The feasibility of a control population for a randomized control trial of seizure prophylaxis in the hypertensive disorders of pregnancy

The feasibility of community level interventions for pre-eclampsia in South Asia and Sub-Saharan Africa: a mixed-methods design

BACKGROUND

Globally, pre-eclampsia and eclampsia are major contributors to maternal and perinatal mortality; of which the vast majority of deaths occur in less developed countries. In addition, a disproportionate number of morbidities and mortalities occur due to delayed access to health services. The Community Level Interventions for Pre-eclampsia (CLIP) Trial aims to task-shift to community health workers the identification and emergency management of pre-eclampsia and eclampsia to improve access and timely care. Literature revealed paucity of published feasibility assessments prior to initiating large-scale community-based interventions. Arguably, well-conducted feasibility studies can provide valuable information about the potential success of clinical trials prior to implementation. Failure to fully understand the study context risks the effective implementation of the intervention and limits the likelihood of post-trial scale-up. Therefore, it was imperative to conduct community-level feasibility assessments for a trial of this magnitude.

METHODS

A mixed methods design guided by normalization process theory was used for this study in Nigeria, Mozambique, Pakistan, and India to explore enabling and impeding factors for the CLIP Trial implementation. Qualitative data were collected through participant observation, document review, focus group discussion and in-depth interviews with diverse groups of community members, key informants at community level, healthcare providers, and policy makers. Quantitative data were collected through health facility assessments, self-administered community health worker surveys, and household demographic and health surveillance.

RESULTS

Refer to CLIP Trial feasibility publications in the current and/or forthcoming supplement.

CONCLUSIONS

Feasibility assessments for community level interventions, particularly those involving task-shifting across diverse regions, require an appropriate theoretical framework and careful selection of research methods. The use of qualitative and quantitative methods increased the data richness to better understand the community contexts.

TRIAL REGISTRATION

NCT01911494.

Magnesium sulphate versus phenytoin in eclampsia - Maternal and foetal outcome - A comparative study

BACKGROUND

Eclampsia manifests as seizures and is unique to the pregnant state. It remains an important cause of maternal mortality especially in resource-challenged countries that lack access to prenatal care.

AIMS

The aim of our study was to compare maternal and foetal outcomes in mothers with eclampsia with the administration of either magnesium sulphate or phenytoin in a resource- challenged situation.

METHOD

The work was conducted from January 2012 to December 2012. A total of 80 patients were assigned alternately to two groups - one group was treated with magnesium sulphate (Group-M; n=40), and the other treated with phenytoin (Group-P; n=40) (Figure 1). The magnesium sulphate was administered according to Pritchard's regimen; phenytoin administered according to Ryan's regimen. With either regimen, anticonvulsant therapy was continued for 24 hours postpartum or 24 hours after the last convulsion, whichever was later.

RESULTS

Fifty-four per cent of patients regained consciousness within eight hours of treatment onset in Group-P compared to 5.3 per cent in Group-M (p=0.0001, χ(2)=19.24). Seven patients in Group-P had recurrence of convulsions as compared to none of the 40 women assigned to Group-M (p=0.032, χ(2)=4.62). The incidence of Caesarean section was greater (62.5 per cent) in Group-M compared to Group-P (25 per cent; p=0.001, χ(2)= 9.96). No statistically significant differences were found in the foetal outcomes between the two groups.

CONCLUSION

Phenytoin use may be reconsidered in selective cases in low and middle income countries (LMIC) as it has been found simpler to use, has several benefits and also curtails treatment cost. Magnesium sulphate is substantially more effective than phenytoin with regard to recurrence of convulsions. Proper training in the management of eclampsia should be given to all health care workers to ensure appropriate management of eclamptic mothers. Thus, the treatment of this disease calls for more research especially in resource-challenged settings.

Cerebral Hemodynamics in Preeclampsia: Cerebral Perfusion and the Rationale for an Alternative to Magnesium Sulfate

