Hypotensive anesthesia and autotransfusion in spinal surgery

Sixty-eight (68) spinal operations performed under normotensive anesthesia were compared with 77 procedures performed under controlled hypotensive anesthesia. Procedures reviewed included Harrington instrumentation and fusion, dorsal arch resection, laminectomies and other spinal fusions. Intraoperative and postoperative blood loss and blood replacement were found to be reduced by approximately 50% in the group undergoing controlled hypotensive anesthesia for each procedure reviewed. This reduction in blood loss was achieved with only a moderate reduction in blood pressure (20 mm Hg systolic). Reduction in systolic blood pressure of greater than 20 mm was not associated with greater reduction in blood loss. Deliberate hypotension was coupled with hemodilution, lowering the hematocrit to 28% to 30% in order to increase cardiac output, increase tissue perfusion and decrease venous stasis. Autotransfusion has further reduced the need for homologous transfusion such that the combined techniques of hypotension and autotransfusion can eliminate the need for homologous blood transfusion in all but the most unusual cases.