Estimating the number of difficult airway carts needed in an operating suite: Resource planning without compromising...

To determine the number of difficult airway (DA) carts required based on the number of anesthetising locations and patients risk of DA.

Binomial distributions.

Various hypothetical settings and patient cohorts.

Binomial distributions were used to calculate the number of distinct combinations of DAs by number of anesthetising locations assuming an average risk of 10%. The 'at least' number of DAs was calculated using cumulative probabilities of having exactly two plus more than 2 DAs up to the total number of simultaneously started anesthetising locations or until the cumulative probability exceeds the 50% threshold, therefore being more likely than not.

The probability of encountering concurrent DAs increases as the number of simultaneously started anesthetising locations increases. For at least 2 concurrent DAs, the probability first exceeds 50% at 17 locations. The corresponding thresholds for at least 3 and 4 concurrent DAs, are 27 and 37 locations respectively. The probability of at least 2 concurrent DAs will exceed 50% when approximately 17 anesthetising sites are started simultaneously and a 10% worst case risk is assumed.

With continuing resource constraints, proper planning of human and capital resources for DAs needs to be addressed without compromising patient safety. It is recommended that every block of 15-20 sites be equipped with a DA cart, that anaesthesia groups develop and rehearse DA algorithms with available equipment, and that preoperative anaesthesia clinics be used to identify DA therefore providing logistical leverage.