4%) |
|
Pacemaker related |
2 (4%) |
|
Vagai response |
1 (2%) |
|
Pulmonary hypertension |
1 (2%) |
|
Tetralogy hypercyanotic spell |
1 (2%) |
|
Respiratory |
30 (20%) |
|
Laryngospasm |
9 (30%) |
|
Airway obstruction |
8 (27%) |
|
Difficult intubation |
4 (13%) |
|
Inadequate oxygenation |
3 (10%) |
|
Inadvertent extubation |
2 (7%) |
|
Presumed respiratory, unclear etiology |
2 (7%) |
|
Inadequate ventilation |
1 (3%) |
|
Bronchospasm |
1 (3%) |
|
Equipment Related |
10 (7%) |
|
Central line |
4 (40%) |
|
Breathing circuit |
2 (20%) |
|
Peripheral intravenous catheter |
1 (10%) |
|
Other |
3 (30%) |
|
Multiple Events |
5 (3%) |
|
Hypothermia |
1 (<1%) |
|
Unclear Etiology |
1 (<1%) |
Modified from Morray JP, Geiduscheck JM, Ramamoorthy C, et al.: Anesthesia-related cardiac arrest in children: Initial findings of the Pediatric Perioperative Cardiac Arrest (POCA) Registry.Anesthesiology 93:6-14, 2000, Table 2, p. 9.
|
FIGURE 34-1 Primary cause of anesthesia-related cardiac arrest in American Society of Anesthesiologists (ASA) physical status 1 to 2 and 3 to 5 patients compared with ASA physical status 3 to 5 patients. *P < 0.01. [From Morray JP, Geiduschek JM, Ramamoorthy C, et al.: Anesthesia-related cardiac arrest in children: Initial findings of the Pediatric Perioperative Cardiac Arrest (POCA) Registry. Anesthesiology 93:6-14, 2000, Fig. 1, p. 10, reproduced with permission.] |
Since the last publication of the POCA Registry, based on data between 1994 and 1997, more than 200 POCA cases have been added to the registry (2000-2003); about one half of these arrests were found to be anesthesia contributory ( Morray, 2004 ). In this new series of cardiac arrests in a recent preliminary report, the cause profile has changed considerably from 1994 through 1997 ( Morray, 2004 ) ( Fig. 34-2 ). Medication-related arrests have decreased markedly from 37% to 12% of the total causes, due primarily to the near disappearance of cardiovascular depression by inhaled anesthetics causing cardiac arrest ( Morray, 2004 ). These welcome changes appear to coincide with the replacement of halothane with sevoflurane as an anesthetic of choice for induction, with its far less myocardial depression and bradycardia. As the consequence of reductions in cardiac arrests with medication (primarily halothane), cardiovascular causes of arrests increased relatively, from 32% to 52%. Hypovolemia from hemorrhage and a metabolic consequence of massive transfusion and resultant hyperkalemia were the frequent causes of arrests under this category ( Morray, 2004 ). Also, with a reduction in medication-related arrests in healthy infants, the incidence of arrests in patients with ASA PS 1-2 has declined considerably from 33% to 19%, one of the most remarkable differences between the 1994-1997 and 2000-2003 databases ( Table 34-5 ).
|
FIGURE 34-2 Causes of anesthesia-related cardiac arrest in children in two time periods: 1994 to 1996 versus 2000 to 2003. (From Morray JP: Unexpected cardiac arrest in the anesthetized child. Presented at Society of Pediatric Anesthesia spring meeting, March 4-7, 2004, figure reproduced with permission.) |
TABLE 34-5 -- Comparison of demographic data from Pediatric Perioperative Cardiac Arrest Registry cases 1994 to 1997 Versus 2000 to 2003
|
|
1994 to 1997 |
2000 to 2003 |
|
ASA PS |
|
|
|
l |
15% |
4% |
|
2 |
18% |
15% |
|
3 |
37% |
46% |
|
4 |
27% |
22% |
|
5 |
2% |
13% |
|
Age |
|
|
|
<1 mo |
15% |
13% |
|
1 to 5 mo |
28% |
25% |
|
6 to 11 mo |
13% |
10% |
|
12 mo to 5 yr |
31% |
25% |
|
6 to 18 yr |
13% |
27% |
|
Emergency surgery |
21% |
30% |
|
Mortality |
26% |
27% |
ASA PS, American Society of Anesthesiologists physical status. Modified from Morray JP: Unexpected cardiac arrest in the anesthetized child. Presented at Society of Pediatrie Anesthesia spring meeting, March 4–7, 2004.
▪ OTHER PERIOPERATIVE ADVERSE EVENTS
Computerized data acquisition on nonfatal adverse outcome has become commonplace in most hospitals for the QA or quality improvement (QI) survey; such information in pediatric anesthesia has started to appear in the literature. Excellent reviews on this subject have been published ( Holzman, 1994 ; Duncan, 1995 ).
Cohen and others (1990) reviewed perioperative adverse events in over 29,000 children between 1982 and 1987 at Winnipeg's Children's Hospital. Unlike the adult surgical population, a majority (70%) of children were healthy and had no preoperative medical problems. Infants under 1 year of age, particularly those under 1 month of age (61% of whom underwent intra-abdominal, intrathoracic, or major cardiovascular surgery), had a significantly increased incidence of airway obstruction and other adverse respiratory events (9.4%) and hypotension (3.9%) intraoperatively. Among children 1 to 10 years of age, the most frequent problem was arrhythmias (3.9% to 9.3%). In the recovery room, infants less than 1 month of age had frequent hypotension (13.9%), respiratory events (11.6%), and abnormal temperature (4.7%). In older children, the most common adverse event in the recovery period was vomiting (5.9%), followed by airway obstruction (3.2%). This study was performed during the presevoflurane era when essentially all inhalation inductions were performed with halothane, with potent myocardial depression and bradycardia ( Table 34-6 ).
TABLE 34-6 -- Perioperative events by age of child, 1982 to 1987 (rate per 10,000 anesthetic cases)
|
|
Age |
|||||
|
<1 mo (n = 361) |
1 to 12 mo (n = 2544) |
1 to 5 yr (n = 12,484) |
6 to 10 yr (n = 7184) |
11+yr (n = 5647) |
Total (N= 29,220) |
|
|
Intraoperative |
||||||
|
Vomiting |
28 |
47 |
56[*] |
99 |
136[*] |
81 |
|
Cardiac arrest |
28 |
12 |
3 |
4 |
5 |
5 |
|
Arrhythmia |
166 |
86 |
391 |
933 |
561 |
528[†] |
|
Blood pressure |
388[*] |
55 |
22[*] |
19 |
46 |
34 |
|
Temperature |
83 |
24 |
13 |
8 |
16 |
14 |
|
Airway obstruction |
222 |
200[*] |
99 |
86 |
90 |
105 |
|
Other respiratory problems |
720[*] |
318[*] |
118 |
82[*] |
99 |
130 |
|
Drug incident |
— |
20 |
20 |
28 |
35 |
25 |
|
Surgical problems |
28 |
31 |
39 |
43 |
39 |
39 |
|
Death |
83[*] |
8 |
3 |
1 |
2 |
4 |
|
Recovery Room |
||||||
|
Laryngospasm |
28 |
43 |
187 |
177 |
165 |
166[†] |
|
Vomiting |
— |
83 |
410 |
855 |
935 |
587[†] |
|
Cardiac arrest |
55[*] |
4 |
2 |
1 |
— |
2 |
|
Arrhythmia |
— |
12 |
8 |
15 |
9 |
10 |
|
Blood pressure |
1385[*] |
12 |
10[*] |
15[*] |
32 |
17 |
|
Temperature |
471[*] |
138 |
57[*] |
86 |
159[*] |
96 |
|
Airway obstruction |
28 |
161 |
444 |
260 |
184 |
319[†] |
|
Other respiratory problems |
1163[*] |
248[*] |
105 |
78[*] |
103 |
124 |
|
Drug incident |
— |
20 |
19 |
19 |
30 |
21 |
|
Surgical problems |
28 |
63 |
131 |
167 |
76 |
122 |
Modified from Cohen MM, et al.: Anesth Analg 70:160, 1990.
|
* |
P < 0.01, exact tail probability calculation based on Poisson distribution. |
|
† |
P < 0.01 χ2 test for association. |
A report from Hopital d'Enfants Armand Trousseau in Paris was based on the Quality Assurance database involving over 24,000 pediatric anesthesia cases for a 30-month period between 2000 and 2002, when halothane had been completely eliminated from clinical use ( Murat et al., 2004 ). Although this database did not include open heart and neurosurgical cases, the nature of adverse events and their frequency have changed considerably. As a whole, respiratory events were most frequent, representing 53% of all intraoperative events ( Table 34-7 ). As with other reports, respiratory events were more frequent among infants (3.6:10,000 versus <1.5:10,000 in older children), in ears, nose, and throat (ENT) surgery than in other surgery, in children who were intubated versus not intubated, and in those with ASA PS 3 to 5 versus 1 or 2 ( Murat et al., 2004 ). Cardiac events represented 12.5% of all intraoperative events and were mostly observed in sick children (ASA PS 3 to 5).
