A Randomised, Double-Blind, Placebo-Controlled Trial Comparing Dexmedetomidine and Clonidine as an Adjuvant to Intrathecal Ropivacaine in Lower Limb Surgery

BACKGROUNDVarious adjuvants are being used with local anaesthetics for prolongation of intraoperative and postoperative analgesia.This study was taken up to compare the duration of postoperative analgesia, extent of motor and sensory block, adverse effects along with the haemodynamic changes between ropivacaine alone, ropivacaine with clonidine and ropivacaine with dexmedetomidine. MATERIALS AND METHODS75 adult patients of both sexes undergoing lower limb surgeries under spinal anaesthesia patients of ASA grade I or II, ages between 20 -50 years, were enrolled in the study.Patients were randomly allocated to three equal groups, Group R received 2.5 mL of 0.75% hyperbaric ropivacaine with normal saline as a placebo, group D received Ropivacaine with 3 μg of dexmedetomidine and Group C received Ropivacaine with 30 μg of clonidine.All solutions were made up to 3 mL with addition of normal saline and injected at L3 -L4 using a 25-G spinal needle.The onset and duration of sensory and motor blockade, time to reach peak sensory and motor level and the sensory and motor regression times were recorded.Haemodynamic changes and time to use first rescue analgesia, Inj.tramadol hydrochloride 50 mg IV, were also recorded.In Post Anaesthesia Care Unit (PACU), pain scores were recorded using Visual Analogue Scale (VAS) for first 24 hours postoperatively.Descriptive statistics was used for describing frequencies, mean and standard deviation.Analysis of Variance (ANOVA) test was used to compare the quantitative variables in between the three groups, which were independent of each other.Chi square test was used to compare categorical variables.All the data was analysed using SPSS vs. 22.P value < 0.05 was considered statistically significant. RESULTSThere was no significant difference in patient's demographics or duration of surgery in the time of onset of sensory block, but motor block was early in Group D and Group C as compared to Group R. Duration of sensory and motor blockade was prolonged in Groups C and D compared with Group R. The mean regression time to S1 segment was 298.6±51 mins. in Group D, 268.6±26.4mins. in Group C and 199.8±32.9mins. in Group R. The regression of motor block to Bromage zero was 249±38.40mins. in Group D, 229±42.57mins. in Group C and 174±28.8mins. in Group R. The time to analgesia was significantly prolonged in Group D compared with Group C, the latter being longer than Group R. CONCLUSIONIntrathecal dexmedetomidine is associated with prolonged motor and sensory block, haemodynamic stability and reduced demand of rescue analgesics in 24 hrs.as compared to clonidine or Ropivacaine alone.