Preeclampsia and eclampsia continue to be major causes of maternal death. Currently, approximately 18% of U.S. maternal deaths are attributed to hypertensive disorders and eclampsia, and several hundred women die from eclampsia and its complications every year. In the United States, preeclamptic women have received magnesium sulfate as a seizure prophylaxis agent for 3 decades, and this practice is becoming more widely accepted internationally. In addition to a recognized failure rate, there are financial, logistic, and safety concerns associated with the universal administration of magnesium sulfate. Many institutions in the developing world lack the necessary equipment and expertise to administer the medication, and many preeclamptic patients thus do not receive magnesium sulfate before their first seizure. As effective as it has been in reducing mortality from eclampsia, magnesium sulfate is also associated with appreciable morbidity and mortality from administration errors and magnesium toxicity. The availability of an easily administered, cheap, safe, and orally administered alternative to magnesium sulfate would be welcomed in the developing world and would provide an extremely useful alternative therapy to the current standard of care. Recent advances in the understanding of the pathophysiology of preeclampsia and eclampsia, primarily related to cerebral perfusion and blood flow, could allow us to reduce the seizure rate in treated preeclamptic women even further than what is currently reported. This article deals with the rationale behind the use of labetalol as an alternative to magnesium sulfate for the prevention of eclampsia.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to recall that hypertensive diseases of pregnancy contribute a significant portion of today's maternal mortality, explain that methods of preventing eclampsia are not applicable worldwide, and state that understanding of the pathophysiology of preeclampsia/eclampsia may assist in developing safe and effective medications that can be used universally.

A prospective randomized trial of magnesium sulfate in severe preeclampsia: use of diuresis as a clinical parameter to determine the duration of postpartum therapy

OBJECTIVE

The purpose of this study was to assess the use of the onset of diuresis in the determination of the duration of postpartum magnesium sulfate therapy among patients with severe preeclampsia.

STUDY DESIGN

A prospective randomized trial of postpartum therapy with magnesium sulfate was conducted. The control group received 24 hours of therapy, and the study group received therapy until the onset of diuresis (urine output >100 mL/hr for 2 consecutive hours). The Student t test, chi 2 test, and Fisher's exact test were used for analysis of data; a probability value of <.05 was considered statistically significant.

RESULTS

There were 50 patients in the control group and 48 patients in the study group. There was no difference in maternal demographic data, severe disease criteria, blood pressure, 24-hour postpartum urine output, or need for antihypertensive therapy. The study group had a significantly shorter duration of therapy, and no patient had eclampsia or required the re-initiation of therapy.

CONCLUSION

The use of the onset of diuresis in the postpartum period as the determinant clinical parameter for the discontinuation of magnesium sulfate in patients with severe preeclampsia was associated with no untoward outcomes or need for the re-initiation of treatment.

Preeclampsia and Eclampsia Revisited

Hypertensive disorders during pregnancy, which account for approximately 15% of pregnancy-related deaths, represent the second-leading cause of morbidity and mortality in the United States. New classifications recommended by the National Institutes of Health's Working Group on High Blood Pressure in Pregnancy have decreased the confusion often associated with these disorders. The cause of preeclampsia-eclampsia still remains elusive, but continued research has provided hope with regard to screening, improved diagnosis, and management. Risk factors that have recently gained attention include inherited thrombophilias, inherited metabolic disorders, and lipid disorders. Treatment and management of the hypertensive disorders of pregnancy have not changed substantially in the past 50 years. Prevention of preeclampsia-eclampsia has been unsuccessful, and recurrence risks remain high. Careful diagnosis, classification, and further investigation of the causes of hypertensive disorders in pregnancy are needed to achieve optimal management of affected women and their fetuses.

Eclampsia in Southern Alberta: is there a role for seizure prophylaxis in all women with gestational hypertension?

OBJECTIVE

To evaluate the predictability of eclampsia and explore the role for seizure prophylaxis in a population with a low frequency of seizure prophylaxis.

METHODS

A retrospective review was conducted of all women with eclampsia registered at the Foothills Hospital in Calgary, Alberta, between 1991 and 2000. The data collected included timing of seizure in relation to diagnosis of gestational hypertension (GHTN) and delivery, method of seizure prophylaxis (if any), and maternal characteristics.

RESULTS

During the study period, 3075 of 38,577 women (8.0%) were diagnosed with GHTN, with or without proteinuria or adverse conditions. Three percent had received magnesium sulfate for seizure prophylaxis. Of these 3075 women, 17 (0.6%) developed eclampsia, none of whom was receiving magnesium sulfate for seizure prophylaxis at the time. Of these, 10 women (59%) exhibited GHTN prior to their first seizure, including 6 women with GHTN with adverse conditions, 3 with GHTN with proteinuria but without adverse conditions, and 1 with GHTN without proteinuria or adverse conditions. Five of the 17 women had seizures that occurred prior to labour, 6 were intrapartum, and 6 were postpartum. Nine (53%) of the 17 women with eclampsia had their initial seizure after the diagnosis of GHTN and before 24 hours postpartum.

