Introduction & Objective: Spinal anesthesia offers many advantages for cesarean section delivery. But one of its disadvantages is higher incidence of hypotension. Comparison of preemptive intramuscular and intravenous ephedrine for reduction of spinal anesthesia induced hypotension during cesarean section was the aim of this study.

Materials & Methods: This study was a randomized double blind clinical trial. 76 women candidate for elective cesarean section & A.S.A (class I,II) after obtaining an informed patients consent were randomly divided in four groups. Group IM50: 10 minutes before spinal anesthesia , 50 mg ephedrine IM and immediately after spinal anesthesia 2 ml N/S Iv were injected. Group IV20: 10 minutes before spinal anesthesia, 1ml N/S IM and immediately after spinal anesthesia 20 mg ephedrine IV were injected. Group IV10: 10 minutes before spinal anesthesia, 1ml N/S IM and immediately after spinal anesthesia 10 mg ephedrine IV were injected. Group P: 10 minutes before spinal anesthesia, 1ml N/S IM and immediately after spinal anesthesia 2 ml N/S IV were injected (Placebo). In all patients blood pressure and heart rate were measured by Reishter manometer and pulse oximetry device (oxypleth 520 A). after infusion of 500 ml ringer IV, spinal anesthesia was performed in sitting position , using needle number 25 gauge , at L3-L4 or L4-L5 level with 1.5 ml hyperbaric lidocaine 5%. Blood pressure and pulse rate were measured every minute for five minutes, also every 5 minutes and after 20 minutes every 10 minutes. Hypotension was defined as decreased blood pressure greather than 25% of baseline blood pressure or systolic blood pressure lower than 90 mmHg , which was treated with 10 mg IV ephedrine . Time and dose of therapeutic ephedrine was recorded.

Results: By considering age and baseline blood pressure and heart rate, all patients were similar. Mean systolic blood pressure (SBP) and mean arterial blood pressure (MAP) in IV20 group were higher than placebo group (P<0.05). Incidence of hypotension and mean dose of rescue ephedrine were also significantly lower in IM50 and IV20 groups.

Conclusion: Prophylactic ephedrine 20 mg IV or 50 mg IM, were effective in preventing hypotension during cesarean section under spinal anesthesia.