Comparative study of Hyperbaric Levobupivacaine (0.5%) with Intrathecal Dexmedetomidine and Hyperbaric Levobupivacaine (0.5%) with Intravenous Dexmedetomidine in patients undergoing lower abdominal and lower limb surgeries under spinal anesthesia- A PROSPECTIVE RANDOMIZED DOUBLE-BLIND STUDY.

Spinal anaesthesia is popular and commonly used worldwide. The advantage of an awake patient, minimal drug cost, excellent intraoperative anaesthesia, prolonged and satisfactory postoperative analgesia, rapid patient turnover has made this method of choice for many surgical procedures.

The increase in day care surgery has generated a need for a local anaesthetic with a quick onset and shorter duration of action allowing early ambulation. Bupivacaine is the first long acting amide linked local anaesthetic with advantage over lignocaine in its longer duration of action. In the last few years, it’s pure enantiomers such as ropivacaine [amides] and levobupivacaine [amides], have been introduced in clinical practice because of lower toxic effects for cardiovascular and central nervous system.

Levobupivacaine is a pure S(-) enantiomers of racemic bupivacaine, it is a long acting local anaesthetic with a relatively slow onset of action. It has a high potency. Levobupivacaine is equally lipophilic to bupivacaine but more than ropivacaine as ropivacaine has 3C side chain instead of 4C side chain as substitution of pipecoloxylidide.

Dexmedetomidine is a highly lipophilic drug that gets rapidly absorbed into the cerebrospinal fluid and bind to alphaâ€2â€adrenergic receptor of spinal cord to produce analgesia. It prolongs the duration of both sensory and motor blockade induced by local anesthetics irrespective of the route of administration whether epidural, caudal, or spinal. Intravenous dexmedetomidine is also known to prolong the duration of sensory block of local anesthetics during spinal anesthesia and peripheral nerve block but the underlying mechanism of this effect is unclear.There are very few evidences regarding efficacy of dexmedetomidine as neuraxial adjuvant.Dexmedetomidine is an alpha-2 adrenoreceptor agonist that is approved as an intravenous sedative and co-analgesic drug. It has an alpha2/alpha1 selectivity ratio which is eight times higher than that of clonidine. In previous clinical studies, intravenous dexmedetomidine resulted in a significant opioid sparing effect and decrease in inhalational anaesthetic requirements.  To improve the block characteristics of intrathecally administered low dose local anaesthetics, addition of adjuvant is must.

Little information is available in the literature regarding the use of hyperbaric levobupivacaine along with dexmedetomidine as adjuvant to produce spinal block for ambulatory surgeries.

The aim of this study is to compare the onset, duration of sensory and motor block, hemodynamic characteristics, assess duration of analgesia, assess sedation score and   side effects of addition of intrathecal dexmedetomidine 0.1ml(5 μg) or intravenous dexmedtomidine 0.5μg/kg to intrathecal 0.5% hyperbaric levobupivacaine.