Page 69 - Journal of Special Operations Medicine - Winter 2015

Figure 3 The average absorption coefficients for each fabric be able to control hemorrhage for 14–15 patients. The
after the initial, secondary, and tertiary trials. The absorption equivalent mass of rayon is nearly twice as effective as
coefficient represents grams of whole bovine blood absorbed cotton on both initial and repeated uses and takes up
per gram of given fabric. Ray-Polypro, rayon–polypropylene. three-quarters the amount of space.

Rayon lap pads and surgical sponges are not a new con-
cept and patents for rayon-based sponges date back to
the 1970s. The benefits of rayon over cotton—decreased
7
lint, leading to fewer adhesions and microgranulomas;
and better absorptive properties—have been described
in surgical literature dating back to the 1940s. Rayon
8,9
is a natural, regenerated cellulose fiber made from wood
pulp and has been referred to as artificial silk, bamboo
silk, bamboo cotton, or artificial cotton. Although it
is manmade, it is entirely natural and biodegradable,
Table 3 Densities of the Four Fabrics and can be easily sterilized. Since its invention in the
mid 1800s, it has been a strong competitor of cotton in
Fabric Fabric Density, g/cm3 many fields, but mostly in the clothing industry. A major
Cotton 0.087 advantage of rayon over cotton, besides those demon-
Rayon 0.12 strated in this study, is cost. Rayon is cheaper than cot-
ton by $1.65 per yard, enough to cause major shifts in
Rayon–polypropylene 0.098
marketplace and textile economics. 10
Microfiber 0.093
Although rayon has existed for hundreds of years, it has
In established operating rooms around the world, the some limitations. Because of the way rayon is manu-
storage and procurement of lap pads are not issues. factured, the strands that compose the fabric are not as
When a small team or solo provider is forced to bring long as cotton strands. Thus, rayon has a much lower
their medical supplies with them, multiple new prob- tensile strength than cotton. Rayon lap pads are sold
lems arise. The austere or remote provider must now both with and without cotton mesh nettings and, based
consider the weight, ease of procurement, and ease of on our search for these products, seem to be more popu-
storage of every item of equipment. They must also look lar in Eastern countries.
for items that can serve multiple uses or be safely reused
or used for longer periods of time. This study demon-
strates that 100% rayon and rayon composite materi-
als offer potential alternatives to traditional lap pads in Figure 4 “Low-lint” rayon
the remote and austere environment by maximizing the laparotomy sponges.
ability to absorb blood and control hemorrhage, while
decreasing the space needed to carry such supplies.

The benefit of rayon-based laparotomy sponges over
cotton can be seen in the following example. Based on
our research, a 30cm brick of cotton (about 125 lap Rayon has been shown to have significantly lower levels
3
pads) would weigh 2.35kg and be able to absorb 17.29L of lint than cotton and to cause a much lower level of
of blood on initial use and 3.95L of blood for each use inflammation. The adhesive properties of cotton have
afterwards. An equivalent mass of rayon (2.35kg) would been well described and have led to the disuse of many
be a brick roughly 27cm (about 28 extra-large sheets; cotton surgical devices, such as cotton sutures. 11,12 Be-
3
about three-quarters the size of the cotton brick) and cause of their the lower potential to cause inflammation
absorb 29.57L of blood on initial use and 6.4L of blood and lower “lint emboli,” rayon sponges seem to be find-
for each use afterward. ing a niche in specialized surgical fields. 13

A typical scenario that demonstrates the potential Based on our data on cotton’s density and its absorp-
benefits of rayon is nonobtunded patients with class tive properties, one can calculate the amount of cotton
3 shock and averaging 2L of blood loss, excluding ex- needed to care for eight surgical casualties with class 3
tremity wounds. The aforementioned 125 cotton lap hemorrhage. For example, our data indicate 2,111g of
pads would be able to evacuate hemorrhage for eight or cotton would be needed to absorb about 16L of blood.
nine patients, while the equivalent mass of rayon would With our measured weight of roughly 18–20g per lap

Alternatives to Cotton Laparotomy Sponges 57