5% dextrose in water is ___ solution?

Appeared in: HPSSC Staff Nurse - 2021

Explanation

5% Dextrose in Water (D5W) is classified as an isotonic solution based on its osmolarity in the IV bag, which is similar to that of blood plasma.
Although isotonic initially, it is known as a 'physiologically hypotonic' solution.
Once administered, the dextrose is rapidly metabolized by the body's cells.
This process leaves behind free water, which has a hypotonic effect, causing fluid to shift from the bloodstream into the cells.

Option A: This describes the solution's effect after it is administered and the dextrose is metabolized, not its initial state in the IV bag.
Option C: Colloid solutions contain large molecules like albumin or starches that do not easily pass through cell membranes and are used as volume expanders. D5W is a crystalloid solution, containing small molecules (dextrose and water).
Option D: Hypertonic solutions have a higher concentration of solutes than blood, causing water to move out of cells. D5W's initial concentration is similar to blood, not higher.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of intravenous (IV) solutions, specifically the properties of 5% Dextrose in Water (D5W) as background academic context rather than a clinical decision trigger.
Understanding the dual isotonic/hypotonic nature of D5W is critical for patient safety. Administering it to the wrong patient can have severe consequences.
D5W is contraindicated in patients with increased intracranial pressure (ICP), such as those with head injuries or neurosurgery, because its hypotonic effect can increase cerebral edema and worsen the patient's condition.
D5W is not used for fluid volume resuscitation (e.g., in hypovolemic shock) because it does not remain in the intravascular space and fails to adequately increase blood pressure.

How to Approach the Question

Identify that the question is asking for the classification of a specific intravenous (IV) fluid.
Recall the three main classifications of IV fluids based on their tonicity compared to blood: isotonic, hypotonic, and hypertonic.
Recognize that 5% Dextrose in Water (D5W) is a unique case that is often tested.
Remember that D5W is classified as 'isotonic' based on its composition in the IV bag.
Also, recall its physiological action: it becomes 'hypotonic' in the body once the dextrose is metabolized.
Since the question asks what the solution is, the most accurate primary classification is isotonic. Select this option while being aware of its physiological effect.

Concept Tested & Keywords

Concept Tested: Classification of intravenous (IV) solutions, specifically the properties of 5% Dextrose in Water (D5W).
Stem keywords: 5% dextrose in water, D5W, solution
Lead-in keywords: is

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E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 142-144

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 68-70

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Attempt every question from this paper in a timed mock, then review the full solution for each one.