The case for magnesium sulfate in preeclampsia-eclampsia

Population Pharmacokinetics of Magnesium Sulfate in Preeclampsia and Associated Factors

Background and Objective

The pharmacokinetic basis of magnesium sulphate (MgSO₄) dosing regimens for preeclampsia (PE) prophylaxis and treatment is not clearly established. The aim of study is to develop a population pharmacokinetic (PK) model of MgSO₄ in PE, and to determine key covariates having an effect in MgSO₄ pharmacokinetics in preeclampsia (PE) and to determine key covariates having an effect in MgSO₄ PK.

Methods

A prospective cohort study was conducted from June 2016 to February 2018 in patients with PE administered MgSO₄ as a 4-g bolus followed by continuous infusion at a rate of 1 g/h. Serum magnesium concentrations were obtained before treatment administration and 2, 6, 12, and 18 h after the initial dose. The software Monolix was used to estimate population PK parameters of MgSO₄ [clearance (CL), volume of distribution (V), half-life] and to develop a PK model with baseline patient demographic, clinical, and laboratory covariates.

Results

The study population consisted of 109 patients. The PK profile of MgSO₄ was adequately described by a one-compartment PK model. The model estimate of the population CL was 1.38 L/h; for V, it was 13.3 L; and the baseline magnesium concentration was 0.77 mmol/L (1.87 mg/dL). The baseline body weight and serum creatinine statistically influenced MgSO₄ CL and V, respectively. The model was parameterized as CL and V.

Conclusion

The PK of MgSO₄ in pregnant women with PE is significantly affected by creatinine and body weight. Pregnant women with PE and higher body weight have a higher V and, consequently, a lower elimination rate of MgSO₄. Pregnant women with PE and a higher serum creatinine value show lower CL and, therefore, lower MgSO₄ elimination rate.

Hypertensive Disease in Twin Pregnancies: A Review

Reports over the past seventy years show that twin gestations lead to an increased risk of hypertensive disorders. Numerous studies discuss the incidence of hypertensive disease in twin versus singleton gestations, as well as effects of parity, race, age, income level, smoking, zygosity and heritability on this condition. The range of relative risk of gestational hypertension, preeclampsia and eclampsia for twin compared to singleton gestations is 1.2 to 2.7, 2.8 to 4.4 and 3.4 to 5.1 respectively. Parity, African-American ethnicity, and young maternal age are all factors that increase the relative risk of acquiring hypertensive disease to 4.0, 1.8 and 1.5 in mothers of twin gestations. Factors such as maternal smoking, income level and zygosity have a negligible effect on the relative risk of acquiring hypertensive disease in twin gestations. In addition to twin mothers exhibiting a higher incidence of hypertensive disease compared to their singleton counterparts, they also exhibit an earlier onset of hypertensive disease at both 35 and 37 weeks of gestation comparatively. Uric acid levels measured at 30–31 weeks of gestation in twin mothers predicted the onset of preeclampsia with a sensitivity of 73% and a specificity of 74%. The range of risks presented in the literature is wide and the therapies avocated are diverse. We therefore decided to summarize the risks in a comparative fashion and to review current therapeutic strategies for the convenience of clinicians who confront increasing numbers of multiple pregnancies. The tables bring all recent published risks together in the first comparative analysis in which the data has been converted to relative risks and confidence intervals. Because the literature is relatively silent on specific management of hypertensive disease in twin pregnancies, general management recommendations for singleton gestations should be used by practitioners caring over twin gestations.

Spinal Anaesthesia for Emergency Caesarean Section in a Morbid Obese Woman with Severe Preeclampsia

Background. Morbid obesity in a pregnancy is a great challenge to medical practice especially when the patient requires caesarean section.Case Summary. A 38-year-old unbooked gravida 3 Para 2+0weight 195 kg, height 1.7 m with a blood pressure of 210/160 mmhg had spinal anaesthesia for emergency caesarean section which was technically difficult for severe preeclampsia at 32-week gestation. She had poor wound healing and spent 18 days postoperatively on hospital admission.Conclusion. Morbid obesity is a challenge to both obstetric and anaesthetic practice. Antenatal care is necessary in reducing both maternal morbidity and mortality.

