🤱 Maternity & Newborn · Lesson 2 of 6 · 7 min
Preeclampsia, Magnesium and the Reflexes You Check
🩺 Blood pressure 162/112 at 34 weeks, a headache, and 3+ protein in the urine. The drug you hang can stop a seizure or stop her breathing. The difference is a reflex hammer.
💡 Key idea
Preeclampsia is 140/90 after 20 weeks with protein or organ signs. Magnesium prevents seizures; lost reflexes, slow breathing and low urine mean toxicity. Calcium gluconate at the bedside.
🧠 Why it matters
PREECLAMPSIA is new hypertension of 140/90 or higher after 20 weeks with proteinuria or organ involvement; severe features include a pressure of 160/110 or more, severe headache, visual disturbances, epigastric or right upper quadrant pain, pulmonary edema and low platelets. HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) is a severe variant. ECLAMPSIA is preeclampsia with seizures. MAGNESIUM SULFATE prevents seizures: it is given IV by pump with a loading dose then maintenance, and the nurse monitors for TOXICITY: loss of DEEP TENDON REFLEXES (the earliest sign), respirations under 12, urine output under 30 mL/hr, and a magnesium level above the therapeutic range of about 4 to 7 mEq/L. Keep CALCIUM GLUCONATE at the bedside as the antidote. Antihypertensives for severe pressures include labetalol, hydralazine and nifedipine. Nursing care: quiet dim room, seizure precautions, side-lying, strict intake and output, daily weights, and monitoring the fetus. During a seizure, protect the client, turn her to the side, and do not restrain; after it, assess the airway, fetal status and for placental abruption. Delivery is the cure, and magnesium usually continues for about 24 hours postpartum.
🏥 In the real world
🔨 Hour six of a magnesium infusion: the nurse taps the patellar tendon and gets nothing, respirations are 11, and the Foley bag holds 20 mL from the last hour. The infusion is stopped, calcium gluconate is given per order, and the provider is called. The seizure the magnesium prevented was real; the respiratory arrest it nearly caused was prevented by a reflex check.
📌 Takeaways
- Severe features: 160/110, headache, visual changes, epigastric pain, low platelets
- Magnesium toxicity: absent reflexes first, then RR under 12 and urine under 30 mL/hr
- Calcium gluconate at the bedside; delivery is the cure
📖 Terms in this lesson
Preeclampsia: New hypertension after 20 weeks with protein in the urine or organ involvement; magnesium sulfate prevents seizures.
Magnesium sulfate therapeutic level: About 4 to 7 mEq/L when infused for preeclampsia; lost deep tendon reflexes are the first sign of toxicity, then respirations under 12 and urine under 30 mL/hr, and calcium gluconate is the antidote at the bedside.
Hydralazine: A direct vasodilator for severe hypertension, including preeclampsia alongside labetalol; expect reflex tachycardia, headache and orthostatic drops, check blood pressure before and after each IV dose, and report joint pain or rash, which can signal a lupus-like reaction with long-term use.
Magnesium sulfate: The IV drug that prevents eclamptic seizures in preeclampsia; check deep tendon reflexes, respirations and urine output every hour, hold for lost reflexes, respirations under 12 or output under 30 mL an hour, and keep calcium gluconate at the bedside as the antidote.
✅ Test yourself
A client receiving magnesium sulfate for severe preeclampsia has absent patellar reflexes and a respiratory rate of 10. What should the nurse do first?
- Stop the magnesium and prepare calcium gluconate
- Turn the client onto her back and elevate her legs
- Administer labetalol
- Increase the infusion rate to prevent an eclamptic seizure
Answer: A · Stop the magnesium and prepare calcium gluconate
These are signs of magnesium toxicity; stopping the drug and giving the antidote prevent respiratory arrest.
Which assessment finding in a client with preeclampsia indicates worsening disease?
- Mild edema of the feet and ankles at the end of the day
- Epigastric pain and visual disturbances
- Blood pressure of 142/92 on repeat measurement
- Trace protein on a routine urine dipstick
Answer: B · Epigastric pain and visual disturbances
Epigastric pain and visual changes are severe features that often precede seizures.
During an eclamptic seizure, what is the nurse's priority?
- Insert an oral airway between the teeth
- Protect the client from injury and turn her to the side when possible
- Restrain the client's arms and legs
- Leave to call the provider
Answer: B · Protect the client from injury and turn her to the side when possible
Safety and airway protection come first; nothing goes in the mouth and the client is never restrained.
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