TABLE 34-7 -- Details of respiratory and cardiac adverse events observed during anesthesia and in postanesthesia care unit (PACU) in different age groups
|
Intraoperative |
PACU |
|||||
|
0 to 1 yr |
1 to 7yr |
8 to 16 yr |
0 to 1 yr |
1 to 7yr |
8 to 16 yr |
|
|
Respiratory Event |
||||||
|
No. of anesthetics |
3681 |
12,495 |
6867 |
3681 |
12,495 |
6867 |
|
Bronchospasm |
19 |
25 |
4 |
4 |
11 |
5 |
|
Hypercarbia |
8 |
10 |
1 |
5 |
5 |
8 |
|
Hypoxemia |
56 |
90 |
24 |
21 |
34 |
15 |
|
Aspiration |
2 |
4 |
4 |
1 |
5 |
3 |
|
Unanticipated difficult intubation |
9 |
7 |
6 |
— |
— |
— |
|
Esophageal intubation |
3 |
2 |
1 |
— |
— |
— |
|
Endobronchial intubation |
6 |
3 |
1 |
3 |
5 |
7 |
|
Laryngospasm |
17 |
31 |
9 |
1 |
6 |
4 |
|
Pulmonary edema |
0 |
0 |
2 |
1 |
9 |
7 |
|
Pneumothorax |
0 |
2 |
0 |
1 |
7 |
6 |
|
Reintubation |
13 |
17 |
7 |
5 |
11 |
9 |
|
Dental trauma |
— |
— |
— |
0 |
3 |
1 |
|
Respiratory depression |
— |
— |
— |
12 |
17 |
10 |
|
Total |
133 |
191 |
59 |
54 |
113 |
75 |
|
Rate per 1000 anesthetics |
36.1 |
15.3 |
8.6 |
14.7 |
9.0 |
10.9 |
|
Cardiac Event |
||||||
|
No. of anesthetics |
3681 |
12,495 |
6867 |
3681 |
12,495 |
6867 |
|
Cardiac arrest |
4 |
2 |
2 |
0 |
0 |
0 |
|
Bradycardia |
12 |
9 |
10 |
0 |
1 |
0 |
|
Hypertension |
0 |
0 |
0 |
1 |
0 |
0 |
|
Hypotension |
4 |
6 |
11 |
0 |
0 |
0 |
|
Hypovolemia |
8 |
6 |
3 |
0 |
0 |
1 |
|
Circulatory insufficiency |
3 |
2 |
1 |
1 |
0 |
0 |
|
Tachycardia |
0 |
0 |
1 |
0 |
0 |
0 |
|
Arrhythmia |
0 |
2 |
5 |
0 |
0 |
0 |
|
Total |
31 |
27 |
33 |
2 |
1 |
1 |
|
Rate per 1000 anesthetics |
8.4 |
2.2 |
4.8 |
0.5 |
0.1 |
0.2 |
Modified from Murat I, Constant I, Maud'huy H: Perioperative anaesthetic morbidity in children: A database of 24,165 anaesthetics over a 30-month period. Pediatr Anesth 14:161, 2004.
In contrast to earlier reports, the incidence of bradycardia was greatly decreased (13:10,000) and arrhythmias essentially disappeared. There were eight cardiac arrests (3.3:10,000), of which five children were in the ASA PS 3 to 5 category and four were infants 6 months old or younger (see Table 34-7 ). There were no anesthesia-related deaths ( Murat et al., 2004 ). Vomiting was the commonest adverse event postoperatively, with an overall incidence of 6%. As with previous studies, vomiting was more frequent in older children than in infants and occurred more often after ENT surgery compared with other surgery and in children who were intubated versus those who were not ( Murat et al., 2004 ). Similarly, based on QA data of 10,000 surgical cases, Tay and others (2001) in Singapore found critical perioperative incidents four times higher in infants less than 1 year of age than older children (8.6% versus 2.1%). Respiratory events were most common (77.4%) with laryngospasm, accounting for 35.7%. There were no anesthesia-related deaths ( Tay et al., 2001 ).
Bradycardia
An outcome study from the Medical College of Virginia examined the incidence of bradycardia in nearly 8000 children less than 4 years of age ( Keenan et al., 1994 ). Bradycardia (<100 beats per minute) was more frequent in infants (1.27%) and decreased with age. The incidence in the 4-year-old group was only 0.16%. Causes of bradycardia included disease or surgery (35%), inhalation anesthesia (35%), and hypoxemia (22%). Of these children, hypotension occurred in 30%, asystole or ventricular fibrillation in 10%, and death in 8%. Significant associated factors predisposing children to bradycardic events, based on multiple logistic regression analysis, were ASA PS, emergency surgery, duration of surgery (> 4 hours), and the absence of a trained pediatric anesthesiologist supervising the anesthetic management ( Keenan et al., 1994 ).
Laryngospasm and Bronchospasm
The incidence of laryngospasm and bronchospasm has been studied in a series of large population studies in Stockholm by Olsson and others (1984, 1987 [101] [99]). The incidence of laryngospasm in children less than 9 years of age was 1.7%. The presence of respiratory infection raises the incidence to 9.6%. The incidence of laryngospasm was also increased in patients with obstructive lung disease (6.4%) and in those with a history of previous anesthetic complications (5.5%). The incidence of bronchospasm in the same age group increased from 0.4% to 4.1% in those with respiratory infection. The incidence of bronchospasm was also elevated (2.4%) in patients at high risk (ASA PS 3 or higher) ( Olsson, 1987 ).
Possible effects of recent or current upper respiratory tract infection (URI) and incidence of respiratory events have been studied by a number of investigators using parental interview or written questionnaires. Of more than 1500 children, Schreiner and others (1996) from Children's Hospital of Philadelphia found that patients who developed laryngospasm were more than twice as likely to have an active URI than were patients in the control group without URI. A survey of more than 2000 children by Parnis and others (2001) from Adelaide, Australia, did not find statistically significant differences in the long-term outcome of children with a recent history of URI. They did, however, find that orotracheal intubation was associated with an increased probability of respiratory complications compared with facemask or laryngeal mask airway. Similarly, in more than 1000 children, Tait and others (2001) found no difference between children with active or recent URI versus asymptomatic children, with respect to the incidence of laryngospasm, bronchospasm, or long-term respiratory sequelae. However, children with current or recent URI had significantly more overall adverse respiratory events, including breath holding and major desaturation (SpO2 < 90%). Independent risk factors for adverse respiratory outcome in children with active URI included tracheal intubation (<5 years of age), history of prematurity, reactive airway disease, parental smoking, surgery involving the airway, and the presence of copious secretions and nasal congestion ( Tait et al., 2001 ).
Aspiration
Studies before the 1970s reported high morbidity and mortality from pulmonary aspiration of gastric contents (Mendelson, 1946). The Baltimore Anesthesia Study Committee reported a mortality rate of 39% in children associated with pulmonary aspiration ( Graff et al., 1964 ) (see Chapter 10 , Induction of Anesthesia and Maintenance of the Airway). Studies reported since the 1980s, however, indicate marked improvements in outcome.
