maximum_allowable_blood_loss: Maximum Allowable Blood Loss (ABL) without Transfusion

In cliot: Clinical Indices and Outcomes Tools

Maximum Allowable Blood Loss (ABL) without Transfusion

Description

Calculates the Maximum Allowable Blood Loss (ABL) for a patient before a red blood cell transfusion is theoretically required. The calculation estimates the patient's total blood volume (EBV) based on weight and age/sex, then uses the Bourke and Smith formula involving the initial and target hematocrit levels.

Usage

maximum_allowable_blood_loss(weight_kg, initial_hct, target_hct, patient_type)

Arguments

weight_kg	Numeric. Patient weight in kilograms.
initial_hct	Numeric. The patient's starting hematocrit percentage (e.g., 45).
target_hct	Numeric. The minimum acceptable hematocrit percentage (e.g., 30).
patient_type	String. The category of the patient used to estimate blood volume (mL/kg). Options: "premature" (95 mL/kg) "neonate" (85 mL/kg) "infant" (80 mL/kg) "child" (75 mL/kg) "adult_male" (75 mL/kg) "adult_female" (65 mL/kg)

Value

A list containing:

Allowable_Blood_Loss_mL	The estimated volume of blood loss permitted to reach the target hematocrit.
Estimated_Blood_Volume_mL	The total estimated blood volume of the patient.

References

Bourke DL, Smith TC. Estimating allowable hemodilution. Anesthesiology. 1974;41(6):609-612. doi:10.1097/00000542-197412000-00013

Examples

# Example 1: Adult Male
# 80kg, Starting Hct 45, Target 30
# EBV = 80 * 75 = 6000 mL
# ABL = 6000 * (45-30) / ((45+30)/2) = 6000 * 15 / 37.5 = 2400 mL
maximum_allowable_blood_loss(80, 45, 30, "adult_male")

# Example 2: Infant
# 8kg, Starting Hct 38, Target 28
# EBV = 8 * 80 = 640 mL
# ABL = 640 * (38-28) / ((38+28)/2) = 640 * 10 / 33 = 194 mL
maximum_allowable_blood_loss(8, 38, 28, "infant")

cliot documentation built on Dec. 1, 2025, 1:06 a.m.