Maternal morbidity, mortality, and risk assessment

Maternal deaths in developed countries continue to decline and are rare. Maternal mortality statistics are essentially similar in the United States and United Kingdom. However, the situation is completely different in developing countries, where maternal mortality exceeds 0.5 million every year. This article not only assesses morbidity risks in some of the leading causes of maternal death but also highlights strategies to minimize the risks and to prevent maternal morbidity and mortality.

Pre-eclampsia: fluids, drugs, and anesthetic management

Severe pre-eclampsia is a complex disease, which taxes the expertise of even the most experienced obstetric anesthesiologist. The treatment should focus on stabilization of blood pressure, optimization of fluid status, and prevention of convulsions. Neuraxial blocks for labor and delivery offer many benefits to the mother and her infant. For cesarean section, there is unequivocal evidence of superiority of neuraxial anesthesia over general anesthesia. If general anesthesia is needed, careful preanesthetic preparation and meticulous airway management is essential. The successful and safe peripartum management of the pre-eclamptic patient and her infant is a team effort among the anesthesiologist, obstetrician, and neonatologist.

Loading dose versus standard regime of magnesium sulfate in the management of eclampsia: a randomized trial

OBJECTIVE

To determine whether only loading dose of magnesium sulfate is effective in controlling convulsion in eclampsia.

STUDY METHODS

This prospective study was conducted in Dhaka Medical College and Hospital, Bangladesh between July and November 1999. Eclamptic patients who were eligible for magnesium sulfate (MgSO4) therapy were randomly assigned by lottery to receive either only loading dose (n = 202) or standard regime (n = 199) of MgSO4. Besides the anticonvulsant, patients of both the groups were managed by same protocol for eclampsia management prepared by Eclampsia Working Group, Bangladesh. Efficacy of both the regimes was assessed by measuring the rate of recurrent convulsion. Results were expressed as mean +/- SD and a proportion. Statistical analysis was done using unpaired t-test, Z-test and chi2 test as appropriate. A P-value of < 0.05 was considered significant.

RESULTS

At the time of randomization there were no significant differences between the two groups in terms of age (22.40 +/- 4.21 vs 22.49 +/- 4.67 years), parity (72.77% vs 70.35% primi), type of eclampsia (84.65% vs 85.42% antepartum eclampsia), number of convulsions (5.30 +/- 3.26 vs 5.48 +/- 3.32 times), gestational age (35.65 +/- 3.37 vs 35.13 +/- 3.26 weeks), systolic blood pressure (153.19 +/- 20.19 vs 154.17 +/- 22.32 mmHg), diastolic blood pressure (106.23 +/- 13.84 vs 105.60 +/- 12.88 mmHg), proteinuria (70.80% vs 72.36% had > + proteinuria) and Glasgow Coma Scale (GCS) (73.26% vs 75.88% > 8) for the loading and standard regime groups. There were also no differences between the two groups in mean fit and treatment interval (6.88 +/- 5.26 vs 7.12 +/- 4.29h), fit and delivery interval (11.35 +/- 10.22 vs 11 +/- 6.69h) and return of consciousness (10.94 +/- 8.29 vs 11.24 +/- 8.37h). The recurrent convulsion rate was almost the same in both the groups (3.96% in loading vs 3.51% in standard regime, P > 0.05). Case fatality rate was 4.45% and 5.02% in loading and standard regime groups, respectively (P > 0.05).

CONCLUSION

Only loading dose of MgSO4 can control convulsion in eclampsia and it is as effective as standard regime.

