Comparison of the Effect of Two Different Doses of Labetalol to Induce Controlled Hypotension on Hemodynamic Changes During Spinal Fusion Surgery

BACKGROUND: Spinal fusion surgery is often associated with heavy bleeding. Labetalol is one of the most effective drugs used to control bleeding in surgery. OBJECTIVES: Here, we measured the effect of two therapeutic doses of labetalol on the amount of bleeding. METHODS: This is a randomized clinical trial that was performed in 2020-2021 in Al-Zahra hospital in Isfahan, Iran, on patients that were candidates for posterior spinal fusion surgery under general anesthesia. A total number of 64 patients were entered and randomized into two groups, one receiving labetalol at the dose of 2 mg/min and another group at 4 mg/min during surgery. The amount of bleeding in patients, heart rate, blood pressure, blood oxygen saturation, hypotension or bradycardia, and the mean length of stay in the recovery room were measured and compared between the groups. RESULTS: Extubation time (14 ± 4) and recovery time (76 ± 17) were significantly lower in patients that received labetalol (2 mg/min) compared to another group (21 ± 7 for intubation time and 116 ± 32 for recovery time (P < 0.001 for both items). Patients that received labetalol (4 mg/min) had significantly lower amounts of hemorrhage compared to other group (P = 0.001), and the surgeon's satisfaction was significantly higher in the second group (P = 0.001). The frequency of hypotension and bradycardia during the surgery were significantly higher among patients that received labetalol at the dose of 4 mg/min (P = 0.002 and P = 0.001, respectively). The patients in the group labetalol at 4 mg/min had also significantly lower systolic and diastolic blood pressure and lower mean arterial pressure (MAP) compared to the other group (P < 0.05). CONCLUSIONS: Administration of labetalol at the dose of 4 mg/min had significantly desirable effects on hemodynamics that resulted in reduced bleeding volume and blood pressures compared to labetalol at the dose of 2 mg/min.