Page 52 - Journal of Special Operations Medicine - Fall 2014

agents had marked effects on the thromboelastographs Schwartz et al. compared ChitoGauze with Combat
4
accelerating the clotting process. In 2011, Watters et al. Gauze in the standard USAISR model and found no sta-
57
also found that chitosan-based Celox Gauze had no ef- tistically significant difference between the ChitoGauze
fect on in vitro TEG clotting parameters compared with and Combat Gauze groups with regard to time to hemo-
control. stasis, resuscitative fluid requirements, blood loss, and
survivability. However, these authors reported strong
trends in all end points in the ChitoGauze group over
Discussion Points
the Combat Gauze group, including mean time to hemo-
Interpreting hemostatic efficacy between injury models stasis (13 minutes vs. 32 minutes) and mean blood loss
can be challenging with animal-based studies. Devlin et following hemostatic dressing application (304mL vs.
37
al. stated that an ideal wound model does not exist be- 796mL). They noted that the differences seen between
58
cause standardizing bleeding wound models is difficult the groups did not achieve statistical significance be-
because of the multiple variables involved (i.e., wound cause of small sample size.
preparation, splenectomy incorporated into the model,
injury mechanism, free bleed duration, agent packing In a caprine (goat) training model, multiple arterial inju-
technique, manual compression duration, frequency ries (50% scalpel transsection) were made (126 injuries
of manual pressure with rebleeding, fluid resuscitation in 45 animals) as part of a TCCC training course. Sev-
variables, and duration of the observation period). Re- eral chitosan-based dressings (HemCon Bandage, Celox

cently, a DoD consensus group accepted a standardized Gauze, ChitoGauze) were tested and compared with
swine hemorrhage wound model (6-mm femoral arte- Combat Gauze. No significant difference was found
riotomy) for topical hemostatic dressings in an effort in hemostasis at 2 and 4 minutes as well as estimated
to decrease the limitations and variability of outcomes volume of post-treatment blood loss. Due to the nature
across these studies. 59 of this study, multiple confounding variables were un-
controlled (location and degree of transsection, baseline
Hemostatic Dressing Efficacy MAP, resuscitation to maintain MAP, etc.); however, the
A DoD-sponsored study by the Naval Medical Re- findings add steady weight and consistent evidence for
search Unit−San Antonio evaluated the largest number the performance of chitosan-based gauze dressings.
8
of hemostatic dressings since the end of the second-gen-
eration phase (April 2008). This study used the DoD- Two studies compared Combat Gauze with chitosan-
6
standardized hemorrhage model for topical hemostatic coated gauze in a “care under fire” (CUF) scenario with
agents. 59 These investigators examined four gauze no compression time using a 6mm femoral arteriotomy
agents in comparison to Combat Gauze. Three of these wound model. These authors compared Combat
57
dressings were chitosan-based gauzes, and one was Gauze and Celox Gauze with standard gauze. No dif-
double-layer Combat Gauze (Combat Gauze XL) with ference was found in post-treatment blood loss or sur-
a higher amount of kaolin than the original product. vival, including the standard gauze arm. In 2013, Kunio
Each gauze group consisted of 10 randomized animals. et al. compared a newer chitosan-based hemostatic
7
For each subject, one of five hemostatic gauzes was gauze, Celox RAPID, with Combat Gauze in the same
used for treatment: Combat Gauze (control), Combat CUF model. All animals survived to study completion.
Gauze XL, Celox Trauma Gauze, Celox Gauze, or Chi- The only significant differences noted were a shorter
toGauze. Direct pressure (3 minutes) was then applied, packing time with Celox RAPID and a decreased post-
and the animals were rapidly resuscitated to achieve and treatment blood loss in comparison. These studies are
maintain a mean arterial pressure (MAP) of 60mmHg more difficult to interpret because all subjects survived
for 150 minutes or until death. Animal survival, he- to study end. It should be mentioned that CUF does not
mostasis, and blood loss were assessed as primary end include treating the wound with any type of hemostatic
points as the dependent measures of efficacy. The study dressing. See Table 3 for a summary of seven animal
found that these FDA-approved hemostatic dressings studies. 1,3,4,6,7,22,57
performed as well as the current TCCC-recommended
agent (Combat Gauze) in terms of hemostasis onset, The U.K. Ministry of Defense selected a third- generation
post-treatment blood loss, and survival. However, in hemostatic dressing (Celox Gauze) for battlefield use by
this model, Celox Gauze (p = .046) and Combat Gauze all British Military Forces with extensive use by their
16
XL (p = .026) outperformed Combat Gauze in achiev- Medical Emergency Response Team (MERT) air evacu-
ing initial 10-minute hemostasis. Furthermore, Celox ation teams. 29,60 See Table 4 for five clinical case series
Gauze and ChitoGauze had higher 150-minute survival with a total of 19 patients in civilian surgical cases and
rates (90% and 70%, respectively) than the 60% rate military combat casualties. 25–29 One NATO military
for Combat Gauze. These differences, however, were service has reported hemostatic dressing effectiveness,
not statistically significant. including two patients with prolonged application of

44 Journal of Special Operations Medicine Volume 14, Edition 3/Fall 2014