A nurse is assessing a client with severe pre-eclampsia who is receiving magnesium sulfate infusion.

Which finding should alert the nurse to suspect magnesium toxicity?

The client has no seizures or eclampsia.This outcome would indicate that the magnesium sulfate therapy is successful because magnesium sulfate is a mineral that reduces seizure risks in women with preeclampsia.

Some additional information for the other choices are:

• Choice B. The client delivers a healthy baby vaginally.

This outcome is desirable but not directly related to the effectiveness of magnesium sulfate therapy.Magnesium sulfate can help prolong a pregnancy for up to two days to allow drugs that speed up the baby’s lung development to be administered, but it does not guarantee a vaginal delivery or a healthy baby.

• Choice C. The client has normal blood pressure and urine output.

This outcome is also desirable but not directly related to the effectiveness of magnesium sulfate therapy.

Magnesium sulfate may help reduce blood pressure in some cases, but it is not the primary treatment for hypertension in preeclampsia.Other medications such as antihypertensives are usually prescribed for that purpose.Urine output should be monitored closely while receiving magnesium sulfate therapy, as a decrease may indicate toxicity or kidney impairment.Urine output should be at least 30 mL/hour while administering magnesium sulfate.

• Choice D. The client has improved liver function and platelet count.

This outcome is also desirable but not directly related to the effectiveness of magnesium sulfate therapy.

Magnesium sulfate does not affect liver function or platelet count in preeclampsia.These parameters may improve after delivery of the placenta, which is the main cause of preeclampsia.

Normal ranges for blood pressure, urine output, liver function and platelet count are:

• Blood pressure: less than 140/90 mm Hg

• Urine output: at least 30 mL/hour

• Liver function: AST and ALT less than 40 U/L, LDH less than 600 U/L, bilirubin less than 1.2 mg/dL

• Platelet count: 150,000 to 450,000 per microliter of blood

Stop the magnesium sulfate infusion.

The client is showing signs of magnesium toxicity, such as absent deep tendon reflexes, which can lead to respiratory depression and cardiac arrest.

Magnesium sulfate is an anticonvulsant that is used to prevent seizures in eclampsia, but it can also cause vasodilation and hypotension.

The nurse should stop the infusion and monitor the client’s vital signs and neurological status.

Choice B. Increase the rate of the hydralazine infusion is wrong because hydralazine is an antihypertensive that lowers blood pressure.

The client’s blood pressure is already within the normal range for eclampsia (140/90 to 160/110 mmHg), so increasing the rate of hydralazine could cause hypotension and compromise placental perfusion.

Choice C. Administer calcium gluconate IV push is wrong because calcium gluconate is an antidote for magnesium toxicity, but it should not be given IV push.

It should be given slowly over 10 to 20 minutes to avoid cardiac arrhythmias and bradycardia.

Choice D. Prepare for immediate delivery of the fetus is wrong because delivery of the fetus is not indicated at this time.

The client’s vital signs are stable and there is no evidence of fetal distress or placental abruption.

Delivery of the fetus is the definitive treatment for eclampsia, but it should be done when the maternal and fetal conditions are optimal.