A nurse is caring for a newborn whose mother was taking methadone during her pregnancy.

Which of the following findings indicates the newborn is experiencing withdrawal?

A. BP 150/92 mm Hg:

• This blood pressure reading is elevated and not a therapeutic effect of magnesium sulfate. In the context of preeclampsia, the goal is usually to lower blood pressure to prevent complications.

B. Pulse rate 100/min:

• The pulse rate of 100/min is not a specific therapeutic effect of magnesium sulfate. However, magnesium sulfate may cause a decrease in heart rate, so monitoring for bradycardia would be important.

C. Flushed face:

• A flushed face is not a specific therapeutic effect of magnesium sulfate. Facial flushing may be associated with other factors, but it is not a primary consideration when monitoring the effectiveness of magnesium sulfate in the context of preeclampsia.

D. Negative clonus:

• Negative clonus is the correct therapeutic effect to monitor. Clonus refers to a series of involuntary, rhythmic, and repetitive muscle contractions and relaxations. In the context of magnesium sulfate administration for preeclampsia, negative clonus (the absence of abnormal reflexes) is a sign that the magnesium levels are within the therapeutic range, helping to prevent seizures.

The correct answer is choice A. Deep tendon reflexes 2+. This indicates that the client is receiving the therapeutic effect of magnesium sulfate, which is to prevent seizures by reducing neuromuscular excitability.

Magnesium sulfate is a mineral that is given intravenously to women with preeclampsia, a condition of high blood pressure and protein in the urine during pregnancy, to reduce the risk of seizures or eclampsia. It can also prolong pregnancy for up to two days, allowing drugs that speed up the baby’s lung development to be administered.

Choice B is wrong because 1+ proteinuria via urine dipstick is not a therapeutic effect of magnesium sulfate, but a sign of preeclampsia.

Proteinuria indicates that the kidneys are not working properly and are leaking protein into the urine. Magnesium sulfate does not improve the outcomes for the baby and can cause side effects such as respiratory depression for the mother.

Choice C is wrong because pulse rate 100/min is not a therapeutic effect of magnesium sulfate, but a possible side effect.

Magnesium sulfate can cause vasodilation, which lowers blood pressure and increases heart rate. A normal pulse rate for an adult is between 60 and 100 beats per minute. A pulse rate higher than 100 beats per minute may indicate tachycardia, which can be caused by various factors such as anxiety, dehydration, fever, infection, or medication.

Choice D is wrong because urine output 20 mL/hr is not a therapeutic effect of magnesium sulfate, but a sign of kidney failure. A normal urine output for an adult is between 800 and 2000 mL per day, or about 30 to 80 mL per hour. A urine output lower than 30 mL per hour may indicate oliguria, which can be caused by various factors such as dehydration, blood loss, shock, or kidney damage. Magnesium sulfate can cause renal toxicity if given in high doses or for prolonged periods.