Control of blood loss during scoliosis surgery.

By combining surgical and anesthetic techniques that minimize blood loss with the use of autotransfusion, it should now be possible to complete a routine posterior spinal fusion without using allogeneic blood transfusions. Surgical efforts should include careful preoperative planning, positioning with the abdomen hanging free, use of topical hemostatic agents, and decortication late in the procedure. Preoperatively donated autogeneic blood or reclaimed red cells from suction can take the place of allogeneic transfusions. Blood loss during scoliosis surgery correlates closely with left ventricular stroke work index (LVSWI), a measure of blood flow calculated from systemic vascular resistance, cardiac output, and heart rate. All of these parameters are under the anesthesiologist's control, making him the primary determinant of blood loss in scoliosis surgery. Induced hypotensive anesthesia may be ineffective in controlling blood loss if the cardiac output or heart rate is high. Halothane, a commonly used hypotensive agent, is not very useful for scoliosis surgery because spinal cord monitoring and wake-up testing are not possible. Rebound hypertension has been noted with the use of sodium nitroprusside. Trimethaphan works well clinically but experimentally it reduces spinal cord blood flow, which may increase the risk of spinal cord injury.