The incidence of potentially serious complications during non-obstetric anaesthetic practice in the United Kingdom: an analysis from the 7th National Audit Project (NAP7) activity survey.

Complications and critical incidents arising during anaesthesia due to patient, surgical or anaesthetic factors, may cause harm themselves or progress to more severe events, including cardiac arrest or death. As part of the 7th National Audit Project of the Royal College of Anaesthetists, we studied a prospective national cohort of unselected patients. Anaesthetists recorded anonymous details of all cases undertaken over 4 days at their site through an online survey. Of 416 hospital sites invited to participate, 352 (85%) completed the survey. Among 24,172 cases, 1922 discrete potentially serious complications were reported during 1337 (6%) cases. Obstetric cases had a high reported major haemorrhage rate and were excluded from further analysis. Of 20,996 non-obstetric cases, 1705 complications were reported during 1150 (5%) cases. Circulatory events accounted for most complications (616, 36%), followed by airway (418, 25%), metabolic (264, 15%), breathing (259, 15%), and neurological (41, 2%) events. A single complication was reported in 851 (4%) cases, two complications in 166 (1%) cases and three or more complications in 133 (1%) cases. In non-obstetric elective surgery, all complications were 'uncommon' (10-100 per 10,000 cases). Emergency (urgent and immediate priority) surgery accounted for 3454 (16%) of non-obstetric cases but 714 (42%) of complications with severe hypotension, major haemorrhage, severe arrhythmias, septic shock, significant acidosis and electrolyte disturbances all being 'common' (100-1000 per 10,000 cases). Based on univariate analysis, complications were associated with: younger age; higher ASA physical status; male sex; increased frailty; urgency and extent of surgery; day of the week; and time of day. These data represent the rates of potentially serious complications during routine anaesthesia care and may be valuable for risk assessment and patient consent.