From a computer database between 1967 and 1985, Olsson and others (1986) identified 83 cases of pulmonary aspiration of gastric content of more than 185,000 anesthetic cases in all ages (4.7:10,000 cases). The rate of gastric aspiration in children less than 9 years of age (8.6:10,000) was nearly three times higher than that in young adults (20 to 49 years old). In 47% of patients with aspiration, pneumonia or atelectasis developed, as confirmed by chest radiograph. The mortality rate in children was relatively low (0.2:10,000) (Olsen et al., 1986). Risk factors associated with aspiration included the skill and experience of anesthetists, a number of coexisting diseases, ASA PS 3-5, emergency surgery, nighttime operation, history indicating an increased risk of regurgitation (esophageal disease, pregnancy), and difficult intubation. Other high-risk categories included children with intestinal obstruction, increased intracranial pressure, increased abdominal pressure, and obesity. Incidence of gastric aspiration was even lower in studies from the French-speaking countries (1.0:10,000) ( Tiret et al., 1988 ) and from Norway (2.9:10,000) (Mellin-Olsen, Fasting and Gisvold, 1996 ) in the 1980s. No fatalities were reported.
Borland and others (1998) studied the incidence and outcome of perioperative aspiration during the 5-year period between 1988 and 1993 involving over 50,000 general anesthetic cases at Children's Hospital of Pittsburgh. They identified 52 cases of aspiration (10.2:10,000 cases), of which 25 patients aspirated gastric content (4.9:10,000) (and the rest were blood or pharyngeal secretions). Approximately 80% of aspirations occurred during induction. Most patients were treated aggressively with fiberoptic bronchoscopy through the endotracheal tube, removal of solid particles, and continuous positive pressure ventilation. Most patients had radiographic evidence of aspiration (infiltration, pneumonia, atelectasis, or pulmonary edema), but fulminant chemical pneumonitis secondary to aspiration, as reported in early publications (Mendelson, 1946), was absent. No death was attributable to aspiration. Among the different pediatric age groups, the incidence of aspiration was highest among children 6 to 11 years of age (0.22%). Several risk factors for intraoperative aspiration were identified: ASA PS 3 or higher, a history of previous esophageal surgery, and patients with previous chemotherapy undergoing central venous catheter (Broviac) placement. Twenty-nine percent of these children were kept intubated in the postanesthetic care unit (PACU) for several hours or longer, but only 23% of these patients stayed overnight. None of these children developed clinically significant pneumonia, and there were no deaths ( Borland et al., 1998 ).
Similarly, a study from the Mayo Clinic reported a low incidence of aspiration (3.8:10,000). In this report, however, the incidence of aspiration was similar to that of adults (3.1:10,000). There was no serious respiratory morbidity and no associated deaths ( Warner et al., 1999 ). These epidemiologic studies suggest that the incidence of gastric aspiration and associated morbidity and mortality, especially in children, has declined considerably. The risk of aspiration in general, with the exception of the Mayo Clinic report ( Warner et al., 1999 ), remained higher in infants and children than in adults ( Olsson et al., 1986 ; Tiret et al., 1988 ; Flick et al., 2002 ).
▪ POSTOPERATIVE COMPLICATIONS
Postoperative Hypoxemia
During general anesthesia, static tension of the thoracic inspiratory muscle is abolished and the balance between the outward recoil of the thorax and the inward recoil of the lungs is altered. This change in balance results in the reduction of resting lung volume (functional residual capacity [FRC]), airway closure, collapse of alveoli (microatelectasis), and increased venous admixture, particularly in infants and young children (see Chapter 2 , Respiratory Physiology in Infants and Children). By means of pulse oximetry, Motoyama and Glazener (1986) were the first to demonstrate that a large proportion (42%) of healthy infants and children undergoing simple elective surgical procedures become hypoxemic in the postoperative recovery room (PACU). Patients sleeping in the PACU tend to be more hypoxemic and for a longer duration than those who are awake and sitting up ( Motoyama and Glazener, 1986 ), but the presence of hypoxemia is not clinically obvious and does not correlate with the recovery score (Soliman et al., 1988 ). In a study involving a large number (N = 1152) of healthy infants, children, and adults (ASA PS 1) undergoing plastic surgical procedures, postoperative oxygen saturation (SpO2) was followed frequently for two hours. The incidences of both moderate (SpO2, 86% to 90%) and severe (SpO2 < 86%) hypoxemia were the highest among infants (36.6% and 16.7%, respectively), followed by toddlers (20% and 10% in 1- to 3-year-olds), children (14% and 3.3%), and adults (8% and 0.6%). The duration of hypoxemia was also significantly longer in infants than in older age groups (Xue et al., 1996 ) ( Fig. 34-3 ).
|
FIGURE 34-3 The recovery tendencies of arterial oxygen saturation (SpO2) within the first hour after operation in four age groups. Group 1: infants <1 year; group 2: toddlers 1 to 3 years; group 3: children 3 to 14 years; group 4: teenagers and adults 14 to 58 years. (From Xue FS, Huang YG, Tong SY, et al.: A comparative study of early postoperative hypoxemia in infants, children, and adults undergoing elective plastic surgery. Anesth Analg 83:709-715, 1996, Fig. 1, p. 712, reproduced with permission.) |
Patients also become hypoxemic as often during the short transport from the operating room to the PACU ( Pullerits et al., 1987 ) because the benefit of oxygen breathing to maintain oxygenation lasts only a few minutes. Children with upper respiratory infection ( DeSoto et al., 1988 ) and infants younger than 6 months of age are at increasing risk of developing hypoxemia ( Kataria et al., 1988 ; Xue et al., 1996 ). Most pediatric anesthesiologists, therefore, recommend routine oxygen administration during the transport of children to and in the PACU ( Duncan, 1995 ).
Postoperative Apnea
Postoperative apnea in prematurely born infants has become a major clinical concern since the early 1980s, when the number of premature infants surviving neonatal intensive care started to increase. Apnea is usually defined as the cessation of breathing lasting longer than 15 to 20 seconds or lasting for a lesser duration associated with bradycardia, cyanosis, or pallor ( Thach, 1985 ). Apneic spells in these infants after simple surgical procedures are mostly central in origin (cessation of respiratory effort), although some infants have mixed (central and obstructive) apneas ( Kurth et al., 1991 ). Postoperative apnea occurs more commonly in infants with a previous history of apnea ( Liu et al., 1983 ) and those younger than 42 to 44 weeks' postconception. Apnea is infrequent after 44 weeks' postconception ( Malviya et al., 1993 ), although apnea in older ex-premature infants (up to 55 weeks' postconception) has been reported after more extensive surgical procedures ( Kurth et al., 1987 ).Malviya and others (1993) recommend that all former premature infants of less than 44 weeks' postconception be monitored for at least 12 hours postoperatively. Another important risk factor for postoperative apnea appears to be the presence of anemia ( Welborn et al., 1991 ).
In 1995, Coté and others published the results of meta analysis of the data from eight published reports of postoperative apnea between 1987 and 1993 involving 384 ex-premature infants following inguinal hernia repair. They concluded that (1) apnea was strongly and inversely correlated both with gestational age and postconceptual age; (2) an associated risk factor was continuing episodes of apnea at home; (3) small-for-gestational-age infants seemed to be somewhat protected from apnea compared with those with normal or large-for-gestational-age infants; (4) anemia (hematocrit < 30) was a significant risk factor even beyond 43 weeks postconceptual age; and (5) relationships of postoperative apnea with history of necrotizing enterocolitis, neonatal apnea, respiratory distress syndrome, bronchopulmonary dysplasia, or operative use of opioids and/or muscle relaxants could not be determined ( Coté et al., 1995 ). The probability of apnea in nonanemic infants, free of apnea in the recovery room, decreases with postconceptual and postnatal ages but is not less than 5% (with 95% confidence limits) until postconceptual age of 48 weeks (with gestational age, 35 weeks) and not less than 1% until postconceptual age of 56 weeks (gestational age, 32 weeks) or postconceptual age of 54 weeks (gestational age, 35 weeks) ( Coté et al., 1995 ) ( Fig. 34-4 ).
|
FIGURE 34-4 Probability of postoperative apnea versus postconceptual and gestational ages of former preterm infants. (From Coté CJ, Zaslavsky A, Downes JJ, et al.: Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis.Anesthesiology 82:809-822, 1995, Fig. 2, p. 813, reproduced with permission.) |
Based on these findings, it is generally recommended that ex-premature infants less than 44 to 46 weeks' postconception be admitted overnight for monitoring following general anesthesia in the United States. Whether the infant with postconceptual age between 46 and 48 weeks or even 52 weeks is admitted overnight depends on the decision made case by case between the anesthesiologist and the surgeon, based on a number of factors. These factors include the general health of the infant and his or her home environment (parents, passive smoking, distance from the hospital, etc.). However, the decision often depends on the general policies of the hospital administration and insurance providers, and these policies do not necessarily represent the best interest of the patient or the health care providers. In countries like France and Japan, where economic pressure on health care resources is less stringent than in the United States, most infants less than 60 weeks' postconception are admitted overnight for monitoring ( Murat, 2002 ).
