Comparative study of clonidine and fentanyl as adjuvants to ropivacaine in spinal anesthesia: impact on analgesic efficacy, hemodynamic stability, and adverse effects

Background & objective: Spinal anesthesia is commonly used for lower limb and abdominal surgeries, but its effectiveness is limited by the duration of action of local anesthetics. To prolong analgesia and improve intraoperative conditions, adjuvants such as clonidine and fentanyl are added to local anesthetics. This study aims to compare the efficacy and safety of clonidine and fentanyl as adjuvants to ropivacaine in spinal anesthesia, focusing on sensory and motor blockade duration, postoperative analgesia, hemodynamic changes, and adverse effects. Methodology: A randomized, double-blind, controlled trial was conducted on 75 patients undergoing elective lower abdominal and lower limb surgeries. Patients were randomly assigned to three groups: Group A: ropivacaine 0.25%, Group B: ropivacaine + clonidine 5 µg, and Group C: ropivacaine + fentanyl 15 µg. The onset and duration of sensory and motor blockade were assessed using the pinprick method and Modified Bromage Scale. Hemodynamic parameters (heart rate, systolic and diastolic blood pressure) were monitored at regular intraoperative intervals. The time to first rescue analgesia and VAS pain scores were recorded at 1, 6, 12, and 24 hours. Adverse effects, including sedation, nausea, hypotension, and bradycardia, were recorded. Statistical analysis was performed using ANOVA and Chi-square tests in SPSS version [X]. P < 0.05 was considered significant. Results: Group B (clonidine group) had the longest sensory and motor blockade duration, followed by Group C (Fentanyl), with Group A showing the shortest duration (p < 0.0001). Time to first rescue analgesia was significantly prolonged in Group B (528.8 ± 12.2 min) compared to Group C (422.1 ± 13.9 min) and Group A (203.3 ± 16.4 min) (P < 0.0001). Hemodynamic instability was more pronounced in Group B, with a higher incidence of hypotension and bradycardia, whereas Group C had a greater incidence of mild sedation and bradycardia. Sedation was significantly higher in Group B (P = 0.0033), while nausea and pruritus were more frequent in Group A. Group A required significantly more rescue analgesia doses compared to Groups B and C (P < 0.0001). Conclusions: Clonidine as an adjuvant to ropivacaine in spinal anesthesia significantly prolongs sensory and motor blockade and enhances postoperative analgesia, but is associated with greater sedation and hemodynamic instability. Fentanyl also improves analgesia with a lower risk of hypotension but increases bradycardia incidence. Abbreviations: DBP: diastolic blood pressure, HR: heart rate, SA: Spinal anesthesia, SBP: systolic blood pressure, Keywords: Spinal Anesthesia; Ropivacaine; Clonidine; Fentanyl; Postoperative Analgesia; Hemodynamic Stability; Adverse Effects; Regional Anesthesia Citation: Ambali L, Thilaak P, Priya MR, Brindha R, Sabapathy VA, Periasamy P, Choudhary AK. Comparative study of clonidine and fentanyl as adjuvants to ropivacaine in spinal anesthesia: impact on analgesic efficacy, hemodynamic stability, and adverse effects. Anaesth. pain intensive care 2025;29(6):528-534; DOI: 10.35975/apic.v29i6.2903 Received: March 05, 2025; Revised: May 06, 2025; Accepted: May 15, 2025