Efficacy and Safety of Different Prophylactic Doses of Phenylephrine for Prevention of Spinal Anaesthesia induced Hypotension in Cesarean Section-A Randomised Controlled Trial

Abstract

Introduction: Spinal anaesthesia is a standard technique for elective caesarean section. But, hypotension is the main complication, which adversely affects both mother and foetus. Aim: To evaluate the efficacy and safety of different prophylactic doses of phenylephrine for prevention of spinal anaesthesia induced hypotension. Materials and Methods: This prospective, randomised, double blinded controlled study was conducted on 104 pregnant mothers who fulfilled the subject selection criteria. Patients were randomly allocated into four groups: Group A received 2 mL of 0.9% saline solution Intramuscularly (IM), Group B, Group C and Group D received 1 mg, 2 mg, and 3 mg of phenylephrine (made in 2 mL of 0.9% saline) IM, respectively. Hyperbaric bupivacaine 0.5%, 2.5 mL was administered intrathecally to all subjects. Haemodynamic parameters: Systolic Blood Pressure (SBP), Mean arterial Blood Pressure (MBP), Diastolic Blood Pressure (DBP), Heart Rate (HR) were recorded throughout the surgery at three minutes interval and 10 minutes interval for one hour after surgery (study period). Adverse events were also noted throughout the study period. Fisher’s exact test, Kruskall-Wallis test, Friedman’s ANOVA were done for statistical analysis. Results: Subjects of Group D had least episode of hypotension (2 times) than Group A (13 times). Subjects of Group D required least amount of rescue medication (73.91±22.85 mcg) than Group A (435±39.25 mcg) that was statistically significant (p<0.001). Incidence of nausea and vomiting were least in subjects of Group D (7.69%) than Group A (66.67%) which was statistically significant (p<0.001). Conclusion: Prophylactic 3 mg IM phenylephrine is effective to lower the incidence of spinal anaesthesia induced hypotension in elective caesarean section with minimal tolerable adverse effects.

Keywords

• anaesthetic techniques
• double blinded study
• phenylephrine