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

Eclampsia in the 21st century

The reported incidence of eclampsia is 1.6 to 10 per 10,000 deliveries in developed countries, whereas it is 50 to 151 per 10,000 deliveries in developing countries. In addition, low-resource countries have substantially higher rates of maternal and perinatal mortalities and morbidities. This disparity in incidence and pregnancy outcomes may be related to universal access to prenatal care, early detection of preeclampsia, timely delivery, and availability of healthcare resources in developed countries compared to developing countries. Because of its infrequency in developed countries, many obstetrical providers and maternity units have minimal to no experience in the acute management of eclampsia and its complications. Therefore, clear protocols for prevention of eclampsia in those with severe preeclampsia and acute treatment of eclamptic seizures at all levels of healthcare are required for better maternal and neonatal outcomes. Eclamptic seizure will occur in 2% of women with preeclampsia with severe features who are not receiving magnesium sulfate and in <0.6% in those receiving magnesium sulfate. The pathogenesis of an eclamptic seizure is not well understood; however, the blood-brain barrier disruption with the passage of fluid, ions, and plasma protein into the brain parenchyma remains the leading theory. New data suggest that blood-brain barrier permeability may increase by circulating factors found in preeclamptic women plasma, such as vascular endothelial growth factor and placental growth factor. The management of an eclamptic seizure will include supportive care to prevent serious maternal injury, magnesium sulfate for prevention of recurrent seizures, and promoting delivery. Although routine imagining following an eclamptic seizure is not recommended, the classic finding is referred to as the posterior reversible encephalopathy syndrome. Most patients with posterior reversible encephalopathy syndrome will show complete resolution of the imaging finding within 1 to 2 weeks, but routine imaging follow-up is unnecessary unless there are findings of intracranial hemorrhage, infraction, or ongoing neurologic deficit. Eclampsia is associated with increased risk of maternal mortality and morbidity, such as placental abruption, disseminated intravascular coagulation, pulmonary edema, aspiration pneumonia, cardiopulmonary arrest, and acute renal failure. Furthermore, a history of eclamptic seizures may be related to long-term cardiovascular risk and cognitive difficulties related to memory and concentration years after the index pregnancy. Finally, limited data suggest that placental growth factor levels in women with preeclampsia are superior to clinical markers in prediction of adverse pregnancy outcomes. This data may be extrapolated to the prediction of eclampsia in future studies. This summary of available evidence provides data and expert opinion on possible pathogenesis of eclampsia, imaging findings, differential diagnosis, and stepwise approach regarding the management of eclampsia before delivery and after delivery as well as current recommendations for the prevention of eclamptic seizures in women with preeclampsia.

Magnesium Sulfate Prevents Placental Ischemia-Induced Increases in Brain Water Content and Cerebrospinal Fluid Cytokines in Pregnant Rats

Magnesium sulfate (MgSO₄) is the most widely used therapy in the clinic to prevent the progression of preeclampsia, a hypertensive disorder of pregnancy, to eclampsia. Eclampsia, manifested as unexplained seizures and/or coma during pregnancy or postpartum, accounts for ~13% of maternal deaths worldwide. While MgSO₄ continues to be used in the clinic, the mechanisms by which it exerts its protective actions are not well understood. In this study, we tested the hypothesis that MgSO₄ protects against placental ischemia-induced increases in brain water content and cerebrospinal fluid cytokines. To test this hypothesis, MgSO₄ was administered via mini-osmotic pump (60 mg/day, i.p.) to pregnant and placental ischemic rats, induced by mechanical reduction of uterine perfusion pressure, from gestational day 14–19. This treatment regimen of MgSO₄ led to therapeutic level of 2.8 ± 0.6 mmol/L Mg in plasma. MgSO₄ had no effect on improving placental ischemia-induced changes in mean arterial pressure, number of live fetuses, or fetal and placental weight. Placental ischemia increased, while MgSO₄ prevented the increase in water content in the anterior cerebrum. Cytokine and chemokine levels were measured in the cerebrospinal fluid using a multi-plex assay. Results demonstrate that cerebrospinal fluid, obtained via the cisterna magna, had reduced protein, albumin, interleukin (IL)-17A, IL-18, IL-2, eotaxin, fractalkine, interferon gamma, vascular endothelial growth factor (VEGF), and macrophage inflammatory protein (MIP)-2 following MgSO₄ treatment. These data support the hypothesis that MgSO₄ offers neuroprotection by preventing placental ischemia-induced cerebral edema and reducing levels of cytokines/chemokines in the cerebrospinal fluid.

Magnesium sulfate for acute traumatic brain injury

BACKGROUND

The purpose of this systematic review was to evaluate the effect of magnesium sulfate in the treatment of acute traumatic brain injury.

MATERIALS AND METHODS

A systematic search of ClinicalTrials.gov, the Cochrane Library database, EMBASE, MEDLINE, Web of Science, and the World Health Organization trial registry, plus manual searches of gray literature, was undertaken in April 2013. Two reviewers independently extracted the data with a predefined data extraction form. RevMan 5 software was used to synthesize data and calculate the risk ratio for mortality with the 95% confidence interval. For the Glasgow Outcome Scale and posttreatment Glasgow Coma Scale data, the weighted mean difference was calculated with the 95% confidence interval.

RESULTS

A total of 8 randomized controlled trials with a total of 786 patients were included. Meta-analysis showed that there was no significant difference between the groups for mortality. The Glasgow Outcome Scale of the treatment group was higher than that of the control group, although the significance was borderline. The Glasgow Coma Scale score change posttreatment was significantly higher than that of the control.

CONCLUSIONS

The present meta-analysis of existing randomized controlled trials does not identify a significant beneficial effect in the mortality of traumatic brain injury patients; however, it suggests that magnesium sulfate shows a tendency to improve the Glasgow Outcome Scale and Glasgow Coma Scale scores, which is a promising result for traumatic brain injury therapy. Further effort is necessary to explore which subgroup of traumatic brain injury patients could benefit from magnesium sulfate.

