Volume 1, No. 3 • Fall 1986

From the Literature: A Survey of 112,000 Anesthetics at One Teaching Hospital

M.M. Cohen; P.G. Duncan; W.D.B Pope; C. Wolkenstein; Jeffrey B. Cooper, Ph.D

Editor’s note: In each APSFA newsletter, a pertinent publication from the anesthesia patient safety literature will be summarized. Suggestions for future issues are welcome.

Cohen, M.M., Duncan, P.G., Pope, W.D.B., and Wolkenstein, C: A survey of 112,000 anesthetics at one teaching hospital (1975-83). Can Anaesth Soc 1, 33: 22-31, 1986.

For nine years, the Department of Anesthesia at the University of Manitoba in Winnipeg methodically collected data on the intraoperative, recovery room, and post-operative complications experienced in 112,000 anesthetics. This large teaching hospital with a high proportion of ASA I or 2 patients (79% during the last 5 years of the study) had almost the full spectrum of procedures, weighted toward perineal (26%) and intraabdominal (23%). There was no obstetrics and open hearts were done during the last three years only. Data on patient pre-operative conditions, intraoperative monitoring, and anesthetic techniques are presented, divided into two time periods to suggest evolving practice patterns in recent years: sicker patients, more monitoring, more narcotic agents, and more local anesthesia.

This is probably the most comprehensive report ever published about the distribution of anesthesia complications in a large, well defined sample of patients. The study methodology is credible. Cooperation from the anesthetists was exceptionally good (about 2% of cases not documented) perhaps because the data collection was incorporated with the billing procedure Most striking is that, during the period 1979-83, fully 10.6% of patients had at least one intraopertive complication; 5.9% had a recovery room complication; 9.4% had a “minor” post-operative complication, and 0.45% had a “major” post-operative complication.

Overall, 17.8% of patients had at least one anesthetic complication.

The most frequent types of problems were. intraoperative arrhythmias and hypotension (7.8/10,000 cardiac arrests and 6.3/10,000 aspirations); recovery room hypotension and hypertension; post-operative nausea and vomiting (about 5%). The reported rate of post-op MI was 13.7/110,000.

The study (and the basic methodology) has some weaknesses. Self-reported data are always questionable. There is no information about causality. No information is given in this report about possible differences in the rates of complications among anesthetists (the relevance of such comparisons emphasized by the recent report from Slogoff, et al on post-operative MI rates).

It is certainly impossible to compare this database to others as there are no standard definitions; there is no objective way to normalize for differences in patient acuity or classification or complexity of surgery. Still, presented here is a detailed baseline distribution of anesthesia-related complications. There are comparisons of patient acuity, anesthetic techniques, and monitoring during two time periods and, thus, this study offers some objective measure on how anesthesia practices are changing. Illustrated is a reasonable way for any group of anesthesia personnel to track its performance

It is often suggested that the risk of death or serious injury from anesthesia is relatively low, yet still intolerably high. But, the fact that so many patients experience some form of anesthetic complication (in what is widely regarded as an anesthesia department of the highest quality) supports the suggestion that anesthesia is serious business. Because mortality rates are so low, they are almost impossible to use as a yardstick for assessing how differences in technique or practices impact outcome. Using a broader definition of adverse outcome, such as the complications described in this report, may be a more useful measure of anesthesia “quality” or performance. Additional reports similar to this one by Cohen, et al, should be encouraged. It is only from many of these, all of which can be justified as valid quality assurance activities, that meaningful comparisons can be made. These investigators and their open-minded clinical colleagues should he thanked for leading the way.

Abstracted by Jeffrey B. Cooper, Ph.D., Harvard Medical School.