Eclampsia
Eclampsia is defined as the occurrence of convulsions associated with pre-eclampsia (13). Most women in the United Kingdom who have an eclamptic seizure will not have established hypertension and proteinuria prior to this.
About 44% of seizures occur postpartum, 38% antepartum, and 18% intrapartum (14). The incidence of eclampsia in the United Kingdom has fallen to 27.5 cases per 100,000 maternities (15) since the introduction of guidelines for management of pre-eclampsia, guided by the Collaborative Eclampsia and Magpie trials (16, 17). Although the case fatality rate of eclampsia is low, eclampsia is associated with a high rate of maternal morbidity and perinatal mortality (14).Prior to a seizure, the woman may experience the classical symptoms of pre-eclampsia: headache, visual disturbance, severe epigastric pain, and rapid onset of oedema. Eclampsia presents as generalized seizures, sometimes associated with tongue biting, urinary incontinence, and cyanosis. Seizures are often self-limiting, resolving within 90 seconds. The recurrence rate is up to 30%.
Initial management of eclampsia
An algorithm for the initial management of eclampsia is displayed in Figure 29.5.
Activate the emergency bell to call for urgent help from the multiprofessional team: senior midwives, obstetricians, and anaesthetists. State the problem clearly: ‘This is an eclamptic seizure’. Request a team member to collect the eclampsia emergency box and to inform the consultant obstetrician and consultant anaesthetist. An example of an eclampsia box and its contents is shown in Figure 29.6.
Support ABC. During the seizure, move the woman into the left-lateral position to maintain her airway, administer high-flow oxygen, and remove any obvious hazards in the environment. Once the seizure has resolved, ensure the airway is patent. Obtain intravenous access and send bloods for full blood count, urea and electrolytes, liver function tests, clotting screen, and group and save. Check vital observations: blood pressure, heart rate, respiratory rate, oxygen saturations, and temperature.
Commence continuous monitoring if possible.Commence magnesium sulphate treatment to control seizures:
• Loading dose: 4 g magnesium sulphate over 5 minutes.
• Maintenance dose: 1 g/hour.
Magnesium sulphate is the first-line treatment for eclampsia. It has been demonstrated to prevent eclampsia and is associated with the lowest recurrence rate of seizures (16, 17). Diazepam, phenytoin, and a lytic cocktail should not be used as alternative treatment.
The loading dose of magnesium sulphate should be given slowly over 5 minutes, as transient side effects of flushing and tachycardia are common. The maintenance infusion should be continued for at least 24 hours after delivery or the last seizure (whichever is longest).
Women who are receiving a magnesium sulphate infusion should be closely monitored for signs of toxicity. Toxicity is not common; however, women with renal impairment or oliguria are at greater risk, as magnesium sulphate is excreted by the kidneys. If toxicity is suspected, the infusion should be stopped and the serum magnesium level measured. Signs of magnesium toxicity are a loss of deep tendon reflexes, followed by respiratory depression, respiratory arrest, and cardiac arrest. The antidote for magnesium sulphate is 1 g calcium gluconate intravenously.
If the woman is hypertensive, administer antihypertensive treatment as per the local hospital guideline for severe pre-eclampsia.
In the event of recurrent seizures, give a 2 g bolus of magnesium sulphate over 5 minutes. If possible, take blood for magnesium levels prior to the bolus. Consider alternative causes of the seizures and discuss additional medications for seizure control with an anaesthetist.