Comparative evaluation of isobaric ropivacaine (0.75%) with the adjuvants - clonidine and dexmedetomidine administered intrathecally in adult patients undergoing infra-umbilical surgeries

INTERVENTION: In this randomized double blind prospective clinical study we plan to evaluate the efficacy of adding Clonidine (30mcg), Dexmedetomidine (5mcg) or isotonic saline to 0.75% isobaric Ropivacaine for administration of subarachnoid lumbar block in infra‐umbilical surgical procedures with regard to characteristics of sensory and motor block and observation of any side effects. Each of these treatments will be given on just one occasion Thereare three groups. GROUP RS (Ropivacaine + Isotonic Saline) is the control group They will be administered 3.0ml of 0.75% isobaric Ropivacaine + 0.2ml of Isotonic Saline (total volume of injectate 3.2ml) GROUP RC (Ropivacaine + Clonidine) They will be administered 3.0ml of 0.75% isobaric Ropivacaine + 30mcg of Clonidine (0.2ml Inj. Clonidine; total volume of injectate 3.2ml) GROUP RD (Ropivacaine + Dexmedetomidine) They will be administered 3.0ml of 0.75% isobaric Ropivacaine + 5mcg of Dexmedetomidine (0.05ml of Dexmedetomidine diluted to 0.2ml in isotonic saline; total volume of injectate 3.2ml) CONDITION: intrathecal drugs PRIMARY OUTCOME: Duration of sensory block ‐ it will be assessed clinically Total duration of analgesia ‐‐ it will be assessed clinically SECONDARY OUTCOME: Time to onset of sensory block to T10 and T8 dermatomal levels Total duration of motor block ‐ clinical assessment INCLUSION CRITERIA: Patients scheduled to undergo elective infra‐umbilical surgery ASA grades 1 and 2 height : 150 to 180 cms Duration of surgery not exceeding 2 1/2 hours