Issues Associated with Anesthesia-Related Mortality

Most of the studies have focused on in-hospital and short-term mortality, but perioperative complications may be the events that directly lead to death. For example, a perioperative stroke or myocardial infarction may lead to death after the period of analysis. Even small myocardial infarctions or unstable angina during the perioperative period has been associated with worse long-term survival in several studies.^{[2] [91] [92]} Should these "late" deaths be attributed to anesthesia complications for the purpose of such analyses? Results from several studies add to the dilemma. For example, Mangano and colleagues^[93] performed a randomized clinical trial in which 7 days of perioperative β-blockade was compared with placebo in high-risk patients undergoing noncardiac surgery. They reported significantly improved survival at 6 months, which remained significant during the 2 years of follow-up. In a subsequent report regarding this trial, Wallace and coworkers^[94] demonstrated that the improved survival in the group receiving β-blockade was associated with a significantly lower incidence of perioperative myocardial ischemia but no difference in perioperative cardiac events. The authors of the original study suggested that atenolol resulted in better plaque stabilization during the perioperative period, resulting in improved long-term survival. If the hyperdynamic perioperative state is not well controlled, this theory suggests that more plaques become destabilized and progress to acute occlusion and sudden death. If atenolol is not used and patients die within 6 months of surgery, should this be attributed to an error in anesthesia and perioperative management? Part of the answer relies on the strength of this study to support the conclusion that routine use of atenolol does result in improved long-term survival. However, work by Poldermans and colleagues^[3] demonstrated a reduction in perioperative morbidity and mortality in high-risk vascular patients given perioperative β-blockade, supporting its use in this subset of patients.

The potential effects of anesthesia on long-term survival were suggested in an abstract by Weldon and colleagues.^[95] They demonstrated that deeper maintenance levels of anesthesia, as assessed by a bispectral index (BIS) monitor, were associated with higher 1-year postoperative

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Figure 24-4 Relationship between adverse events in the American Society of Anesthesiologists (ASA) Closed Claims Study and preventable complications. Preventable events related to respiratory complications were significantly more common than those related to all nonrespiratory complications. Of the respiratory complications, difficult intubation had the least number of preventable complications (P < 0.05 compared with nonrespiratory claims). (From Caplan RA, Posner KL, Ward RJ, Cheney FW: Adverse respiratory events in anesthesia: A closed claims analysis. Anesthesiology 72:828, 1990.)