Estimating Blood Loss from 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.