A client at 35 weeks gestation is admitted to the labor and delivery unit for severe pre-eclampsia. She is started on IV magnesium sulfate for seizure prophylaxis. Which of the following signs indicate that the client has developed magnesium sulfate toxicity? Select all that apply.

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11ecbb05_cbec_ffbf_b433_4d3115460cb6_MD0009_00 IV magnesium sulfate is administered for seizure (eclampsia) prophylaxis in pregnant clients with pre-eclampsia. A loading dose of 4-6 g of magnesium sulfate, followed by a maintenance dose of 1-2 g/hr, helps achieve therapeutic magnesium levels of 4-7 mEq/L (2.0-3.5 mmol/L). Magnesium toxicity may occur when magnesium levels are >7 mEq/L (3.5 mmol/L), which causes central nervous system depression and blocks neuromuscular transmission (Option E). Absent or decreased deep tendon reflexes (DTRs) are the earliest sign of magnesium toxicity. DTRs, scored on a scale of 0 to 4+, should be frequently assessed during magnesium sulfate infusion; normal findings are 2+ (Option A). If toxicity is not recognized early (eg, decreasing DTRs), clients can progress to respiratory depression (<12 breaths/min), followed by cardiac arrest (Option D). Administration of calcium gluconate (antidote) is recommended in the event of cardiorespiratory compromise. (Option B) Hypertension is a sign of pre-eclampsia, not of magnesium toxicity. Hydralazine (Apresoline) and/or labetalol are used to lower blood pressure if needed (ie, when >160/110 mm Hg). (Option C) Urine output <30 mL/hr is a sign that magnesium toxicity may be likely, as magnesium is excreted through the urine. Educational objective: The therapeutic level of magnesium for pre-eclampsia/eclampsia treatment is 4-7 mEq/L (2.0-3.5 mmol/L). Signs of magnesium toxicity may be noted with serum levels >7 mEq/L (3.5 mmol/L) and include absent or decreased deep tendon reflexes, respiratory depression, and cardiac arrest. Calcium gluconate (antidote) should be readily available in the event of cardiorespiratory compromise.

A Client at 35 Weeks Gestation Is Admitted to the Labor