ABSTRACT : Various adjuvants have been tried to prolong the duration of spinal anaesthesia with small volume of drug and minimal adverse effects. A study was conducted with this purpose to compare the effect of intrathecal clonidine 75 μg or neostigmine 50 μg added to intrathecal hyperbaric bupivacaine,with regards to sensory & motor characteristics,haemodynamic stability and side effects.

METHODS : This was a prospective randomized double blinded study in 50 patients posted for vaginal hysterectomies belonging to ASA I and II status, aged between 45- 60 years. A total of 3ml of drug injected intrathecally with One group receiving clonidine 75 μg (group BC) and other group neostigmine 50 μg(group BN), with intrathecal 0.5% hyperbaric bupivacaine and were compared with sensory,motorcharacteristics,haemodynamic stability,post operative analgesia and PONV.

RESULTS : Addition of 50 μg neostigmine significantly enhanced the onset of sensory block (BN 85 ± 20 secs, BC 140 ± 15 secs, p value as <0.05 ) and motor block (BN 100 ± 15 secs, BC 200 ± 20 secs, p value as <0.05) compared to clonidine. Group BC had prolonged analgesia (302 ± 30 mins) compared to BN group (260 ± 20 mins) (P < 0.05).Haemodynamic events are more with clonidine and required intervention with atropine and vasopressors.There were no serious post operative side effects in both the groups.

CONCLUSIONS : The use of low dose intrathecal neostigmine 50 μg added to 12.5 mg hyperbaric bupivacaine significantly hastens the onset of sensory and motor block without serious adverse effects compared to clonidine 75 μg. Post op analgesia is more with clonidine but clonidine is associated with increased incidence of hypotension & bradycardia.