Fixed dose vs height and weight adjusted dose of bupivacaine for caesarean section: A randomised controlled trial

Objective: To determine frequency of maternal hypotension during spinal anaesthesia for elective caesarean section by comparing fixed dose with height and weight-adjusted dose of hyperbaric 0.5% bupivacaine. Method: This randomised controlled trial was carried out at Pakistan Naval Ship Shifa Hospital, Karachi, and comprised patients with singleton pregnancy who were randomly divided into two groups. After preloading with 10ml/kg of Ringers lactate, Group A received fixed dose of 10mg of 0.5% hyperbaric bupivacaine, while Group B received dose according to height and weight using Harten's dose chart. Patients were made supine with wedge placed below the right hip. Variation in blood pressure was recorded and hypotension was treated with phenylephrine. Data was analysed with SPSS 16. Results: There were 80 subjects divided into groups of 40(50%) each. Hypotension occurred in 20(50%) subjects in group A and in 15(37.5%) patients in group B(p>0.05). Median dose of 0.5% bupivacaine in group B was 9(IQR=0.5)mg and minimum dose was 8mg. Additional analgesia with ketamine was given to 2(5%) patients in group A and 3(7.5%) patients in group B. Conclusion: Fixed dose of 10mg of hyperbaric 0.5% bupivacaine had similar results to height and weight-adjusted dose of bupivacaine in spinal anaesthesia for caesarean section.