Do Obese Patients Need Larger Endotracheal Tubes?

Abstract

Objectives: 1) Correlate tracheal airway size with Body Mass Index (BMI) and other height and weight measurements. 2) Discuss implications for choosing endotracheal tube sizes in adult patients of varying body habitus. Methods: This was a radiographic (computed tomography [CT]) study of 123 consecutive hospitalized patients undergoing tracheotomy over a 4-year period (2007-2011). Personal observation of the senior author was that obese patients do not have larger tracheas. In morbidly obese patients, the tracheal dimensions appeared to be even smaller. We expected BMI to not be a good predictor of airway size. We measured airway dimensions in axial CT imaging and made comparisons with their height, weight, BMI, gender, and age. Measurements were taken at the level of the first tracheal ring including anterior-posterior length, width, and calculated area. Results: The linear regression model showed BMI was significantly inversely related to CT width after controlling for gender and age. For every 1 kg/m2 increase in BMI the CT width decreased by 0.05 points ( P = 0.0389). Among all patients there was a trend for airway area to diminish with increasing BMI. Conclusions: The results support our hypothesis that obese patients do not have larger airways. Moreover, the results indicated a trend toward smaller airways as BMI increased. Specifically, as BMI increases, tracheal width appears to decrease. This information should help medical professionals avoid the tendency to use a larger tube to intubate an obese patient. Hopefully this will result in fewer airway injuries in a society where obesity has become an epidemic.