“A COMPARATIVE STUDY OF EQUIPOTENT DOSES OF INTRATHECAL CLONIDINE AND DEXMEDETOMIDINE ON CHARACTERISTICS OF BUPIVACAINE SUBARACHNOID BLOCK

Abstract

To increase the duration of analgesia produced by local anaesthetics a number of adjuvants have been added to centrineuraxial block. Administration of intrathecal Clonidine or Dexmedetomidine has shown to improve the quality of spinal anaesthesia. It abolishes pain of somatic origin without any neurotoxicity. In view of the above considerations, this clinical study was undertaken to assess the behaviour and feasibility of administration of intrathecal Clonidine or Dexmedetomidine as an adjuvant for bupivacaine intrathecally in patients posted for elective lower abdominal or lower limb surgeries. Method This clinical study was conducted on 156 adult patients of ASA physical status I, II and III in the age group of 18-60years of either sex posted for elective lower abdominal or lower limb surgeries under spinal anaesthesia after taking informed consent. Patients were randomly divided on an alternative basis into 3 groups of 52 each Group-B: 0.5% Bupivacaine 15mg + 0.5 ml Normal saline Group-C: 0.5% Bupivacaine 15mg + 50 µg Clonidine (Test solution was diluted with Normal saline to a total volume of 3.5ml) Group-D : 0.5% Bupivacaine 15mg + 5 µg Dexmedetomidine(Test solution was diluted with Normal saline to a total volume of 3.5ml) Parameters Onset and duration of sensory block and motor block, highest level of sensory blockade, duration of analgesia, vitals and side effects were assessed. XIII Results The onset of motor block was faster in group C and group D as compared to group B, fastest in group C followed by group D. The duration of sensory and motor blockade and duration of analgesia was longer in group C and D as compared to group B, longest in group D followed by C and B. There was no significant haemodynamic changes in all the three groups. Conclusion Supplementation of bupivacaine spinal block with a low dose of intrathecal Dexmedetomidine (5 µg) or Clonidine (50 µg) produces a significantly shorter onset of motor and sensory block and a significantly longer sensory, motor block and longer analgesia than bupivacaine alone. These doses have an effect on sedation level, heart rate and mean arterial pressure which does not however require any therapeutic intervention.