PRE-ECLAMPSIA AND ECLAMPSIA Medication

 

 

 

Magnesium sulphate should be considered for women with pre-eclampsia for whom there is concern about the risk of eclampsia. This is usually in the context of severe pre-eclampsia once a delivery decision has been made and in the immediate postpartum period. In women with less severe disease the decision is less clear and will depend on individual case assessment.

The MAGPIE study has demonstrated that administration of magnesium sulphate to women with pre-eclampsia reduces the risk of an eclamptic seizure.⁰²⁰² Women allocated magnesium sulphate had a 58% lower risk of an eclamptic seizure, (95% CI 40?71%). The relative risk reduction was similar regardless of the severity of pre-eclampsia. More women need to be treated when pre-eclampsia is not severe (109) to prevent one seizure when compared with severe pre-eclampsia (63).When conservative management of a woman with severe hypertension and a premature fetus is made it would be reasonable not to treat until the decision to deliver has been made. If magnesium sulphate is given, it should be continued for 24 hours following delivery or 24 hours after the last seizure, whichever is the later, unless there is a clinical reason to continue. When magnesium sulphate is given, regular assessment of the urine output, maternal reflexes, respiratory rate and oxygen saturation is important.

 

 

The principles of management should follow the basic principles of airway, breathing and circulation.

Magnesium sulphate is the therapy of choice to control seizures. A loading dose of 4 g should be given by infusion pump over 5?10 minutes, followed by a further infusion of 1 g/hour maintained for 24 hours after the last seizure.

Recurrent seizures should be treated with either a further bolus of 2 g magnesium sulphate or an increase in the infusion rate to 1.5 g or 2.0 g/hour.

Do not leave the woman alone but call for help, including appropriate personnel such as the anaesthetist and senior obstetrician. Ensure that it is safe to approach the woman and aim to prevent maternal injury during the convulsion. Place the woman in the left lateral position and administer oxygen. Assess the airway and breathing and check pulse and blood pressure.

Pulse oximetry is helpful.

Once stabilised, plans should be made to deliver the woman but there is no particular hurry and a delay of several hours to make sure the correct care is in hand is acceptable, assuming that there is no acute fetal concern such as a fetal bradycardia. The woman?s condition will always take priority over the fetal condition. Magnesium sulphate is the therapy of choice and diazepam and phenytoin should no longer be used as first-line drugs.⁹⁵⁰¹ The intravenous route is associated with fewer adverse effects. Although a trial in Bangladesh⁰²⁰¹ has shown no significant reduction in recurrent seizures when using only a loading dose as opposed to the standard regimen, further studies would be needed before this practice could be recommended, as this finding may relate to body size. The seizure rates were 3.96% in loading versus 3.51% in standard regimen (P > 0.05).

Magnesium toxicity is unlikely with these regimens and levels do not need to be routinely measured. Magnesium sulphate is mostly excreted in the urine. Urine output should be closely observed and if it becomes reduced below 20 ml/hour the magnesium infusion should be halted. Magnesium toxicity can be assessed by clinical assessment as it causes a loss of deep tendon reflexes and respiratory depression. If there is loss of deep tendon reflexes, the magnesium sulphate infusion
should be halted. Calcium gluconate 1 g (10 ml) over 10 minutes can be given if there is concern over respiratory depression.

In the collaborative eclampsia trial,⁹⁵⁰¹ a further bolus of 2 g magnesium sulphate was administered for recurrent seizures. An alternative is to increase the rate of infusion of magnesium sulphate to 1.5 g or 2.0 g/hour. If there are repeated seizures then alternative agents such as diazepam or thiopentone may be used, but only as single doses, since prolonged use of diazepam is associated with an increase in maternal death.⁹⁵⁰¹ If convulsions persist, intubation is likely to be necessary to protect the airway and maintain oxygenation. Transfer to intensive care facilities with intermittent
positive pressure ventilation is appropriate in these circumstances.