CONCLUSION

Seizure prophylaxis for all the women with GHTN, from the time of diagnosis through 24 hours postpartum, may have been able to prevent as many as 53% of eclamptic episodes. Three hundred and seven women with GTHN would have to receive seizure prophylaxis to prevent one seizure.

Effects of pregnancy on the renal and pulmonary manifestations in women with tuberous sclerosis complex

PURPOSE

To determine whether pregnancy increases the risk of renal or pulmonary complications in women with tuberous sclerosis complex (TSC).

METHODS

We surveyed female members of the Tuberous Sclerosis Alliance and reviewed the files of adult women seen in our genetics clinics for complications of TSC.

RESULTS

Among 145 individuals, there was no significant difference in incidence of renal and pulmonary involvement between the pregnant and never-pregnant groups, although there were differences in age at diagnosis (25 vs. 16) and current age (41 vs. 35). There was no significant difference in the rate of renal complications (57% vs. 67%, P = 0.62) or pneumothorax (40% vs. 38%, P = 1.00) for the pregnant and never-pregnant groups, respectively. Pregnancy loss in women with TSC did not differ from population risks.

CONCLUSIONS

Pregnancy does not increase the risk of developing renal or pulmonary complications in women with TSC.

Preeclampsia. Part 1: clinical and pathophysiologic considerations

Preeclampsia-eclampsia is still one of the leading causes of maternal and fetal morbidity and mortality. Despite active research for many years, the etiology of this disorder exclusive to human pregnancy is an enigma. Recent evidence suggests there may be several underlying causes or predispositions leading to the signs of hypertension, proteinuria, and edema, findings that allow us to make the diagnosis of the "syndrome" of preeclampsia. Despite improved prenatal care, severe preeclampsia and eclampsia still occur. Although understanding of the pathophysiology of these disorders has improved, treatment has not changed significantly in over 50 years. Although postponement of delivery in selected women with severe preeclampsia improves fetal outcome to a degree, this is not done without risk to the mother. In the United States, magnesium sulfate and hydralazine are the most commonly used medications for seizure prophylaxis and hypertension in the intrapartum period. The search for the underlying cause of this disorder and for a clinical marker to predict those women who will develop preeclampsia-eclampsia is ongoing, with its prevention the ultimate goal. This review begins with the clinical and pathophysiologic aspects of preeclampsia-eclampsia (Part 1). In Part 2, the experimental observations, the search for predictive factors, and the genetics of this disorder will be reviewed.

Eclampsia in Sweden

OBJECTIVE

Assess the actual rate of eclampsia in Sweden, describe the clinical picture of the disease and the maternal and perinatal outcomes.

METHODS

Analysis of data regarding incidence of eclampsia registered in the Swedish Medical Birth Register 1991-1992. The records of all the cases with the diagnosis of eclampsia in Sweden during 1991-1992 were retrospectively evaluated regarding maternal and fetal outcomes.

RESULTS

The incidence of eclampsia after case review was 3.3/10,000 births. There was no maternal mortality. Severe maternal complications occurred in 30%. Recurrent fits were reported in 41%. Antenatal eclampsia was usually either not preceded by symptoms or signs of preeclampsia or by just a very short period of prodromal symptoms. Among intrapartum and postnatal cases of eclampsia, preeclampsia or high blood pressure was more frequently noted when convulsions occurred. Perinatal mortality rate was 4/80 (4.7%). Of the infants, 13% were small for gestational age.

CONCLUSION

Compared with earlier studies, the incidence of eclampsia has increased significantly. It is questionable whether the incidence of eclampsia could be reduced by earlier diagnosis and treatment of preeclampsia. The risk of severe complications and recurrent fits was substantial, which underlines the importance of adequate treatment of eclampsia.

Drugs in pregnancy. Antihypertensives

Fifty per cent of pregnancies are unplanned, and 1-6% of young women have pre-existing hypertension. However, no commonly used antihypertensive agent is known to be teratogenic. ACE inhibitors (and angiotensin-receptor antagonists) should be discontinued due to fetotoxicity. Five to 10% of pregnant women have hypertension, of which pre-existing hypertension is but one type. There is consensus that severe maternal hypertension (blood pressure >or=170/110 mmHg) should be treated to minimize the risk of acute cerebrovascular complications. Parenteral hydralazine may be associated with a higher risk of maternal hypotension, and intravenous labetalol with neonatal bradycardia. There is no consensus that mild-to-moderate hypertension in pregnancy should be treated. Clinical trials indicate that transient severe hypertension, antenatal hospitalization, proteinuria at delivery and neonatal respiratory distress syndrome may be decreased by normalizing blood pressure, but intrauterine fetal growth restriction may be increased. Methodological problems with published trials warrant cautious interpretation of these findings. Methyldopa and beta-blockers have been used most extensively, although atenolol may impair fetal growth in particular and should be avoided.

