Effects of magnesium on central arterial compliance in preeclampsia

OBJECTIVE: The objective of the study was to investigate the effect of MgSO4 infusion on central arterial compliance, using radial artery applanation tonometry in women with preeclampsia. STUDY DESIGN: Seventy women with preeclampsia were prospectively recruited. Radial pulse waveforms were obtained and the aortic waveforms constructed. The arterial compliance surrogates, augmentation pressure (AP) and augmentation index (AIx-75), were derived from the aortic waveform and then compared: prior to MgSO4 (t1), 1 hour after MgSO4 bolus (t2), 4 hours after MgSO4 infusion (t3), and 24 hours after MgSO4 cessation (t4). Statistical analysis was performed using differences of least squared means with Tukey Kramer adjustments. RESULTS: The AP and AIx-75 at t2-t4 were significantly lower compared with t1, with the greatest decrease in arterial stiffness at t3 ( P < .05). CONCLUSION: In preeclampsia, MgSO4 improved central arterial compliance. This effect was most exaggerated after 4 hours of infusion and remained 24 hours following MgSO4 completion, suggesting either a sustained arterial compliance effect or resolution of the vasoconstrictive effect of preeclampsia.