A comparative study of three different doses of 0.5% hyperbaric bupivacaine for spinal anaesthesia in elective...

We conducted a double-blind comparison of three doses (7.5 mg, 8.75 mg and 10 mg) of 0.5% hyperbaric bupivacaine in women undergoing elective caesarean under spinal anaesthesia. Sixty women were randomised into 3 groups of 20. Group A received 7.5 mg, group B 8.75 mg and C 10 mg of study drug. The time to maximum sensory blockade did not differ among the groups (P > 0.05). Mean time to start of regression of sensory block was greater in group C than in groups A and B (P < 0.001 and P < 0.05 respectively). Time required for complete regression of sensory block was longer in group C than in groups A and B (P < 0.001). Duration of motor block was greater in group C than in groups A and B (P < 0.001 and < 0.05 respectively). Neonatal outcome was good in all the groups. None of the patients in any group experienced pain before delivery. After delivery of the baby, however, group C women had a lower incidence of visceral pain than did groups A and B (P < 0.05). The incidence of hypotension was greater in groups B and C than in group A (P < 0.05). Group C women had a greater incidence of bradycardia than did groups A and B (P < 0.05). The 7.5-mg dose of 0.5% hyperbaric bupivacaine was observed to provide acceptable analgesia without any significant incidence of adverse effects such as maternal hypotension or bradycardia.