Unfractionated heparin infusion for thromboprophylaxis in highest risk gastric bypass surgery

Patients undergoing gastric bypass for obesity are at risk for postoperative venous thromboembolic complications. Per our routine, these patients receive unfractionated heparin (UFH) per a previously described, blood volume-based, subcutaneous prophylactic UFH protocol. However, some patients have additional risk factors for thromboembolism, and we consider these patients to be at highest risk. To increase the predictability and reliable achievement of prophylactic anti-factor Xa levels for these patients at highest risk, we developed a prophylactic UFH continuous intravenous infusion protocol.

An UFH prophylactic protocol was developed in which the initial UFH loading dose and infusion rate were determined, based on patient blood volume and age. The target prophylactic anti-factor Xa activity range was 0.15-0.20 units/mL. 19 patients were admitted to the hospital the day before gastric bypass surgery. A prophylactic UFH infusion was initiated, and anti-factor Xa levels were checked and adjusted per protocol. The patients underwent surgery the following day and the UFH infusion was continued intra-operatively.

No patients were diagnosed with a deep venous thromboembolism. 2 patients experienced peri-operative hemorrhagic complications in spite of anti-factor Xa activity levels in, or only slightly above, the targeted range. Both patients recovered without further complications.

For highest risk gastric bypass patients, an UFH prophylactic continuous infusion protocol was effective in preventing postoperative thromboembolic events. Hemorrhagic complications were easily managed and did not result in long-term sequelae.