### Description

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

 Size Area in square cm Size Volume Volume to Area Ratio 4 by 7 inches 181 small 300 mL 1.66 7.5 by 8 inches 387 medium 750 mL 1.94 11.75 by 11.75 in 891 large 1,000 mL 1.12 18 x 22 in 2,116 abdomen 2,500 mL 1.18

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.