Effect of magnesium sulfate on maternal brain blood flow in preeclampsia: a randomized, placebo-controlled study.
OBJECTIVE
The purpose of this study was to determine the effect of a 6 gm intravenous bolus of magnesium sulfate on maternal brain blood flow velocity waveforms in patients with preeclampsia.


METHODS
Twelve patients with preeclampsia were randomized to two groups and studied with Doppler ultrasonography before and immediately after infusion of either a 6 gm intravenous loading dose of magnesium sulfate or a placebo. The middle cerebral, common carotid, and internal carotid arteries were studied.


RESULTS
Magnesium sulfate significantly reduced the pulsatility index in the middle cerebral artery (change in pulsatility index = -0.16 + 0.09) when compared with the placebo (change in pulsatility index = -0.02 + 0.06), p = 0.01. There were no significant changes in the Doppler indexes of the carotid vessels.


CONCLUSIONS
These data suggest that magnesium sulfate vasodilates the smaller-diameter intracranial vessels distal to the middle cerebral artery and may exert its main effect in the prophylaxis and treatment of eclampsia by relieving cerebral ischemia.
Belfort
M A
MA
Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX 77030.
Moise
K J
KJ
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D011225:Pre-Eclampsia / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D011247:Pregnancy / Q000502:physiology*; D011446:Prospective Studies; D011674:Pulse / Q000187:drug effects; D014463:Ultrasonography
D008278:Magnesium Sulfate