Comparison of the Effect of Scalp Block With Ropivacaine vs. Ropivacaine and Clonidine on Postoperative Pain in Patients Undergoing Craniotomy Surgery Under General Anesthesia

Abstract

Introduction Clonidine, an α2 agonist known for its hypotensive and analgesic effects, has proven beneficial in various routes of administration such as oral, intravenous, and local infiltration. Scalp blocks enhance hemodynamic stability during surgery and reduce intraoperative opioid requirements compared to controls in numerous studies. Additionally, they are effective in managing postoperative pain, resulting in reduced opioid consumption. Research has shown that clonidine can enhance and prolong the effects of intrathecal, epidural, and peripheral nerve blocks (e.g., brachial plexus, peribulbar). Here, we investigated the impact of adding clonidine at a dose of 1 μg/kg to scalp blocks performed with 0.5% ropivacaine for supra-tentorial craniotomy Material and methods This study was conducted on 60 patients under the American Society of Anesthesiologists (ASA) grade I and II who were scheduled for elective supratentorial craniotomy. Patients were divided into two equal groups of 30 and received a scalp block following general anesthesia. Patients in Group A (n=30) received a scalp block of 0.5% ropivacaine plus 1 ml of normal saline (total 21 cc). Patients in Group B (n=30) received a scalp block of 0.5% ropivacaine and clonidine (1 μg/kg) combined with 0.5 ml of normal saline (total 21 cc). Blood pressure, heart rate, peripheral oxygen saturation (SpO₂), visual analog score, Ramsay sedation score, duration of analgesia, and analgesia requirement in the first 24 hours were recorded from baseline and postoperatively. Results The duration of first rescue analgesia for Group A was 4.30 ± 1.5 hours and that of Group B was 9.10 ± 1.4 hours. Duration of analgesia was significantly prolonged in patients receiving ropivacaine with clonidine for scalp nerve block. The amount of tramadol given in the first 24 hours in Group A, 62.50 ± 25.00 mg, was high compared to Group B, 57.14 ± 18.89 mg. The mean arterial blood pressure differed significantly in both groups at 30 minutes, 1 hour, 3 hours, and 12 hours after scalp block postoperatively and lower in Group B. Although changes in pulse rate, and SpO₂ were not statistically significant in both groups, patients were hemodynamically stable and did not require any ionotropic support. Ramsay sedation score and visual analog score postoperatively were not significant. There were no significant adverse effects noted in any groups. Conclusion Our study concluded that administering clonidine at a dosage of 1 μg/kg, in combination with 0.5% ropivacaine for scalp nerve block procedures, significantly extends the duration of analgesia and enhances its quality, all while maintaining stable hemodynamic parameters.

Keywords: clonidine; postoperative pain; ramsay sedation score; ropivacaine; scalp block; supratentorial craniotomy; visual analog score.

Figure 1. Comparison of mean arterial blood pressure (mmHg)

MAPB: Mean arterial blood pressure at baseline; MAP: Mean arterial blood pressure

Figure 2. Comparison of pulse rates

HR: Heart rate

Figure 3. Mean duration of first rescue analgesia