Differential loss of fat and lean mass in the morbidly obese after bariatric surgery.

BACKGROUND: Bariatric surgery has become a common treatment for morbid obesity. The relative changes in body tissue that comprise the substantial weight loss over time are not completely understood. METHODS: We evaluated the differential rates of fat and lean tissue losses in morbidly obese patients who underwent Roux-en-Y gastric bypass surgery. Body composition was assessed using whole-body dual energy X-ray absorptiometry (DXA) performed at two timepoints in the postoperative period. Patients were stratified by the tertile of rapidity of weight loss expressed as percent reduction in body mass index per month. RESULTS: Thirty two patients (25 women, 7 men) with a mean age of 46.7 +/- 10.4 years and an average initial body weight of 141.4 +/- 29.4 kg experienced a 52.3 +/- 16.6 kg (36.5 +/- 5.5%) weight loss over 13.9 +/- 6.0 months. The incremental rates of lean body mass loss by tertiles were 0.3 +/- 0.6, 0.5 +/- 0.2, and 1.0 +/- 0.8 kg/month (P = 0.02), whereas the rates of fat loss were 1.2 +/- 0.9, 1.8 +/- 0.4, and 2.9 +/- 1.0 kg/month (P = 0.0001). The ratios for lean to fat loss among the respective tertiles were 1:4.0, 1:3.6, and 1:3.0. The correlation between rates of lean and fat mass loss was r = 0.37 (P = 0.04). Only three of the 32 patients (9.4%) patients maintained or gained lean mass following Roux-en-Y gastric bypass surgery. CONCLUSIONS: After bariatric surgery, those patients losing weight at the greatest rate appear to have accelerated losses of both lean and fat mass. Few patients maintain lean body mass after bariatric surgery, despite self-reported participation in conventional exercise programs. These data suggest the need for more aggressive interventions to preserve lean body mass during the weight loss phase after Roux-en-Y gastric bypass surgery.

Predictors of mortality after muscle flap advancement for deep sternal wound infections.

BACKGROUND: Deep sternal wound infection is a devastating complication following median sternotomy, with mortality rates reported from 1.0 to 36 percent. Several studies have evaluated the risk factors for the development of a deep sternal wound infection, but the factors predicting survival after debridement and muscle flap advancement are not well known. METHODS: A retrospective chart review was performed from September of 1997 to January of 2004 on all patients referred to a single plastic surgeon for treatment of a deep sternal wound infection following median sternotomy for cardiovascular surgery. The authors collected cardiovascular operative and intensive care unit data and information regarding patient demographics, medical history, laboratory studies, and follow-up. Data were analyzed as possible prognostic factors. RESULTS: During the collection period, a total of 8414 cardiovascular surgery cases were performed through a median sternotomy. Deep sternal wound infections were identified and treated with muscle flap advancement in 124 patients (1.5 percent). Most patients (90 percent) were treated with bilateral pectoralis major flap advancements. Eighty-five patients underwent debridement and muscle flap advancement as a single-stage procedure. There were 26 perioperative deaths (21 percent). Presternotomy end-stage renal disease, presternotomy chronic obstructive pulmonary disease, and prolonged poststernotomy mechanical ventilation were found to be significant independent predictors of mortality despite muscle flap advancement. CONCLUSIONS: These data identify patients with deep sternal wound infections who may be at increased risk for mortality after debridement and muscle flap advancement. This information may help the patient, family, and surgeon modify medical management or surgical treatment of this devastating problem.