The effect of cardiac output on intraoperative blood loss during total hip arthroplasty.

Overview

BACKGROUND AND OBJECTIVES: It is not clear whether cardiac output affects intraoperative blood loss under epidural hypotensive anesthesia. METHODS: Thirty patients undergoing primary total hip arthroplasty were randomly assigned to receive intravenous infusions of either low-dose epinephrine or phenylephrine to maintain mean arterial pressure at 50 to 60 mm Hg throughout surgery under lumbar epidural anesthesia. Patients were monitored with radial artery and thermodilution pulmonary artery catheters. Hemodynamic parameters were measured every 10 minutes during surgery, and blood loss was estimated by a blinded observer weighing sponges. RESULTS: Mean arterial pressure was similar between groups. Cardiac output remained unchanged in patients receiving low-dose epinephrine but declined significantly in patients receiving phenylephrine (p = 0.0001). Blood loss was 228 and 236 mL in patients receiving low-dose epinephrine and phenylephrine, respectively (p = 0.86). No correlation was observed between cardiac output and blood loss at any point during surgery. CONCLUSIONS: Cardiac output is not a factor influencing blood loss during hypotensive epidural anesthesia in elderly patients undergoing primary total hip arthroplasty.