There is no debate about the utility of magnesium sulfate in severe preeclampsia, but when it comes to intrapartum management of mild preeclampsia or cases in which preeclampsia first manifests in the postpartum period, data are not so clear. This debate will not be resolved to anyone’s satisfaction in the course of this article. Historically, the practice has been to use magnesium in these circumstances, but the pendulum has begun to shift based on a few arguments:
- Eclampsia is a rare event (about 1 case for every 300 to 1,000 deliveries).
- Most cases occur outside of the hospital.
- Some women experience seizures before preeclampsia has been diagnosed.
- Some patients experience seizures while taking magnesium sulfate.
Regardless of one’s position on this debate, there is broad consensus that regular careful clinical assessment of the patient who has preeclampsia is essential to minimize morbidity and mortality. This disease can progress from mild to severe rapidly. Only through regular careful assessment can a physician observe this change soon enough to alter management as necessary.
Treatment of magnesium toxicity
Most often, an ampule of 10% calcium gluconate (1 g) is administered IV to reverse the effects of suspected magnesium toxicity.
In addition, because magnesium freely crosses the placenta, we recommend that a newborn resuscitation team be present at all deliveries during which the mother was receiving magnesium sulfate because neonatal respiratory and cardiac depression have been reported in this setting.
CHALLENGE NO. 6: Delivering the patient
Preeclampsia, severe preeclampsia, and eclampsia present a dilemma for the managing clinician: subject her to the rigors of labor, or to the heightened risk of cesarean delivery? Overall, a properly managed vaginal delivery is less hemodynamically stressful than cesarean delivery for the mother. To accomplish vaginal delivery, it is necessary to provide optimal anesthesia and analgesia.
Risks of regional anesthesia
Women who have preeclampsia are volume-depleted. As such, they are prone to hypotension after administration of regional anesthesia if the block sets up too rapidly. For this reason, epidural anesthesia or some of the newer combined techniques offer optimal analgesia by allowing for slower implementation of the regional block.
Women who have preeclampsia, especially severe preeclampsia, are usually candidates for regional analgesia and anesthesia. Some requisites for regional anesthesia under these conditions include the following:
- The patient can tolerate preblock hydration.
- She has adequate IV access.
- There is a reproducible means of determining BP.
- The patient has a normal coagulation profile. (A normal platelet count with normal transaminase should be sufficient to confirm this; women who have preeclampsia are not at increased risk of having altered prothrombin time, partial thromboplastin time, or fibrinogen levels, provided there are no other mitigating clinical circumstances.)
- The anesthesiology team is skilled in the administration of regional anesthesia.
If eclampsia occurs
Do not proceed to emergent cesarean section. Rather, stabilize the mother, protect her from injury during the seizure, protect her airway, and allow the seizure to take its course.
Begin magnesium at once. If it was being infused before the seizure, consider giving an additional 2-g bolus over several minutes. As the mother stabilizes, the fetal heart rate will recover and she can be reassessed to determine optimal timing and route of delivery.
Continue magnesium after delivery?
Yes, but how long remains unclear. Most authorities have recommended 24 hours, based on the observation that most eclamptic seizures that occur in the first 48 hours postpartum actually occur in the first 24 hours.
Clinical assessment can guide management to some degree. The most reliable sign of disease resolution is spontaneous, brisk diuresis, so some clinicians use this finding as an indication to discontinue magnesium.
Regardless of clinical preference, if magnesium sulfate is being used postpartum, continue it until there is evidence of disease resolution, such as the diuresis noted above.
When HELLP syndrome arises
If HELLP [Hemolysis, Elevated Liver en zymes, Low Platelets] syndrome is present, continue magnesium sulfate until there is laboratory evidence of improvement in the platelet count and transaminase. Because a return to normal levels can take several days, it is not required before discontinuation of magnesium in cases of HELLP syndrome. However, at the time of discontinuation, it should be clear that there is no longer evidence of a worsening laboratory or clinical trend.
CHALLENGE NO. 7: Managing HELLP, atypical eclampsia
These two diagnoses pose daunting clinical challenges too numerous to cover in detail in this article, but a few key points merit consideration. When HELLP syndrome is diagnosed (using established criteria, TABLE 4), follow guidelines for severe preeclampsia. Use of dexamethasone remains somewhat controversial, as randomized clinical trials so far do not support it.6