Original Research Article DOI: 10.18231/2394-4994.2017.0014 Indian Journal of Clinical Anaesthesia, 2017;4(1): 64-68 64 Evaluation and comparison of intravenous clonidine and intravenous dexmedetomidine on duration of bupivacaine spinal anesthesia Kalyani Nilesh Patil 1,* , Kavita Udaykumar Adate 2 , Shalini Pravin Saredesai 3 1 Assistant Professor, 2 Associate Professor, 3 Professor, Dept. of Anaesthesia, Srimati Kashibai Navale Medical College & General Hospital, Pune, Maharashtra *Corresponding Author: Email: kalyanish19@gmail.com Abstract Context: Alpha-2 agonists improve the block characteristics in regional anesthesia, when added to local anesthetics. Aim: To evaluate and compare efficacy of dexmedetomidine and clonidine, as an intravenous adjuvant to intrathecal bupivacaine. Settings and Design: Prospective, randomized, double-blind placebo-controlled study. Methods and Material: 75 patients of American Society of Anaesthesiologists status I or II, scheduled for orthopaedic lower limb surgery under spinal anaesthesia, were randomly allocated into three groups of 25 each. Patients in group D received dexmedetomidine 1μg/kg; group C received clonidine 2μg/kg and group PL received physiological saline, each premixed to 20 ml intravenously over 20 min, starting 20 min after the subarachnoid block with 15 mg of 0.5% hyperbaric bupivacaine. Duration of sensory and motor blockade, postoperative analgesia, sedation scores and side effects were recorded. Statistical analysis used: Parametric testing done using one-way analysis of variance (ANOVA), intergroup comparison with post-hoc analysis Tukey’s test. Categorical data analyzed using Chi-square test. P< 0.05 was statistically significant. Results: Duration of sensory block was significantly prolonged by dexmedetomidine (231.20+24.84 min) and clonidine (200+23.67 min) than placebo (171+12.25 min) (p<0.001). Duration of motor block was 135.20+12.87 min with placebo, 180.40+24.70 min with clonidine and 205.20+25.56 min with dexmedetomidine (p<0.001). Postoperative analgesia was significantly prolonged by dexmedetomidine (255+23.14 min) than by clonidine (221.40+ 24.30 min) and placebo (202.60+14.08 min) (p<0.001). The mean sedation score was significantly higher in dexmedetomidine group. Conclusion: Single-dose intravenous dexmedetomidine and clonidine given after spinal anaesthesia prolong duration of sensory and motor block and postoperative analgesia. Keywords: Clonidine, Dexmedetomidine, Spinal anesthesia. Key Messages: Alpha-2 agonists prove to be useful intravenous adjuncts to spinal anesthesia. They effectively prolong the duration or both sensory and motor block as well as postoperative analgesia, without any clinically significant adverse effects. Introduction Clonidine as well as dexmedetomidine are commonly added to the local anesthetics administered by different routes, including peripheral nerve blocks, intrathecal, epidural, caudal as well as in intravenous regional anaesthesia. (1-4) The concurrent injection of alpha-2 adrenergic agonist drugs improves the nerve block characteristic of local anaesthetics through either local vasoconstriction and facilitation of C fibre blockade or spinal action caused by retrograde axonal transport or simple diffusion along the nerve. (5-7) Clonidine and dexmedetomidine are selective α-2 adrenergic agonists with some α-1 agonist property. Dexmedetomidine is around eight to ten times more selective at α2 receptors as compared to clonidine. (3,4) In our study we have evaluated the effect of intravenous dexmedetomidine and clonidine on duration of motor and sensory block as well as postoperative analgesia, by intrathecal bupivacaine. Subjects and Methods We carried out this prospective, double-blind study after approval of the ethical committee of our institute. 75 patients of ASA (American Society of Anaesthesiologists) physical status I and II, of either sex, aged 18‑60 years, weighing 50‑70 kg, measuring 150‑170 cm in height, undergoing orthopaedic lower extremity surgery (plating and nailing for fracture tibia, plating for fracture shaft femur, triple arthrodesis for ankle) under spinal anesthesia were included. Exclusion criteria were presence of uncontrolled diabetes mellitus, cardiac disease, hypertension, chronic obstructive airway disease, hepatic and/or kidney disease, alcohol or drug dependence, psychological disease, spinal deformities or any condition contraindicating subarachnoid anesthesia, pregnant or lactating females, allergy to amide type of local anesthetics and those on adrenoreceptor agonist or antagonist therapy. Thorough preoperative assessment was done and a written, valid and informed consent was obtained from all the patients. On arrival to the OT, patients' baseline heart rate(HR), non-invasive blood pressure(NIBP) and electrocardiogram(ECG) were noted. 18G intravenous cannula was inserted in peripheral vein and patients were prehydrated with 500 ml of lactated Ringer’s solution. Under strict aseptic precautions, lumbar puncture was performed in the L3-L4 interspace via midline, using a 27-G Whitacre needle with the patient in sitting position. Hyperbaric bupivacaine (0.5%), 15 mg was injected in subarachnoid space and the patients