Fluids & Blood Loss
Recomputed from the patient strip above.
Maintenance
Holliday-Segar 4-2-1, with the NICE adult daily range alongside.
Set weight above
Set weight above
Set weight above
Holliday & Segar, Pediatrics 1957;19:823 — 100/50/20 ml/kg/day, hourly as 4-2-1. A paediatric rule, not an adult prescription.
NICE CG174, 2013 (updated 2017) — routine maintenance 25–30 ml/kg/day water, ~1 mmol/kg/day each of Na⁺, K⁺ and Cl⁻, 50–100 g/day glucose; ideal body weight in obesity; 20–25 ml/kg/day in the older, frail, or in renal or cardiac failure.
Fasting deficit
Set weight above and enter fasting hours
Each hour = share of deficit + one hour of maintenance
Furman et al, Anesthesiology 1975;42:187.
A calculation, not a measurement: Jacob et al, Acta Anaesthesiol Scand 2008;52:522 found blood volume normal after an overnight fast, and clear fluids are permitted to 2 h (ASA fasting guidelines, Anesthesiology 2023;138:132).
Estimated blood volume
Set age and sex above to select a band, or tap one to override. Preterm is never inferred.
Set weight above and select an age band
University of Iowa Head and Neck Protocols, Maximum Allowable Blood Loss (preterm 90–100, term neonate 80–90, infant 70–80, child 70–75, adult 65–70 ml/kg) · OpenAnesthesia, Maximum Allowable Blood Loss (12–18 yr 70, adult male 75, adult female 65 ml/kg). Each band spans both sources; results carry the spread through.
Obesity correction: Lemmens, Bernstein & Brodsky, Obesity Surgery 2006;16:773 — indexed TBV = 70 ÷ √(BMI ÷ 22) ml/kg, anchored on 70 ml/kg at BMI 22. OpenAnesthesia gives 45–60 ml/kg for the obese adult.
Allowable blood loss
A planning estimate, not a transfusion instruction.
Enter both in the same unit — the formula is a ratio (Hct % ≈ 3 × Hb g/dl).
Set weight, band and both values
Set weight, band and both values
Uncorrected: ABL = EBV × (H0 − Ht) ÷ H0. Gross, Anesthesiology 1983;58:277 substitutes the average haematocrit Hav = (H0 + Ht) ÷ 2, giving the larger figure.