What is the primary use for isotonic solutions in IV therapy?

Isotonic solutions in IV therapy are primarily used to replace fluid and electrolytes. These solutions have the same osmolarity as the body's plasma, which means they do not cause a shift of fluid into or out of the cells. Instead, they help maintain fluid balance in the extracellular space, making them ideal for situations where a patient has lost significant amounts of body fluids due to dehydration, surgery, or trauma. By providing a balance of water and electrolytes, isotonic solutions help restore homeostasis effectively.

The other options pertain to different uses of IV solutions. Providing free water to cells is associated with hypotonic solutions, which can cause cells to swell. Delivering medications that require slow absorption is generally better suited to specialized solutions or administration methods. Additionally, correcting metabolic acidosis typically requires specific electrolyte solutions or buffers rather than isotonic solutions alone. Thus, the use of isotonic solutions is distinct in its role of replenishing fluid and electrolytes in a safe and effective manner.