An elderly woman with severe dehydration is treated in the ED. Which IV fluid is indicated initially?

An elderly woman with severe dehydration is treated in the ED. Which IV fluid is indicated initially?

• A. 0.45% saline
• B. Lactated Ringers
• C. 5% dextrose in water
• D. 0.9% saline

Answer: (D)

When a patient has severe dehydration with hypovolemia, the priority is to rapidly restore intravascular volume with fluids that stay in the circulating compartment. An isotonic crystalloid that matches plasma osmolality, like 0.9% saline, does exactly that by expanding the extracellular fluid and improving perfusion without shifting water into cells. It also provides sodium and chloride, which are commonly depleted in dehydration and essential for restoring circulating volume quickly. Fluid choices that are hypotonic or that add free water don’t help with initial resuscitation: a hypotonic solution would draw water into cells and worsen circulation, while 5% dextrose in water becomes free water after metabolism and doesn’t reliably increase intravascular volume. Lactated Ringers is another isotonic option and can be used for resuscitation, but in many ED scenarios 0.9% saline is the standard initial choice to promptly restore perfusion.

When a patient has severe dehydration with hypovolemia, the priority is to rapidly restore intravascular volume with fluids that stay in the circulating compartment. An isotonic crystalloid that matches plasma osmolality, like 0.9% saline, does exactly that by expanding the extracellular fluid and improving perfusion without shifting water into cells. It also provides sodium and chloride, which are commonly depleted in dehydration and essential for restoring circulating volume quickly.

Fluid choices that are hypotonic or that add free water don’t help with initial resuscitation: a hypotonic solution would draw water into cells and worsen circulation, while 5% dextrose in water becomes free water after metabolism and doesn’t reliably increase intravascular volume. Lactated Ringers is another isotonic option and can be used for resuscitation, but in many ED scenarios 0.9% saline is the standard initial choice to promptly restore perfusion.