Which fluid type is indicated for large-volume fluid administration?

• A. Isotonic crystalloids
• B. Hypertonic crystalloids
• C. Hypotonic crystalloids
• D. Colloids

Answer: (A)

When you need to restore circulating volume quickly, you want a fluid that stays in the bloodstream long enough to raise blood pressure and tissue perfusion without causing harmful shifts into or out of cells. Isotonic crystalloids have a composition close to that of plasma, so they distribute primarily in the extracellular space rather than moving into cells. This makes them safe, effective, and widely available for large-volume resuscitation, providing rapid intravascular volume expansion without the risk of cellular edema that hypotonic fluids can cause or the extreme shifts that hypertonic solutions provoke. Colloids can be considered in some situations, but they are more costly and carry different risks, so they are not the usual first choice for large-volume administration.