The effect of magnesium sulfate on maternal retinal blood flow in preeclampsia: A randomized placebo-controlled study

OBJECTIVES: Our purpose was to determine the effect of a 6 gm intravenous bolus of magnesium sulfate on maternal retinal blood flow velocity waveforms in patients with preeclampsia. STUDY DESIGN: Twenty-two patients were randomized to two groups and were studied with color flow Doppler before and immediately after infusion of either 6 gm of magnesium sulfate or placebo. The central retinal and posterior ciliary arteries were studied. RESULTS: Magnesium sulfate significantly reduced the pulsatility index (p < 0.005) in both vessels (change in pulsatility index = -0.26 ± 0.23 for central retinal and -0.22 ± 0.15 for posterior ciliary) when compared with placebo (change in pulsatility index = 0.02 ± 0.10 for central retinal and -0.03 ± 0.09 for posterior ciliary). CONCLUSIONS: These data suggest that magnesium sulfate dilates the vessels distal to the central retinal and posterior ciliary arteries. Changes in pulsatility index in the retinal arteries may be indicative of similar changes in other cerebral vessels.