Certified Registered Nurse Anesthetist (CRNA) Practice Exam

What is the critical reason for monitoring serum osmolality when administering Mannitol?

1. To prevent dehydration and hypernatremia

2. To ensure proper sedation levels

3. To assess kidney function

4. To monitor blood pressure

The correct answer is: To prevent dehydration and hypernatremia

Monitoring serum osmolality when administering Mannitol is crucial primarily because Mannitol is an osmotic diuretic that can lead to significant changes in fluid balance in the body. Mannitol works by increasing osmotic pressure in the renal tubules, resulting in decreased reabsorption of water and electrolytes, ultimately leading to diuresis. This diuretic effect can potentially cause severe dehydration and alterations in sodium levels, specifically hypernatremia. As Mannitol draws water out of the cells and into the intravascular space, it raises serum osmolality. If not monitored, this can result in an excessively high serum osmolality, which may cause cellular dehydration and further complications. Therefore, it is essential to closely monitor serum osmolality to ensure patient safety and to adjust fluid management appropriately, which directly correlates to preventing dehydration and hypernatremia. The importance of monitoring serum osmolality underscores the specific focus of providing safe anesthesia care during procedures where Mannitol is used, ensuring that the osmotic effects are controlled and side effects are mitigated.