Single Loading Dose of Magnesium Sulphate in Severe Preeclampsia and Eclampsia-Is it Effective? A Randomized Prospective Study

Importance of the (Pro)renin Receptor in Activating the Renin-Angiotensin System During Normotensive and Preeclamptic Pregnancies

PURPOSE OF REVIEW

For a healthy pregnancy to occur, a controlled interplay between the maternal circulating renin-angiotensin-aldosterone system (RAAS), placental renin-angiotensin system (RAS) and intrarenal renin-angiotensin system (iRAS) is necessary. Functionally, both the RAAS and iRAS interact to maintain blood pressure and cardiac output, as well as fluid and electrolyte balance. The placental RAS is important for placental development while also influencing the maternal circulating RAAS and iRAS. This narrative review concentrates on the (pro)renin receptor ((P)RR) and its soluble form (s(P)RR) in the context of the hypertensive pregnancy pathology, preeclampsia.

RECENT FINDINGS

The (P)RR and the s(P)RR have become of particular interest as not only can they activate prorenin and renin, thus influencing levels of angiotensin II (Ang II), but s(P)RR has now been shown to directly interact with and stimulate the Angiotensin II type 1 receptor (AT1R). Levels of both placental (P)RR and maternal circulating s(P)RR are elevated in patients with preeclampsia. Furthermore, s(P)RR has been shown to increase blood pressure in non-pregnant and pregnant rats and mice. In preeclamptic pregnancies, which are characterised by maternal hypertension and impaired placental development and function, we propose that there is enhanced secretion of s(P)RR from the placenta into the maternal circulation. Due to its ability to both activate prorenin and act as an AT1R agonist, excess maternal circulating s(P)RR can act on both the maternal vasculature, and the kidney, leading to RAS over-activation. This results in dysregulation of the maternal circulating RAAS and overactivation of the iRAS, contributing to maternal hypertension, renal damage, and secondary changes to neurohumoral regulation of fluid and electrolyte balance, ultimately contributing to the pathophysiology of preeclampsia.

A randomized controlled trial of loading dose alone versus pritchard regimen of magnesium sulphate, for seizure prophylaxis in severe preeclampsia

Background

Preeclampsia poses a significant risk of maternal and neonatal morbidity and mortality. Magnesium sulfate superiority for seizure prophylaxis in severe preeclampsia has been proven globally. However, the search for the lowest effective dose is an area of continuing research.

Aim

The aim of this study was to compare the effectiveness of loading dose with the Pritchard regimen of magnesium sulfate for seizure prophylaxis in severe preeclampsia.

Materials and Methods

A total of 138 eligible women after 28-week gestation with severe preeclampsia were randomized to either receiving a single loading dose of MgSO₄ (study arm: n = 69) or Pritchard regimen of MgSO₄ (control: n = 69). The effectiveness was assessed by the development of seizure. The results obtained were analyzed using SPSS version 21. Categorical variables were analyzed using the Chi-square test and normally distributed continuous variables were analyzed with t-test and Fisher's exact test. P < 0.05 was considered statistical significance.

Results

There were no significant differences between those who received only the loading dose when compared with those who had Pritchard regimen other than a single recorded convulsion among the control group (P = 0.316). Similarly, except for the duration of hospital stay which was significantly longer in the Pritchard group (P = 0.019), both the arms of the study shared similar maternal and fetal outcomes.

Conclusion

This study suggests the effectiveness of just the loading dose of magnesium sulfate when compared with the standardized Pritchard regimen in the prevention of seizure among women with severe preeclampsia. The study also demonstrated safety and similarity in fetal-maternal outcome. The loading dose only had an added advantage of shorter duration of hospital stay.

Intravenous magnesium sulfate in the management of severe pre-eclampsia: A randomized study of 12-hour versus 24-hour maintenance dose

OBJECTIVE

To assess the effectiveness of a 12-hour versus 24-hour intravenous maintenance dose of magnesium sulfate (MgSO₄ ) in women with pre-eclampsia, and the maternal and fetal outcomes.

METHODS

This was a randomized controlled trial conducted at the labor ward complex of University College Hospital, Ibadan, Nigeria between May and August 2014. Pregnant women with severe pre-eclampsia were randomized to receive a 12-hour versus 24-hour maintenance dose of MgSO₄ . Study outcomes were occurrence of seizures, adverse maternal effects, neonatal survival, and admission to the intensive care unit. Data analysis involved descriptive statistics and bivariate analysis using Statistical Package for Social Science (SPSS) version 20.

RESULTS

There were 80 patients randomized to the 12-hour (n=40) and 24-hour (n=40) groups. The participants in the two groups had comparable demographic features. There was no significant difference (P>0.999) between the satisfactory maternal outcome following the 12-hour maintenance dose and the standard 24-hour regimen (95.0% vs 97.5%). Similarly, there was no significant difference (P=0.276) in perinatal mortality in the 12-hour versus 24-hour arm (17.5% vs 12.5%, respectively). No case of eclampsia and maternal death was recorded.

CONCLUSION

A 12-hour maintenance dose of intravenous MgSO₄ in the management of severe pre-eclampsia is effective and safe when compared with the 24-hour maintenance dose.