Effects of perioperative use of two doses of magnesium sulfate infusion on intraoperative blood loss in patients undergoing lumbar spinal fusion surgery

Abstract

Objective: In general, spinal fusion surgery causes heavy bleeding. The purpose of this study was to evaluate the use of two different doses of magnesium sulfate to control the bleeding in lumbar fusion surgery. Methods: This study was carried out as a randomized double-blinded clinical trial in 2020 in Al-Zahra hospital in Isfahan. The participants were 60 patients selected using inclusion and exclusion criteria and were randomly allocated into three groups. In the first group, 50 mg/kg and in the second group, 40 mg/kg magnesium sulfate was infused. The third group received normal saline. From the beginning of anesthesia, heart rate, diastolic and systolic blood pressure, respiratory rate and blood oxygen saturation percentage were monitored and logged every 30 minutes during the operation and recovery. The volume of bleeding during the operation was calculated by counting the number of gauzes used and the amount of suctioned blood during the operation. Other required information such as the duration of operation, duration of anesthesia, time of intubation and the time period of hospitalization and recovery were determined and recorded in all patients. We used independent t-test and repeated measure ANOVA tests to compare data between different time lines and also different groups. P value<0.05 was considered as significance threshold. The collected data were analyzed by using SPSS software version 23. Results: The group receiving 50 mg/kg magnesium sulfate had a significantly lower systolic blood pressure compared to other groups within 15, 30 and 45 minutes after the injections (P=0.04 for all). The pulse rate was significantly lower in the 50 mg/kg magnesium sulfate group compared to other groups within 15, 30 and 45 minutes after the injections (P<0.05 for all). Patients that received 50 mg/kg magnesium sulfate had a lower duration of surgery (P=0.007), lower duration of anesthesia (P=0.007), lower bleeding volume (P<0.001), lower fluid intake (P=0.01) and also lower transfused blood (P=0.01). The surgeons also had a significantly higher satisfaction with these patients (P=0.001). Conclusion: Injection of 50 mg/kg magnesium sulfate had a correlation with reduced blood pressure as well as bleeding volume compared to 40 mg/kg magnesium sulfate.