Which finding should prompt a nurse to report potential magnesium sulfate toxicity in a client?

A respiratory rate of 10 breaths per minute is significant and should prompt a nurse to report potential magnesium sulfate toxicity. Magnesium sulfate is a medication commonly used in obstetrics, particularly for managing preeclampsia and to prevent seizures. One of the serious side effects of magnesium sulfate is respiratory depression, which can occur when magnesium levels become elevated.

A respiratory rate below 12 breaths per minute is considered a clinical sign of respiratory distress and may suggest that the client is experiencing toxicity due to magnesium's depressant effects on the central nervous system. Monitoring respiratory rate is a critical part of assessing a patient's response to magnesium sulfate therapy, and a rate of 10/min indicates a potential danger that requires immediate attention.

Other findings, such as an elevated heart rate, elevated blood pressure, or decreased urine output, may be relevant in assessing the overall health status of the client but are not direct indicators of magnesium sulfate toxicity in the same way that respiratory rate is. Therefore, the low respiratory rate stands out as a concerning symptom that warrants prompt medical evaluation.