Comparative Evaluation of Intrathecal Clonidine and Nalbuphine as an Adjuvant to Hyperbaric Ropivacaine in Subarachnoid Block

Subarachnoid block is a widely used anesthetic technique for lower abdominal and lower limb surgeries. Adding adjuvants to local anesthetics enhances block quality and prolongs postoperative analgesia. This prospective, randomized, double-blind study compared the efficacy of intrathecal clonidine versus nalbuphine as adjuvants to hyperbaric ropivacaine. Ninety patients undergoing lower limb orthopedic surgery were randomly allocated into three groups (n=30 each): Group R received 15mg hyperbaric ropivacaine 0.75% alone, Group RC received ropivacaine plus 30μg clonidine, and Group RN received ropivacaine plus 0.8mg nalbuphine. Primary outcomes included onset and duration of sensory and motor block. Secondary outcomes comprised duration of analgesia, hemodynamic parameters, and adverse effects. Both adjuvant groups showed significantly faster onset of sensory block (RC: 4.2±0.8min, RN: 4.5±0.9min) compared to control (5.8±1.1min) (p<0.001). Duration of sensory block was prolonged in Group RC (246±28min) and Group RN (218±24min) versus Group R (168±21min) (p<0.001). Motor block duration was longest in Group RC (198±22min), followed by RN (176±19min) and R (142±17min) (p<0.001). Time to first rescue analgesia was significantly extended in RC (386±42min) and RN (342±38min) compared to R (246±31min) (p<0.001). Hypotension incidence was higher in Group RC (33.3%) compared to RN (16.7%) and R (13.3%) (p=0.041). Both clonidine and nalbuphine effectively enhance ropivacaine spinal anesthesia, with clonidine providing superior block characteristics but increased hypotension risk.