Extensive preoperative testing is not necessary in morbidly obese patients undergoing gastric bypass

Morbidly obese patients are considered at high risk for perioperative complications and often undergo extensive testing for preoperative clearance. We analyzed prospectively collected data from 193 patients undergoing weight loss surgery between November 2000 and November 2002. Preoperative chest x-ray examination, pulmonary function tests, noninvasive cardiac testing, and blood work were performed routinely. Preoperative testing identified abnormalities on eight chest x-ray films (4%) and 29 electrocardiograms (15%), none of which required preoperative intervention. Spirometry was abnormal in 41 patients (21%); logistic regression identified preexisting asthma as predictive of obstructive physiology (odds ratio [OR] 3.3; 95% confidence interval [CI] 1.2 to 8.9), and body mass index as predictive of restrictive physiology (OR 1.1; 95% CI 1.01 to 1.2). Arterial blood gases identified only one case of severe hypoxemia requiring intervention. Mild hypoxemia was associated with increasing age (OR 14.5; 95% CI 1.8 to 114). Echocardiography demonstrated four abnormalities (2%); previous history of cardiac disease was the only risk factor (OR 14.5; 95% CI 1.8 to 114). Complete blood count did not identify 84% and 50% of the patients with iron (n=31) and vitamin B(12) (n=12) deficiencies, respectively. Age, body mass index, and history of asthma were associated with abnormal pulmonary function tests and previous cardiac disease with abnormal cardiac testing. These tests are not mandatory as a routine preoperative evaluation and can be used selectively on the basis of medical history.