Effect Of Obesity On Duration Of Mechanical Ventilation in The Surgical Intensive Care Unit

Abstract

Rationale: Nearly one-third of intensive care unit (ICU) patients are obese and nearly 7% are morbidly obese. Obese patients are prone to atelectasis, aspiration and have decreased lung and chest wall compliance. Consequently, increased duration of mechanical ventilation (MV) and longer ICU stay has been reported in critically sick obese patients compared to non-obese. However, a recent meta-analysis reported no association between obesity and duration of MV in critically sick patients.Obesity has not been associated with postoperative pulmonary complications and no studies have reported its effect on duration of MV in patients in surgical ICU. Methods: We included cohort studies evaluating the association between obesity (BMI≥30) and duration of mechanical ventilation in patients admitted to a surgical ICU. We classified studies according to baseline risk of moderate to high mortality among patients undergoing emergency non-cardiac surgical (NCS); trauma surgery and patients undergoing elective Coronary Artery Bypass Graft (CABG). Three investigators conducted independent literature searches using Medline, the Web of Sciences and Scopus until September 1, 2009. The association between obesity and duration of MV was expressed as the mean difference (MD) in days and its 95% confidence interval (CI). Analysis was stratified by risk of studies and random effects models were used to account for heterogeneity. Results: A total of 14 studies that provided duration of MV with mean and standard deviation in obese and non-obese groups were included. The eight NCS and trauma studies had a total of 8069 patients (1906 [24%] obese). In these studies, duration of MV was non-significantly longer for the obese than for the non-obese group (MD 0.85 days, 95% CI -0.37 to 2.07, p = 0.2). Differences of duration of MV were