Incidence of postoperative apnea was reported to be lower after spinal anesthesia alone than after general (halothane) anesthesia, but spinal anesthesia combined with ketamine increases the incidence of apnea more than that with general anesthesia ( Welborn et al., 1990 ). Caffeine seems to be helpful in preventing postoperative apnea ( Welborn et al., 1988 ).
Postintubation Croup
The major cause of postintubation croup is subglottic injury and edema associated with traumatic intubation, especially with an oversized endotracheal tube. Koka and others (1977) made an important observation that the incidence of postintubation croup increases markedly when there is no air leak around the endotracheal tube with the airway pressure exceeding 40 cm H2O. Consequently, it has become a standard practice in pediatric anesthesia to choose an endotracheal tube that produces air leak around the tube with a pressure lower than 30 cm H2O. With this preventive measure in clinical practice, the incidence of postintubation croup has decreased dramatically from 1% to less than 0.1%, along with reductions in the severity of croup ( Litman and Keon, 1991 ). With the presence of URI, however, the incidence of airway complications and the tendency for oxygen desaturation increase (Cohen and Cameron, 1992; Rolf and Coté, 1992 ).
Postoperative Nausea and Vomiting
Although rarely life-threatening, postoperative nausea and vomiting (PONV) remains the single most common complication resulting in unscheduled overnight admissions in same-day surgery settings (Cohen et al., 1990 ; Patel and Rice, 1991 ). The average incidence of PONV in children over 3 years of age was reported to be over 40%. The incidence of PONV has decreased considerably with newer anesthetics and techniques as well as with more effective medications ( Murat et al., 2004 ). The incidence of PONV is higher after certain types of surgery including adenotonsillectomy, eye muscle surgery for strabismus, and orchiopexy. Other factors affecting the incidence of PONV include the gender and age of the child (infrequent in infants), PONV after previous surgery or history of motion sickness, anesthetic techniques (inhaled anesthetics and nitrous oxide versus intravenous anesthesia with propofol), intraoperative opioids, inadequate pain control, gastric distention, and the skill of the anesthesiologist ( Patel and Rice, 1991 ; Martin et al., 1993 ; Weir et al., 1993 ; Weinstein et al., 1994 ; Duncan, 1995 ). A mandatory requirement for oral fluid intake and early ambulation before discharge from the short stay unit was also associated with increased incidence of vomiting ( Schreiner et al., 1992 ; Weinstein et al., 1994 ). Serotonin (5-HT3) receptor antagonists (such as ondansetron and granisetron) have shown to be highly effective in preventing or treating PONV (Patel et al., 1996; Fujii et al., 1996 ). Prophylactic use of dexamethasone was also found to be effective ( Aouad et al., 2001 ) (see Chapter 11 , Intraoperative and Postoperative Management).
▪ COMPLICATIONS OF REGIONAL ANESTHESIA
A survey by the ASA Closed Claims Study on the complication of regional anesthesia revealed that of 2400 closed anesthesia malpractice claims cases, 29 adult patients and 1 pediatric patient were identified who developed cardiac arrest during regional anesthesia, resulting in death or severe brain damage ( Morray et al., 1993 ). From the analysis of these data, it can be concluded that (1) cardiac arrest resulting in death or other major outcomes can occur during apparently well-managed spinal or epidural anesthesia in young, healthy patients undergoing relatively minor procedures, because respiratory insufficiency from sedation is not recognized, and (2) pulse oximetry would have given an early warning of respiratory insufficiency ( Caplan et al., 1988 ; Cheney, 1988 ; Keats, 1988 ).
Valley and Bailey (1991) , in a retrospective survey involving 138 pediatric patients who received caudal morphine, reported 11 patients (8%) with postoperative respiratory depression. All but one incident occurred in infants less than 12 months of age and within 12 hours of caudal morphine administration (70 mcg/kg). Krane (1988) reported a life-threatening delayed respiratory depression in a 2.5-year-old boy 3.5 hours after the administration of caudal morphine (100 mcg/kg, a much higher dose than today's standards of 30 to 50 mcg/kg) for postoperative analgesia. Intravenous naloxone was continued until 16.5 hours after caudal morphine to maintain adequate breathing. Jones and others (1984) used intrathecal morphine in 56 children undergoing open-heart surgery. Respiratory depression occurred (most frequently, 3.5 to 4.5 hours after morphine administration) in 6 of 27 patients (22%) who received 30 mcg/kg of morphine and 3 of 29 children (10%) who received 20 mcg/kg. Patients receiving epidural or intrathecal morphine should therefore be admitted overnight and their respiration continuously monitored.
Giaufré, Dalens, and Gombert (1996) reported a 1-year prospective study (1993-1994) of morbidity/mortality associated with regional anesthesia by the French Language Society of Pediatric Anesthesia involving over 24,000 regional blocks of about 85,000 pediatric anesthesia cases of which central blocks (approximately 15,000 cases [62%]) were the most common, followed by peripheral nerve blocks (17%) and others (22%). Of the central block, caudal block was most common (12,000, or 80% of central block or 50% of the total), followed by lumbar epidural (1700) and spinal anesthesia (500). A total of only 23 incidents was reported, including 0% for peripheral blocks, 11% (0.7:1000) for caudal blocks, 9% (3.7:1000) for lumbar epidural blocks, 2% (6.8:1000) for sacral epidural blocks, and 1% (2:1000) for spinal anesthesia (Giaufré, et al., 1996). Complications included eight dural punctures (resulting in total spinal block in four), six intravascular injections (resulting in seizures or arrhythmias), two overdosage with arrhythmias, and one opioid-related apnea. No fatalities were reported.
▪ COMPLICATIONS ARISING FROM SEDATION
According to the data compiled by the U.S. Department of Health and Human Services, more than 80 deaths attributable to midazolam occurred within 3 years after its introduction for clinical use in 1986. Midazolam was used, often in combination with fentanyl, for the sedation of patients undergoing various procedures without the supervision of anesthesiologists ( Bailey et al., 1990 ). Of these deaths associated with midazolam, 78% were respiratory events, with opioids being used in 57% of these cases ( Bailey et al., 1990 ).
A collaborative study by the American Society of Gastrointestinal Endoscopy and the U.S. Food and Drug Administration, involving over 21,000 endoscopic procedures under sedation, revealed the incidence of serious cardiorespiratory outcome to be 54:10,000 cases with a mortality rate of 3:10,000 ( Arrowsmith et al., 1991 ); that is 10 to 50 times higher than the reported deaths associated with general anesthesia ( Tiret et al., 1986 , 1988; Buck et al., 1987 ; Holland, 1987 ; Eichhorn, 1989 ). These extremely high morbidity and mortality rates of conscious and deep sedations (apparently including inadvertent general anesthesia and deaths) performed by nonanesthesiologists without adequate skills, proper monitoring, or supervision have led the way to the establishment and modifications of the new sedation guidelines by the Section of Anesthesiology, American Academy of Pediatrics ( Committee on Drugs, Section on Anesthesiology, American Academy of Pediatrics, 1985 , 1992). Although the terminology adopted (“conscious” sedation in particular) were misnomers (if not oxymorons), in hindsight the guidelines included the approach similar to that commonly practiced by anesthesiologists, that is, proper fasting, preprocedural history and physical examinations with a special attention to airways, informed consent, monitoring including pulse oximetry, documentation of drugs used and vital signs during and after the procedure, and discharge criteria ( Coté, 2004 ).
