Question

A patient is admitted to the hospital and given intravenous (IV) fluids. Four hours later, the patient complains that his mouth and eyes feel dry. You notice that he displays signs of dehydration, and when you check his IV, you see that he was given the wrong kind of fluids. Were these fluids likely hypotonic, isotonic, or hypertonic? Explain.

Accepted Answer

Step 1: Understand the definitions of hypotonic, isotonic, and hypertonic solutions. Hypotonic solutions have a lower solute concentration than the cells, causing water to move into the cells. Isotonic solutions have the same solute concentration as the cells, maintaining equilibrium. Hypertonic solutions have a higher solute concentration than the cells, causing water to move out of the cells. Step 2: Analyze the symptoms of the patient. Dry mouth and eyes, along with signs of dehydration, suggest that water has been drawn out of the cells, leading to a loss of intracellular fluid. Step 3: Relate the symptoms to the type of IV fluid. If water is moving out of the cells, the IV fluid is likely hypertonic, as hypertonic solutions create an osmotic gradient that pulls water out of the cells into the extracellular space. Step 4: Consider the physiological effects of hypertonic fluids. Hypertonic fluids increase the osmolarity of the extracellular fluid, which can lead to dehydration symptoms as water leaves the cells to balance the solute concentration. Step 5: Conclude that the IV fluids given to the patient were likely hypertonic, as they caused water to move out of the cells, leading to dehydration symptoms such as dry mouth and eyes.

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Key Concepts

Fluid Tonicity

Dehydration Signs

IV Fluid Types