Effect of different anesthesia techniques on red blood cell endogenous recovery in hip arthroplasty

STUDY OBJECTIVE: To compare the magnitude of postoperative red blood cell (RBC) recovery with 3 different anesthetic techniques, general anesthesia (GA), epidural anesthesia (EA) alone, and the combination of these 2 techniques (CA), in patients undergoing total hip arthroplasty. DESIGN: Randomized, controlled study. SETTING: Seven university or hospital departments of anesthesia. PATIENTS: Two hundred ten patients with American Society of Anesthesiologists physical status I to III were randomly selected to receive EA, GA, or CA. INTERVENTION: Patients undergoing total hip replacement were randomly assigned to 3 statistically comparable groups based on the type of anesthesia received: GA, EA, and CA groups. MEASUREMENTS AND MAIN RESULTS: Intra- and postoperative blood loss was evaluated as either compensated or noncompensated blood loss by using Nadler's formula. The intra- and postoperative bleeding, referred to as compensated blood loss, was similar among groups. The circulating RBC mass, noncompensated blood loss, dropped on the first postoperative day to a similar extent among the groups. The endogenous recovery of the RBC is carried out on the fifth day after surgery in patients who underwent EA, whereas no RBC recovery was observed in those who had received GA alone or GA combined with EA. CONCLUSIONS: Patients who had received EA had a faster recovery of the circulating erythrocyte mass than those who had had GA or CA. The presence of nitrous oxide in the anesthetic gas mixture might inhibit erythropoiesis by altering vitamin B(12) functions.