Factors associated with difficult intubation in prehospital emergency medicine.

Objectives: When managing airways in a prehospital setting, emergency physicians have to deal with difficult intubation (DI), which increases morbidity and mortality. The primary goal of this study was to determine predictors of DI in the out-of-hospital field faced by the French physician-staffed Emergency Medical Service.

Methods: The study was a prospective, observational study, including all consecutive patients intubated during a 30-month period. Patients having experienced standard intubation (two attempts or less) or DI (more than two attempts) were compared.

Results: Six hundred and ninety-four patients were included: 70 (11%) were classified as DI and 583 as standard intubations. Logistic regression showed that airways obstruction [odds ratio (OR), 4.1; 95% confidence interval (CI), 1.71-14.4], intubation on the floor (OR, 2.6; 95% CI, 1.04-6.6), and a hyoid-mental distance less than three fingers (OR, 2.3; 95% CI, 1.2-4.7) were independent predictors of DI. Immediate complications occurred in 89 patients (16%): 66 (11%) in the standard intubation group and 23 (31%) in the DI group (P<0.01).

Conclusion: For prehospital orotracheal intubation, independent risk factors of DI are a mental-thyroid distance less than three fingers, a patient on the floor, and a superior airways obstruction. Anticipation of DI could result in fewer attempts, and fewer complications, as the rate of complication increases with the difficulty of intubation.