Pregnant women with chronic hypertension and superimposed pre-eclampsia have high cerebral perfusion pressure

OBJECTIVE

To determine any differences in cerebral perfusion pressure in patients with chronic hypertension compared with those with chronic hypertension and superimposed pre-eclampsia.

DESIGN

A prospective observational study.

SETTING

University hospital clinic and labour and delivery suite.

PARTICIPANTS

Fifteen women with chronic hypertension and 15 with superimposed pre-eclampsia.

METHODS

Transcranial Doppler ultrasound was used to measure blood velocity in the middle cerebral arteries of the patients. Systemic blood pressure in the brachial artery was measured simultaneously. Middle cerebral artery. resistance index, pulsatility index, and cerebral perfusion pressure were calculated and plotted on the same axes as data from normal pregnant women. Cerebral perfusion pressure values outside of the 5th and 95th centiles were regarded as abnormal. Cerebral perfusion pressure data from the chronic hypertension and superimposed pre-eclampsia groups were also expressed in terms of the number of normative standard deviations from the mean value for normal pregnancy (Multiples of the Standard Deviation: MOS). All studies were conducted before labour, under similar conditions, and before volume expansion or treatment. Statistical analysis was by Student's t test and Fisher's exact test as appropriate with significance set at a two-tailed P<0.05.

RESULTS

Patient demographics and blood pressure were not significantly different between the two groups. The resistance index and pulsatility index were not significantly different (neither absolute nor multiples of the standard deviation values). The absolute cerebral perfusion pressure was significantly higher in the patients with superimposed pre-eclampsia. The group of women with superimposed pre-eclampsia had a significantly higher mean value of cerebral perfusion pressure measured as multiples of the standard deviation from the mean value for normal pregnancy, despite there being no blood pressure difference.

CONCLUSIONS

Superimposed pre-eclampsia is associated with significantly higher cerebral perfusion pressure measurements compared with women with uncomplicated chronic hypertension. This is not directly related to a higher blood pressure. The difference in cerebral perfusion pressure may be used to speculate upon the pathophysiology of the increased risk for eclampsia seen in patients with superimposed pre-eclampsia.

Treating hypertension in women of child-bearing age and during pregnancy

Hypertension is found among 1 to 6% of young women. Treatment aims to decrease cardiovascular risk, the magnitude of which is less dependent on the absolute level of blood pressure (BP) than on associated cardiovascular risk factors, hypertension-related target organ damage and/or concomitant disease. Lifestyle modifications are recommended for all hypertensive individuals. The threshold of BP at which antihypertensive therapy should be initiated is based on absolute cardiovascular risk. Most young women are at low risk and not in need of antihypertensive therapy. All antihypertensive agents appear to be equally efficacious; choice depends on personal preference, social circumstances and an agent's effect on cardiovascular risk factors, target organ damage and/or concomitant disease. Although most agents are appropriate for, and tolerated well by, young women, another consideration remains that of pregnancy, 50% of which are unplanned. A clinician must be aware of a woman's method of contraception and the potential of an antihypertensive agent to cause birth defects following inadvertent exposure in early pregnancy. Conversely, if an oral contraceptive is effective and well tolerated, but the woman's BP becomes mildly elevated, continuing the contraceptive and initiating antihypertensive treatment may not be contraindicated, especially if the ability to plan pregnancy is important (e.g. in type 1 diabetes mellitus). No commonly used antihypertensive is known to be teratogenic, although ACE inhibitors and angiotensin receptor antagonists should be discontinued, and any antihypertensive drugs should be continued in pregnancy only if anticipated benefits outweigh potential reproductive risk(s). The hypertensive disorders of pregnancy complicate 5 to 10% of pregnancies and are a leading cause of maternal and perinatal mortality and morbidity. Treatment aims to improve pregnancy outcome. There is consensus that severe maternal hypertension (systolic BP > or = 170mm Hg and/or diastolic BP > or = 110mm Hg) should be treated immediately to avoid maternal stroke, death and, possibly, eclampsia. Parenteral hydralazine may be associated with a higher risk of maternal hypotension, and intravenous labetalol with neonatal bradycardia. There is no consensus as to whether mild-to-moderate hypertension in pregnancy should be treated: the risks of transient severe hypertension, antenatal hospitalisation, proteinuria at delivery and neonatal respiratory distress syndrome may be decreased by therapy, but intrauterine fetal growth may also be impaired, particularly by atenolol. Methyldopa and other beta-blockers have been used most extensively. Reporting bias and the uncertainty of outcomes as defined warrant cautious interpretation of these findings and preclude treatment recommendations.

