Original article / research
Dexmedetomidine versus Clonidine as Intrathecal Adjuvants to Hyperbaric Ropivacaine for Subarachnoid Block in Patients with History of Scorpion Bite undergoing Infraumbilical Surgery: A Double-blinded Randomised Clinical Study
UC32-UC36
Correspondence
Dr. Mouna Rao,
Junior Resident, Department of Anaesthesiology, Krishna Vishwa Vidyapeeth (Deemed to be University), Karad-415539, Maharashtra, India.
E-mail: mounarao850@gmail.com
Introduction: Patients with previous scorpion sting may show variable response to spinal local anaesthetics because scorpion toxins can alter voltage-gated sodium-channel behaviour. Ropivacaine and intrathecal alpha-2 agonists may improve block reliability in this subgroup.
Aim: To compare intrathecal dexmedetomidine and clonidine as adjuvants to 0.75% hyperbaric ropivacaine for Subarachnoid Block (SAB) in patients with history of scorpion bite undergoing infraumbilical surgery.
Materials and Methods: This double-blinded randomised clinical study was conducted in the Department of Anaesthesiology, Krishna Vishwa Vidyapeeth (Deemed to be University), Karad, Maharashtra, India. The study included 78 American Society of Anaesthesiologists (ASA) I-II adults aged 18-60 years with documented scorpion bite history scheduled for elective infraumbilical surgery. Patients were allocated equally. Group RD received 3 mL 0.75% hyperbaric ropivacaine with dexmedetomidine 5 μg intrathecally, while Group RC received 3 mL 0.75% hyperbaric ropivacaine with clonidine 30 μg. Block characteristics, block success and haemodynamic variables were recorded. Normality was assessed using the Shapiro-Wilk test. Continuous variables were compared using the independent-samples t-test, and categorical variables using the Chi-square or Fisher’s exact test. A p-value <0.05 was considered significant.
Results: A total of 78 patients were randomised, with 39 patients allocated to each group. Baseline characteristics were comparable between Group RD and Group RC, including age (42.6±9.8 vs 43.9±10.2 years), sex distribution (21/18 vs 23/16 male/female), weight (63.4±8.1 vs 64.1±7.6 kg), height (162.8±6.9 vs 163.2±7.1 cm), baseline heart rate (78.4±7.0 vs 79.5±6.8 beats/min), baseline mean arterial pressure (94.8±5.9 vs 93.7±6.1 mmHg), and duration of surgery (73.4±15.2 vs 75.1±14.8 minutes). Among patients with successful measurable block, sensory onset was significantly faster in Group RD than in Group RC (3.5±0.9 vs 5.3±1.3 minutes; p-value <0.001), and motor onset was also earlier (4.3±0.9 vs 5.7±1.2 minutes; p-value <0.001). Group RD demonstrated a longer duration of sensory block (274.2±24.9 vs 228.8±23.7 minutes; p-value <0.001) and motor block (245.8±28.0 vs 196.7±23.4 minutes; p-value <0.001). Successful spinal block was achieved in 38/39 (97.4%) patients in Group RD and 36/39 (92.3%) patients in Group RC; however, the difference was not statistically significant (p-value=0.615).
Conclusion: Intrathecal dexmedetomidine added to 0.75% hyperbaric ropivacaine produced faster sensory and motor onset and prolonged block duration compared with clonidine in patients with previous scorpion bite. Both regimens were haemodynamically acceptable, but dexmedetomidine showed superior overall block characteristics and reliability.