A nurse is directed to administer hypotonic intravenous solution to a patient. She should use?

WCL Staff Nurse - 2019

Nursing Foundation

Easy

Appeared in: WCL Staff Nurse - 2019

Explanation

The question asks to identify a hypotonic intravenous solution.
45% NaCl, also known as half-normal saline, is a hypotonic solution.
It has a lower osmolality (approximately 154 mOsm/L) compared to body plasma.
This lower concentration causes a fluid shift from the extracellular space into the intracellular space, hydrating the cells.
It is commonly used to treat cellular dehydration and hypernatremia (high sodium levels).

Option B: 9% NaCl, or Normal Saline, is an isotonic solution. Its osmolality (≈308 mOsm/L) is similar to that of body fluids, so it does not cause a significant fluid shift into the cells. It is used to expand extracellular fluid volume.
Option C: 5% Dextrose in water (D5W) is considered isotonic in the IV bag but has a physiologically hypotonic effect. The body rapidly metabolizes the dextrose, leaving free water that moves into cells. While it has a hypotonic effect, 0.45% NaCl is a true hypotonic solution by its initial composition.
Option D: Dextrose with normal saline (e.g., D5NS, which is 5% Dextrose in 0.9% NaCl) is a hypertonic solution. Its osmolality is significantly higher than that of body fluids, causing water to be pulled out of the cells and into the bloodstream.

Clinical Relevance

Nursing practice connection: Use the key finding related to Classification of Intravenous (IV) Solutions by Tonicity to guide bedside assessment, documentation, and the next nursing action.
Administering the correct IV fluid is a critical nursing responsibility. Using the wrong tonicity can lead to serious complications.
Hypotonic solutions are used to treat conditions like diabetic ketoacidosis (DKA) and hypernatremia, where cells are dehydrated.
A critical safety consideration is that hypotonic solutions should NEVER be given to patients with, or at risk for, increased intracranial pressure (e.g., head trauma, stroke). The fluid shift into brain cells can cause cerebral edema, which can be fatal.

How to Approach the Question

First, identify the key term in the question: 'hypotonic'. This tells you the question is about the classification of IV fluids.
Recall the three main types of IV solutions: hypotonic, isotonic, and hypertonic.
Mentally review the common examples for each category.
Analyze each option: 0.45% NaCl is 'half-normal saline', a classic hypotonic solution. 0.9% NaCl is 'normal saline', the standard isotonic solution. Dextrose solutions can be tricky; remember that D5W becomes hypotonic in the body. A combination like D5NS is hypertonic.
Select the option that is directly classified as hypotonic by its composition, which is 0.45% NaCl.

Concept Tested & Keywords

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