Spinal anaesthesia with low-dose bupivacaine in marginally hyperbaric solutions for caesarean section: A randomised controlled trial.

Background: Conventional hyperbaric spinal anaesthesia solution (SAS) with 8% glucose and low-dose bupivacaine may reduce the incidence of hypotension in caesarean section compared to standard doses, and marginally hyperbaric SAS (≤0.8% glucose) can induce a lower block level and a lower incidence of hypotension in nonobstetric patients than conventional 8% glucose SAS.

Objective: The objective of this study was to evaluate the clinical efficacy of marginally hyperbaric low-dose bupivacaine solutions used for spinal anaesthesia during caesarean section.

Design: A randomised, controlled clinical trial.

Setting: Single medical centre.

Patients: One hundred twenty women scheduled for elective caesarean section were randomised into four groups.

Interventions: Caesarean section after combined spinal-epidural anaesthesia using hyperbaric preparations of low-dose SAS (7.2 mg bupivacaine and 2 μg 1.6 ml sufentanil in one of the following: 8%, 0.8%, 0.5% or 0.33% glucose solution.

Main Outcome Measures: The dermatomal sensory block and degree of motor block of the lower extremities and adverse effects of anaesthesia were recorded.

Results: The maximum cephalad sensory block level and the incidence of hypotension decreased as the density of SAS fell (T1, T2, T4 and T6, P < 0.001; 48.3, 30, 13.3 and 10.3%, P = 0.003). The incidence of shivering reduced with decreasing density of SAS (P < 0.05). There was no significant difference in the quality of anaesthesia (efficacy of motor block and sensory block) between the groups (P > 0.05).

Conclusion: Compared with conventional 8% glucose hyperbaric SAS, marginally hyperbaric (0.5 or 0.33% glucose) low-dose bupivacaine solutions led to a significantly lower height of cephalad spread and incidence of hypotension with no impact on the efficacy of spinal anaesthesia for caesarean section.