Preeclampsia into eclampsia: toward a new paradigm

OBJECTIVE

This study was undertaken to characterize aspects of the natural history of eclampsia.

STUDY DESIGN

A retrospective analysis was performed on the records of patients with eclampsia who were delivered at two tertiary care hospitals.

RESULTS

Fifty-three pregnancies complicated by eclampsia were identified. Thirty-seven of the women were nulliparous. The mean age was 22 years (range, 15-38 years). Mean gestational age at the time of seizures was 34.2 weeks' gestation (range, 22-43 weeks' gestation). Twenty-eight women had antepartum seizures (53%); 23 of the 28 had seizures at home. Nineteen women had intrapartum seizures (36%). Eight of these women had seizures while receiving magnesium sulfate, and 7 had therapeutic magnesium levels. Six women had postpartum seizures (11%), 4 >24 hours after delivery. Headache preceded seizures in 34 cases. Visual disturbance preceded seizures in 16 cases. The uric acid level was elevated to >6 mg/dL in 43 women. There were no maternal deaths or permanent morbidities. There were 4 perinatal deaths. Two patients had intrauterine fetal deaths at 28 and 36 weeks' gestation. These mothers had seizures at home. One infant died of complications of prematurity at 22 weeks' gestation and one died of respiratory complications at 26 weeks' gestation. There were 4 cases of abruptio placentae, 1 of which resulted in fetal death. Of the 53 cases of eclampsia, only 9 were potentially preventable. One of these was that of a woman who was being observed at home. The other 8 women were hospitalized and had hypertension and proteinuria. Only 7 women could be considered to have severe preeclampsia before seizure (13%), and 4 of these 7 women were receiving magnesium sulfate.

CONCLUSIONS

Eclampsia was not found to be a progression from severe preeclampsia. In 32 of 53 cases (60%) seizures were the first signs of preeclampsia. In this series eclampsia appeared to be more of a subset of preeclampsia. Only 9 cases of eclampsia were potentially preventable with current standards of practice. Our paradigm for this disease, as well as our approach to seizure prophylaxis, should be reevaluated.

Hypertension in pregnancy: new recommendations for management

Hypertension in pregnancy is a frequent complication that has substantial adverse perinatal outcomes. Hypertension may be preexisting (chronic) essential or secondary hypertension; a second entity is pregnancy induced (gestational hypertension, preeclampsia). Recent advances have identified newer markers for pregnancy hypertension: several potential candidate genes may explain the apparent family inheritance of preeclampsia, and some thrombophilic markers have been associated with the condition. Management options for mild to moderate hypertension include a short hospital stay to exclude ongoing severe hypertension and to ascertain fetal well-being. Outpatient care with appropriate maternal and fetal surveillance, including umbilical artery doppler velocimetry, is recommended for better perinatal outcomes. Acute care for severe hypertension includes the use of magnesium sulfate to prevent eclampsia and antihypertensive medication. Expeditious delivery is recommended when the maternal or fetal states cannot be stabilized. Follow-up after delivery allows the uncovering of any other coexisting hypertensive or cardiovascular disorder.

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.

Effect of magnesium prophylaxis and preeclampsia on the duration of labor

OBJECTIVE

Our goals were to compare duration of labor at term for (1) women with preeclampsia versus normotensive nulliparous women and (2) nulliparous women with preeclampsia who received magnesium for seizure prophylaxis versus those who did not.

STUDY DESIGN

We performed a retrospective cohort study of all nulliparous, term vaginal deliveries from 1989 through 1995 at University of California, San Francisco. The perinatal database and medical records were reviewed for information on duration of labor, maternal and labor characteristics, and neonatal outcomes. The chi2 odds ratio, and Student t tests were used to compare categoric and continuous variables between women with preeclampsia and control women and between women with preeclampsia who did and those who did not receive magnesium. Logistic regression was used to evaluate variables predictive of labor duration.

