0.45% Saline is an Example of?

Appeared in: AIIMS Delhi NO - 2018

Explanation

45% Saline is classified as a hypotonic solution because its solute concentration (154 mOsm/L) is lower than that of plasma.
When administered intravenously, hypotonic solutions cause water to move from the extracellular space into the intracellular space, causing cells to swell.
This type of solution is used to treat conditions like hypertonic dehydration and to provide free water for the kidneys to excrete metabolic wastes.

Option A: Isotonic solutions have the same solute concentration as body fluids. The standard isotonic saline solution is 0.9% NaCl (Normal Saline).
Option C: Hypertonic solutions have a higher solute concentration than body fluids. Examples include 3% or 5% NaCl.
Option D: Hyperosmotic is a term often used interchangeably with hypertonic. It describes a solution with a higher osmolarity than body fluids, which is the opposite of 0.45% Saline.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Tonicity of IV Fluids as background academic context rather than a clinical decision trigger.
Nurses must understand IV fluid tonicity to prevent complications. Administering a hypotonic solution to a patient with increased intracranial pressure (ICP) is contraindicated because it can worsen cerebral edema by shifting fluid into brain cells.
When administering hypotonic solutions, nurses should monitor for signs of fluid shifts, such as hypotension, cardiovascular collapse, and changes in level of consciousness.
What if the patient had severe hyponatremia? In that case, a hypertonic solution (like 3% Saline) would be administered cautiously to pull fluid out of the swollen brain cells, not a hypotonic solution which would worsen the condition.

How to Approach the Question

First, identify the core concept: the question is asking to classify an IV fluid based on its tonicity.
Recall the benchmark for isotonicity in the body: 0.9% Sodium Chloride (Normal Saline).
Compare the given solution, 0.45% Saline, to the 0.9% benchmark.
Since 0.45% is less than 0.9%, the solution has a lower solute concentration than body fluids.
Conclude that a solution with a lower concentration is defined as 'hypotonic'.
Evaluate the options to find 'Hypotonic solution' as the correct answer.

Concept Tested & Keywords

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

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