Patient and surgery factors associated with the incidence of failed and difficult intubation

Summary Estimates of the rate and risk‐factors for difficult airway rarely include a denominator for the number of anaesthetics. Approaches such as self‐reporting and crowd‐sourcing of airway incidents may help identify specific lessons from clinical episodes, but the lack of denominator data, biased reporting and under‐reporting does not allow a comprehensive population‐based assessment. We used an established state‐wide dataset to determine the incidence of failed and difficult intubations between 2015 and 2017 in the state of Victoria in Australia, along with associated patient and surgical risk‐factors. A total of 861,533 general anaesthesia episodes were analysed. Of these, 4092 patients with difficult or failed intubation were identified; incidence rates of 0.52% (2015–2016) and 0.43% (2016–2017), respectively. Difficult/failed intubations were most common in patients aged 45–75 and decreased for older age groups, with risk being lower for patients aged >85 than patients aged 35–44. The risk for failed/difficult intubation increased significantly for: patients undergoing emergency surgery (OR 1.80); obese patients (OR 2.48); increased ASA physical status; and increased Charlson Comorbidity Index. Across all age groups, procedures on the nervous system (OR 1.92) and endocrine system (OR 2.03) had the highest risk of failed/difficult intubation. The relative reduced risk for failed/difficult intubations in the elderly population is a novel finding that contrasts with previous research and may suggest a ‘compression of morbidity’ effect as a moderator. Administrative databases have the potential to improve understanding of peri‐operative risk of rare events at a population level.