Management and monitoring of severe preeclampsia

Preeclampsia is associated with increased maternal and perinatal morbidity and mortality. Preeclampsia is more than pregnancy-induced hypertension. The hypertension is only one manifestation of an underlying multifactorial, multisystem disorder, initiated early in pregnancy. In established severe disease there is volume contraction, reduced cardiac output, enhanced vascular reactivity, increased vascular permeability and platelet consumption. Medical treatment of severe hypertension in pregnancy is required. The more controversial issues are the role of pharmacological treatment in conservative management of severe preeclampsia aiming at prolongation of pregnancy, the ability of such therapy to modify the course of the underlying systemic disorder and the effects on fetal and maternal outcome. This paper presents an overview concerning the current developments in management and monitoring of severe preeclampsia. Controversial topics such as the role of plasma volume expansion in preeclampsia, expectant versus aggressive management of severe preeclampsia remote from term, and pharmacological interventions in the management of eclampsia and the HELLP syndrome are addressed.

The prevention and management of eclampsia

Hypertensive disease remains second only to embolic phenomena as a leading cause of maternal mortality. This article covers the major physiologic and pathologic findings to be considered when managing pregnant women with eclampsia. Attention to detail and an increased degree of suspicion will improve fetal and maternal outcomes.

Modern management of eclampsia

Eclampsia, the occurrence of a seizure in association with pre-eclampsia, remains an important cause of maternal mortality and morbidity. Despite being recognised since antiquity, consistent management practices are still lacking. Given that the aim of good care is to prevent seizures, it is disappointing that in the majority of cases the first eclamptic convulsion occurs after admission to hospital. This indicates that either the women who are likely to have a convulsion were not identified accurately, or the treatment given was ineffective. The answer to poor management of eclampsia lies in better education and training of all obstetricians, anaesthetists, midwives, and general practitioners in the diagnosis and treatment of severe pre-eclampsia and eclampsia. Protocols for the management of fluid balance, antihypertensive and anticonvulsant therapies should be available and reviewed regularly. The universal adoption of such guidelines in all obstetric units would substantially reduce elements of substandard care which have repeatedly been identified in the triennial reports of the confidential enquiries into maternal deaths in the UK.

Pseudotoxemia: new onset psychogenic seizure in third trimester pregnancy

Eclampsia, or toxemia of pregnancy, is a disorder of pregnancy characterized by seizures associated with hypertension, edema, and proteinuria. Toxemia carries significant maternal and fetal morbidity and mortality. Psychogenic seizures are defined as events that clinically resemble epileptic seizures but are not accompanied by abnormal electrical activity of the cerebral cortex. We report the case of a third trimester pregnant patient who presented with new onset convulsive activity that was associated with peripheral edema, intermittent hypertension, and proteinuria. The initial impression of the treating physicians--emergency medicine, obstetrical, and neurology--was toxemia of pregnancy. After further review and the application of numerous procedures and therapies with potential risk, the diagnosis of psychogenic seizure was made.

Drug management of hypertensive disorders of pregnancy

Drugs used in the acute and long-term management of hypertension in pregnancy and the preeclampsia-eclampsia syndrome have been reviewed and their therapeutic effects and maternal and fetal adverse effects have been considered. The review also focuses on recent developments in the areas of prevention and management of pre-eclampsia-eclampsia syndrome. Although a number of new drugs have emerged, as potentially useful in the management of hypertension in pregnancy and pre-eclampsia-eclampsia syndrome, some remain at the cornerstone of therapy; for example, methyldopa for long-term treatment of chronic hypertension, hydralazine or nifedipine for rapid reduction of severely elevated blood pressure, and magnesium sulphate for eclampsia. Some of these agents, especially the calcium antagonists, show promise in that their use is associated with fewer side effects. Safety for the fetus, however, has not been adequately evaluated yet. Neither aspirin nor calcium supplements appear to improve the outcome in pregnancy. Currently, the dilemma whether to treat hypertension in pregnancy and pre-eclampsia-eclampsia syndrome with old, established, cost-effective drugs or the promising newer drugs provides an interesting academic challenge.

