A COMPARATIVE STUDY OF HYPERBARIC ROPIVACAINE VS HYPERBARIC LEVOBUPIVACAINE IN SPINAL ANAESTHESIA

• Spinal anaesthesia is a regional anaesthesia technique in which minimal doses of intrathecal local anaesthetic agents are used so that only the nerve roots supplying specific areas are anaesthetised.

• Hyperbaric bupivacaine injection is the most commonly used drug for spinal anaesthesia. It causes a long-lasting motor block associated with hypotension and bradycardia, which eliminates it as the drug of choice for day care surgeries.

• Day care surgery is suited to provide patient centered treatment, which allows them to receive treatment as per their needs and to return home on the day of surgery and recover in a familiar home enviornment.

• The increased in no. of day care surgeries has resulted in quest for alternative local anaesthetics and combinations which can produce spinal anaesthesia of relatively shorter duration with better haemodynamic stability.

• Ropivacaine and Levobupivacaine are newer local anaesthetics which appear to have a favourable profile.

• Ropivacaine is the ‘S’ isomer of the propyl analogue of bupivacaine with long duration of action, low lipid solubility, low potency and low cardiovascular and CNS toxicity. It blocks nerve fibres involved in pain transmission (Aδ and C fibres) to a greater degree than those controlling motor function (Aβ fibres).

• Levobupivacaine, a pure S(-) enantiomer of bupivacaine is also a long acting amide local anaesthetic which produces differential neuraxial block, that is, early onset and prolonged duration of sensory block with shorter duration of motor block and has lower cardiac toxicity.

• Clinical studies have shown that ropivacaine and levobupivacaine are equally effective. However, levobupivacaine has lower affinity for sodium channels in the heart and therefore it is less frequently associated with cardiovascular events.

• Hyperbaric local anaesthetic solution is heavier than cerebrospinal fluid at 37 °C. Spread of hyperbaric solution depends on position of patients; in head up position, it spreads caudally and in head down position, it spread in cephalic direction. Hyperbaric solution will preferentially spread to the dependent regions of the spinal canal.

• Hyperbaric local anaesthetics injected at the L3-L4 interspace will spread from the height of lumbar lordosis down toward the trough of thoracic kyphosis, resulting in a higher level of anaesthetic effect than isobaric or hypobaric solutions.

• A randomised comparative study will be conducted to assess the efficacy of the newer local anaesthetic agents ropivacaine and levobupivacaine in spinal anaesthesia.