Comparing Intravenous Single Low Doses of Magnesium Sulphate versus Dexamethasone as Adjuvants to Ultrasound Guided Transversus Abdominis Plane (TAP) Block for Prolongation of Postcesarean Analgesia

The TAP block is a regional anesthetic technique, which blocks neural afferents between T6 and L1, which provide anterior abdominal walls and therefore help to alleviate postoperative pain.

The aim is to compare the efficacy of preoperative single low dose of intravenous MgSO₄ versus intravenous dexamethasone as adjuvants to ultrasound guided TAP block for prolongation of postcesaren analgesia.

A total 60 pregnant females were selected undergoing elective caesarean sections under general anesthesia with ultrasound-guided transversus abdominis plane (TAP) block done at the end of surgery. Patients were randomly and equally allocated into three groups of 20 patients each. The first group of patients were classified as magnesium sulphate group (M)who received 50 mg/Kg IV, the second group of patients were classified as dexamethasone group (D) who received 2 mg IV and the third group was classified as the placebo group (C) who received IV saline.

Comparison of the VAS at 6 and 12 hours postoperatively showed statistically significantly lower values in group (M) and group (D) compared to group (C) and also group (M) was significantly lower than group (D) as well. The time interval until first rescue analgesia (Nalbuphine) needed by the patients (VAS ≥ 50) was significantly longer in group (M) compared to group (D) and group (C) consecutively. Additionally, it was significantly longer in group (D) than in the control group(C). The total dose of rescue analgesia consumed during the first 24 hours postoperatively was significantly lower in groups (M) than in group (D) and both groups showed lesser doses compared to group (C)

We concluded that both MgSO₄ and dexamethasone could prolong the postoperative duration and analgesic efficiency provided by the TAP block in cesarean sections. This further reduced the demands for postoperative rescue analgesia, with MgSO₄ found to be more efficient than IV dexamethasone.

Clinical Trial Registration Number: NCT04223128