Impact of obesity in mechanically ventilated patients: a prospective study

To analyze the influence of severe obesity on mortality and morbidity in mechanically ventilated intensive care unit (ICU) patients.

Prospective, multi-center exposed/unexposed matched epidemiologic study.

Hospital setting.

Severely obese patients (body mass index (BMI) >or= 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.

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.

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.