Pharmacologic Management of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) remains a condition with suboptimal functional outcomes, especially in the young population. Pharmacotherapy has an accepted role in several aspects of the disease and an emerging role in several others. No preventive pharmacologic interventions for SAH currently exist. Antiplatelet medications as well as anticoagulation have been used to prevent thromboembolic events after endovascular coiling. However, the main focus of pharmacologic treatment of SAH is the prevention of delayed cerebral ischemia (DCI). Currently the only evidence-based medical intervention is nimodipine. Other calcium channel blockers have been evaluated without convincing efficacy. Anti-inflammatory drugs such as statins have demonstrated early potential; however, they failed to provide significant evidence for the use in preventing DCI. Similar findings have been reported for magnesium, which showed potential in experimental studies and a phase 2 trial. Clazosentane, a potent endothelin receptor antagonist, did not translate to improve functional outcomes. Various other neuroprotective agents have been used to prevent DCI; however, the results have been, at best inconclusive. The prevention of DCI and improvement in functional outcome remain the goals of pharmacotherapy after the culprit lesion has been treated in aneurysmal SAH. Therefore, further research to elucidate the exact mechanisms by which DCI is propagated is clearly needed. In this article, we review the current pharmacologic approaches that have been evaluated in SAH and highlight the areas in which further research is needed.

Vasospasm in cerebral inflammation

All forms of cerebral inflammation as found in bacterial meningitis, cerebral malaria, brain injury, and subarachnoid haemorrhage have been associated with vasospasm of cerebral arteries and arterioles. Vasospasm has been associated with permanent neurological deficits and death in subarachnoid haemorrhage and bacterial meningitis. Increased levels of interleukin-1 may be involved in vasospasm through calcium dependent and independent activation of the myosin light chain kinase and release of the vasoconstrictor endothelin-1. Another key factor in the pathogenesis of cerebral arterial vasospasm may be the reduced bioavailability of the vasodilator nitric oxide. Therapeutic trials in vasospasm related to inflammation in subarachnoid haemorrhage in humans showed a reduction of vasospasm through calcium antagonists, endothelin receptor antagonists, statins, and plasminogen activators. Combination of therapeutic modalities addressing calcium dependent and independent vasospasm, the underlying inflammation, and depletion of nitric oxide simultaneously merit further study in all conditions with cerebral inflammation in double blind randomised placebo controlled trials. Auxiliary treatment with these agents may be able to reduce ischemic brain injury associated with neurological deficits and increased mortality.

Magnesium sulfate treatment improves outcome in patients with subarachnoid hemorrhage: a meta-analysis study

OBJECTIVE

To elucidate the role of magnesium sulfate in patients with subarachnoid hemorrhagic (SAH) brain injury

METHOD

Studies for the meta-analysis were identified from PubMed (1966 to 2009), Embase (1980 to 2009), and two Chinese journals (1989 to 2009). Paper selection was based on randomized controlled trials comparing magnesium sulfate to placebo treatment in patients with SAH. Two independent review authors extracted the data and assessed trial quality. Meta-analysis was performed using the Cochrane Review Manger software.

RESULTS

Five trials involving 482 patients were included in the review. Magnesium sulfate reduced the risk of poor outcome and reduced the occurrence of delayed cerebral ischemia. In the treatment groups, relative risk for poor outcome was 0.73 (CI 0.57-0.93) and 0.66 (CI 0.47-0.92) for delayed cerebral ischemia. Case fatality assessment at three to six months did not show statistically significant data (RR 0.88; CI 0.61-1.29).

CONCLUSION

Magnesium sulfate appears to be an effective treatment option in the management of SAH. Further clinical trials are needed before magnesium sulfate can become a routine treatment for SAH.

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.

Obstetric Ultrasounds in Africa: Is it Necessary to Promote their Appropriate Use?

This paper reviews the situation of obstetric ultrasound scans in Africa (extent of use, sonographer training, indications and results, etc.). Special emphasis is given to the advisability of legally regulating their use, the need for improved training among today's sonographers and the potential dangers that the incorrect and indiscriminate use of ultrasounds can involve. The paper condemns the commodification of the technique and reviews the current status of scientific production.

Magnesium sulphate versus phenytoin for eclampsia

BACKGROUND

Eclampsia, the occurrence of a seizure in association with pre-eclampsia, remains a rare but serious complication of pregnancy. A number of different anticonvulsants have been used to control eclamptic fits and to prevent further seizures.

OBJECTIVES

The objective of this review was to assess the effects of magnesium sulphate compared with phenytoin when used for the care of women with eclampsia. Magnesium sulphate is compared with diazepam and with lytic cocktail in other Cochrane reviews.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2010).

SELECTION CRITERIA

Randomised trials comparing magnesium sulphate (intravenous or intramuscular administration) with phenytoin for women with a clinical diagnosis of eclampsia.

DATA COLLECTION AND ANALYSIS

Two review authors assessed trial quality and extracted data.

MAIN RESULTS

We have included data from seven trials, involving 972 women. One large trial (775 women) was of good quality. Magnesium sulphate was associated with a substantial reduction in the recurrence of seizures, when compared to phenytoin (six trials, 972 women; risk ratio (RR) 0.34, 95% confidence interval (CI) 0.24 to 0.49). The trend in maternal mortality favours magnesium sulphate, but the difference does not reach statistical significance (three trials, 847 women; RR 0.50, 95% CI 0.24 to 1.05). There were reductions in the risk of pneumonia (one trial, RR 0.44, 95% CI 0.24 to 0.79), ventilation (one trial, RR 0.68, 95% CI 0.50 to 0.91) and admission to an intensive care unit (one trial, RR 0.67, 95% CI 0.50 to 0.89) associated with the use of magnesium sulphate rather than phenytoin.For the baby, magnesium sulphate was associated with fewer admissions to a special care baby unit (SCBU) (one trial, 518 babies; RR 0.73, 95% CI 0.58 to 0.91) and fewer babies who died or were in SCBU for more than seven days (one trial, 643 babies; RR 0.77, 95% CI 0.63 to 0.95) than phenytoin. There was no clear difference in perinatal deaths (two trials, 665 babies; (RR 0.85, 95% CI 0.67 to 1.09).

AUTHORS' CONCLUSIONS

Magnesium sulphate, rather than phenytoin, for women with eclampsia reduces the risk ratio of recurrence of seizures, probably reduces the risk of maternal death, and improves outcome for the baby. Magnesium sulphate is the drug of choice for women with eclampsia. The use of phenytoin should be abandoned.

