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Overview :
The amount of blood lost following trauma can be estimated
from the amount of blood in field dressings.
Approaches:
(1) size of the blood stain
(2) weight of the dressing before and after removal
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Size
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Area in square cm
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Size
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Volume
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Volume to Area Ratio
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4 by 7 inches
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181
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small
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300 mL
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1.66
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7.5 by 8 inches
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387
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medium
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750 mL
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1.94
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11.75 by 11.75 in
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891
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large
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1,000 mL
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1.12
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18 x 22 in
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2,116
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abdomen
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2,500 mL
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1.18
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from Emergency War Surgery pg 6.6
where:
• One issue
affecting this table is the thickness of the field dressing. Most military
dressings are relatively thick compared to the standard piece of gauze. The
ratios in the table above could be explained by a thickness in the dressings.
There are 2 ways to use this data:
(1) fit a line to the data
(2) classify a wound based on size and then use a proportion
from the table above
A line fit to the data with MINITAB:
volume of blood in mL =
= (0.000118 * ((area in square cm)^2)) + (0.807 * (area in
square cm)) + 254.9
To use the proportionate method:
volume of blood in mL =
= (area of wound) / (area from reference table) * (volume in
reference table)
If there is a means of weighing the dressing, then the
weight before and after use can be used to estimate blood loss.
weight of blood in a dressing in grams =
= (weight after removal) - (weight before application)
volume of blood loss in mL =
= (weight of blood in dressing in grams) / 1.06
where:
• 1.06 is the density of whole blood.
• It is assumed that weight is due only to blood and not
environmental water or debris.
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