A Comparative Study of Fentanyl and Clonidine as an Adjuvant to Bupivacaine for Spinal Anesthesia

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A Comparative Study of Fentanyl and Clonidine as an Adjuvant to Bupivacaine for Spinal Anesthesia

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Photo by Toa Heftiba on Unsplash

Photo by Toa Heftiba on Unsplash

Why is it important?

Background: Spinal Anesthesia is the regional anesthesia obtained by blocking spinal nerves in subarachnoid space, the aesthetic agents are deposited in the subarachnoid space and act on spinal nerve roots and not on the substance of cord. Intrathecal opioids are synergistic with local aesthetic and intensity of sensory block without increasing motor block and offer Hemodynamic stability. Intrathecal opioids like fentanyl citrate is combined with local anesthetics which has milder side effects, also fentanyl citrate is lipophilic drugs. It has rapid onset compared lyophobic morphine. This property may affect onset of sensory block. When fentanyl citrate is added to bupivacaine hydrochloride for subarachnoid block. An intrathecal Clonidine has substantial antinociceptive effect by its action on 2 Receptor in dorsal Horn of spinal cord and by adding Clonidine with Bupivacaine hydrochloride improves intraoperative analgesia and might prolong the duration of spinal Analgesia. We compared the effects of fentanyl and Clonidine as an adjuvant to Bupivacaine for spinal Anesthesia. Methods: The study was carried out by selecting the patients presenting for surgery of lower limb, perineal surgery, lower abdominal surgery etc. Study was done in 50 patients belonging to ASA 1 and 2 selected for the study. Group - BF: Inj. Bupivacaine Hydrochloride (20 mg) (0.5%) + inj. Fentanyl citrate 25 µg. Group - BC: Inj. Bupivacaine Hydrochloride (20 mg) (0.5%) + inj. Clonidine Hydrochloride 50 µg. Time at which sensory and motor blockade reached highest dermatome level & stabilized at highest level. Recording of vital signs was started from the point of injection of drug in CSF. Heart Rate, Blood Pressure, SpO2, were noted every 1 min for first 10 min, then every 5 min till 30 min and then every 15 min till 60 min. Duration of total sensory and Motor Blockade is noted. Hypotension was defined as Systolic - Blood Pressure less than 90 mm HG or 30% decrease in Systolic Blood Pressure from Base line and Brady cardia was defined as Heart Rate less than 50 min. Patients were observed for following complication during procedure Hypotension, Bradycardia, Sedation, Respiratory depression, Nausea, Vomiting, Rigors, Pruritus. Duration of Motor & Sensory Blockade was noted. Results: We studied that mean time for onset of sensory block (sec) and motor block (sec) was shorter in Group - BF as compared to Group - BC. Total duration of motor and sensory block was longer in Group - BC as compared Group - BF. Changes in pulse rate, systolic BP and diastolic BP shows statistical significance in both Group. First analgesic requirement was more prolonged in Group - BC. Group - BF shows some complications like Nausea, Pruritus, and Hypotension. Group - BC shows complications like sedation, Hypotension and bradycardia. Conclusion: Clonidine Hydrocloride caused intense sensory and motor blockade when injected with bupivacaine. Clonidine also didn’t show side effects like respiratory depression, pruritus, urinary retention. Which were noted with the use of fentanyl. But onset of action was delayed with use of clonidine and increased chances of more bradycardia, hypotension and sedation compared to fentanyl which required more supportive care.

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