Page 67 - Journal of Special Operations Medicine - Winter 2015

the large amount of liquid and clotted blood is removed.
Laparotomy pads are bulky and the amount needed to
effectively prepare for multiple hemorrhaging patients Figure 2 The 100%
can be substantial. According to one study by Cichon et rayon “chamoix”
al. that evaluated blunt trauma patients requiring sur- used in our
gical intervention, the average amount of blood found experiment.
within the peritoneal cavity was 4,500mL. The lapa-
3
rotomy pads required to absorb this amount of blood
would be excessive for the provider attempting to bring
equipment with them. Advanced Trauma Life Support
doctrine holds that an average range of 750–2,000mL
4
of blood is lost either on scene or within a target body A zeroed scale with an attached receptacle was used
cavity when class 1–3 shock has occurred. While the to contain any blood spilled during the weighing pro-
5
weight of the necessary laparotomy pads may not be cess. The fabric samples in each of the four groups were
a significant burden, the space necessary to carry this weighed to obtain dry initial weights. It was not neces-
much cotton is. Providers would need to devote an sary to have all initial fabrics weigh the same, because
entire bag or large portion of a rucksack just to carry the absorption coefficients we calculated are natural
enough cotton laparotomy pads. This limits any addi- properties specific to each fabric. Regardless of the start-
tional equipment they can bring into the field. ing weights, the coefficient will always be identical and
is expressed in grams of blood absorbed by 1g of fabric.
Our objective was to evaluate alternative materials to
traditional laparotomy pads and test not only their abil- Absorbance Coefficient
ity to absorb blood but also their occupation of space. The absorbance coefficient (ACo) is defined as the
The hope was to find a fabric with similar or superior amount of target fluid that 1g of target fabric is able to
absorption to cotton that also occupies less space. This absorb. The ACo for each fabric is different when the
would allow the forward provider to provide the same fluid being absorbed is changed (i.e., a given fabric has
or improved care with less equipment. a different ACo for each type of fluid). This is due to
intrinsic properties of both the fabric and fluid, such as
the charge of the fluid and material, porosity of the ma-
Methods terial, and particular content of the fluid. This measure-
ment is used by industry to measure and compare the
Model Development ability of fabrics to absorb fluids. This coefficient is also
This study was reviewed by and approved by our in- referred to absorbance capacity and is calculated using
6
stitutional review board. Fresh whole bovine blood the following equation: [(wet weight of material used)
was obtained during euthanasia procedures that were − (dry weight of material used)]/dry weight of material
performed for food processing; thus, no animals were used = absorbance capacity. This coefficient allows for
harmed for the sole purpose of collecting blood. Three side-by-side comparison of materials and their ability to
gallons of fresh whole bovine blood was collected and absorb given fluids.
combined with 500mL of normal saline and 25,000
units of heparin. Study
The fabric samples were saturated in whole blood by
Five untested samples were obtained for each of the fol- submerging the fabric for a total of 30 seconds; each
lowing fabrics: 100% woven cotton laparotomy pads was swirled five times, squeezed, and released five times,
(lap pads) (Figure 1); 100% rayon chamoix (Figure and shaken while submerged five times. The fabrics were
2); rayon–polypropylene chamoix; and 20/80 nylon– then removed from the whole blood and immediately
polyester composite towels (microfiber towels). transferred to the receptacle on the scale to obtain an ini-
tial wet weight. The fabrics where then manually wrung
dry until no more blood could be expressed. The fabrics
were then placed back on the scale to obtain a secondary
dry weight. They were then replaced in the whole blood
and saturated using the same technique, to obtain sec-
Figure 1 Cotton laparotomy
sponges currently used in most ondary dry and wet weights. This process was repeated a
operating rooms. third time to obtain tertiary dry and wet weights.

The equation given above was used to calculate the ACos
for each of the five samples of fabrics for the four fabrics

Alternatives to Cotton Laparotomy Sponges 55