Landsfeld et al used an equation for estimating blood loss in the Bleeding Severity Index.
amount of blood loss in units of blood =
= (number of units transfused) + (((hematocrit initial in percent) – (hematocrit after in percent)) / 3) – ((estimated surgical blood loss in mL) / 400)
• The original equation had the hematocrit divided by 0.03, which would mean that the hematocrits would be as decimal fractions.
• Dividing the hematocrit by 3 (preferably 2.941) gives the hemoglobin in g/dL.
• As a rough rule of thumb, 1 unit of blood will raise the hemoglobin by 1 g/dL.
• The 400 factor is an estimate for the volume of 1 unit whole blood. 1 unit of whole blood may vary in volume from 405 – 495 ml (AABB Technical Manual).
Blood Loss in Units
>= 3 units
2 to < 3 units
1 to < 2 units
• Categories for minimal and massive blood loss could probably also be defined.
• The hematocrit would be affected by hemoconcentration and hemodilution.
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Purpose: To estimate the volume of blood loss experienced by a patient using the equation used in the Bleeding Severity Index.
Specialty: Clinical Laboratory, Surgery, general, Anesthesiology, Emergency Medicine, Critical Care
Objective: severity, prognosis, stage, complications
ICD-10: D62, T79-T79, Z51.3,