A Randomized Comparative Study to Evaluate the Effects of Successional Versus Premixed Administration of Intrathecal Hyperbaric Ropivacaine 0.75% and Fentanyl in patients scheduled for Elective Urological Surgery Under Spinal Anaesthesia

Now a days, spinal anaesthesia is being utilized in many operations which are below the umbilicus as being cost effective, associated with few respiratory complications, the airway is not manipulated which reduces the risk of airway obstruction or aspiration of gastric components, blood loss is less intraoperatively comparative to same operation being conducted under general anaesthesia. The introduction of Hyperbaric Ropivacaine (0.75%) has revolutionized the safety profile of local anaesthetic agents. Ropivacaine is the pure S-enantiomer which is associated decreased cardiotoxicity as compared to Bupivacaine. Other advantages of Ropivacaine are that it produces sensorimotor differential blockade with early recovery from motor blockade and thus leading to early ambulation of patient and also has decreased central nervous system toxicity.  Blending opioids with hyperbaric bupivacaine affects the amount of drug that spreads into the intrathecal space because it changes the density of the hyperbaric solution.

. At 37°C, cerebrospinal fluid (CSF) has a density of 1.00059 g/ml. Fentanyl has a baricity of 0.99410 while hyperbaric bupivacaine has a baricity of 1.02360. After annexing Fentanyl(20mcg) to the identical syringe as local anaesthetic, baricity of the solution becomes 1.018502. A change in a solution’s baricity of 0.0006 can change how local anaesthesia spreads in the cerebrospinal fluid (CSF). Hyperbaric solutions improve intraoperative physiological state, lengthen the period of impact, and become more easy to predict, with greater unfold within the direction of gravity and less inter-patient variability, provide with stable haemodynamic and prolonged postoperative analgesia. [15] The specific gravity of Ropivacaine hydrochloride in dextrose injection is between 1.025 and 1.035 at 250 C and about 1.03 at 370 C which is more comparative to Bupivacaine. Though the Fentanyl has been used extensively premixed with hyperbaric bupivacaine for spinal anaesthesia, there is paucity of literature on clinical effects and understanding of mechanism of influence of fentanyl on subarachnoid block produced by hyperbaric ropivacaine when administered separately by another syringe, either before or after ropivacaine. Correlating with the available literatures on premixed versus sequential administration of intrathecal fentanyl and bupivacaine - The present study will be done to evaluate the effects of successional versus premixed administration of intrathecal hyperbaric ropivacaine and fentanyl in spinal anaesthesia undergoing elective urological surgery.