Pediatrics

Maintenance Fluids (4-2-1 Rule)

Calculates hourly IV fluid rate using the 4-2-1 rule.

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Parameters

Maintenance Fluids (4-2-1 Rule) Result

Formula

4 mL/kg/hr for the first 10 kg
2 mL/kg/hr for the next 10 kg (11-20 kg)
1 mL/kg/hr for every kg above 20 kg

Clinical Pearls

Ensures patients who are NPO (nil per os) or unable to tolerate oral intake receive adequate daily water and electrolytes to prevent dehydration.

Normal Values / Reference

For adults, maintenance fluids generally cap out around 100-125 mL/hr unless there are ongoing losses.

Limitations

Does not account for resuscitation needs in dehydration, shock, or ongoing abnormal losses (e.g., diarrhea, fistulas, burns). Max rate in adults is usually capped by clinical judgment rather than strictly following the formula for obese patients.