Peri-operative cardiac arrest due to suspected anaphylaxis as reported to the 7th National Audit Project of the Royal College of Anaesthetists

The 7th National Audit Project (NAP7) of the Royal College of Anaesthetists studied peri-operative cardiac arrest. Among 59 cases reported as possible anaphylaxis, 33 (56%) were judged to be so by the review panel with high or moderate confidence. Causes in excluded cases included: isolated severe hypotension; bronchospasm; and oesophageal intubation. Severe bronchospasm leading to cardiac arrest was uncommon, but notably in one case led to a reported flat capnograph. In the baseline survey, anaesthetists estimated anaphylaxis as the cause of 10% of cases of peri-operative cardiac arrests and to be among the four most common causes. In a year-long registry of peri-operative cardiac arrest, suspected anaphylaxis was the seventh most common cause accounting for 4% of reports. Initial management was most often with low-dose intravenous adrenaline, and this was without complications. Both the NAP7 baseline survey and case registry provided evidence of reluctance to starting chest compressions when systolic blood pressure had fallen to below 50 mmHg and occasionally even when it was unrecordable. All 33 patients were resuscitated successfully but one patient later died. The one death occurred in a relatively young patient in whom chest compressions were delayed. Overall, peri-operative anaphylaxis leading to cardiac arrest occurred with a similar frequency and patterns of presentation, location, initial rhythm and suspected triggers in NAP7 as in the 6th National Audit Project (NAP6). Outcomes in NAP7 were generally better than for equivalent cases in NAP6.