A client with severe preeclampsia is receiving IV magnesium sulfate. The nurse notes respirations 10/min, absent patellar reflexes, and urine output 20 mL/hr. Which action should the nurse take first?

Respirations 10/min, absent reflexes, and urine output 20 mL/hr indicate magnesium accumulation and toxicity. Stop the infusion, support breathing, notify the provider, and prepare calcium gluconate as the reversal agent.

Quick answer
Stop magnesium sulfate and prepare calcium gluconate. Respirations 10/min, absent patellar reflexes, and urine output 20 mL/hr are converging toxicity cues.

Why this is correct
Magnesium is cleared by the kidneys and depresses neuromuscular and respiratory function as it accumulates. Low urine output increases accumulation risk, while absent reflexes and respiratory slowing show clinically important toxicity that requires immediate interruption of the infusion and escalation.

Easy analogy or mental picture
Think of the kidneys as the drain for a magnesium bath. When the drain slows, the level rises until muscle and breathing signals are submerged; the picture explains accumulation but does not replace laboratory monitoring or emergency respiratory support.

Memory hook
Low urine output plus lost reflexes plus slow breathing means stop magnesium and prepare calcium.

NCLEX decision rule
During magnesium sulfate therapy, connect renal output, reflexes, and respirations. If reflexes disappear or breathing slows, stop the infusion, support airway and breathing, notify the provider, and prepare the prescribed calcium antidote.

Why the other choices are wrong
Lateral positioning does not remove the accumulating medication. Increasing magnesium worsens toxicity, and continuing the infusion while giving a diuretic delays the essential first step and may introduce additional fluid and electrolyte risk.