Which solution is considered hypertonic in comparison to plasma osmolality?

A solution is considered hypertonic when it has a higher osmolality compared to plasma, leading to an osmotic effect that pulls water out of cells and into the extracellular space. In this case, D5 0.45 NS (5% dextrose in 0.45% saline) is commonly recognized as a hypertonic solution.

This solution provides both glucose and sodium chloride, and the addition of dextrose increases its osmolality compared to normal plasma. The 0.45% saline, which is less concentrated in terms of sodium compared to normal saline, still plays a role in drawing water from cells into the bloodstream when administered, especially in a context where the dextrose metabolizes quickly, leading to a higher overall solute concentration.

On the other hand, the other options like D5W (dextrose in water) and Ringer's lactate do not meet the criteria for being hypertonic. D5W is isotonic initially but becomes hypotonic once the dextrose is metabolized, as it does not contribute to the solute concentration in the plasma. Ringer's lactate is designed to be isotonic and closely resembles plasma composition, thus maintaining the osmolality