The effects of ritodrine and magnesium sulfate on maternal and fetal Doppler blood flow patterns in women with preterm labor

OBJECTIVE

To determine the effects of ritodrine and magnesium sulfate on maternal-fetal blood flows.

STUDY DESIGN

A total of 85 pregnant women between 26th and 36th weeks with preterm labor, and 83 healthy pregnant women were included. Patients in the study group were randomly assigned to receive either ritodrine (with the addition of verapamil) (n=46) or magnesium sulfate (n=39). Blood flow examinations on the umbilical artery (UA), middle cerebral artery (MCA), bilateral uterine arteries (Ut.A) and ductus venosus (DV) were performed before and 48 h after initiating therapy.

RESULTS

UA pulsatility index (PI) significantly differed in women receiving tocolysis compared to controls after 48 h. DV PI increased in women receiving MgSO(4), whereas it decreased in the ritodrine and control groups. Ut.A values did not significantly change after 48 h in the groups. In women between the 26th and 32nd weeks, UA, MCA and DV PI did not significantly change after 48 h in the three groups. However, in women between the 32nd and 36th weeks UA and MCA PI significantly differed in the treatment groups compared to controls after 48 h. DV PI increased in women receiving MgSO(4), whereas it decreased in the ritodrine and control groups.

CONCLUSIONS

MgSO(4) and ritodrine affect blood flow patterns after 48 h in some maternal-fetal vessels. These effects on blood flow are particularly significant in women between 32nd and 36th weeks. The effects of both drugs on fetal and maternal Doppler flows seem similar, except the increased resistance to flow in DV in women receiving MgSO(4).

Magnesium in obstetrics

Magnesium is a critical physiological ion, and magnesium deficiency might contribute to the development of pre-eclampsia, to impaired neonatal development and to metabolic problems extending into adult life. Pharmacologically, magnesium is a calcium antagonist with substantial vasodilator properties but without myocardial depression. Cardiac output usually increases following magnesium administration, compensating for the vasodilatation and minimising hypotension. Neurologically, the inhibition of calcium channels and antagonism of the N-methyl-d-aspartic acid (NMDA) receptor raises the possibility of neuronal protection, and magnesium administration to women with premature labour may decrease the incidence of cerebral palsy. It is the first-line anticonvulsant for the management of pre-eclampsia and eclampsia, and it should be administered to all patients with severe pre-eclampsia or eclampsia. Magnesium is a moderate tocolytic but the evidence for its effectiveness remains disputed. The side effects of magnesium therapy are generally mild but the major hazard of magnesium therapy is neuromuscular weakness.

Retrospective analysis of parenteral magnesium sulfate administration in decreased incidence of clinical and neuroradiological cerebral vasospasm: a single center experience

OBJECTIVE

Experimental work suggests a neuroprotective role for magnesium sulfate in aneurysmal subarachnoid hemorrhage. We retrospectively review the incidence of clinically relevant vasospasm in patients treated or not with continuous magnesium infusion after onset of subarachnoid hemorrhage.

METHODS

All patient records in Albany Medical Center with the diagnosis of SAH between January 1999 and June 2004 were reviewed. Patients who presented to the emergency department within 72 hours of onset were entered in the study. Patients were defined as in clinical vasospasm if there was an acute neurological change in association with abnormal trancranial Doppler (TCD), CT angiogram (CTA) or digital subtraction angiography (DSA).

RESULTS

A total of 85 patients were selected. Magnesium sulfate was infused in 43 patients. When compared with patients who did not receive MgSO(4), there was a statistically significant lower incidence of clinical and radiological vasospasm in those who had the continuous infusion of magnesium sulfate (p<0.01). There was no statistically significant difference between patients who were coiled or clipped.

CONCLUSION

Continuous magnesium sulfate infusion for the management of clinically significant cerebral vasospasm is safe and reduces the incidence of clinically significant cerebral vasospasm. Large, multicenter, controlled studies should be performed in order to determine the true effectiveness of the treatment in a controlled setting.

The effect of magnesium sulfate on large cerebral artery blood flow in preeclampsia

OBJECTIVES

To determine the effect of a 6 gram intravenous bolus of magnesium sulfate on maternal cerebral blood flow in women with preeclampsia.

STUDY DESIGN

Velocity-encoded phase-contrast magnetic resonance imaging studies were performed on twelve preeclamptic women prior to and immediately after infusion of a 6 gram magnesium sulfate loading dose. Cerebral blood flow was determined at the bilateral proximal middle and posterior cerebral arteries. Study participants returned 6 weeks postpartum for a non-pregnant measurement of cerebral blood flow. The Wilcoxon paired-sample test was used with statistical significance defined as p<0.05.

RESULTS

There was no significant difference in cerebral vessel diameter nor blood flow for any of the examined arteries between the pre- and post magnesium sulfate therapy states.

CONCLUSIONS

The absence of a significant difference in cerebral blood flow of the middle and posterior cerebral arteries before and after infusion of a 6 gram loading dose of magnesium sulfate in women with preeclampsia could suggest the absence of vasoconstriction of the large cerebral arteries in preeclampsia and question the role of magnesium sulfate as a vasodilator of these arteries.

Magnesium sulfate for the treatment of eclampsia: a brief review

BACKGROUND AND PURPOSE

Magnesium sulfate is used extensively for prevention of eclamptic seizures. Empirical and clinical evidence supports the effectiveness of magnesium sulfate; however, questions remain as to its safety and mechanism. This review summarizes current evidence supporting the possible mechanisms of action and several controversies for magnesium sulfate treatment.

SUMMARY OF REVIEW

Several mechanisms are presented, including the effects of magnesium sulfate on peripheral and cerebral vasodilation, blood-brain barrier protection, and as an anticonvulsant.

CONCLUSIONS

Though the specific mechanisms of action remain unclear, the effect of magnesium sulfate in the prevention of eclampsia is likely multi-factorial. Magnesium sulfate may act as a vasodilator, with actions in the peripheral vasculature or the cerebrovasculature, to decrease peripheral vascular resistance or relieve vasoconstriction. Additionally, magnesium sulfate may also protect the blood-brain barrier and limit cerebral edema formation, or it may act through a central anticonvulsant action.

