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

Step 1: Read what the numbers are telling us.
The raised blood urea of 60 mg/dl points to reduced kidney blood flow from volume loss, which is called prerenal azotemia. A pH of 7.27 with a base excess of -10 mEq/L shows a clear metabolic acidosis, caused here by loss of bicarbonate rich fluid in diarrhea and by poor tissue perfusion. The sodium of 134 mEq/L is only mildly low, and potassium at 3.8 mEq/L is close to normal. Together these values describe a child in severe dehydration with early circulatory compromise, not just simple fluid loss.

Step 2: Recall the two stages of fluid therapy in severe dehydration.
When dehydration is severe, the first goal is to restore the circulating blood volume quickly and safely. Only once the child is stable do we move to slower maintenance and deficit replacement using more dilute, potassium containing fluids. Using a maintenance type fluid too early does not correct the volume deficit fast enough.

Step 3: Match this to the initial resuscitation fluid.
Normal saline is isotonic, meaning it stays inside the blood vessels and expands the circulating volume efficiently. Adding 5% dextrose supplies calories and prevents hypoglycemia, which is common in a sick, poorly feeding child. This combination corrects the volume deficit and supports perfusion, which in turn improves the metabolic acidosis as tissue oxygen delivery gets better.

Step 4: Explain why the N/3 saline options are wrong.
N/3 saline is one third the strength of normal saline, so it is hypotonic and much of it will move out of the blood vessels into the cells rather than staying in circulation. This makes it too weak to correct severe volume depletion quickly, and it is really a maintenance fluid, not a resuscitation fluid. The 10% dextrose version adds even less benefit for volume correction and is not the standard maintenance strength used in this setting either.

Step 5: Explain why 3% saline is wrong.
3% saline is a hypertonic solution reserved for severe, symptomatic low sodium, usually below about 120 mEq/L with seizures or altered mental state. Here the sodium is only mildly reduced at 134 mEq/L, so hypertonic saline is not indicated and could even cause a harmful and rapid shift in sodium levels.

Step 6: Final answer.
The most appropriate initial fluid for this severely dehydrated child is normal saline with 5% dextrose. \[ \boxed{\text{Normal saline with 5% dextrose}} \]