The Joint Commission on the Accreditation of Healthcare Organizations in the United States (JCAHO, 1992) modified its regulations and published rules to develop new guidelines in each health care institution it accredits (available at www.jcaho.org). To further improve patient safety for sedation in accordance with the new JCAHO regulations, a task force by the ASA developed new guidelines for sedation by nonanesthesiologists ( Gross et al., 2002 ). The sedation guidelines were again updated in 2002 ( American Society of Anesthesiologists Task Force on Sedation and Analgesia by Non-Anesthesiologists, 2002 ) with the new terminology (available at ASA Web site: www.asahq.org/standards) and were later incorporated by JCAHO and by the AAP ( Committee on Drugs, Section on Anesthesiology, American Academy of Pediatrics, 2002 ). The term “conscious sedation” has been eliminated, and instead, three stages of procedural sedation are described: minimal, moderate, and deep stages (plus general anesthesia) ( Coté, 2004 ).
Under the new JCAHO regulations, the director of anesthesia service in each institution has a responsibility for developing new “within-institution” sedation guidelines by nonanesthesiology services to further improve patient safety. General guidelines include onsite availability of oxygen and positive pressure oxygen delivery system (which can provide the minimum of 90% oxygen for 60 minutes), availability of a resuscitation kit (including drugs, laryngoscope, and endotracheal tubes), a suction apparatus, and monitors (pulse oximeter, electrocardiography, and blood pressure apparatus). Documentation for sedation should include evaluation of health status before sedation, informed consent, record of drugs given (the time and doses), and vital signs (oxygen saturation, heart and respiratory rates). For deep sedation, there must be a dedicated person (registered nurse, respiratory therapist, etc.) in addition to the practitioner, whose responsibility is only monitoring and who is trained to perform resuscitation.
Using the QA database created specifically for procedural sedation, Malviya and others (1997) identified 239 adverse outcomes (20% of 1140 children), mostly after receiving recommended doses of chloral hydrate. Oxygen desaturation (5.5%) was the most common adverse outcome including laryngospasm and apnea in five children. Inadequate sedation occurred in 150 (13.2%) children. These findings appear to indicate that the establishment and enforcement of safety guidelines for procedural sedation have considerably reduced the incidence of adverse outcomes.
Analysis of adverse sedation events reported to the U.S. Food and Drug Administration between 1969 and 1996 by Coté and others (2000) revealed that of 95 incidents reported, 60 ended up in death (51) or permanent neurologic injury (9). Although the incidence of respiratory events (about 80% of all events, mostly hypoxia, laryngospasm, and/or apnea) was similar between hospital and nonhospital settings, inadequate resuscitation (57.1% versus 2.3%) and death or permanent neurologic injury (92.8% versus 37.2%) occurred more frequently in nonhospital versus in hospital environments. Death or severe outcome occurred disproportionately more often (32 of 95 cases) involving sedation for dental procedures (mostly at nonhospital settings). Ten children sustained death or permanent neurologic injury in the car or at home after being discharged from medical supervision despite deep levels of residual sedation. Unsupervised sedative medication by a parent at home (or by a technician at a facility) caused an additional two arrests in the car on the way to the hospital or clinic ( Coté et al., 2000 ). The results of this report imply the inadequacy of existing (or the nonexistence of) discharge criteria and their practice. Two reports have further addressed these issues.
Motas and others (2004) studied the efficacy and safety of procedural (light or deep grade) sedation in 86 children under 12 years of age undergoing sedation by nonanesthesia services (for computed tomography scans, cardiac catheterizations, gastrointestinal endoscopy, and dental procedures). A variety of medications were used by different services, including intravenous pentobarbital, intravenous midazolam with fentanyl or meperidine, oral chloral hydrate with meperidine and hydroxyzine, and intramuscular or intravenous ketamine ( Motas et al., 2004 ). An independent observer applied the Bispectral Index (BIS) monitor (40 to 60, general anesthesia; 61 to 70, deep sedation; 71 to 90, minimum, and >90, awake) and the University of Michigan Sedation Scale (UMSS) (0 to 4 observational scale: 0, awake; 1, minimal sedation [tired, sleepy]; 2, moderately sedated [easily arousable]; 3, deeply sedated [deep sleep, arousable only with strong stimulus]; and 4, unarousable or general anesthesia) at 10-minute intervals for 1 hour. The goal of either light or deep sedation was attained in 53% (BIS) and 72% (UMSS). Depth consistent with general anesthesia was observed in 35% (BIS) and 0% (UMSS) of patients, and those consistent with awake state (failure) was observed in 12% (BIS) and 28% (UMSS). About 8% of patients experienced desaturation and airway events. The patients were often sedated either too deeply or not enough, and the goal of either light or deep procedural sedation was not achieved in large numbers of children.
Malviya and others (2004) assessed the readiness of discharge in 29 children following the procedural sedation for echocardiographic examinations with either chloral hydrate (93%) or midazolam with diphenhydramine (7%). A trained observer used BIS monitor, UMSS scores every 10 to 15 minutes, a Modified Maintenance of Wakefulness Test (MMWT), and the visual observation of the time the child was able to stay awake for 20 minutes, until revised discharge criteria were met (BIS > 90, UMSS of 0 or 1, MMWT > 20 minutes). There were moderate correlations among BIS, UMSS, and MMWT (P < 0.01). Revised criteria correctly identified wakefulness (BIS value > 90) in 88% of patients. However, when discharged by the nurse, only 55% of patients returned to the baseline BIS value (>90); it took longer to meet the revised criteria (more appropriate and safer) compared with standard criteria (nursing judgment) (75 minutes versus 13 minutes, P = 0.001).
Thus, Melviya and others (2004) clearly demonstrated that sedation with chloral hydrate can result in prolonged sedation even after the children reached currently used (but unsatisfactory) discharge criteria by nurses, with a potential for airway obstruction and adverse outcome ( Coté et al., 2000 ). The results of this study have several important implications. First, the currently practiced guidelines are inadequate and need changes, using more reliable criteria, such as UMSS, MMWT, BIS monitor, or their combinations, to further improve patient safety associated with procedural sedations. Second, the duration of postsedation monitoring should be increased beyond what is currently practiced, and the hospital must respond to increase staffing needs for nurses in the recovery area and to provide additional space for adequate patient observation (quiet space for MMWT) and recovery, changes that have associated cost increases. Third, anesthesia service should provide additional guidelines to nonanesthesiologists for the proper selection of sedative and hypnotic drugs, with shorter elimination half-life to shorten the recovery time ( Coté, 2004 ). In addition, office-based procedures under sedation should either be performed under the care of anesthesiologists within the office setting or moved to hospital-based facilities to further decrease untoward events (see Chapter 26 , Office-Based Anesthesia).
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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.
Copyright © 2005 Mosby, An Imprint of Elsevier
▪ COMMON CAUSES OF ANESTHESIA-RELATED MISHAPS
▪ JUDGMENT ERRORS
If one accepts the theory that “to err is human” ( Kohn et al., 1999) and recognizes that “all human beings, without any exception whatsoever, make errors and [errors]… are a completely normal and necessary part of human cognitive function” ( Allnut, 1987) , then it is not surprising to realize that most anesthetic mishaps involve human errors and are preventable ( Salem et al., 1975 ; Cooper et al., 1978 ; Holland, 1987 ). Cooper and others (1978) , with the use of a carefully structured interview technique with a group of anesthesiologists, collected incidents in which human error or equipment failure occurred. These investigators found that 82% of incidents were caused by preventable human error; the remaining incidents were mostly caused by equipment failure. Analysis of 238 closed anesthesia malpractice claims involving pediatric patients revealed that 43% of these claims were related to inadequate ventilation and resulted in death or severe permanent neurologic damage ( Morray et al., 1993 ). Morray and others concluded that 89% of these cases could have been prevented if they were monitored with pulse oximetry or capnography.
Holland (1987) compared incidences of various categories of mishaps during his three decades of investigation involving anesthesia-related mortality in patients of all ages ( Table 34-8 ). In the 1960s, anesthetic overdose, wrong choice of anesthetics, inadequate preoperative preparation, and inadequate crisis management dominated as frequent causes of adverse outcomes, indicating inadequacy (according to today's standard) of equipment and physician experience administering anesthesia. The total incidence of management errors involving fatality was 2.7:10,000 anesthetics. There has been a dramatic decrease in the incidence of management errors with time as well as changes in the dominant categories of error in management over the decades. In the 1980s, inadequate preparation and inadequate postoperative management ranked high among the categories of errors causing anesthesia-related fatalities. Incidence of management errors decreased to 0.55:10,000 anesthetics, about one fifth that in the 1960s. Factors frequently associated with preventable adverse outcomes (both fatal and nonfatal) include a failure to perform proper review of patients and anesthesia apparatus, distraction (inattention, haste, fatigue, and boredom), lack of experience, and lack of a skilled assistant ( Craig and Wilson, 1981 ; Derrington and Smith, 1987 ).
