A Randomised Clinical Trial To Compare Between The Effectiveness Of Dexmedetomidine And Fentanyl As Adjuvants In Spinal Anaesthesia

Abstract

BACKGROUND AND OBJECTIVES Subarachnoid block or spinal anesthesia has increasingly become the technique of choice for surgeries below the diaphragm including lower limb surgeries. Spinal anaesthesia with 0.5% Bupivacaine as a standard drug for infra-umbilical surgeries is still the most commonly used technique. However, insufficient duration of anesthesia and inadequate postoperative analgesia with local ananesthetics like 0.5% Bupivacaine solely is unable to provide an extended duration of anesthesia or postoperative analgesia. In order to maximise duration of anesthesia and postoperative analgesia, a number of adjuvant were added to local anaesthetics. With demonstration of µ opiod receptors in substantiagelatinosa of spinal cord, the deficiency of inadequate duration of anesthesia of local anaesthetics is overcome by addition of opiods like Fentanyl. Dexmedetomidine, a new highly selective alpha2–adrenergic agonist, a potent analgesic, free of some side effects of opiods, is under evaluation as a neuraxial adjuvant to intrathecal local anaesthesia as it provides stable hemodynamic conditions, good quality of intraoperative and prolonged postoperative analgesia with minimal side effects(7,8,9). Considering the above facts this study was carried out to compare the two adjuvant agents, Dexmedetomidine (5ug) and Fentanyl (25ug) added to 15mg of 0.5% hyperbaric Bupivacaine introduced intrathecally for infraumbilical surgeries. MATERIALS AND METHODS 90 patients belonging to ASA grade- I and grade-II of both the sexes in 3 groups (each group with 30 patients, n= 30, Group C – hyperbaric bupivacaine, Group D – hyperbaric bupivacaine with dexmedetomidine, Group F – hyperbaric bupivacaine with fentanyl) were randomly selected for the study. The time of onset of sensory and motor block, time to achieve maximum sensory & motor block, XII maximum dermatomal levels achieved, time to two segment regression & regression to T12, total duration of block, haemodyamic changes, duration of analgesia and complications were compared among the three groups. RESULTS The mean time for onset of sensory and motor block was significantly shorter in Group D and Group F when compared to Group C but were comparable between each other. Mean time to achieve maximum sensory block in Group C (9.41 ± 0.56 min) was significantly longer (p<0.001) when compared to group D (7.33 ± 0.73 min) and group F (7.13 ± 0.61 min). Mean dermatomal level achieved in group C (T 6.8 ± 1.09) was statistically significant as compared to group D (T 5.96 ± 0.67) and group F (T 6.2 ± 0.76). Mean time to achieve maximum motor block in group C (8.6 ± 0.57 min) was significantly longer (p<0.001) when compared to group D (6.67 ± 0.63 min) and group F (6.41 ± 0.39 min). Mean time to achieve two segment regression of sensory level in group C (92.83 ± 8.37 min) was significantly shorter (p<0.05) when compared to group D (146.83 ± 9.14 min) and group F (122.16 ± 11.86 min). Mean time to achieve two segment regression of sensory level in group D was significantly longer than group F, which in turn was longer than group C. Mean time to achieve sensory regression to T12 level in group C (139.5 ± 13.60 min) was shorter as compared to group F (169.66 ± 13.76 min) and group D (2.8.116 ± 16.21 min) and these differences were found to be highly significant statistically (p<0.001). CONCLUSION From the present study it can be concluded that using Dexmedetomidine as an additive to spinal anaesthesia results in prolonged duration of block, with excellent quality of anaesthesia and prolonged duration of complete analgesia. Keywords : Intrathecal, fentanyl, bupivacaine, visual analogue scale, dexmedetomidine, quality of anaesthesia, post operative analgesia.