Combination of buprenorphine with hyperbaric bupivacaine administered either as a mixture or sequentially for spinal anaesthesia for caesarean section

Introduction: Density of local anesthetic is an important determining factor for the distribution, duration and degree of the block achieved in spinal anaesthesia, with small changes influencing its distribution. Mixing of opiods with hyperbaric bupivacaine in the same syringe for injecting into subarachnoid space is a routine practice, which can change the density of both drugs thus affecting their spread. Our study aims to compare the efficacy of premixed or sequential injections of bupivacaine and buprenorphine for spinal anaesthesia for caesarean section in terms of block characteristics and haemodynamics. Materials and Method: 120 parturients undergoing elective caesarean section were randomly allocated to two groups, Group M received spinal anaesthesia with 10 mg of 0.5% hyperbaric bupivacaine mixed with 90 micrograms of buprenorphine in a single syringe. Group S received 0.5% hyperbaric bupivacaine 10mg followed by 90 micrograms of buprenorphine through separate syringes. Results: There was significant difference in the highest level of sensory block to pin prick in Group M compared to Group S (T5 vs T6) (P < 0.0001). 20% patients had sensory level of T1 in Group M where as none of the patients in Group S had sensory level T1. Hypotension was noted in 58.3% of patients in Group S and 21.7% in Group M. The total mean dose of vasopressor used in Group M was 5.75+/- 5.85 and 1.85+/- 4.03 in Group S (P < 0.0001). Conclusion: Mixing of Buprenorphine with hyperbaric bupivacaine is associated with greater incidence of hypotension which necessitates the use of larger doses of vasopressor intraoperatively, which could be due to higher level of sensory blockade.