All of these fluids are isotonic except
**Core Concept**
Isotonic fluids have the same osmotic pressure as blood and do not cause a shift in water balance between the intravascular space and the cells. This is crucial in fluid resuscitation, as isotonic fluids do not affect the concentration of solutes in the blood.
**Why the Correct Answer is Right**
The correct answer is an isotonic fluid, which means it has an osmotic pressure equal to that of blood (approximately 300 mOsm/L). This is achieved by having a solute concentration similar to that of blood, such as sodium chloride (0.9% NaCl). When administered, isotonic fluids do not cause a significant shift in water balance, making them ideal for fluid resuscitation and maintenance.
**Why Each Wrong Option is Incorrect**
**Option A:** Hypotonic fluids have a lower osmotic pressure than blood, causing water to shift from the intravascular space into the cells. This can lead to cellular edema and potentially life-threatening complications.
**Option B:** Hypertonic fluids have a higher osmotic pressure than blood, causing water to shift from the cells into the intravascular space. This can lead to cellular dehydration and potentially life-threatening complications.
**Option C:** The correct option is not specified, but typically, isotonic fluids like 0.9% NaCl are isotonic, whereas other fluids like 5% dextrose are hypotonic.
**Clinical Pearl / High-Yield Fact**
When administering fluids, it's essential to consider the osmotic pressure and the potential effects on the patient's water balance. Isotonic fluids are generally the safest choice for fluid resuscitation and maintenance.
**Correct Answer:** A. Hypotonic fluids have a lower osmotic pressure than blood, causing water to shift from the intravascular space into the cells.