Crystalloid solutions are generally adequate for most fluid management because they are composed of...

• A. Solution of high molecular weight proteins and large-chain glucose polymers
• B. Solution of low molecular weight ions and rapid equilibrium with extracellular space
• C. Hetastarch and albumin
• D. Dextrose-only solutions

Answer: (B)

Crystalloids are solutions of small, low molecular weight solutes that freely cross capillary membranes and equilibrate rapidly with the extracellular space. Because these tiny solutes move quickly out of the intravascular compartment into the interstitial (and eventually intracellular) space, crystalloids can quickly replace extracellular fluid losses and provide overall volume expansion that fits the needs of most fluid management. They’re inexpensive, readily available, and effective for many scenarios, even though only a portion remains in the intravascular space at any given time. In contrast, the other options describe colloids (large-molecule solutions that stay longer in the vascular space) or involve solute compositions that don’t reflect the rapid extracellular distribution typical of crystalloids.