Impact of a transversus abdominis plane block with low-dose magnesium sulphate coupled to bupivacaine on postoperative pain after laparoscopic cholecystectomy: A randomized trial

Objectives

The subcostal transversus abdominis plane (STAP) block has recently been included in the enhanced recovery after surgery (ERAS) protocol for laparoscopic cholecystectomy (LC). In our study on STAP for LC, we compared the effectiveness of adding low-dose magnesium sulphate (MgSO₄) to bupivacaine versus using bupivacaine alone. MgSO₄ was hypothesized to enhance the analgesic effects of bupivacaine and therefore aid in the recovery process.

Methods

Sixty patients, aged 18–65 years, ASA I–II, undergoing LC, were randomly assigned to receive bilateral STAP 15 min before skin incision with 20 ml bupivacaine 0.25 % and either 150 mg MgSO₄ (BM group) or 1.5 ml normal saline (B group). Pain scores, time to initial analgesic demand, overall analgesic requirement, sedation, emetic episodes, time to get out of bed, and patient satisfaction were recorded for the first 24 h following surgery. The Mann-Whitney U test was used to analyze the non-normally distributed data between groups, while the Chi-square test or Fisher^’s exact test was used to test categorical data.

Results

The BM group had statistically significant but clinically insignificant lower pain scores at rest and during coughing in the post-anesthesia care unit (PACU) (P = 0.005 and P = 0.003), at 1 h (P = 0.005 and P = 0.015), 6 h (P = 0.009 and P = 0.003), 12 h (P = 0.017 and P = 0.001), and 24 h (P = 0.001 and P = 0.001) after surgery compared to the B group. Kaplan–Meier curves for times to the first paracetamol and morphine doses showed significant differences (log-rank test) between the groups (P = 0.001 and P = 0.003, respectively). Additionally, the total doses of paracetamol (P = 0.001) and morphine (P = 0.001) in the BM group were significantly lower than those in the B group during the first 24 h after surgery. Sedation and emetic episodes were identical between the groups. The Patient in the BM group ambulated faster (P = 0.001) and were more satisfied (P = 0.026) than those in the B group.

Conclusions

Adding a low-dose (150 mg) of MgSO₄ to bupivacaine in the STAP block for LC was associated with improved analgesic outcomes in the first 24 h after surgery.

Ethical approval

Medical Ethics Committee of Faculty of Medicine, IRB no: 17,100,622 on November 15, 2016.

Trial registration

ClinicalTrials.gov (NCT03612947) on August 2, 2018.