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Fluid Management Calculator

Maintenance Fluid Calculator

Holliday-Segar 4-2-1 rule with age-adjusted and condition-specific modifications. Paediatric, adult, elderly, CKD, heart failure, liver disease, sepsis, PE/ARDS.

Patient Details
⚠️ This calculator provides a starting estimate only. Always prescribe IV fluids after full clinical assessment including fluid balance, electrolytes, and renal/cardiac function. NICE CG174 applies.
Fluid Requirement
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Enter weight and select condition to calculate

Maintenance Fluids: The Complete Clinical Guide

4-2-1 rule, age adjustments, and condition-specific fluid management across 14 clinical scenarios

The 4-2-1 Rule (Holliday-Segar)

The Holliday-Segar formula (1957) provides a weight-based method for estimating daily and hourly maintenance fluid requirements. It was derived from metabolic rate data in children and estimates insensible losses plus obligatory renal output. It remains the standard starting point for maintenance fluid calculation across all ages — but must always be modified for clinical context, age, and organ function.

4-2-1 Rule (Hourly Rate)
4 mL/kg/hr for first 10 kg
+ 2 mL/kg/hr for next 10 kg (11–20 kg)
+ 1 mL/kg/hr for each kg above 20 kg
Multiply by 24 for daily volume

Why Age Matters — The Elderly Patient

The Holliday-Segar formula was derived in children and young adults. Elderly patients have significantly reduced total body water (TBW), declining renal concentrating ability (GFR falls ~1 mL/min/1.73m² per year after age 40), reduced cardiac reserve, and polypharmacy interactions. Standard maintenance volumes routinely cause iatrogenic fluid overload in patients over 75. This calculator applies age-based reductions of 15–35% for elderly patients based on published physiological data.

Condition-Specific Modifications

ConditionModifierKey Principle
Standard×1.0Full 4-2-1 rate
Fever+10% per °CIncreased insensible losses
HF Mild×0.75Total fluids ≤1.5–2 L/day
HF Decompensated×0.50Diuresis target, not fluids
CKD Stage 3×0.90Avoid volume depletion + K+ care
CKD Stage 4×0.80Nephrology input required
ESRD/Dialysis×0.60Max 1 L inter-dialytic
Cirrhosis + Ascites×0.70Avoid Na loads; use albumin
Sepsis×1.0*Resuscitation first, then conservative
ARDS/Pulm Oedema×0.70Conservative strategy (FACTT)

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References

  1. Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832.
  2. NICE CG174. Intravenous fluid therapy in children and young people in hospital. 2015, reviewed 2023.
  3. Evans L et al. Surviving Sepsis Campaign: International Guidelines 2021. Intensive Care Med. 2021.
  4. National Heart, Lung and Blood Institute ARDS Clinical Trials Network (FACTT). N Engl J Med. 2006;354:2564-2575.
  5. Semler MW et al. Balanced Crystalloids versus Saline in Critically Ill Adults (SMART). N Engl J Med. 2018;378:829-839.
  6. Meyhoff TS et al. Restriction of IV Fluid in ICU Patients with Septic Shock (CLASSIC). N Engl J Med. 2022;386:2459-2470.
  7. KDIGO AKI Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012.
  8. KDIGO CKD Work Group. KDIGO 2024 Clinical Practice Guideline for CKD. Kidney Int. 2024.
  9. McDonagh TA et al. ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42:3599-3726.
  10. Spasovski G et al. Clinical practice guideline on hyponatraemia. Eur J Endocrinol. 2014;170:G1-G47.
  11. Kanbay M et al. IV fluid therapy in accordance with kidney injury risk. Clin Kidney J. 2023;16(4):684-692.

⚠️ Medical Disclaimer: This calculator provides an estimated starting point only. IV fluid prescribing requires full clinical assessment of volume status, organ function, electrolytes, and clinical context. This tool does not replace clinical judgement. MedDraftPro accepts no clinical liability.

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