When a person is dehydrated, his or her IV fluids
are not necessary, since a dehydrated person would not require IV fluids.
should be isotonic, because either a hypertonic or hypotonic IV would damage red blood cells.
should be hypertonic, because if dehydrated, he or she probably needs salt as well.
should be hypotonic, because if dehydrated, he or she needs as much water as possible.
The correct answer and explanation is:
Correct Answer:
Should be isotonic, because either a hypertonic or hypotonic IV would damage red blood cells.
Explanation:
When a person is dehydrated, the choice of IV fluid is critical to restore fluid balance without causing harm. Isotonic IV fluids, such as normal saline (0.9% sodium chloride) or lactated Ringer’s solution, are commonly used for rehydration because they closely match the osmolarity of blood plasma. Here’s why isotonic fluids are the safest option:
- Cellular Integrity:
Blood plasma has a certain osmolarity, and isotonic fluids are designed to match this. When isotonic fluids are administered, there is no significant net movement of water into or out of cells. This prevents red blood cells and other tissues from swelling (in a hypotonic environment) or shrinking (in a hypertonic environment), maintaining cellular integrity and function. - Restoring Fluid Volume:
Dehydration typically involves a loss of water and electrolytes. Isotonic fluids help replenish both, effectively increasing blood volume and restoring perfusion to tissues without altering the electrolyte balance drastically. - Avoiding Complications from Hypertonic or Hypotonic Fluids:
- Hypertonic fluids (e.g., solutions with higher solute concentrations) can cause water to move out of cells into the bloodstream, potentially leading to cell shrinkage and damage, particularly to red blood cells and neurons.
- Hypotonic fluids (e.g., pure water or half-normal saline) can cause water to rush into cells, risking cell swelling, lysis (bursting), and complications like cerebral edema.
- Clinical Practice:
In medical settings, isotonic fluids are the first-line choice for rehydrating dehydrated individuals unless there are specific conditions (e.g., hypernatremia, hyponatremia) requiring tailored solutions. The aim is to restore fluid balance safely without disrupting normal physiological processes.
In summary, isotonic IV fluids provide a balanced approach, ensuring effective hydration while protecting red blood cells and tissues from osmotic damage.