Effects of preoperative β-blocker on blood loss and blood transfusion during spinal surgeries with sodium nitroprusside–controlled hypotension

BACKGROUND: The present study sought to determine whether premedication with oral β-blocker before hypotensive anesthesia with sodium nitroprusside could improve the quality of surgical field, decrease the blood loss, and decrease the need for homologous blood transfusion and duration of surgery. METHODS: Eighty patients scheduled for spinal fixation surgery were included in a prospective, randomized, double-blinded study. Patients were classified into two groups: Group I received oral atenolol 50 mg twice one day before surgery; and Group II received placebo tablets identical in appearance to atenolol tablets for the same period and interval. All patients in both the groups received intraoperative sodium nitroprusside (SNP) as a hypotensive agent. Hemodynamic variables, amount of sodium nitroprusside used, quality of surgical field, and the amount of homologous blood transfusion and blood loss were compared between groups. RESULTS: Heart rate and amount of SNP used were significantly less (P<0.0001) in the atenolol group, but no significant difference was found in intraoperative mean arterial blood pressure (MABP) between the two groups. The time of surgeries was significantly shorter in Group I than in Group II (185±15.21 vs 225±12.61 min), P<0.0001. The quality of surgical field was better in Group I than in Group II in all times of measurements, P<0.0001. The amount of blood loss and the amount of packed red blood cells transfused were significantly less in Group I than in Group II, P<0.0001. No clinically significant complications were observed in either group. CONCLUSION: Premedication with oral atenolol 50 mg twice/day for one day before hypotensive anesthesia with SNP during spinal surgeries seems to be clinically safe and effective to reduce heart rate, amount of SNP used, amount of blood loss, and amount of blood transfused with better quality of surgical field.