Final answer:
Crystalloids and colloids are used to expand vascular volume in critical care patients exhibiting symptoms of shock.
Step-by-step explanation:
When a critical care patient is exhibiting symptoms of shock, the goal is to expand their vascular volume. The fluids used for this purpose are intravenous fluids administered directly into the bloodstream. The most commonly used fluids for vascular volume expansion in such cases are crystalloids and colloids.
Crystalloids are fluids that contain small molecules that can easily pass through blood vessels. Examples of crystalloids include normal saline (0.9% sodium chloride) and Ringer's lactate.
Colloids are fluids that contain larger molecules that tend to stay within the bloodstream and help to maintain vascular volume. Examples of colloids include albumin and hetastarch.