Eclampsia: a neurological perspective

Eclampsia is a poorly understood disorder characterized by seizures or unexplained coma in setting of gestational hypertension. Its neurological manifestations are varied and are an important cause of the morbidity and mortality associated. We present a comprehensive prospective study of forty women recruited over four years describing neurological symptoms and signs, neuroimaging and laboratory studies as well as prognosis including 3-6 months follow-up. The seizures occurred in the postpartum period in majority of women (55%), while 45% had seizures before labor, and the rest (5%) during labor. Interestingly, one third of the women suffered their first seizures more than 48 h postpartum (late postpartum eclampsia). A sizable minority suffered more than one seizure and some had documented partial seizures. Headache preceded seizures by more than a day and was described as throbbing or pounding pain by most. The visual symptoms in decreasing frequency were blurring, blindness, scotoma and visual processing deficits. The most common finding during the neurological exam was memory deficits, followed by increased deep tendon reflexes (asymmetric in some), visual perception deficits, visual information processing deficits, altered mental status and cranial nerve deficits. Intracranial or intraspinal pressure when examined was elevated. Among neuroimaging studies, MRI was more sensitive compared to CT scan. The MRI abnormalities included both white as well as gray matter and the most common location of abnormalities was high frontal/parietal lobe. The laboratory studies revealed proteinuria in majority, but not in all. The liver function tests were abnormal in many, while few patients had HELLP syndrome. The neurological deficits resolved by the time of discharge in all. At follow-up, some patients developed new neurological problems such as recurrent headaches or seizures.

Magnesium sulphate treatment decreases blood-brain barrier permeability during acute hypertension in pregnant rats

Eclampsia is associated with increased blood-brain barrier (BBB) permeability and formation of cerebral oedema. Magnesium sulphate is used to treat eclampsia despite an unclear mechanism of action. This study was to determine the effect of magnesium sulphate on in vivo BBB permeability and formation of cerebral oedema during acute hypertension and on brain aquaporin-4 (AQP4) protein expression. An in vivo model of hypertensive encephalopathy was used in late-pregnant (LP) rats following magnesium sulphate treatment, 270 mg kg(-1) i.p. injection every 4 h for 24 h. Permeability of the BBB was determined by in situ brain perfusion of Evan's Blue (EB) and sodium fluorescein (NaFl), and dye clearance determined by fluorescence spectrophotometry. Cerebral oedema was determined following acute hypertension by measuring brain water content. The effect of magnesium treatment on AQP4 expression was determined by Western blot analysis. Acute hypertension with autoregulatory breakthrough increased BBB permeability to EB in both brain regions studied (P < 0.05). Magnesium attenuated BBB permeability to EB during acute hypertension by 41% in the posterior cerebrum (P < 0.05) but had no effect in the anterior cerebrum (P > 0.05). Treatment with magnesium did not change NaFl permeability, cerebral oedema formation or AQP4 expression. In summary, BBB permeability to Evan's Blue was increased by acute hypertension in LP rats, and this was attenuated by treatment with magnesium sulphate. The greatest effect on BBB permeability to EB was in the posterior cerebrum, an area particularly susceptible to oedema formation during eclampsia.

Posterior Reversible Encephalopathy Syndrome with Vasospasm in a Postpartum Woman After Postdural Puncture Headache Following Spinal Anesthesia

We describe a postpartum woman who, after an uneventful pregnancy, developed posterior reversible encephalopathy syndrome after spinal anesthesia, complicated by postdural puncture headache.

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 review of the management of eclampsia: practical issues

We reviewed 90 cases of eclampsia, an obstetric emergency associated with high blood pressure and convulsions, treated in two hospitals in Durban, South Africa. We present a protocol for the management of eclampsia based on this review and extensive clinical experience on this subject, which includes hemodynamic stabilization of the mother, prevention of recurrent convulsions, prompt delivery, and intensive monitoring in the immediate post-partum period.

Magnesium sulfate: role as possible attenuating factor in vasospasm morbidity

BACKGROUND

Among the many complications of SAH, one of the most important is vasospasm. Several treatment alternatives have been proposed for this condition, with far-from-ideal results being obtained. Magnesium sulfate recently returned to the scene (with still unproven benefit) as an adjuvant in the treatment of vasospasm.

METHODS

Seventy-two patients diagnosed with SAH by aneurysm rupture were submitted to microsurgery craniotomy and subdivided in 2 groups. Group 1, formed by 48 patients, received prophylactic hypervolemic and hemodilution therapy in addition to nimodipine. Group 2, composed of 24 patients, received the same treatment of group 1 with the addition of magnesium sulfate in continuous infusion from 120 to 150 mg a day, keeping serum magnesium levels close to double normal values.

RESULTS

Age was 49 +/- 12.6 years. Ratio of female to male was 3.16:1. Most patients were admitted in a Hunt-Hess grade 2 (46.4%) and Fisher grade 3 (52.8%). Anterior communicating artery aneurysms were the most common in location (38.8%). Both groups were compared, and there was no statistical difference related to age, sex, and Glasgow, Fisher, or Hunt-Hess admission grades. No statistical difference in vasospasm incidence was found between the two groups. However, in group 1, vasospasm was correlated with a longer hospitalization time (P = .0003), different from group 2, in which patients with vasospasm receiving magnesium sulfate required less hospitalization time.

CONCLUSION

Magnesium did not seem to interfere in vasospasm frequency but apparently acted favorably in decreasing morbidity and length of hospital stay.

Evidence and practice: the magnesium sulphate story

There is now strong evidence from systematic reviews of randomised trials to support the use of magnesium sulphate for the prevention and treatment of eclampsia. Magnesium sulphate more than halves the risk of eclampsia for women with pre-eclampsia (relative risk (RR) 0.41, 95% confidence interval (CI) 0.29-0.58; number needed to treat (NNT) 102 (95% CI 72-173) compared to placebo. For treatment of eclampsia, magnesium sulphate lowers the risk of maternal death (RR 0.59, 95% CI 0.37-0.94) and of recurrence of further fits (RR 0.44, 95% CI 0.34-0.57) compared to diazepam. Magnesium sulphate also reduces the risk of further fits compared to phenytoin (RR 0.31, 95% CI 0.20-0.47) and to lytic cocktail (RR 0.09, 95% CI 0.03-0.24).

