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

From a prospectively defined cohort of patients who underwent either general, 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 remained unintentionally comatose 24 h after anaesthesia were classified to determine a relationship with anaesthesia. These deaths ( n = 119; 15%) were further analysed to identify contributing aspects of the anaesthetic management, 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 peri‐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 with 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 anaesthesia‐related deaths. During induction of anaesthesia, choice of anaesthetic technique ( n = 18 (15%)) and performance of the anaesthesiologist ( n = 8 (7%)) were most commonly associated with death. During maintenance, the most common factors were cardiovascular management ( n = 43 (36%)), ventilatory management ( n = 12 (10%)) and patient monitoring ( n = 12 (10%)). In both the recovery and the postoperative phases, patient monitoring was the most common factor ( n = 12 (10%) for both). For cardiovascular, ventilatory and other anaesthetic management, human failure contributed to 89 (75%) deaths and organisational factors to 12 (10%). For inadequate patient monitoring, human factors contributed to 71 (60%) deaths and organisational factors to 48 (40%). Other contributing factors were inadequate communication (30 deaths (25%) for all four aspects of the anaesthetic management) and lack of supervision (particularly for ventilatory management). Inadequate care was delivered in 19 (16%) of the anaesthesia‐related deaths with respect to cardiovascular management, in 20 (17%) with respect to ventilatory management, in 18 (15%) with respect to patient monitoring and in 23 (19%) with respect to other anaesthetic management.