Preventable anesthesia mishaps: a study of human factors

Anesthesiology. 1978 Dec;49(6):399-406. doi: 10.1097/00000542-197812000-00004.


A modified critical-incident analysis technique was used in a retrospective examination of the characteristics of human error and equipment failure in anesthetic practice. The objective was to uncover patterns of frequently occurring incidents that are in need of careful prospective investigation. Forty-seven interviews were conducted with staff and resident anesthesiologists at one urban teaching institution, and descriptions of 359 preventable incidents were obtained. Twenty-three categories of details from these descriptions were subjected to computer-aided analysis for trends and patterns. Most of the preventable incidents involved human error (82 per cent), with breathing-circuit disconnections, inadvertent changes in gas flow, and drug-syringe errors being frequent problems. Overt equipment failures constituted only 14 per cent of the total number of preventable incidents, but equipment design was indictable in many categories of human error, as were inadequate experience and insufficient familiarity with equipment or with the specific surgical procedure. Other factors frequently associated with incidents were inadequate communication among personnel, haste or lack of precaution, and distraction. Results from multi-hospital studies based on the methodology developed could be used for more objective determination of priorities and planning of specific investments for decreasing the risk associated with anesthesia.

PIP: This study attempted to quantitate anesthesia mishaps related to human error rather than to operative procedures, the patient's disease, age, physical status, or other factors. This risk study collected information by interview with staff and residient anesthesiologists in a large metropolitan teaching hospital. The analysis technique, called critical-incident, was used to determine patterns of frequently occurring incidents leading to anesthetic failure or patient injury. 47 interviews were conducted, and 359 preventable accidents were described. There were 23 categories of details gleaned from these descriptive interviews which were computer analyzed for trends and patterns. The incidents ranged in seriousness from laryngoscope malfunctions to breathing-circuit disconnections resulting in death. Human error was involved in 82% of preventable accidents, and equipment failure accounted for 14%. The remaining 16 incidents did not fall in either category. The 10 most frequently occurring incidents (human error and equipment failure combined) were: 1) breathing circuit disconnection; 2) inadvertent gas flow change; 3) syringe swap; 4) gas supply problem; 5) intravenous apparatus disconnection; 6) laryngoscope malfunction; 7) premature extubation; 8) breathing circuit connection error; 9) hypovolemia; and 10) tracheal airway device position changes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Accident Prevention
  • Anesthesia / adverse effects*
  • Anesthesiology / instrumentation
  • Computers
  • Humans
  • Task Performance and Analysis