Magnesium sulfate for brain protection during temporary cerebral artery occlusion

We evaluated the effects of magnesium sulfate on brain tissue oxygen (PtO2) tension, carbon dioxide (PtCO2) tension and pH (pHt) in patients undergoing temporary artery occlusion for clipping of cerebral aneurysm. We studied 18 patients with aneurysmal subarachnoid hemorrhage. All patients received standard anesthetics using target controlled infusion of propofol (3 microg/ml) and remifentanil (10 ng/ml). After craniotomy, a calibrated multiparameter sensor (Neurotrend, Diametrics Medical, Minneapolis, MN) was inserted to measure PtO2, PtCO2 and pHt in tissue at risk of ischemia during temporary artery occlusion. Patients were then randomly allocated to receive either intravenous saline or magnesium 20 mmol over 10 min followed by an infusion 4 mmol/h. Plasma magnesium concentration, brain tissue gases and pHt were determined at baseline, 30 min after study drug infusion and 4 min after temporary clipping. Data were analyzed by factorial ANOVA with repeated measures. Intergroup difference was compared with unpaired t test. P value < 0.05 was considered significant. Patient characteristics, baseline brain tissue gases and pHt did not differ between groups. Magnesium infusion increased PtO2 by 34%. Following temporary artery occlusion, PtO2 and pHt decreased and PtCO2 increased in both groups. However, tissue hypoxia was less severe and the rate of PtO2 decline was slower in the magnesium group. Our data suggested that magnesium enhances tissue oxygenation and attenuates hypoxia during temporary artery occlusion.

Deep Tendon Reflexes, Magnesium, and Calcium: Assessments and Implications

The perinatal nurse, in collaboration with physicians, can use deep tendon reflexes as a powerful tool in determining the need to start, adjust, or stop magnesium infusion. Toxicity can be detected using physical manifestations as a guide. Clinical signs may be a better indicator than serum levels of tissue levels of magnesium. Whether magnesium is given to prevent seizures or for tocolysis, patients in both situations are at risk for developing toxicity and must be assessed regularly to ensure patient safety.

Magnesium and experimental vasospasm

Object. Interest has developed in the use of magnesium (Mg++) as a neuroprotectant and antivasospastic agent. Magnesium may increase cerebral blood flow (CBF) and reduce the contraction of cerebral arteries caused by various stimuli. In this study the authors tested the hypothesis that a continuous intravenous infusion of Mg++ reduces cerebral vasospasm after experimental subarachnoid hemorrhage (SAH).

Methods. A dose-finding study was conducted in five monkeys (Macaca fascicularis) to determine what doses of intravenous MgSO4 elevate the cerebrospinal fluid (CSF) concentrations of Mg++ to vasoactive levels and to determine what effects these doses have on the diameters of cerebral arteries, as shown angiographically. After a standard dose of MgSO4 had been selected it was then administered in a randomized, controlled, blinded study to 10 monkeys (five animals/group) with SAH, beginning on Day 0 and continuing for 7 days, at which time angiography was repeated. A 0.086-g/kg bolus of MgSO4 followed by an infusion of 0.028 g/kg/day MgSO4 significantly elevated serum and CSF levels of Mg++ (five monkeys). Magnesium sulfate significantly elevated the serum level of total Mg++ from a control value of 0.83 ± 0.04 mmol/L to 2.42 ± 1.01 mmol/L on Day 7 and raised the CSF level from 1.3 ± 0.04 mmol/L to 1.76 ± 0.14 mmol/L. There was no angiographic evidence of any effect of MgSO4 on normal cerebral arteries. After SAH, the vasospasm in the middle cerebral artery was not significantly reduced (46 ± 8% in the MgSO4-treated group compared with 35 ± 6% in the placebo [vehicle]-treated group, p > 0.05, unpaired t-test).

Conclusions. Magnesium sulfate did not significantly reduce cerebral vasospasm after SAH in the doses tested. An investigation of SAH is warranted mainly to test whether a benefit can be achieved by neuroprotection or by augmentation of CBF by dilation of small vessels and/or collateral pathways.

The effect of treatment on endothelin-1 concentration and mean arterial pressure in preeclampsia and eclampsia

OBJECTIVE

The aim of this study was to determine the effect of treatment on endotelin-1 concentration that is considered to have role in etiopathogenesis of eclampsia and preeclampsia.

METHODS

Nine patients with eclampsia and 12 patients with preeclampsia were included to the study. Endothelin-1 levels were measured before and after magnesium sulfate treatment. After the magnesium sulfate administration, if the blood pressure was still elevated, nifedipine was given.

RESULTS

Endothelin-1 levels of preeclamptic patients before and after magnesium sulfate treatment were 16.9 +/- 2.3 fmol/ml and 14.6 +/- 1.9 fmol/ml respectively (p < 0.05). The same measurements of eclamptic patients were 18.1 +/- 3.2 and 14.7 +/- 3.4 respectively (p < 0.05). The mean blood pressures of preeclamptic patients before and after magnesium sulfate were 125.8 +/- 7.3 mm-Hg, 118.2 +/- 8.7 mm-Hg respectively, and the same measurements of eclamptic patients were 136.0 +/- 12.4 mm-Hg and 123.1 +/- 10.6 mm-Hg respectively (p < 0.05, p < 0.05).

CONCLUSION

Treatment had been found to have negative effects on endothelin-1 levels that is considered to play an important role on etiopathogenesis of eclampsia and preeclampsia.

Pharmacokinetics and clinical effects of phenytoin and fosphenytoin in children with severe malaria and status epilepticus

AIMS

Status epilepticus is common in children with severe falciparum malaria and is associated with poor outcome. Phenytoin is often used to control status epilepticus, but its water-soluble prodrug, fosphenytoin, may be more useful as it is easier to administer. We studied the pharmacokinetics and clinical effects of phenytoin and fosphenytoin sodium in children with severe falciparum malaria and status epilepticus.