RESULTS

Our study subjects were 4083 normotensive nulliparous women and 154 women with preeclampsia. A sample size calculation revealed that 1764 normotensive control subjects were needed to show a 10% difference in labor duration with 80% power and alpha of 0.05. Among women with preeclampsia, 93 (60%) were treated with magnesium and 61 (40%) were not. More women with preeclampsia than normotensive women had induction of labor and received epidural anesthesia, prostaglandin gel, and oxytocin (P <.003). Total labor duration did not differ between women with preeclampsia and normotensive women (P =.15) or between women with preeclampsia who received magnesium and those who did not (P =.09). In comparison with normotensive women, those with preeclampsia had a higher rate of postpartum hemorrhage (31% vs 22%, P =.005), and the rate was even higher among preeclamptic women treated with magnesium versus those who received no magnesium (34% vs 26%, P =.002). Logistic regression, with prolonged first stage of labor (>12 hours) used as the outcome variable, indicated that epidural anesthesia (odds ratio 2.3, 95% confidence interval 1.9-2. 6), oxytocin (odds ratio 1.8, 95% confidence interval 1.6-2.2), and persistent occipitoposterior presentation (odds ratio 1.6, 95% confidence interval 1.1-2.4) were associated with prolonged labor, whereas preeclampsia (odds ratio 0.9, 95% confidence interval 0.7-1. 1) and treatment with magnesium were not (odds ratio 1.1, 95% confidence interval 0.9-1.4). Induction (odds ratio 0.5, 95% confidence interval 0.4-0.6) and birth weight <2500 g (odds ratio 0. 5, 95% confidence interval 0.4-0.8) were associated with faster labor.

CONCLUSIONS

In term nulliparous women, neither preeclampsia nor magnesium prophylaxis affected labor duration.

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.

Prevention of eclampsia

Eclampsia continues to be a major cause of maternal morbidity and mortality rates, especially in underdeveloped nations. Our data indicate that eclampsia may represent the end stage of at least two very different pathophysiological pathways: one in which cerebral perfusion is low because of vasospasm and another in which cerebral perfusion is increased because of abnormal autoregulation and a failure of the normal protective mechanisms. Magnesium sulfate has been extensively used in the management and prevention of eclamptic seizures in the United States and has been recently shown to be superior to both diphenylhydantoin and diazepam. We have shown that magnesium sulfate is a potent vasorelaxant and that its action may depend on improving cerebral perfusion. Nimodipine, a calcium channel blocker with selective cerebrovascular effect, is currently under investigation in severe preeclampsia. The data show that it is as effective as magnesium sulfate in preventing eclampsia, with less maternal and fetal side effects. Magnesium sulfate and nimodipine have opposite effects on the estimated cerebral perfusion pressure as determined with the Doppler ultrasound. We speculate that the estimated cerebral perfusion pressure may be used to determine the type of cerebrovascular abnormality and the most appropriate treatment in each individual patient with preeclampsia.

A randomised controlled trial of intravenous magnesium sulphate versus placebo in the management of women with severe pre-eclampsia

OBJECTIVE

To determine whether the administration of prophylactic intravenous magnesium sulphate reduces the occurrence of eclampsia in women with severe pre-eclampsia.

DESIGN

Randomised controlled trial.

SETTING

A tertiary referral obstetric unit.

POPULATION

Eight hundred and twenty-two women with severe pre-eclampsia requiring termination of pregnancy by induction of labour or caesarean section.

METHODS

The women were randomised to receive either placebo (saline) or magnesium sulphate intravenously. The investigators were blinded to the contents of the pre-mixed solutions.

MAIN OUTCOME MEASURE

The occurrence of eclampsia in the two groups.

RESULTS

The data of 699 women were evaluated. Fourteen were withdrawn after randomisation. The overall incidence of eclampsia was 1.8%. Of 345 women who received magnesium sulphate, one developed eclampsia (0.3%); in the placebo group, 11/340 women (3.2%) developed eclampsia (relative risk 0.09; 95% confidence interval 0.01-0.69; P = 0.003).

CONCLUSION

The use of intravenous magnesium sulphate in the management of women with severe pre-eclampsia significantly reduced the development of eclampsia.

Parenteral hydralazine revisited

Historical aspects of the development and application of the vasodilator hydralazine are reviewed. The pharmacology, pharmacokinetics, metabolism, and mechanism of action are discussed, with emphasis on the parenteral use of this drug. It is reiterated that parenteral hydralazine is the preferred drug for the treatment of severe preeclampsia, but its usefulness in other forms of accelerated hypertension is also addressed. Through comparisons with other established antihypertensive agents, the efficacy and pharmacoeconomic potential of hydralazine are stressed.

Seizure prophylaxis in hypertensive pregnancies: a framework for making clinical decisions

OBJECTIVE

To describe a framework for generating therapeutic recommendations using seizure prophylaxis in hypertensive pregnancies as an example.

