Key result
Pre-emptive intravenous magnesium sulphate at a fixed dose of 2.47 g resulted in comparable 24-hour post-operative PCA morphine requirements (7.7 mg vs 6.4 mg, p=0.323) compared to a weight-based 50 mg/kg dose.
Why the study?
The study aimed to compare the analgesic effects of different dosages of pre-emptive intravenous magnesium sulphate in patients undergoing lower abdominal gynaecological surgery.
Does a fixed dose of 2.47 g intravenous magnesium sulphate provide comparable post-operative analgesia to a weight-based dose of 50 mg/kg in patients undergoing lower abdominal gynaecological surgery?
RCT (n=56)
Double-blind
Computer-generated (Microsoft Excel)
No
Does a fixed dose of 2.47 g intravenous magnesium sulphate provide comparable post-operative analgesia to a weight-based dose of 50 mg/kg in patients undergoing lower abdominal gynaecological surgery?
Absolute Event Rate: 7.7% vs 6.4%
p-value: p=0.323
A fixed dose of 2.47 g intravenous magnesium sulphate provides comparable post-operative analgesia to a 50 mg/kg weight-based dose in non-obese patients undergoing gynaecological surgery, avoiding unnecessary drug wastage.
Supports fixed-dose magnesium to reduce wastage in gynaecological surgery; confirms equivalence to weight-based dosing.
This study compared the analgesic effects of pre-emptive intravenous magnesium sulphate of different dosages in patients undergoing lower abdominal gynaecological surgery. Fifty-six patients with Body Mass Index (BMI) <35 kg/m2 who underwent lower abdominal gynaecological surgery were randomly recruited into two groups. Group I received one ampoule (2.47 g) of magnesium sulphate and Group II received 50 mg/kg magnesium sulphate (based on body weight), pre-operatively. Pain score and patient controlled analgesia (PCA) morphine requirement were compared at 30 minutes, 12 hours and 24 hours post-operatively. The pain score was comparable at all intervals between the two groups (30 minutes, p = 0.450; 12 hours, p = 0.402; and 24 hours, p = 1.000). Post-operative PCA morphine requirement was not statistically significant between the two groups at 30 minutes, 12 hours, and 24 hours (2.7 vs 2.4 mg, p = 0.545; 12.5 vs 9.8 mg, p = 0.154; 7.7 vs 6.4 mg, p = 0.323). The side-effects of magnesium sulphate on blood pressure, heart rate and sedation were not statistically significant between the two groups. In conclusion, the analgesic effects of pre-emptively administered intravenous MgSO4 of 2.47 g (one ampule) was comparable to 50 mg/kg in patients with BMI less than 35 kg/m2 following lower abdominal gynaecological surgery under general anaesthesia with negligible side effects.
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Joanna Ooi Su Min (2020) conducted an RCT in Post-operative pain after lower abdominal gynaecological surgery (n=56). Intravenous magnesium sulphate vs. 50 mg/kg magnesium sulphate was evaluated on PCA morphine requirement at 24 hours post-operatively (p=0.323). Pre-emptive intravenous magnesium sulphate at a fixed dose of 2.47 g resulted in comparable 24-hour post-operative PCA morphine requirements (7.7 mg vs 6.4 mg, p=0.323) compared to a weight-based 50 mg/kg dose.
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