Fundamentals of Critical Care Nursing (FCCN) Level 1 Practice Exam 2026 - Free FCCN Practice Questions and Study Guide

A hypertonic fluid is one that has a higher osmolarity than the fluid in the cells, causing water to move out of the cells and into the extracellular space. This can lead to cellular shrinkage.

In the case of 3% NaCl, this solution contains a significantly higher concentration of sodium chloride compared to normal blood plasma. Normal saline (0.9% NaCl) is isotonic, meaning it has the same osmolarity as blood plasma. D5 .45NS is a hypotonic solution since it has a lower osmolarity than plasma due to the dilution from the water in the dextrose and the lower concentration of sodium. Ringer's lactate, like normal saline, is also considered isotonic.

Therefore, 3% NaCl is classified as hypertonic because it effectively draws water out of cells, making it useful in specific clinical situations such as treating hyponatremia or cerebral edema. Understanding the osmotic effects of intravenous fluids is crucial for managing fluid and electrolyte imbalances in critically ill patients.