TABLE 34-8 -- Errors of management: Numbers and rank order of frequency
|
Error |
1960 to 1969 |
1970 to 1980 |
1983 to 1985 |
Whole Series |
||||
|
|
No. |
Rank |
No. |
Rank |
No. |
Rank |
No. |
Rank |
|
Inadequate preparation |
102 |
3 |
93 |
1 |
23 |
1 |
218 |
1 |
|
Wrong choice |
120 |
2 |
65 |
3 |
13 |
4 |
198 |
4 |
|
Overdose |
127 |
1 |
34 |
7 |
14 |
3 |
175 |
4 |
|
Aspiration |
41 |
9 |
18 |
11 |
1 |
9 |
60 |
10 |
|
Inadequate resuscitation |
63 |
7 |
49 |
4 |
6 |
5 |
118 |
6 |
|
Hypoxie mixture |
14 |
12 |
0 |
— |
0 |
— |
14 |
12 |
|
Inadequate ventilation |
68 |
5 |
21 |
9 |
1 |
9 |
90 |
7 |
|
Inadequate monitoring |
22 |
11 |
19 |
10 |
6 |
5 |
47 |
11 |
|
Technical mishap |
25 |
10 |
40 |
6 |
1 |
9 |
66 |
9 |
|
Inadequate crisis management |
102 |
3 |
80 |
2 |
4 |
8 |
186 |
3 |
|
Inadequate reversal |
52 |
8 |
22 |
8 |
5 |
7 |
79 |
8 |
|
Inadequate postoperative management |
68 |
5 |
43 |
5 |
16 |
2 |
127 |
5 |
|
Total errors |
804 |
|
484 |
|
90 |
|
1378 |
|
|
Errors per patient |
2.4 |
|
2.0 |
|
1.8 |
|
2.2 |
|
Modified from Holland R: Br J Anaesth 59:834, 1987.
▪ EMERGENCY OR URGENT CASES
Inadequate preanesthetic preparation occurs most frequently with emergency or “urgent” cases and most commonly represents failure to appreciate the degree of dehydration and electrolyte imbalance (Holland, 1987 ). In the British CEPOD study cited previously, more than 20% of anesthesia-related deaths occurred after surgery performed as emergencies and an additional 40% occurred in operations classified as urgent ( Buck et al., 1987 ). In the New South Wales study, the risk of anesthesia-attributable death in patients undergoing emergency anesthesia is 10 times that of the overall incidence (Holland, 1987 ). In the CEPOD study, anesthetists were dissatisfied with preoperative preparations in 14% of cases that ended with anesthesia-related deaths, but they presumably were pressured or persuaded by surgeons into administering anesthesia. On the basis of these findings, Lunn and Devlin (1987) emphasize the importance of proper preanesthetic preparation as an important deterrent of tragic outcome. In children the incidence of bradycardic episodes, both fatal and nonfatal, during anesthesia was reported to be significantly higher among emergency surgical procedures (2.7%) than in elective procedures (1.1%) ( Keenan et al., 1994 ).
▪ TIMING OF OCCURRENCE
Keenan and Boyan (1985) , in a 15-year study of cardiac arrest resulting from anesthesia in a university hospital setting, found 18 of 27 cases occurred during the induction of anesthesia, whereas the remaining 9 occurred intraoperatively. However, in five of six patients in the pediatric age group who sustained cardiac arrest (1 day to 6 years), the arrest occurred during the maintenance of anesthesia. In most other reports, critical incidents or mishaps have occurred most frequently during the maintenance period of anesthesia ( Cooper et al., 1978 ; Craig and Wilson, 1981 ; Gibbs, 1986 ). The maintenance period is not the quiet interlude between often stormy induction and emergence that many anesthesiologists had for a long time supposed ( Epstein, 1978 ). In the survey involving 112,000 general anesthetic cases in a teaching hospital between 1975 and 1983 ( Cohen, Duncan, and Tait, 1988 ), the incidence of intraoperative adverse events among adults was lower than events in the PACU. In contrast, the incidence of adverse events in children tended to be higher in the PACU (12.9% to 13.2%) than during surgery (8.6% to 9.5%) ( Tiret et al., 1988 ). Machine-patient disconnection was a frequent occurrence in the 1970s ( Cooper et al., 1978 ) before the disconnect alarm became a standard feature of anesthesia machines, mandated by the American National Standard Institute Z79 Committee on Anesthesia Equipment.
▪ ANESTHETIC OVERDOSAGE
Drug overdose as the cause of anesthetic death occurs, although the incidence has decreased since the 1980s (Holland, 1984, 1987 [58] [59]), and it accounted for only 5.4% of anesthetic deaths reported to the Medical Defense Union of the United Kingdom between 1970 and 1979 ( Utting, Gray, and Shelley, 1979 ). In a 15-year study between 1969 and 1983 by Keenan and Boyan (1985) , an “absolute” overdosage (a dose well in excess of the usual clinical range) caused one third of all cardiac arrests resulting from anesthesia. Of six incidents of cardiac arrest in children in this series, absolute overdosage with halothane was responsible in five cases; the other resulted from airway obstruction during nitrous oxide-curare anesthesia.
As described earlier, the POCA Registry database revealed that between 1994 and 1997, cardiovascular depression with halothane accounted for 66% of all medication-related cardiac arrests. In healthy children with ASA PS 1 or 2, 64% of all arrests were medication related in comparison with 23% in those with ASA PS 3 to 5 ( Morray et al., 2000 ). The database between 2000 and 2003, when halothane had been replaced by sevoflurane as the primary inhalation induction agent, showed a dramatic decrease in medication-related cardiac arrest, from 37% to 12% of the total arrests ( Morray, 2004 ), indicating the importance of safer anesthetic drugs for reducing medication-related complications (see Fig. 34-2 ).
▪ RISK FACTORS IN PEDIATRIC ANESTHESIA
A number of perioperative risk factors specific to infants and children have been identified.
Age
Infants less than 1 year of age are at higher risk of developing complications ( Tiret et al., 1988 ; Cohen et al., 1990 ). A prospective survey in France between 1978 and 1982 involving 440 institutions and a total of 40,240 anesthetic procedures found 27 major complications, of which 9 occurred in infants (0.43:10,000 cases), an incidence significantly higher than that in children (0.05:10,000) ( Tiret et al., 1988 ). Infants less than 1 year of age also showed a significantly higher incidence of airway obstruction and other respiratory problems than did older children ( Cohen et al., 1990 ). Cohen and others (1990) reported that the intraoperative incidence of complications in children was about the same as that in adults, but postoperative complications (35%) were twice as frequent as in adults (17%). The POCA Registry database (1994-1997) revealed 83 of 150, or 55%, anesthesia-related cardiac arrests occurred in infants less than 12 months of age ( Morray et al., 2000 ) (see Table 34-5 ).
Physical Status
Correlation between perioperative cardiac arrest and ASA PS has been reported in adults ( Keenan and Boyan, 1985 ). In a large-scale prospective survey in France involving infants and children, Tiret and others (1988) showed a highly significant correlation between the ASA PS classification and the incidence of major perianesthetic complications in children ( Table 34-9 ). They also found a highly significant correlation between the perioperative adverse outcomes and the number of coexisting diseases. The POCA Registry database between 1994 and 1997 showed 100 of 150 (66.7%) of all anesthesia-related cardiac arrests occurred among children with ASA PS 3 to 5 ( Morray et al., 2000 ) (see Table 34-5 ).
