The ABL Calculator serves as a pivotal resource for healthcare practitioners involved in surgical procedures. It calculates the allowable blood loss based on the patient’s blood volume and hematocrit levels. This information aids medical professionals in determining the maximum blood loss a patient can endure during surgery while maintaining stable health.
Formula of Allowable Blood Loss Calculator
The formula for the Allowable Blood Loss (ABL) is calculated using the following equation:
ABL = (BV * (Hct – Min Hct)) / Hct
Variables:
- ABL (Allowable Blood Loss): The safe amount of blood a patient can lose.
- BV (Blood Volume): Typically around 70 mL/kg for adults.
- Hct (Initial Hematocrit): The patient’s initial hematocrit value, expressed as a decimal (e.g., 0.42 for 42%).
- MinHct (Minimum Acceptable Hematocrit): The minimum acceptable hematocrit value, expressed as a decimal (e.g., 0.30 for 30%).
Blood Volume for Different Age Groups:
- Adults (aged 18-65): BV = Weight (kg) * 70 mL/kg (males) or 65 mL/kg (females)
- Children (aged 1-17): BV = Weight (kg) * 80 mL/kg
- Infants (under 1 year old): BV = Weight (kg) * 85 mL/kg
General Terms Table
| Term | Definition |
|---|---|
| ABL | Allowable Blood Loss, the safe amount of blood a patient can lose |
| BV | Blood Volume |
| Hct | Initial Hematocrit |
| MinHct | Minimum Acceptable Hematocrit |
| mL | Milliliters |
| kg | Kilograms |
Example of Allowable Blood Loss Calculator
Walk through a practical example of using the ABL Calculator.
- Input Values:
- Patient’s Weight: 70 kg
- Initial Hematocrit (Hct): 0.38
- Minimum Acceptable Hematocrit (Min Hct): 0.32
ABL = (70 * (0.38 – 0.32)) / 0.38
Allowable Blood Loss (ABL) ≈ 9.47 mL
Most Common FAQs
Blood volume for adults is calculated based on weight and gender-specific values.
Initial hematocrit is crucial as it reflects the baseline concentration of red blood cells.
ABL calculation guides medical professionals in ensuring patient safety by limiting permissible blood loss.