Impact of obesity in mechanically ventilated patients: a prospective study

Objective: To analyze the influence of severe obesity on mortality and morbidity in mechanically ventilated intensive care unit (ICU) patients. Design: Prospective, multi-center exposed/unexposed matched epidemiologic study. Setting: Hospital setting. Patients: Severely obese patients (body mass index (BMI) >= 35 kg/m(2)), mechanically ventilated for at least 2 days were matched with unexposed nonobese patients (BMI < 30 kg/m(2)) for center, gender, age (+/- 5 years), and the simplified acute physiology (SAPS) II score (+/- 5 points). We recorded tracheal intubation, catheter placement, nosocomial infections, development of pressure ulcers, ICU and hospital outcome. Results: Eighty-two severely obese patients (mean BMI, 42 +/- 6 kg/m(2)) were compared to 124 nonobese patients (mean BMI, 24 +/- 4 kg/m(2)). The ICU course was similar in both the groups, except for the difficulties during tracheal intubation (15 vs. 6%) and post-extubation stridor (15% vs. 3%), which were significantly more frequent in obese patients (P < 0.05). The ICU mortality rate did not differ between obese and nonobese patients (24 and 25%, respectively); nor did the risk-adjusted hospital mortality rate (0.76, 95% confidence interval 0.41-1.16 in obese patients versus 0.82, 95% confidence interval 0.54-1.13 in nonobese patients). Conditional logistic regression confirmed that mortality was not associated with obesity. Conclusion: The only difference in morbidity of obese patients who were mechanically ventilated was increased difficulty with tracheal intubation and a higher frequency of post-extubation stridor. Obesity was not associated either with increased ICU mortality or with hospital mortality.