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Br J Obstet Gynaecol. 1992 Aug;99(8):641-5.

The effect of magnesium sulphate on blood flow velocity in the maternal retina in mild pre-eclampsia: a preliminary colour flow Doppler study.

Author information

1
Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030.

Abstract

OBJECTIVES:

To investigate the use of colour flow Doppler ultrasound to identify retinal blood vessels in women with mild pre-eclampsia and to assess the effects of an infusion of magnesium sulphate on the baseline retinal blood flow-velocity.

DESIGN:

Prospective descriptive study.

SETTING:

Ben Taub Hospital, Baylor College of Medicine, Houston, Texas, USA.

SUBJECTS:

Eight women with mild pre-eclampsia.

INTERVENTIONS:

Baseline colour flow Doppler ultrasound assessment of the central retinal artery (CRA) and posterior ciliary artery (PCA) blood flow-velocity before intravenous infusion of 6 g of magnesium sulphate in 100 ml of 5% dextrose water over 20 min, followed by repeat Doppler measurement.

MAIN OUTCOME MEASURES:

Blood pressure, heart rate, pulsatility index (PI), resistance index (RI), angle-corrected flow-velocity (cm/s).

RESULTS:

The CRA and PCA were easily and reliably identified. The infusion of 6 g of magnesium sulphate significantly reduced (P < 0.05) the mean CRA PI from 1.42 (SD 0.67) to 0.93 (SD 0.18) and the mean CRA RI (P < 0.008) from 0.62 (SD 0.07) to 0.53 (SD 0.10). The PCA PI decreased (P = 0.01) from 0.97 SD (0.14) to 0.78 SD (0.18) and the PCA RI decreased (P = 0.02) from 0.58 SD (0.07) to 0.48 SD (0.09). Angle-corrected flow-velocity decreased non-significantly after the magnesium sulphate infusion.

CONCLUSIONS:

Patients with pre-eclampsia have high CRA and PCA flow-velocity suggestive of vasospasm. Magnesium sulphate acutely vasodilates the small arteries in the retina, increasing retinal blood flow. Changes in the blood flow in the retina may be indicative of similar changes in other end-arterial branches of the internal carotid artery. This non-invasive Doppler method may provide a means to monitor the effects of therapeutic interventions in patients with pre-eclampsia.

[Indexed for MEDLINE]

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