Mortality associated with anaesthesia: a qualitative analysis to identify risk factors

From a prospectively defined cohort of patients who underwent either genera l, regional or combined anaesthesia from 1 January 1995 to 1 January 1997 ( n = 869 483), all consecutive patients (n = 811) who died within 24 h or re mained unintentionally comatose 24 h after anaesthesia were classified to d etermine a relationship with anaesthesia. These deaths (n = 119; 15%) were further analysed to identify contributing aspects of the anaesthetic manage ment, other factors and the appropriateness of care. The incidence of 24-h peri-operative death per 10 000 anaesthetics was 8.8 (95% CI 8.2-9.5), of p eri-operative coma was 0.5 (0.3-0.6) and of anaesthesia-related death 1.4 ( 1.1-1.6). Of the 119 anaesthesia-related deaths, 62 (52%) were associated w ith cardiovascular management, 57 (48%) with other anaesthetic management, 12 (10%) with ventilatory management and 12 (10%) with patient monitoring. Inadequate preparation of the patient contributed to 30 (25%) of the anaest hesia-related deaths. During induction of anaesthesia, choice of anaestheti c technique (n = 18 (15%)) and performance of the anaesthesiologist (n = 8 (7%)) were most commonly associated with death. During maintenance, the mos t common factors were cardiovascular management (n = 43 (36%)), ventilatory management (n = 12 (10%)) and patient monitoring (n = 12 (10%)). In both t he recovery and the postoperative phases, patient monitoring was the most c ommon factor (n = 12 (10%) for both). For cardiovascular, ventilatory and o ther anaesthetic management, human failure contributed to 89 (75%) deaths a nd organisational factors to 12 (10%). For inadequate patient monitoring, h uman factors contributed to 71 (60%) deaths and organisational factors to 4 8 (40%). Other contributing factors were inadequate communication (30 death s (25%) for all four aspects of the anaesthetic management) and lack of sup ervision (particularly for ventilatory management). Inadequate care was del ivered in 19 (16%) of the anaesthesia-related deaths with respect to cardio vascular management, in 20 (17%) with respect to ventilatory management, in 18 (15%) with respect to patient monitoring and in 23 (19%) with respect t o other anaesthetic management.