Which solution is an example of isotonic fluid?

Lactated Ringer's solution (LR) is an example of an isotonic fluid as it closely matches the body's plasma osmolality, making it suitable for volume resuscitation and fluid replacement in various clinical situations. Isotonic solutions maintain the osmotic balance between the fluid inside cells and the fluid in the vascular compartment, which helps to prevent cellular swelling or shrinkage.

Lactated Ringer's contains a mix of electrolytes including sodium, chloride, potassium, calcium, and lactate, which mimics the electrolyte composition of plasma. This property makes it effective for rehydrating patients without causing significant shifts of fluid into or out of cells.

In contrast, the other options are either hypotonic or hypertonic solutions. For instance, 0.45% normal saline is hypotonic, meaning it has a lower concentration of solutes compared to plasma, which can lead to water moving into cells. Glucose 5% in water can initially be considered isotonic, but once metabolized by the body, it behaves more like a hypotonic solution due to the absence of solutes. Similarly, Dextrose 10% in water is hypertonic; while the dextrose solution is more concentrated, it can