Allowable Blood Loss (ABL)
Info
Group Premature neonate Newborn-6 months 6 mos-2 yrs 2 yrs-Adult Adult male Adult female
Weight
unit lbs Kgs
Initial Hct
unit % Fraction
Final Lowest acceptable HCT
unit % Fraction
R e s u l t s
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Allowable Blood Loss
 
Estimated Blood Volume
 
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Allowable Blood Loss (ABL)

This is an accurate method of estimating Blood volume and the Allowable Blood Loss before and during a surgery.

Allowable Blood Loss (ABL) is calculated using a modification of the Gross formula:

ABL (ml) = EBV*(Hctin - Hctfi)/[(Hctin+Hctfi)/2)]

  • EBV (Estimated Blood Volume in mL) = Weight(kg)* Average Blood Volume
  • Hctin = Initial Hematocrit (Fraction)
  • Hctfi = Final lowest acceptable Hematocrit (Fraction)

Average Blood Volumes

Age Average blood volume
Premature Neonates 90 mL/kg
Newborn-6 mos 85 mL/kg
6 mos-2 yrs 80 mL/kg
2 yrs-adult 70 mL/kg
Adult male 75 mL/kg
Adult female 65 mL/kg

If the patient is obese, using the Ideal Body Weight will give more accuracy than an actual weight.

Reference:

  1. Bourke DL, Smith TC. Estimating allowable hemodilution. Anesthesiology . 1974;41(6):609-12.
  2. Darrow DC, Soule HC, Buckman TE.. Blood volume in normal infants and children. J Clin . Invest . 1928 Feb;5(2):243-58.
  3. Eipe N, Ponniah M. Perioperative Blood Loss Assessment - How Accurate? Indian J. Anaesth . 2006;50(1):35-8.
  4. Gross JB. Estimating allowable blood loss: corrected for dilution. Anesthesiology . 1983;58(3):277-80.
  5. Guay J, de Moerloose P, Lasne D., et al. Minimizing perioperative blood loss and transfusions in children. Can J Anaesth . 2006;53(6 Suppl):S59-67.