TABLE 34-9 -- Risks of pediatric anesthesia
|
|
No. of Anesthetics |
Rate of Complications (per 1000) |
Significance |
|
ASA PS |
|||
|
1 |
36,903 |
0.4 |
|
|
2 |
1461 |
3.4 |
P < 0.001 |
|
3 |
518 |
11.6 |
|
|
4, 5 |
122 |
16.4 |
|
|
No. of Coexisting Diseases |
|||
|
0 |
36,544 |
0.5 |
|
|
1 |
3064 |
1.3 |
P < 0.001 |
|
2 |
490 |
4.1 |
|
|
≥3 |
142 |
21.1 |
|
|
Previous Anesthetic |
|||
|
No |
25,517 |
0.5 |
|
|
Yes |
11,343 |
1.1 |
P < 0.05 |
|
Duration of Preoperative Fasting (hours) |
|||
|
<8 |
5189 |
1.5 |
|
|
>8 |
34,067 |
0.6 |
P < 0.05 |
|
Emergency |
|||
|
No |
33,391 |
0.5 |
|
|
Yes |
5918 |
1.5 |
P < 0.05 |
Modified from Tiret L, et al.: Br J Anaesth 61:263, 1988.
|
ASA PS, American Society of Anesthesiologists physical status. |
Emergency Surgery
The French study ( Tiret et al., 1988 ) showed a three-fold increase in perioperative complications in pediatric emergency cases compared with the scheduled cases (see Table 34-9 ). Similarly, Keenan and others (1994) found a highly significant increase of bradycardic episodes in children during emergency surgery compared with those with elective procedures (2.7% versus 1.1%).
Training
Proper training or experience is particularly important in pediatric anesthesia for minimizing the incidence of adverse outcome. In a retrospective study in a large university hospital over a span of 7 years,Keenan and others (1991) reviewed the incidence of cardiac arrests occurring in infants less than 1 year of age. No anesthesia-related cardiac arrests occurred when trained pediatric anesthesiologists were in charge of pediatric cases. In contrast, when nonpediatric anesthesiologists were supervising, cardiac arrests occurred at a frequency of 19.7:10,000 pediatric anesthetics, including deaths. In a subsequent prospective study from the same institution for the period of 9 years ending in 1992, the incidence of bradycardic episodes was significantly higher when pediatric anesthesiologists were not supervising the trainees administering anesthetics to infants (2.1%) compared with when pediatric anesthesiologists supervised the trainees (0.8%) ( Keenan et al., 1994 ).
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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.
Copyright © 2005 Mosby, An Imprint of Elsevier
▪ PREVENTION OF ANESTHESIA-RELATED MISHAPS
The first important step toward patient safety is prevention of critical events. As is clear from the foregoing discussion, a number of steps should be taken to achieve this goal.
▪ PREANESTHETIC PREPARATION
Preoperatively, the patient's past medical history, especially anesthetic history, if any, should be reviewed thoroughly, and the patient should be examined carefully. The anesthesia machine, accessories, and drugs should also be checked carefully, because failure to perform these steps properly has been identified as a major cause of anesthesia-related mishaps, including death (Holland, 1984, 1987 [58] [59];Derrington and Smith, 1987 ). In an emergency or urgent situation (perhaps with the exception of exsanguination, cardiac tamponade, or acute upper airway obstruction), one should try to take at least minimal necessary steps (e.g., fluid resuscitation, transfusion, correction of electrolytes, acid-base imbalance, and fever) to stabilize the patient for anesthesia and surgery in a coordinated effort with the surgeon. One should not yield to unreasonable pressures to start the case before the patient is best prepared under these circumstances. Indeed, hypovolemia and anemia are reported to be the major causes of anesthesia-related cardiac arrest in infants and children ( Salem et al., 1975 ).
If the anesthesiologist is unfamiliar or uncomfortable with uncommon pathophysiology (for instance, an infant with cyanotic heart disease coming for noncardiac surgery or a child with craniopharyngioma and diabetes insipidus), the anesthesiologist should not hesitate to ask for consultation with a senior anesthesiologist or other specialists. In addition, especially in an emergency situation (such as post-tonsillectomy bleeding or acute epiglottitis), an experienced assistant, preferably an attending pediatric anesthesiologist, should be standing by for the induction. Keenan and others (1994) found a significantly lower incidence of bradycardic events with the presence of a pediatric anesthesiologist during induction. In teaching institutions, resident trainees should always be supervised by a pediatric attending anesthesiologist for a pediatric patient. Lack of an experienced assistant has been associated with anesthesia-related mortality and major morbidity ( Craig and Wilson, 1981 ; Derrington and Smith, 1987 ; Eichhorn et al., 1989; Keenan et al., 1994 ). A reluctance to ask for help, whether out of insecurity, pride, or ill-conceived heroism (or machismo), has no place in a pediatric anesthesia emergency and is the first step toward disaster.
▪ VIGILANCE
A timely recovery from impending failure is the key to patient safety. It is, therefore, extremely important to recognize without delay that something is going wrong. Sustained attention or vigilance is essential for patient safety during the maintenance of anesthesia, when critical events most frequently occur ( Cooper et al., 1978 ; Craig and Wilson, 1981 ; Gibbs, 1986 ) at the time of presumably reduced mental and physical workload ( Gaba et al., 1987 ). One should develop the habit of scanning all of the monitors regularly in an orderly fashion, as a pilot in flight scans the instrument panel at regular intervals, to keep up with minute deviations in the patient's cardiorespiratory stability. A survey by Cooper and others (1984) , however, suggests that at least 33% of critical incidents occurring during the maintenance of anesthesia resulted from errors in judgment rather than from inattentiveness. Vigilance is an important deterrent but by itself is not sufficient for prevention of critical incidents. However, the notion that all human beings, including all anesthesiologists, make mistakes ( Allnutt, 1987 ) should not be used as an excuse to discount the importance of vigilance, especially in pediatric anesthesia. One should aim for near perfection by minimizing factors that adversely affect vigilance, such as fatigue, distraction, and boredom. A better understanding and application of ergonomic principles may improve vigilance and help reduce anesthesia-related mishaps in the future ( Gravenstein and Weinger, 1986 ).
▪ MONITORS AND MONITORING STANDARDS
The fact that most anesthesia-related fatalities involve human error clearly supports the concept that monitoring devices are essential for patient safety even for the experienced, conscientious, and vigilant anesthesiologist. The ASA Closed Malpractice Claims Study indicated that in 28% of these cases, proper monitoring already available commercially could have averted the mishaps ( Cheney, 1988 ). Of particular interest to anesthesiologists is that the median cost of legal settlement in cases in which improved monitoring would probably have prevented the complication or death was more than 10 times higher than in cases in which better monitoring would have had no effect on occurrence or outcome ( Cheney, 1988 ). In a similar review involving 238 (10% of 2400 total claims) closed anesthesia malpractice claims concerning children, a vast majority (estimate, 89%) of pediatric claims that were related to inadequate ventilation (43% of total) could have been prevented with pulse oximetry, capnography, or both ( Morray et al., 1993 ).
In 1985, minimum standards for patient monitoring during anesthesia at Harvard University teaching hospitals were adopted and later published ( Eichhorn et al., 1986 ). Similar but slightly more specific standards for basic intraoperative monitoring, proposed by the ASA, were approved by the House of Delegates in 1986. Both of these standards specifically mandate that oxygenation, ventilation, circulation, and body temperature be evaluated continually (at frequent intervals) or continuously (without interruption). For each of the components, the clear objective to ensure adequacy, followed by specific methods, is stated (see Chapters 9 and 11 , Anesthetic Equipment and Monitoring and Intraoperative and Postoperative Management). There is a strong emphasis on combining clinical evaluation and technologic methods. Although no specific methodology or instrumentation is mandated for monitoring cardiopulmonary and other indices, the ASA standards strongly encourage quantitative methods, such as pulse oximetry and capnography, over qualitative clinical assessment, with inspection and auscultation for cardiopulmonary monitoring. In addition, the New York State Hospital Code (1988) dictates that pulse oximetry and capnography be used to monitor all patients undergoing general anesthesia to reduce anesthesia-related morbidity and mortality. Eventually, most other states have followed with similar laws mandating intraoperative monitoring with pulse oximetry and capnography. Accordingly, most malpractice liability insurers in the United States have required that anesthesiologists follow these standards whenever possible ( Orkin, 1989 ).
Similar standards for basic patient monitoring have also been proposed in the United Kingdom ( Sykes, 1987 ), Australia ( Cass, Crosby, and Holland, 1988 ; Runciman, 1988b ), and other industrialized countries. They are similar to the ASA standards in terms of machine monitoring (oxygen analyzer, low-flow alarm, and ventilator disconnect alarm). The standards for minimum patient monitoring, however, differ considerably, depending in part on the patient's physical status and the degree of surgical involvement (minor, standard, or major operation) ( Sykes, 1987 ).