METHODS

Children received intravenous (i.v.) phenytoin as a 18 mg kg-1 loading dose infused over 20 min followed by a 2.5 mg x kg(-1) 12 hourly maintenance dose infused over 5 min (n = 11), or i.v. fosphenytoin, administered at a rate of 50 mg x min(-1) phenytoin sodium equivalents (PE; n = 16), or intramuscular (i.m.) fosphenytoin as a 18 mg x kg(-1) loading dose followed by 2.5 mg x kg(-1) 12 hourly of PE (n = 11). Concentrations of phenytoin in plasma and cerebrospinal fluid (CSF), frequency of seizures, cardiovascular effects (respiratory rate, blood pressure, trancutaneous oxygen tension and level of consciousness) and middle cerebral artery (MCA) blood flow velocity were monitored.

RESULTS

After all routes of administration, a plasma unbound phenytoin concentration of more than 1 microg x ml(-1) was rapidly (within 5-20 min) attained. Mean (95% confidence interval) steady state free phenytoin concentrations were 2.1 (1.7, 2.4; i.v. phenytoin, n = 6), 1.5 (0.96, 2.1; i.v. fosphenytoin, n = 11) and 1.4 (0.5, 2.4; i.m. fosphenytoin, n = 6), and were not statistically different for the three routes of administration. Median times (range) to peak plasma phenytoin concentrations following the loading dose were 0.08 (0.08-0.17), 0.37 (0.33-0.67) and 0.38 (0.17-2.0) h for i.v. fosphenytoin, i.v. phenytoin and i.m. fosphenytoin, respectively. CSF: plasma phenytoin concentration ratio ranged from 0.12 to 0.53 (median = 0.28, n = 16). Status epilepticus was controlled in only 36% (4/11) following i.v. phenytoin, 44% (7/16), following i.v. fosphenytoin and 64% (7/11) following i.m. fosphenytoin administration, respectively. Cardiovascular parameters and MCA blood flow were not affected by phenytoin administration.

CONCLUSIONS

Phenytoin and fosphenytoin administration at the currently recommended doses achieve plasma unbound phenytoin concentrations within the therapeutic range with few cardiovascular effects. Administration of fosphenytoin i.v. or i.m. offers a practical and convenient alternative to i.v. phenytoin. However, the inadequate control of status epilepticus despite rapid achievement of therapeutic unbound phenytoin concentrations warrants further investigation.

The effect of isosorbide dinitrate, a donor of nitric oxide, on maternal cerebral blood flow in gestational hypertension and preeclampsia

OBJECTIVE

The purpose of this study was to investigate the effect of a nitric oxide donor on cerebral perfusion pressure and other blood flow index values in the maternal middle cerebral and basilar arteries.

STUDY DESIGN

Sublingual tablets of 5-mg isosorbide dinitrate were administered to 19 hypertensive pregnant patients. Doppler velocimetry of the middle cerebral and basilar arteries was obtained with a transcranial Doppler with the use of the transtemporal and suboccipital approach.

RESULTS

The mean (+/-SEM) flow velocity in the middle cerebral artery significantly decreased from a baseline of 65.9 +/- 3.1 cm/s to 55.2 +/- 2.2 and 52.0 +/- 2.1 cm/s at 10 and 20 minutes (P <.0001). Resistance area product insignificantly increased from a baseline of 2.0 +/- 0.1 before isosorbide dinitrate to 2.19 +/- 0.11 at 20 minutes. No significant changes were observed in the resistance and pulsatility indices in the middle cerebral artery. The cerebral perfusion pressure did not change significantly after isosorbide dinitrate (84.5 +/- 7.3, 80.8 +/- 6.6, and 78.5 +/- 5.0 mm Hg at 0, 10, and 20 minutes, respectively) nor did the cerebral blood flow index.

CONCLUSION

The results obtained demonstrate that cerebral perfusion pressure is unaltered by isosorbide dinitrate, despite significant changes in maternal blood pressure and in blood flow velocities in the middle cerebral artery.

Maternal transcranial Doppler in pre-eclampsia and eclampsia

Pre-eclampsia affects 3-7% of women and is associated with significant maternal and perinatal morbidity and mortality. Transcranial Doppler (TCD) has been used in pre-eclampsia/eclampsia to evaluate non-invasively the cerebrovascular hemodynamics in the maternal middle cerebral artery. TCD has demonstrated in pre-eclamptic women maternal cerebral vasospasm, which does not correlate with mean arterial pressure assessed simultaneously. Estimated cerebral perfusion pressure, assessed using a modified formula, has been shown to be increased in women with severe and non-severe pre-eclampsia. However, in severe pre-eclampsia, elevated cerebral perfusion pressure is counterbalanced by increases in cerebrovascular resistance and cerebral blood flow is unaffected. In eclampsia a significant fall in cerebral vascular resistance occurs which, in the presence of increases in cerebral perfusion pressure, leads to hyperperfusion. Cerebral vascular changes to date have not been sensitive enough to predict the development of pre-eclampsia or eclampsia. Longitudinal studies with the aim of predicting the onset of pre-eclampsia and to assess the effects of various drugs on the maternal cerebral circulation need to be designed.

Magnesium sulphate versus phenytoin for eclampsia

BACKGROUND

Eclampsia, the occurrence of a convulsion (fit) in association with pre-eclampsia, remains a rare but serious complication of pregnancy. A number of different anticonvulsants are used to control eclamptic fits and to prevent further convulsions.

OBJECTIVES

The objective of this review was to assess the effects of magnesium sulphate compared with phenytoin when used for the care of women with eclampsia. Magnesium sulphate is compared with diazepam and with lytic cocktail in other Cochrane reviews.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth trials register (28 November 2002) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2002).

SELECTION CRITERIA

Randomised trials comparing magnesium sulphate (intravenous or intramuscular administration) with phenytoin for women with a clinical diagnosis of eclampsia.

DATA COLLECTION AND ANALYSIS

Both reviewers assessed trial quality and extracted data.

