National census of airway management techniques used for anaesthesia in the UK: first phase of the Fourth National Audit Project at the Royal College of Anaesthetists.

BACKGROUND: The first stage of the Royal College of Anaesthetists Fourth National Audit Project (NAP4) (to determine the incidence of major complications of airway management in the UK) required a national census of airway management techniques currently in use.
METHODS: A network of local reporters (LRs) was established, with a link to each of the 309 National Health Service hospitals believed to undertake surgery. LRs were requested to report the primary airway management technique used for all general anaesthetics performed in their hospital during a specified 2 week period. Individual unit's data for the survey period were extrapolated using a multiplier of 25 to provide an estimated annual usage.
RESULTS: Data were received from all 309 hospitals. The number of general anaesthetics reported in the 2 weeks was 114,904 giving an estimate of 2.9 million annually. Eighty-nine per cent of returns were reported by the LR to be 'accurate' or 'a close estimate' (an error of <10%). The primary airway management device for general anaesthesia was a supraglottic airway in 64,623 (56.2%), a tracheal tube in 44,114 (38.4%), and a facemask in 6167 (5.3%).
CONCLUSIONS: The second stage of NAP4 is designed to register and collect details of each major airway complication from the same hospitals over a 12 month period. The individual case reports will produce the numerator to calculate the incidence of airway complications associated with general anaesthesia in the UK. The results of the census presented here will provide the denominator.