Comparison of efficacy of intrathecal fentanyl as an adjuvant to bupivacaine and ropivacaine in lower limb orthopaedic surgeries for post-operative analgesia

Abstract

Background: Sub-arachnoid block or spinal anaesthesia is a common mode of anaesthesia that is used for lower limb orthopaedic surgeries. Bupivacaine hydrochloride is a long-acting amide anaesthetic used extensively intrathecally. It has the ability to effectively block sensory and motor pathways. However, it has drawbacks, like cardiotoxicity and neurotoxicity. Ropivacaine is a long-acting amide local anaesthetic agent. It has the capacity to block sensory nerves more than motor nerves. Ropivacaine has reduced potential for neurotoxicity and cardiotoxicity. Fentanyl is a synthetic opioid. It can be added as an adjuvant to local anaesthetic agents used intrathecally. Fentanyl is characterised by its high potency, rapid serum elimination, and minimal histamine release. The blood-brain barrier can be quickly crossed by fentanyl, which takes one to two minutes to generate analgesia. Objectives: To compare post-operative analgesia in patients receiving bupivacaine with fentanyl and ropivacaine with fentanyl in lower limb orthopaedic surgeries via sub-arachnoid block; onset, duration of analgesia, duration of sensory and motor blockade; study the haemodynamic stability of patients in both groups; compare the requirement of 24 hours rescue analgesia; to compare the incidence of side effects. Methodology: This study will be a comparative interventional study which will be conducted on 60 adult patients of both sexes posted for lower limb orthopaedic surgery. They will be randomly divided into two groups with 30 patients in both groups. Group A: Patients receiving bupivacaine 3 mL with fentanyl 25 µg and Group B:  Patients receiving ropivacaine 3mL with fentanyl 25 µg. The onset of and duration of block (sensory as well as motor), hemodynamic parameters, post-operative analgesia time and side effects (if any) will be recorded. Trial registration: Submitted to Clinical Trial Registry of India (CTRI) Trial REF/2023/05/067586