Dexamethasone and magnesium sulphate as adjuvants to bupivacaine in ultrasound guided subcostal transverse abdominis plane block during laparoscopic cholecystectomy: A prospective randomized comparative study

• Author Details:   
• Aparna Rayala
• Sushma Konduri ^*
• Srinivas Upadhyayula
• Sachidanand Rachamalla

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Background and Aims: Dexamethasone and magnesium sulphate (MgSO4) are commonly used adjuvants to prolong the efficacy of regional nerve blocks. However, their specific effectiveness in subcostal transverse abdominis plane (SCTAP) blocks during laparoscopic cholecystectomy (LC) remains unclear. This study aimed to evaluate and compare the efficacy of dexamethasone and MgSO4 as adjuvants to bupivacaine in ultrasound-guided (USG) bilateral SCTAP blocks for postoperative analgesia.

Methods: Sixty-eight patients (94.2% females, 5.8% males) classified as American Society of Anaesthesiologists (ASA) category I or II undergoing LC were enrolled. Patients were randomized to receive bupivacaine 0.25% (45 mg) combined with either dexamethasone (8 mg, Group-D) or MgSO4 (200 mg, Group-M) on each side via USG-guided SCTAP blocks performed using a 10 cm Braun Stimuplex needle and a linear USG probe after surgery and before extubation. Postoperative pain was assessed using the Visual Analog Scale (VAS) at intervals of 10 min, 30 min, 2 hrs, 4 hrs, 8 hrs, 12 hrs, and 16 hrs. Rescue analgesia with intravenous (IV) fentanyl (25 μg) or IV paracetamol (1 g) was administered as needed. Data were analyzed using the Student’s t-test and Chi-square test, with normality assessed using the Shapiro-Wilk W test.

Results: Group-M (MgSO4) demonstrated consistently lower VAS pain scores, which were statistically significant at all time points except 4 and 12 hours. A smaller proportion of patients in Group-M required rescue analgesia compared to Group-D (8.82% vs. 29.41%, respectively).

Conclusion: MgSO4 as an adjuvant to bupivacaine in subcostal transverse abdominis plane (SCTAP) blocks for laparoscopic cholecystectomy provides superior analgesic effects, with a longer postoperative pain-free period and reduced need for rescue analgesics compared to dexamethasone.