Perioperative Coagulation Changes with Gastric Bypass: association with venous thrombosis?

Blood coagulation protein analyses were obtained before, during and after Roux-Y gastric bypass in 82 patients to observe the individual perioperative changes indicative of clot formation and fibrinolysis. Pneumatic compression devices were placed on the legs during this time in order to provide deep venous thrombosis (DVT) prophylaxis, and non-invasive venous thrombosis detection studies were performed before and after operation. No occasions of DVT or pulmonary emboli were detected postoperatively. Preoperative balanced ratios of antithrombin III/plasminogen were maintained intraoperatively and were increased postoperatively, reflecting on-going fibrinolysis. Changes in alpha-2 antiplasmin confirmed this interpretation. Patients subdivided into super- vs morbid obese groups showed less plasminogen reduction and a lower protein ratio during and after operation, and less antiplasmin consumption intraoperatively, in the heavier group. A linear regression analysis of excess weight on the protein ratio also showed lower ratios in the heavier patients. However, calf or thigh leg circumferences were not different between super- and morbid obese patients. These results suggest that leg pneumatic compression should be as effective but the immobility of super-obese patients may contribute to perioperative hypofibrinolysis and perhaps make them more susceptible to DVT and pulmonary embolism.