Influence of the severity of obesity on morbidity and mortality after gastric bypass surgery

OBJECTIVE: To determine the influence of severity of obesity on morbidity and mortality following Roux-en-Y gastric bypass and vertical ringed gastroplasty, with severity classified as morbid obesity (MO) defined by a body mass index (BMI) between 35 and 55 Kg/m2 and super-morbid obesity (SMO) defined by a BMI exceeding 55 Kg/m2. METHOD: A series of patients who underwent the aforementioned type of gastric bypass surgery were followed for 5 years. The patients were classified as to whether they had associated sleep apnea syndrome, alveolar hypoventilation, or "overlap syndrome". RESULTS: A total of 105 patients were enrolled: 70 (66.7%) classified as having MO and 35 (33.3%) classified as having SMO. Distribution by sex was significantly different in the 2 groups, but respiratory diseases were similar. PaO2 was higher in the MO group, PaCO2 was lower, and the alveolar-arterial gradient was smaller. Duration of surgery was shorter in the MO group (120.43 +/- 32.97 vs. 136.76 +/- 28.28 minutes). The percentage of complications was similar in the 2 groups (32.86% and 45.7% in the MO and SMO groups, respectively), although the incidence of respiratory complications was higher in SMO patients (8.57% vs. 20% in the MO and SMO groups, respectively). No differences were observed in the rates of surgical, hemodynamic, or infectious complications. Length of hospital stay was similar (6.44 vs. 6.69 for MO and SMO patients, respectively). CONCLUSIONS: More severe obesity can be associated with preoperative arterial blood gas alterations in patients with concomitant respiratory disease and a higher incidence of respiratory complications in the early phase of recovery from gastric bypass surgery.