Background: Clonidine added to bupivacaine prolongs the duration of anesthesia and postoperative analgesia with minimal side effects. Ropivacaine has lower lipid solubility and better safety profile as compared to bupivacaine. This study is designed to evaluate the effects of low-dose clonidine when added to hyperbaric ropivacaine.
Materials and methods: Ninety patients belonging to American Society of Anesthesiologists-I scheduled for lower limb or lower abdominal surgeries under spinal anesthesia were randomly allocated into three groups (n = 30). Group R: 0.5% hyperbaric ropivacaine 12 mg + saline, Group 15C: 0.5% hyperbaric ropivacaine 12 mg + 15 mcg clonidine and Group 30C: 0.5% hyperbaric ropivacaine 12 mg + 30 mcg clonidine for spinal anesthesia in a total volume of 3.2 ml. Block characteristics, hemodynamic parameters, and side effects were monitored.
Results: Addition of low-dose clonidine to hyperbaric ropivacaine, significantly prolongs the duration of sensory and motor blockade as well as postoperative analgesia compared with placebo (mean ± standard deviation min; 152.50 ± 15.3, 246 ± 23.5, and 217 ± 37.73, respectively with 15 mcg clonidine, 193 ± 16.59, 284 ± 23.28, and 234.83 ± 36.45, respectively with 30 mcg clonidine, 131 ± 14.7, 211.5 ± 24.39, and 192.33 ± 37.02, respectively with saline). The addition of low-dose clonidine significantly increases the incidence of intra-operative hypotension (46.7% and 83.3%, respectively compared to 16.7%), bradycardia (6.7% and 23.3%, respectively compared to 0%).
Conclusions: Addition of low-dose clonidine to intrathecal hyperbaric ropivacaine causes a significant prolongation of the duration of sensory and motor blockade as well as postoperative analgesia compared with saline placebo. However, it increases the incidence of hypotension and bradycardia which can be managed with routine clinical measures.
Keywords: Bupivacaine; clonidine; ropivacaine; spinal anesthesia.