Re-evaluation of im ephedrine as prophylaxis against hypotension associated with spinal anaesthesia for Caesarean section

Purpose: To assess the safety and efficacy of 37.5 mg ephedrine im in preventing hypotension associated with spinal anaesthesia for Caesarean section. Methods: In a double-blind randomised controlled study, 40 patients (20 in each group) were given either 37.5 mg ephedrine or placebo im. The following parameters were recorded: (i) blood pressure; (ii) heart rate; (iii) ephedrine iv supplementation; (iv) umbilical venous blood gases and neonatal Apgar scores. Results: The incidence of hypertension in the study group was 30% compared with 20% for the control group (P:NS). There was no difference in mean highest blood pressure or mean highest heart rate between the groups. The incidence of hypotension was lower but not significantly lower in the study group (50%) than in the control group (80%) (P:NS). However, the incidence of delayed hypotension was only 10% in the study group patients compared with;50% in the control group patients (P < 0.05). Conclusion: Giving 37.5 mg ephedrine im prior to spinal anaesthesia was not associated with reactive hypertension or tachycardia. Intramuscular ephedrine provided more sustained cardiovascular support than intravenous ephedrine.