Comparative study of the effect of two different doses of remifentanil on bleeding control in lumbar fusion surgery: A randomized clinical trial.

Objectives: Spinal fusion surgery completely prevents movement or friction between the two vertebrae. Remifentanil, a selective drug agonist, suppresses and decreases the vasomotor system upon release of histamine. In this study, the efficacy of remifentanil infusion at doses of 0.1 and 0.3 μg/kg/min in the control of low blood pressure was compared. Methods: In this randomized clinical trial, 110 candidates for selective spinal fusion surgery were entered and randomized into 2 groups. The first group received 0.1 μg/kg/min and in the second group 0.3 μg/kg/min remifentanil. The systolic and diastolic blood pressure, pulse rate, SPO2, and surgeon's satisfaction were measured and compared between groups. Results: the systolic blood pressure was significantly lower in patients receiving 0.3 μg of remifentanil by the time 30, 45, 60, and 90 min during the surgeries (P < 0.05). No significant difference was observed in terms of PR (P = 0.19) and SPO2 (P = 0.41) between the two groups. We also observed significantly higher duration of surgeries (P = 0.002), duration of anesthesia (P = 0.009), significantly higher bleeding volume (P < 0.001), higher fluid intake (P = 0.01) and higher transfused blood (P = 0.01) in patients that received 0.1 μg remifentanil compared to other patients. Conclusion: Here we showed that administration of 0.3 μg/kg/min remifentanil was associated with significantly lower systolic blood pressure during the surgeries. On the other hand, patients that received 0.1 μg/kg/min remifentanil had significantly higher duration of surgeries, duration of anesthesia, significantly higher bleeding volume, higher fluid intake, and also higher transfused blood.