A nurse is monitoring a client with severe preeclampsia receiving a continuous IV infusion of magnesium sulfate at 2 g/hr. Which of the following assessment findings indicates it is safe to continue the magnesium sulfate infusion?

Magnesium sulfate is a central nervous system depressant used to prevent seizures in severe preeclampsia, but it carries a narrow therapeutic window and can cause toxicity. Before continuing or administering each dose, the nurse must confirm that deep tendon reflexes are present, respirations are at least 12 breaths per minute, and urinary output is at least 25–30 mL per hour. Deep tendon reflexes rated 2+ indicate normal neuromuscular function and suggest the serum magnesium level has not reached the toxic range; a respiratory rate of 12 breaths per minute meets the minimum safe threshold. Together, these findings confirm it is safe to continue the infusion. Absent deep tendon reflexes and drowsiness are early signs of magnesium toxicity — loss of reflexes typically occurs around serum levels of 7–10 mEq/L and precedes respiratory depression. A urinary output of 20 mL/hr for two consecutive hours falls below the 25 mL/hr minimum required, signaling inadequate renal clearance of magnesium and heightened risk of accumulation. A respiratory rate of 8 breaths per minute represents frank respiratory depression and is an absolute indication to stop the infusion and administer the antidote, calcium gluconate. Therefore, the only combination that supports safe continuation is present reflexes with an acceptable respiratory rate.