Final answer:
The first sign of Magnesium toxicity in a pre-eclamptic patient receiving Magnesium Sulfate IV is decreased deep tendon reflexes, which is an important early indicator to monitor.
Step-by-step explanation:
The first sign of Magnesium toxicity in a client diagnosed with pre-eclampsia and receiving Magnesium Sulfate IV is decreased deep tendon reflexes. Magnesium Sulfate is used to prevent seizures in pre-eclampsia, but it is important to monitor for signs of toxicity. While symptoms such as nausea and vomiting, respiratory depression, and visual blurring can occur with magnesium toxicity, the initial sign that is typically assessed for in clinical practice is a decrease in deep tendon reflexes, which can indicate elevated magnesium blood levels. It is crucial for the nurse to monitor the deep tendon reflexes regularly to detect any early signs of magnesium toxicity.