DESIGN

A decision-making framework was built using: 1. evidence of therapeutic benefit, with number needed to treat as the effect measure; 2. baseline rates of the target disorder that the treatment was designed to prevent; and 3. a treatment threshold, determined by weighting the potential risks against the potential benefits of the treatment.

METHODS

Evidence of therapeutic benefit (i.e. reduction in eclamptic seizures associated with magnesium sulphate therapy in hypertensive pregnancies) was determined by a systematic quantitative overview of controlled clinical trials. Baseline rates of seizures without magnesium sulphate therapy were derived from a recent cohort study. A treatment threshold was generated using estimates of treatment associated morbidities which were weighted against the potential reduction in seizures from magnesium sulphate therapy considering the relative values assigned to these outcomes by obstetricians practising in our hospital.

RESULTS

The number of hypertensive women needed to be treated with magnesium sulphate to prevent a single case of eclamptic seizures varied in a curvilinear fashion dropping from 1000 to 14 as the baseline rate of seizures increased from 0.1% to 10%. The treatment threshold as measured by number needed to treat was 64 (range 57-77). The number needed to treat for nonproteinuric hypertension was 1000 (95% CI 180-40,000), whereas it was 32 (95% CI 20-57) for proteinuric hypertension. Considering the uncertainty in estimation of the numbers needed to treat and treatment threshold, magnesium sulphate therapy may be recommended for women at high risk of eclampsia (e.g. severe pre-eclampsia) while it should be withheld in cases at low risk (e.g. nonproteinuric hypertension and mild pre-eclampsia).

CONCLUSION

While awaiting further research obstetricians intuitively make decisions about seizure prophylaxis in hypertensive pregnancies. Our decision-making framework generated therapeutic recommendations by explicit consideration of the available evidence.

The changing pattern of eclampsia over a 60-year period

OBJECTIVE

To determine changes in the incidence and pattern of eclampsia within the same geographical area over a 60-year period.

DESIGN

A retrospective, descriptive study of 1259 consecutive women classified, at the time, as having had an eclamptic convulsion between the years 1931 and 1990.

SETTING

A large city centre teaching hospital and the surrounding catchment area.

MAIN OUTCOME MEASURES

The changes in the incidence and timing of the convulsion and the outcomes for the mother and baby.

RESULTS

Over the study period, the incidence of eclampsia fell by more than 90%, from 74.1/10,000 in the 1930s to 7.2/10,000 in the 1980s. Most of the reduction occurred over the first four decades, with little change in the last 20 years. Overall, 44% of the cases of eclampsia occurred in the antenatal period, 33% intrapartum and 23% postpartum. Since the biggest decreases were seen in the incidence of antenatal and particularly intrapartum eclampsia, there has been a relative increase in the proportion of eclampsia occurring postpartum. Maternal death from eclampsia occurred in 15.1% of cases between 1931 and 1940, 13.4% between 1941 and 1950, but fell dramatically to < or = 3.9% after 1950. There has been no maternal death since 1964. Apart from the first decade, postpartum eclampsia was associated with significantly less risk of death to the mother throughout the study period. Perinatal death rate has fallen steadily from 432.6/1000 cases of eclampsia between 1931 and 1940 over the first three decades, to 168.7/1000 between 1961 and 1970. There has been little change since, although a lower proportion of neonatal deaths occurred as stillbirths.

CONCLUSIONS

We found a significant reduction in both the incidence of eclampsia and associated morbidity in this population over the last 60 years. This has occurred in association with the introduction of the National Health Service, widespread antenatal care for all and a general improvement in health and welfare. Any further reduction in the incidence in the UK may be difficult to achieve. Since the incidence of eclampsia is now low, efforts should perhaps be directed at minimising the morbidity associated with severe pre-eclampsia rather than prevention of convulsions.

The effect of magnesium sulfate therapy on the duration of labor in women with mild preeclampsia at term: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

The primary outcome was to determine whether magnesium sulfate therapy prolongs the duration of labor in women with mild preeclampsia. Secondary outcomes were to assess the side effects associated with magnesium sulfate therapy: hours and maximum dose of oxytocin, incidence of progression to severe preeclampsia, incidence of cesarean delivery, change in maternal hematocrit, incidence of postpartum hemorrhage, incidence of maternal infection, and Apgar scores.

STUDY DESIGN

Women with a diagnosis of mild preeclampsia at term were randomized to receive standard therapy during labor and for 12 hours post partum with either magnesium sulfate (n = 67) or a matching placebo solution (n = 68).

