Question

A 3-year old child develops severe dehydration following acute gastroenteritis. Investigations show blood urea 60mg/dl, pH 7.27, base excess -10 mEq/L, sodium 134 Eq/L and potassium 3.8 mEq/L. The most appropriate fluid for initial treatment of this child is

• A. N/3 saline in 5% dextrose
• B. N/3 saline in 10% dextrose
• C. Normal saline with 5% dextrose
• D. 3% saline

Hint:

Severe dehydration with acidosis first needs a fluid that stays in the blood vessels and restores volume quickly.

Answer 1

The Correct Option is C

This child has severe dehydration from gastroenteritis, with a raised blood urea, a clear metabolic acidosis, and only mildly low sodium. The question is which fluid to start with.

1. N/3 saline in 5% dextrose: This is a hypotonic maintenance fluid. In severe dehydration the priority is to expand blood volume fast, and a fluid this dilute leaks out of the vessels too easily to do that job well.
2. N/3 saline in 10% dextrose: Same problem as above with the sodium strength, and the extra dextrose does not help correct the volume deficit either. Not suited for initial resuscitation.
3. Normal saline with 5% dextrose: Normal saline is isotonic and stays in the blood vessels, which quickly restores circulating volume and improves perfusion. The added dextrose covers calorie needs and guards against low blood sugar in a sick child. This fits the initial resuscitation need.
4. 3% saline: A strong hypertonic fluid used only for dangerously low sodium with symptoms like seizures. This child's sodium of 134 mEq/L is only mildly low, so this fluid is not needed and could cause harm.

Restoring volume with an isotonic fluid comes first in severe dehydration, and normal saline with 5% dextrose does exactly that while also correcting the acidosis indirectly by improving perfusion.

Let's summarize:

• Severe dehydration needs isotonic fluid first, not hypotonic maintenance fluid.
• Hypertonic saline is reserved for severe symptomatic hyponatremia, which is not present here.

So normal saline with 5% dextrose is the correct initial fluid.