MAIN RESULTS

Six trials involving 897 women are included. Most of the data are from trials of good quality. Magnesium sulphate is associated with a substantial reduction in the recurrence of convulsions, when compared to phenytoin (five trials, 895 women; relative risk (RR) 0.31, 95% confidence interval (CI) 0.20 to 0.47). The trend in maternal mortality favours magnesium sulphate, but this difference is not statistically significant (two trials, 797 women; RR 0.50, 95% CI 0.24 to 1.05). There are also reductions in the risk of pneumonia (RR 0.44, 95% CI 0.24 to 0.79), ventilation (RR 0.66, 95% CI 0.49 to 0.90) and admission to an intensive care unit (RR 0.67, 95% CI 0.50 to 0.89) associated with the use of magnesium sulphate. For the baby, magnesium sulphate was associated with fewer admissions to a special care baby unit (SCBU) (one trial, 518 babies; RR 0.73, 95% CI 0.58 to 0.91) and fewer babies who died or were in SCBU for more than seven days (one trial, 665 babies; RR 0.77, 95% CI 0.63 to 0.95).

REVIEWER'S CONCLUSIONS

Magnesium sulphate appears to be substantially more effective than phenytoin for treatment of eclampsia.

Angioplasty for cerebral vasospasm from eclampsia

BACKGROUND

Neurological deterioration in eclampsia is considered to be secondary to cerebral vasospasm. Magnesium sulfate therapy improves symptoms and controls seizures, possibly related to its vasorelaxive effects in spastic arteries. Some cases, however, are refractory to magnesium therapy. To our knowledge, there is no report of angioplasty for vasospasm from eclampsia in the literature.

METHODS

A 27-year-old woman presented 10 days postpartum with severe mental status changes and left arm and bilateral leg weakness that were refractory to magnesium therapy. Cerebral angiography demonstrated diffuse, severe vasospasm. We treated her with angioplasty of the bilateral middle and posterior cerebral arteries, basilar artery, and bilateral internal carotid arteries.

RESULTS

Angioplasty resulted in excellent angiographic improvement. The patient immediately became responsive and appropriate with improved strength in all extremities. She continued to improve throughout her hospital stay and was discharged 10 days postangioplasty.

CONCLUSIONS

Cerebral angioplasty is an effective treatment for vasospasm from eclampsia refractory to magnesium therapy. Angiography should be considered early in the course of neurological deterioration, but delayed therapy may also be effective.

Cerebral blood flow velocity response to magnesium sulfate in patients after subarachnoid hemorrhage

Magnesium sulfate therapy, standard in preventing seizures in preeclampsia, is under active investigation as a neuroprotective agent. The authors studied the effect of magnesium as a cerebral vasodilator by measuring the cerebral blood flow velocity (CBFV) response to a 5g intravenous bolus of MgSO4 compared with a saline placebo after subarachnoid hemorrhage (SAH). Transcranial Doppler ultrasonography of the middle cerebral artery (MCA) was measured after each infusion. Patients were studied up to three times after SAH at prescribed time intervals. Fourteen patients (11 women, 3 men; mean age 58 years) underwent 29 studies. All patients underwent hypertensive, hypervolemic therapy. Four patients developed cerebral vasospasm. Doubling serum magnesium levels did not affect MCA CBFV but slightly lowered mean arterial blood pressure and systemic vascular resistance. Intravenous magnesium bolus did not reduce elevated CBFV in the subset of SAH patients with clinical vasospasm. The role of magnesium sulfate as a cerebral vasodilator in patients with SAH requires further study.

Magnesium sulfate in the management of patients with Fisher Grade 3 subarachnoid hemorrhage: a pilot study

OBJECTIVE

To evaluate the effect of magnesium sulfate (MgSO4) on the clinical course of patients with severe aneurysmal subarachnoid hemorrhage (SAH).

METHODS

Ten patients with Fisher Grade 3 aneurysmal SAH were evaluated. The patients were given a bolus as well as a constant infusion of intravenous MgSO4 up to 10 days postictus. Blood magnesium levels were obtained to adjust the daily requirement of MgSO4. The goal was to raise the serum level to 2.0 to 2.5 mmol/L or twice the baseline serum level. Daily transcranial Doppler (TCD) ultrasonography was performed on each patient, insonating both anterior cerebral and middle cerebral arteries. Further management followed standard protocols, including the use of nimodipine and hypervolemic therapy. TCD ultrasonographic findings, as well as clinical evidence of cerebral vasospasm, were documented. All patients had a 3-month assessment using the Glasgow Outcome Scale.

RESULTS

After administration of a 20 mmol MgSO4 bolus infusion and an average daily continuous infusion of 84.7 mmol, 8 of 10 patients achieved the predetermined serum magnesium levels. No adverse affects were noted during the infusions. Five patients exhibited evidence of vasospasm on TCD ultrasonography; vasospasm was severe in two patients (velocities, >200 cm/s). Three patients, including the two patients in whom TCD ultrasonography demonstrated severe vasospasm, exhibited clinical evidence of vasospasm. Two patients had a Glasgow Outcome Scale score of 3; the remainder had Glasgow Outcome Scale scores of 5.

CONCLUSION

Administration guidelines for the use of MgSO4 in aneurysmal SAH were established. A prospective double-blind placebo-controlled trial is required to establish the effectiveness of MgSO4 for treating vasospasm in aneurysmal SAH.

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.

Transcranial Doppler ultrasonography: year 2000 update

In this update, the main clinical applications of transcranial Doppler ultrasonography are reassessed. A specific format for technology assessment, personal experience, and an extensive review of the literature form the basis of the evaluation. The document is approved by the American Society of Neuroimaging and the Neurosonology Research Group of the World Federation of Neurology.

