A comparison of the haemodynamic effects of low doses of prophylactic intravenous ephedrine in spinal anaesthesia for lower abdominal surgeries

Abstract

Background: Vasopressors are often needed for prevention of spinal anaesthesia-induced hypotension despite intravenous fluid preload. Prophylactic intravenous ephedrine in doses of 5mg and above has been used successfully to prevent this condition. However, there is limited data on the use of doses lower than 5mg as prophylaxis. This study compared the efficacy of prophylactic intravenous ephedrine 3mg with 6mg ephedrine in the prevention of spinal anaesthesia-induced hypotension in patients undergoing lower abdominal (general) surgeries.

Patients and methods: Sixty nine ASAI and II patients scheduled for elective lower abdominal surgeries were randomly allocated into 3 groups (A, B and C). Spinal anaesthesia was induced in all the patients using 3.0mls of 0.5% plain bupivacaine after a preload with 10ml/kg of 0.9% Normal saline. Patients in group A received 2mls of Normal saline intravenously, while those in groups B and C received 3mg and 6mg intravenous ephedrine respectively, diluted in 2mls of normal saline, all within 2 minutes of intrathecal injection of bupivacaine. The incidence and severity of hypotension and also the intraoperative ephedrine use were compared.

Results: Results showed no significant difference in incidence of post-spinal hypotension between patients in groups B and C, p= 0.69. There was no significant difference in intra-operative ephedrine consumption by patients in groups B and C, p= 0.38.

Conclusion: Prophylactic intravenous ephedrine 3mg is as effective as ephedrine 6mg in reducing the incidence and severity of spinal anaesthesia-induced hypotension during lower abdominal (general) surgeries.

Keywords: Spinal anaesthesia-induced hypotension, prophylaxis, low-doses ephedrine