The role of serotonin in preeclamptic hypertension. A review and case report

Generalized arteriolar vasospasm and subsequent damage to vascular endothelium are fundamental to the development of preeclampsia. A possible mechanism underlying this involves increased deportation of trophoblast cells into maternal venous circulation with 5-hydroxytryptamine (serotonin, 5-HT) release as a consequence of platelet aggregation onto these fragments. Ketanserin, a 5-HT(2) receptor blocker, has been used successfully to treat preeclampsia. An examination of the therapeutic role of ketanserin indicates that there should now be a much more detailed assessment of serotonin antagonists in the treatment and prophylaxis of preeclampsia and eclampsia.

Randomised study assessing the effect of phenytoin and magnesium sulphate on maternal cerebral circulation in eclampsia using transcranial Doppler ultrasound

OBJECTIVE

To assess maternal middle cerebral artery flow velocity patterns as measured by transcranial Doppler ultrasound (TCD) in eclampsia and to investigate the effect of the anticonvulsants magnesium sulphate (MgSO4) and phenytoin on cerebral circulation.

DESIGN

Prospective randomised study.

SETTING

High care obstetric unit, King Edward VIII Hospital, Durban, South Africa.

PARTICIPANTS

Twenty-four eclamptic patients: 13 received MgSO4 and 11 phenytoin.

INTERVENTION

Middle cerebral artery flow velocity waveforms were measured using 2 MHz pulsed Doppler ultrasound via the transtemporal approach in eclamptic patients, before and 15 minutes after the loading dose of anticonvulsant.

RESULTS

Magnesium sulphate significantly reduced the pulsatility index (P = 0.002) and mean flow velocity (P = 0.02) in the middle cerebral artery, whereas phenytoin failed to produce any statistically significant effect. However, differences between groups were not statistically significant. Systolic and diastolic blood pressures were reduced in both the MgSO4 and phenytoin groups.

CONCLUSION

These findings provide firm evidence that MgSO4 relieves cerebral vasospasm, compared with phenytoin, and may therefore be the better drug for the prevention of eclamptic convulsion.

The effects of dihydralazine, labetalol and magnesium sulphate on the isolated, perfused human placental cotyledon

OBJECTIVE

To assess the effects of dihydralazine, labetalol and magnesium sulphate on the vascular tone in the isolated, perfused human placental cotyledon.

METHODS

In vitro perfusion of the fetal compartment of isolated, human placental cotyledons.

RESULTS

None of the drugs affected basal vascular tone. The thromboxane A2-mimic U46619 and endothelin-1 induced a concentration-dependent increment in perfusion pressure, while 5-hydroxytryptamine induced a variable increase, and norepinephrine induced a small, transient increase in perfusion pressure. After preconstriction with U46619, magnesium sulphate (1.5 x 10(-3) to 6 x 10(-3) mol/l) induced a decrease in perfusion pressure, while dihydralazine (10(-6) to 10(-4) mol/l) or labetalol (10(-7) to 10(-4) mol/l) enhanced the perfusion pressure. These effects of dihydralazine and labetalol were unaffected by treatment with indomethacin 10(-6) mol/l, but could be reversed by addition of magnesium sulphate 6 x 10(-3) mol/l. Labetalol 10(-6) to 10(-4) mol/l also caused an increase in the perfusion pressure induced by endothelin-1, but showed no effects after preconstriction with 5-hydroxytryptamine. Pretreatment with labetalol 10(-4) mol/l inhibited the transient increase in perfusion pressure induced by norepinephrine 3 x 10(-5) mol/l.

CONCLUSIONS

The present data demonstrated that the commonly used vasodilating agents labetalol and dihydralazine do not produce vasodilatation in the human perfused cotyledon after vasoconstriction induced by agents of suggested importance for maintenance of fetal placental vascular tone, and that high concentrations of these drugs may even enhance vasoconstriction induced by thromboxane and endothelin-1 in this area. Magnesium sulphate may show the potential to reverse such unwanted effects of dihydralazine and labetalol.