Difficult tracheal intubation is more common in obese than in lean patients

Whether tracheal intubation is more difficult in obese patients is debatable. We compared the incidence of difficult tracheal intubation in obese and lean patients by using a recently validated objective scale, the intubation difficulty scale (IDS). We studied 134 lean (body mass index, <30 kg/m2) and 129 obese (body mass index, greater than or equal to35 kg/m(2)) consecutive patients. The IDS scores, categorized as difficult intubation (IDS greater than or equal to5) or not (IDS <5), and the patient data, including oxygen saturation (SpO2) while breathing oxygen, were compared between lean and obese patients. In addition, risk factors for difficult intubation were determined in obese patients. The IDS score was greater than or equal to5 in 3 lean and 20 obese patients (P = 0.0001). A Mallampati score of III-IV was the only independent risk factor for difficult intubation in obese patients (odds ratio, 12.51; 95% confidence interval, 2.01-77.81), but its specificity and positive predictive value were 62% and 29%, respectively. SpO2 values noted during intubation were (mean +/- SD) 99% +/- 1% (range, 91%-100%) and 95% +/- 8% (range, 50%-100%) in lean and obese patients, respectively (P < 0.0001). We conclude that difficult intubation is more common among obese than nonobese patients. None of the classic risk factors for difficult intubation was satisfactory in obese patients. The high risk of desaturation warrants studies to identify new predictors of difficult intubation in the obese.