Associations of obesity with tracheal intubation success on first attempt and adverse events in the emergency department: An analysis of the multicenter prospective observational study in Japan.

Obesity is deemed to increase the risk of difficult tracheal intubation. However, there is a dearth of research that examines the relationship of obesity with intubation success and adverse events in the emergency department (ED). We analyzed the data from a prospective, observational, multicenter study-the Japanese Emergency Airway Network (JEAN) 2 study from 2012 through 2016. We included all adults (aged ≥18 years) who underwent tracheal intubation in the ED. Patients were categorized into three groups according to their body mass index (BMI): lean (<25.0 kg/m²), overweight (25.0-29.9 kg/m²), and obesity (≥30.0 kg/m²). Outcomes of interest were intubation success on the first attempt and intubation-related adverse events. Of 6,889 patients who are eligible for the analysis, 5,370 patients (77%) were lean, 1,177 (17%) were overweight, and 342 (4%) were obese. Compared to the lean patients, the intubation success rates were significantly lower in the overweight and obese patients (70.9% in lean, 66.4% in overweight, and 59.3% in obese patients; P