Comparison of the Effects of Intravenous Phenylephrine and Ephedrine in Treatment of Hypotension after Spinal Anesthesia in Orthopedic Surgery

BACKGROUND AND OBJECTIVE: Hypotension after spinal anesthesia is a common and potentially dangerous complication, prompt and accurate prevention and treatment of which are of paramount importance. In the recent studies there have been conflicting results regarding the efficacy of phenylephrine and ephedrine in the prevention and treatment of hypotension after spinal anesthesia. Thus, in this study, we purport to compare the effects of phenylephrine and ephedrine in the treatment of hypotension after spinal anesthesia for lower limb orthopedic surgery. METHODS: This double-blind clinical trial was conducted on 110 ASAI-II patients aged 40-65 years, who were candidates for orthopedic surgery of lower limbs under spinal anesthesia with 3 mL of bupivacaine 0.5%. The subjects were randomly divided into two groups of 55. After observing 20% fall in blood pressure or blood pressure less than 90/60 mm/Hg, the first group received 50 μg of phenylephrine and the second group was administered 5 mg of intravenous ephedrine. Information concerning the hemodynamic status of the patients was collected and compared. FINDINGS: Phenylephrine was more effective in the treatment of systolic and diastolic hypotension following spinal anesthesia compared to ephedrine (systolic blood pressure: 119±10.6 vs. 112.35±10.34 nc and diastolic blood pressure: 73.42±6.67 vs. 70.05±6.15 nc). However, it should be noted that except for 2 and 4 minutes after administration of vasopressor, there was no statistically significant difference between the two groups. In both groups, heart rate elevated simultaneously with decrease in blood pressure. CONCLUSION: The results revealed that phenylephrine was more effective in the treatment of hypotension following spinal anesthesia compared to ephedrine in lower limb orthopedic surgery.