With the advent of pulse oximetry in the late 1980s, the anesthesiologist's ability to detect hypoxemia has improved markedly (see Chapter 9 , Anesthesia Equipment and Monitoring). Coté and others (1988, 1991) [29] [31] have demonstrated that major hypoxemic events (SaO2 ≤ 80% lasting more than 30 seconds) can occur without visible cyanosis or obvious changes in the cardiorespiratory patterns in children and that pulse oximetry detects such events more quickly than other means of monitoring. Cooper and others (1987), as part of perianesthetic QA activity, found a significant reduction in undesirable anesthesia-related incidents that require intervention after the introduction of pulse oximetry in the operating room.
▪ SELECTION OF SAFER ANESTHETICS AND ADJUVANT DRUGS
The POCA Registry data analyses have clearly demonstrated the safety of sevoflurane over halothane as the agent of choice for inhalation induction of anesthesia ( Morray, 2004 ). During the period between 1994 and 1997, cardiac arrest associated with medication accounted for 37% of all arrests, of which halothane with or without other drugs accounted for 66% ( Morray et al., 2000 ). During the period from 2000 to 2003, when sevoflurane had replaced halothane as the inhalation induction agent of choice, medication-related cause of cardiac arrests decreased drastically, from 37% to 12%. Concomitantly, the incidence of arrests among healthy children (ASA PS 1 or 2) decreased from 33% to 19% of all arrests ( Morray, 2004 ). Although halothane may still be useful and could even be superior (and definitely far less expensive) than sevoflurane for anesthetic maintenance in certain situations (such as bronchoscopy) in experienced hands, there is no question that halothane should be avoided as an induction agent, especially for inexperienced trainees without close supervision. There is a strong indication that the clinical availability of halothane may end in the near future in the United States. A similar comparison can also be made with bupivacaine versus less toxic ropivacaine and levobupivacaine for conduction anesthesia in children ( Ala-Kokko et al., 2002 ; Bosenberg et al., 2002 ;Mazoit and Dalens, 2004 ) (see Chapter 14 , Pediatric Regional Anesthesia).
▪ BETTER EDUCATION AND TRAINING
The steady decline in anesthesia-related mortality and morbidity over the past several decades has been attributed to increases in better-trained and better-qualified physicians administering anesthesia (Holland, 1987 ). In a survey of potentially harmful anesthesia-related events, Cooper and others (1978) found that 25% of these events were associated with inadequate training or unfamiliarity with equipment or devices; further training of these anesthetists (presumably trainees) would have prevented some of these events. In addition, an anesthesia-related mortality study from Harvard University (Eichhorn, 1989 ) has shown that in 8 of 11 cases of fatalities attributed primarily to anesthesia, inadequate supervision of residents, medical students, and nurse anesthetists was considered contributory.
As mentioned previously, Keenan and others (1991) reported the importance of specialty training in pediatric anesthesia for the reduction of cardiac arrests in infants. No anesthesia-related cardiac arrests occurred when trained pediatric anesthesiologists were in charge of pediatric cases, whereas arrests occurred at a frequency of 19.7:10,000 when nonpediatric anesthesiologists were supervising trainees. The same investigators also reported in a subsequent prospective study that the incidence of bradycardic episodes was significantly higher when pediatric anesthesiologists were not supervising the trainees anesthetizing infants (2.1%) than when trained pediatric anesthesiologists were in charge (0.8%) ( Keenan et al., 1994 ). These results emphasize the importance of training and experience for a better anesthetic outcome.
▪ QUALITY ASSURANCE
Documentation of the QA or QI process, especially that of fatal and morbid events, has been mandated in an effort to reduce the risk to and improve the outcome of patients undergoing anesthesia. In a pilot prospective study, Currie and others (1988) found the QA survey helpful in identifying nonfatal, nonmorbid, often transient events for peer review soon after such events took place. The survey demonstrated disproportionately high incidences of nonfatal events occurring with pediatric and emergency or out-of-hours cases. Induction and maintenance periods seem to be equally hazardous, up to four times more so than the emergence and recovery periods. As noted in other studies (Cooper et al., 1978, 1984 [26] [27]; Craig and Wilson, 1981 ), airway events were most frequent (53%). The authors concluded that the advantage of their method lies for the most part in its inherent lack of inertia'rapid evaluation, response, and feedback'in a confidential and nonjudgmental atmosphere, resulting in the improvement of patient care in a unique manner ( Cooper et al., 1978 ; Currie et al., 1988 ). QA or QI programs should be continued to prevent adverse events due to human factors or errors (active failure) by learning from events and “near-misses” as a group. Equally important, the QA program is the process of continually evaluating the environment, in which anesthesia is practiced, and identifying systemic problems (environmental factors or latent failures) responsible for or potentially causing adverse events, which have not been obvious, so as to implement strategies or new guidelines to improve the structure or environment and prevent future occurrence of adverse events.
Environmental factors (latent failures) may play a major role and may be responsible for adverse outcomes impeding the safety and quality of patient care. These factors may include inadequate safety mechanisms (organizational, clear drug labeling, etc.), inadequate or nonfunctional monitoring systems, and poor communication among the surgeons, anesthesiologists, and operating room personnel. Indeed, in an analysis of 110 adverse events from more than 13,000 anesthetic procedures, Lagasse and others (1995) identified only 8% caused by human errors, whereas 92% of adverse events were attributable to system errors.
Critical events related to anesthesia occur frequently during the practice of anesthesia. A well-trained, motivated, vigilant anesthesiologist normally detects these events in time and takes proper measures to prevent disaster. Anesthesia-related accidents causing catastrophic injury or death, therefore, are very rare, especially in relation to the frequency of such potentially harmful events. Because humans are imperfect and make mistakes as part of normal human cognitive behavior, catastrophic accidents can occur almost at random to any anesthesiologist ( Allnutt, 1987 ). The availability of both machine and patient monitors and adherence to monitoring standards are indispensable.
From the foregoing presentation, it is apparent that young children, especially infants, are more vulnerable to anesthesia-related mishaps, whereas such a risk in older, healthy children is relatively low. Because of the small size and physiologic differences in cardiopulmonary and other organ systems in young infants, as outlined earlier in this book, safety in pediatric anesthesia demands additional clinical training and vigilance. Anesthetic complications in infants and children and their management, when applicable, have been discussed in appropriate chapters elsewhere in this book.
For the safety of infants and young children, a high-risk group in terms of anesthesia-related morbidity and mortality, more clinical training, adequate preoperative preparation, more vigilance, and adherence to monitoring standards (especially the use of a pulse oximeter and precordial stethoscope continuously) are all important and indispensable. When in doubt, one should not hesitate to transfer the young and unstable patient to a specialized center for pediatric anesthesia and surgery to provide a better opportunity for survival.
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Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.
Copyright © 2005 Mosby, An Imprint of Elsevier
▪ SUMMARY
Anesthesia-related mortality has declined steadily over the past several decades as the percentage of general anesthetics administered by trained anesthesiologists has increased and as newer and safer anesthetics and adjuvant drugs, anesthetic equipment, monitoring, and safety standards in the industrialized nations have improved. Yet, anesthesia-related adverse events remain relatively higher in infants less than 1 year of age than in older children and adults. As in adults, anesthetic catastrophe is still caused predominantly by judgment errors and environmental factors that are potentially preventable. Critical incidents occur more frequently during the induction and maintenance of anesthesia than during emergence and recovery. Emergency surgery and “urgent” surgery are associated with a disproportionately high incidence of anesthesia-related adverse events, in part because of inadequate preanesthetic patient preparation.
Analyses of closed malpractice insurance claims as well as the POCA Registry sponsored by the ASA have been informative in developing a future strategy for preventing anesthesia-related mishaps. Emphasis on strict monitoring standards and QA surveillance, developed and sustained since the late 1980s, seem valuable both in preventing “near-misses” and in heightening anesthesiologists' awareness of such events. For patient safety in pediatric anesthesia, better clinical training, adequate preanesthetic preparations, vigilance, and adherence to monitoring standards are all important and essential.
Copyright © 2008 Elsevier Inc. All rights reserved. - www.mdconsult.com
Motoyama & Davis: Smith's Anesthesia for Infants and Children, 7th ed.
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