Which among the following is a colloid solution?

Appeared in: AIIMS Patna NO - 2020

Explanation

Colloid solutions contain large molecules that remain in the intravascular space, increasing oncotic pressure and expanding plasma volume.
Dextran is a synthetic colloid, a polysaccharide that acts as a plasma volume expander.
It is used to treat hypovolemia, particularly in early shock, to increase blood pressure and cardiac output.
Unlike crystalloids, the large molecules in Dextran do not easily pass through capillary membranes.

Option A: 9% normal saline is an isotonic crystalloid solution. Its small electrolyte molecules (Na+ and Cl-) pass freely between the intravascular and interstitial spaces, so it does not exclusively expand plasma volume.
Option C: 45% normal saline is a hypotonic crystalloid solution. It provides more free water than electrolytes and causes fluid to shift from the bloodstream into the cells.
Option D: 25% dextrose is a hypertonic crystalloid solution. The dextrose is quickly metabolized, leaving free water. It is primarily a source of calories and free water, not a volume expander.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of Intravenous (IV) Fluids (Colloids vs. Crystalloids) as background academic context rather than a clinical decision trigger.
Nurses must understand the difference between colloids and crystalloids to administer IV fluids safely. Using a colloid when a crystalloid is needed (or vice-versa) can lead to fluid shifts and complications like pulmonary edema or cellular dehydration.
When administering colloids like Dextran, nurses must monitor for signs of fluid volume overload (e.g., crackles in the lungs, shortness of breath, jugular vein distention) and for potential allergic reactions.
Dextran can interfere with blood cross-matching and coagulation tests by coating platelets. The lab should be notified if a patient is receiving Dextran.

How to Approach the Question

First, identify the core question. The question asks to identify a 'colloid solution'.
Recall the definitions of the two main types of IV fluids: crystalloids and colloids.
Crystalloids contain small molecules (electrolytes, glucose) that pass easily through capillary membranes.
Colloids contain large molecules (proteins, starches) that stay in the blood vessels and act as plasma expanders.
Evaluate each option against these definitions.
9% and 0.45% saline are salt solutions (crystalloids). 25% dextrose is a sugar solution (crystalloid). Dextran is a known large-molecule plasma expander (colloid).

Concept Tested & Keywords

Concept Tested: Classification of Intravenous (IV) Fluids (Colloids vs. Crystalloids)
Stem keywords: colloid solution, intravenous fluids
Lead-in keywords: Which among the following
Negative lead-in flag: false

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