Maintenance Fluid Calculator (4-2-1 Rule)
4-2-1 Rule (Holliday-Segar)
Formula
First 10 kg: 4 mL/kg/hr | Next 10 kg: 2 mL/kg/hr | Each kg > 20: 1 mL/kg/hr
Frequently Asked Questions
What is the 4-2-1 rule?
The 4-2-1 rule calculates hourly maintenance fluids: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, 1 mL/kg/hr for each kg above 20.
What fluid type is used?
Common choices include D5 0.45% NS for adults and D5 0.2-0.45% NS for pediatrics with KCl. Individualize based on labs and condition.
When should fluids be adjusted?
Adjust for fever (+10% per degree C above 37), burns, surgical losses, renal failure, and heart failure.
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