Controlled hypotension for spinal surgery.

Controlled, deliberate hypotension during anesthesia for major spinal surgery reduces intraoperative blood loss and transfusion requirement. Hypotension may be achieved with increased doses of volatile anesthetic agents or by continuous infusion of vasodilating drugs. Safe application of this technique requires knowledge of the physiology of hemorrhagic shock and close intraoperative monitoring to avoid vasoconstriction and end-organ ischemia.