Page 55 - Journal of Special Operations Medicine - Fall 2015

therapy was not available. Additionally, because the Figure 5 Delivery system procedural steps. (A) The system is
pain of foam administration cannot be easily assessed, aerated; (B) it is assembled. (C) A mixing nozzle is positioned
casualties should receive receive analgesia and amnesia, within the abdominal cavity. (D) The foam is deployed.
further necessitating airway control. To examine this re-
quirement, we conducted a preclinical study wherein the
foam was deployed into the abdominal compartment of
naïve, spontaneously breathing swine. Animals were
able to breathe spontaneously following foam deploy-
ment, but we observed decreased tidal volume and an
increase in arterial partial pressure of carbon dioxide.
25
For first use in humans, intubation and mechanical
ventilation are recommended to ensure consistent tidal
volumes are maintained. Definitive airway control can
be administered by military medics and corpsmen. Mul-
tiple militarywide reviews demonstrate that emergent,
prehospital intubation has a 90% success rate. 45,46 With
appropriate training and practice, the success rate may
be higher when performed by skilled SOF providers; this
includes surgical airway access, when required. Con-
47
current with airway control, casualties will require clini-
cally appropriate amnesia and analgesia before foam
treatment, as recommended by TCCC. 48 enabling it to be removed so that the ratcheting handle
can be engaged. The delivery nozzle (with similar dimen-
Intraperitoneal foam deployment requires users to ac- sions to a laparoscopic trocar) is then positioned within
cess the abdominal cavity. To do so, we envision that the abdomen, as described above, and connected to the
users will perform a small skin incision just below the delivery device. The liquid phases are deployed by re-
umbilicus, and dissect through subcutaneous and fascial peatedly squeezing the ratcheting handle. As the liquid
layers. The abdominal cavity can subsequently be ac- phases travel through the nozzle, they are mixed together
cessed by a gloved finger, followed by inserting the foam by a series of elements, initiating the chemical reactions.
delivery nozzle, which has been designed with a blunt, The resulting mixture forms the foam in the body.
atraumatic tip. The proposed method is identical to the
open (Hasson) technique used for intra-abdominal tro- Preclinical animal testing in a severe liver hemorrhage
car placement in routine laparoscopic surgery. Because model confirmed that the fieldable delivery device, de-
there are currently no existing SOF technologies requir- veloped with SOF medical provider input, was usable
ing abdominal access, this would represent a new skill and effective. Foam treatment using the field system
for SOF providers. However, SOF users perform surgi- (n = 12) resulted in a survival benefit (67% versus 8%,
cal procedures of similar complexity such as cricothy- p = .006) and reduction in hemorrhage rate (0.48 ± 0.41
rotomy 45,49,50 and tube thoracostomy. We believe that versus 3.1 ± 1.2 g/kg per minute; p < .0001) relative to
this procedure could be conducted safely by SOF medi- the control group (Table 1). Additionally, we confirmed
24
cal providers with sufficient training. effectiveness at extreme operational temperatures (10°C
and 50°C) and after 1 year simulated shelf life (Table 1). 24
Appropriate patient assessment and preparation is criti-
cal for effective foam performance. We propose that Conclusion
SOF providers can rapidly identify exsanguinating pa-
tients in the prehospital environment, intubate, provide Over the past decade of war, the military has made sig-
analgesia, and access the abdominal cavity for foam nificant gains in reducing preventable deaths. Tourni-
deployment. quets, improved body armor, and TCCC have reduced
killed-in-action and died-of-wounds rates to the lowest
Delivery System levels in history. 12,51 In spite of these gains, noncompress-
Delivery of foam necessitates a system that is compatible ible abdominal hemorrhage remains a significant cause
with a far-forward environment. In the selected system, of death. Prehospital exsanguination rescue with percu-
a four-step process is used to deliver foam (Figure 5). taneous foam damage control is safe and effective, with
First, air is entrained into the polyol phase by turning a a favorable risk-benefit profile in preclinical studies.
hand crank; doing so produces small air bubbles in this Battlefield, presurgical use by SOF medical providers
liquid phase, facilitating foam formation. Upon reaching is conceptually possible. We recognize that the proce-
the desired aeration density, the aeration device unlocks, dures required for foam administration are not trivial,

Self-expanding Foam in Noncompressible Hemorrhage 43