Magnesium sulfate in eclampsia and pre-eclampsia: pharmacokinetic principles

Magnesium sulfate (MgSO4) is the agent most commonly used for treatment of eclampsia and prophylaxis of eclampsia in patients with severe pre-eclampsia. It is usually given by either the intramuscular or intravenous routes. The intramuscular regimen is most commonly a 4 g intravenous loading dose, immediately followed by 10 g intramuscularly and then by 5 g intramuscularly every 4 hours in alternating buttocks. The intravenous regimen is given as a 4 g dose, followed by a maintenance infusion of 1 to 2 g/h by controlled infusion pump. After administration, about 40% of plasma magnesium is protein bound. The unbound magnesium ion diffuses into the extravascular-extracellular space, into bone, and across the placenta and fetal membranes and into the fetus and amniotic fluid. In pregnant women, apparent volumes of distribution usually reach constant values between the third and fourth hours after administration, and range from 0.250 to 0.442 L/kg. Magnesium is almost exclusively excreted in the urine, with 90% of the dose excreted during the first 24 hours after an intravenous infusion of MgSO4. The pharmacokinetic profile of MgSO4 after intravenous administration can be described by a 2-compartment model with a rapid distribution (a) phase, followed by a relative slow beta phase of elimination. The clinical effect and toxicity of MgSO4 can be linked to its concentration in plasma. A concentration of 1.8 to 3.0 mmol/L has been suggested for treatment of eclamptic convulsions. The actual magnesium dose and concentration needed for prophylaxis has never been estimated. Maternal toxicity is rare when MgSO4 is carefully administered and monitored. The first warning of impending toxicity in the mother is loss of the patellar reflex at plasma concentrations between 3.5 and 5 mmol/L. Respiratory paralysis occurs at 5 to 6.5 mmol/L. Cardiac conduction is altered at greater than 7.5 mmol/L, and cardiac arrest can be expected when concentrations of magnesium exceed 12.5 mmol/L. Careful attention to the monitoring guidelines can prevent toxicity. Deep tendon reflexes, respiratory rate, urine output and serum concentrations are the most commonly followed variables. In this review, we will outline the currently available knowledge of the pharmacokinetics of MgSO4 and its clinical usage for women with pre-eclampsia and eclampsia.

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.

Change in estimated cerebral perfusion pressure after treatment with nimodipine or magnesium sulfate in patients with preeclampsia

OBJECTIVE

Data are accumulating to suggest that cerebral perfusion pressure may be either abnormally high or low in preeclampsia and eclampsia. Little is known of the cerebral perfusion pressure effects of magnesium sulfate or nimodipine. Our objective in this study was to compare the change in cerebral perfusion pressure in patients with severe preeclampsia randomly selected to receive nimodipine or magnesium sulfate.

STUDY DESIGN

Patients with severe preeclampsia were randomly selected to receive magnesium sulfate (6 g bolus and 2 g/hr intravenous infusion) or nimodipine (60 mg taken orally every 4 hours). Transcranial Doppler ultrasonography was used to measure flow velocities in the right and left middle cerebral arteries, and the results were averaged. Measurements were obtained before treatment (baseline) and 30 minutes after the magnesium sulfate bolus was completely infused or 30 minutes after the nimodipine was ingested. Studies were performed before any other intervention. The person performing the ultrasonography was unaware of the patient's group assignment. Estimated cerebral perfusion pressure was calculated with the following formula: Estimated cerebral perfusion pressure = Velocity(mean) x [(Blood pressure(mean ) - Blood pressure(diastolic ))/(Velocity(mean) - Velocity(diastolic ))]. The difference between estimated cerebral perfusion pressure at baseline and after treatment was compared between the 2 groups by means of the Mann-Whitney rank sum test.

RESULTS

Nine patients were randomly selected to receive nimodipine and 12 to receive magnesium sulfate. Patient demographics and severity of condition were not significantly different between the 2 groups. The change in estimated cerebral perfusion pressure was significantly different between the groups. Estimated cerebral perfusion pressure increased after nimodipine use and decreased after magnesium sulfate use.

CONCLUSION

Shortly after administration to patients with severe preeclampsia, nimodipine resulted in increased cerebral perfusion pressure in comparison with magnesium sulfate.

Anesthetic management of preeclampsia/eclampsia

Preeclampsia/eclampsia affects only a small proportion of all pregnancies, yet accounts for much of the obstetric morbidity and mortality seen in the USA and UK. A full understanding of preeclampsia/eclampsia, its variable presentation and complex pathophysiology allows the consulting anesthesiologist to optimize a plan for anesthetic management of the afflicted patient.

Changes in maternal middle cerebral artery blood flow velocity associated with general anesthesia in severe preeclampsia

In women with severe preeclampsia, significant increases in mean arterial pressures (MAP) are common after rapid induction of general anesthesia (GA) and tracheal intubation. The objectives of this prospective study were to assess the effects of the rapid induction-intubation technique on middle cerebral artery (MCA) flow velocity in severe preeclampsia and to examine the correlation between mean MCA flow velocity (Vm) and MAP. Eight women with severe preeclampsia (study group) and six normotensive women at term (control group) scheduled to undergo cesarean section under GA were studied. Before induction, patients in the study group received i.v. labetalol in divided doses to lower diastolic pressures to <100 mm Hg. Anesthesia was induced with pentothal 4-5 mg/kg, followed by succinylcholine 1.5 mg/kg to facilitate tracheal intubation. A transcranial Doppler was used to measure Vm. Both Vm and MAP were recorded before induction and every minute for 6 min after intubation. In the study group, after the administration of labetalol, MAP decreased from 129 +/- 9 to 113 +/- 9 mm Hg (P < 0.05), and Vm decreased from 59 +/- 11 to 54 +/- 10 cm/s (P < 0.05). After intubation, MAP increased from 113 +/- 9 to 134 +/- 5 mm Hg (P < 0.001), and Vm increased from 54 +/- 10 to 70 +/- 10 cm/s (P < 0.001). In the control group, while MAP increased significantly from 89 +/- 6 to 96 +/- 4 mm Hg (P < 0.05) after intubation, the concurrent increase in Vm from 49 +/- 5 to 54 +/- 7 cm/s was not significant. There was a significant positive pooled correlation between Vm and MAP (r = 0.5, P < 0.0006) in the study group but not in the control group (r = 0.24). After induction and intubation, both Vm and MAP values were significantly increased in the study group patients at all observation points compared with the control group patients. The findings indicate that Vm increases significantly after rapid-sequence induction of GA and tracheal intubation in women with severe preeclampsia, and there seems to be a direct relationship between MAP and Vm.

IMPLICATIONS

In women with severe preeclampsia, rapid-sequence induction of general anesthesia and tracheal intubation can cause severe hypertension. Our results indicate that the increase in blood pressure is associated with a significant increase in maternal cerebral blood flow velocity and that there is a significant correlation between these two variables.