How is the free water deficit calculated to resuscitate a hypernatremic patient?

In the management of hypernatremia, calculating the free water deficit is essential for proper resuscitation and correcting sodium levels in a safe and controlled manner. For a hypernatremic patient, the free water deficit reflects the volume of water needed to dilute the serum sodium concentration back to normal levels.

The correct approach involves understanding that the total body weight (BW) in kilograms is a critical factor in determining fluid requirements. The formula that effectively accounts for the need to resuscitate a hypernatremic patient is based on a basic estimate of the free water deficit, which is often centered around 2 times the body weight. This calculation serves as a guideline for infusing a sufficiently safe amount of D5W (5% dextrose in water) to help rehydrate the patient.

Employing this formula allows healthcare providers to opt for an infusion rate that considers an additional amount of fluid to address the water deficit. It is vital to start treatment slowly to avoid rapid shifts in sodium levels, which can lead to serious complications. Therefore, the equation of 2 times the body weight in kilograms effectively establishes a method to approximate the infusion rate to restore serum sodium levels while safely managing the free water deficit.

This process ensures that the patient