RESULTS

There was no difference between magnesium sulfate and placebo with respect to the primary outcome variables: total length of labor (median 17.8 hours vs 16.5 hours, p = 0.7) and length of the active phase of labor (median 5.4 hours vs 6.0 hours, p = 0.5). In addition, no difference was observed in the secondary outcome variables: hours of oxytocin use, change in hematocrit, frequency of maternal infection, progression to severe preeclampsia, incidence of cesarean delivery, and Apgar scores. Although not statistically significant, the incidence of postpartum hemorrhage was approximately fourfold greater in the magnesium sulfate group (relative risk 4.1, 95% confidence interval 0.5 to 35.4). There was a significant difference in the maximum dose of oxytocin used (13.9 +/- 8.6 mU/min with magnesium sulfate vs 11.0 +/- 7.6 mU/min with placebo, p = 0.036).

CONCLUSION

The use of magnesium sulfate during labor in women with mild preeclampsia at term does not affect any component of labor but did necessitate a higher dose of oxytocin.

Review: immunobiology of preeclampsia

Preeclampsia has been recognized clinically since the time of Hippocrates: however its etiology and pathophysiology remain enigmatic. This pregnancy-specific syndrome typically presents in late pregnancy as hypertension, edema, and proteinuria. Investigations over the past 15 years have revealed that preeclampsia is associated with abnormal placentation, reduced placental perfusion, endothelial cell dysfunction, and systemic vasospasm. Since it occurs more commonly in primigravidae and in women with underlying collagen-vascular diseases, an immunological component has long been suspected. Increased prevalence in high-order and molar pregnancies and those associated with increased placental mass suggests that trophoblastic volume and fetal antigen load are correlated with the syndrome. Epidemiological reports indicate that the prevalence of preeclampsia is decreased in women who received heterologous blood transfusions, practiced oral sex, or when a long period of cohabitation preceded an established pregnancy. Conversely, the use of condoms as a primary mode of contraception is associated with a higher risk of preeclampsia. These studies suggest that prior exposure to foreign or paternal antigens imparts a protection against the likelihood of developing preeclampsia. Clinical evidence of cellular and humoral immune dysfunction is associated with the syndrome. Fibrin and complement deposition and "foam" cells in atherosis lesions resemble the histopathology of renal allograft rejection. Relative T-cell, natural killer cell, and neutrophil activation have been reported in preeclampsia and circulating cytokines and antiphospholipid antibodies are more prevalent in preeclampsia than in normal pregnant women. These abnormalities are consistent with the systemic endothelial cell dysfunction that has been postulated as a pathophysiological feature of preeclampsia. While such associations do not prove causality, they suggest testable hypotheses for continued basic and clinical investigation of this major complication of human pregnancy.

Magnesium sulphate in the treatment of eclampsia and pre-eclampsia: an overview of the evidence from randomised trials

OBJECTIVE

To evaluate the effectiveness of magnesium sulphate in the treatment of eclampsia and pre-eclampsia by a systematic quantitative overview of controlled clinical trials.

DESIGN

Online searching of the MEDLINE database between 1966 and 1995, and scanning of the bibliography of known primary studies and review articles on the use of magnesium sulphate in eclampsia and pre-eclampsia. Study-selection, study quality assessment and data extraction were performed independently by two reviewers under masked conditions. Where possible outcome data from trials were pooled and summarised using the Mantel-Haenszel method.

PARTICIPANTS

One thousand seven hundred and forty-three women with eclampsia and 2390 with pre-eclampsia included in nine randomised trials that evaluated the effects of magnesium sulphate.

MAIN OUTCOME MEASURES

Seizure activity and maternal death.

RESULTS

In eclampsia, recurrence of seizures was less common with magnesium sulphate therapy compared with phenytoin (odds ratio [OR] 0.27, 95% CI 0.17-0.45, P = 0.00) and diazepam (OR 0.41, 95% CI 0.30-0.57, P = 0.00). As indicated by the point estimate, there was a trend towards a reduction in maternal mortality with magnesium sulphate in eclampsia (OR 0.51, 95% CI 0.24-1.07, P = 0.10 versus phenytoin; OR 0.78, 95% CI 0.41-1.45, P = 0.52 versus diazepam). When used for seizure prophylaxis in pre-eclampsia, magnesium sulphate was found to be more effective than phenytoin (OR 0.15, 95% CI 0.03-0.72, P = 0.01).

CONCLUSION

Magnesium sulphate is a superior drug in preventing the recurrence of seizures in eclampsia and in seizure prophylaxis in pre-eclampsia.