Effect of magnesium sulfate in patients with preeclampsia with severe features on gastric antrum cross-sectional area: a prospective observational study.

BACKGROUND

While the systemic effects of magnesium sulfate administration are well described, its effects on gastric motility and aspiration risk remain underexplored. We evaluated the effect of magnesium sulfate administration on the gastric antrum cross-sectional area (CSA) in the setting of preeclampsia with severe features.

METHODS

This prospective observational study included 31 patients with preeclampsia and severe features receiving an intravenous bolus of magnesium sulfate 5 g over 20 min, followed by an infusion (1 g/h). Gastric ultrasound was performed at baseline (pre-bolus) and 10- and 20-min post-bolus. Serum magnesium levels were measured at baseline and 20 min post-bolus. The primary outcome was the change in gastric CSA from baseline to 20 min post-bolus. The secondary outcomes included the proportion of patients with unsafe gastric volume (CSA > 608 mm2) and correlation between the increasing serum magnesium levels and change in CSA.

RESULTS

There was an increase in gastric antrum CSA from baseline to 10- and 20-min post-bolus, with median CSA values rising from 403 mm2 to 440 mm2 and 507 mm2, respectively (P < 0.001). Serum magnesium levels increased from 1.96 ± 0.26 mg/dL to 5.24 ± 0.86 mg/dL (mean difference: 3.27 ± 0.80 mg/dL). At baseline and 10- and 20-min post-bolus, 2, 5, and 7 of 31 participants, respectively, met criteria for unsafe gastric volume. A strong positive correlation was observed between change in serum magnesium levels and change in CSA (r = +0.896, P < 0.001)

CONCLUSIONS

In patients with preeclampsia with severe features, magnesium sulfate 5 g is associated with a significant increase in gastric antrum CSA. The strong positive correlation between serum magnesium levels and CSA supports a potential dose-dependent effect on gastric smooth muscle relaxation. However, further research is warranted to determine whether these sonographic changes correspond to clinically significant increases in gastric volume or translate into a measurable risk of pulmonary aspiration.