Page 52 - Journal of Special Operations Medicine - Fall 2015

Figure 1 Schematic representation of ResQFoam. high flow) in swine. A midline laparotomy was used
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(A) Foam is deployed into the abdomen as a mixture of for strategic placement of intrahepatic cutting wires; the
two liquid phases and reacts in situ to form a solid foam. abdominal cavity was closed, and severe, noncompress-
(B) The foam conforms to anatomy and tamponades injury. ible liver injury was subsequently induced by retract-
(C) The foam is removed after definitive surgery.
ing the wires. Foam was injected into the abdomen at
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varying doses 10 minutes after injury, and findings were
compared with a control group receiving fluid resuscita-
tion alone. Animals were monitored for 3 hours or until
the time of death, followed by foam explantation.

Usability Study
cavity, self-expands to approximately 35 times its initial Initially, three very experienced SOF medical providers
volume, and conforms around anatomical features. A si- were introduced to the foam technology during routine
multaneous reaction gels the material into a solid, cohe- training evolutions and were interviewed regarding
sive polyurethane foam. The foam spreads throughout their preferences for delivery-system design. Proto-
13
the abdominal cavity and elevates intra-abdominal pres- type delivery systems were then designed to meet the
sure, providing a tamponade effect to temporarily reduce specifications preferred by the SOF end-users. These
or eliminate bleeding. designs were presented to the initial three SOF medical
providers, who down-selected the designs to a single,
The concept of using foam for the treatment of non- preferred prototype. An observational pilot study was
compressible hemorrhage was first described by Hol- conducted to evaluate the human factors and usability
comb et al., who used fibrin sealant formulations in aspects for the prototype system. Eight study partici-
14
small- animal models. 15–17 While these foams were effec- pants from the active-duty SOF medical community (all
tive when delivered directly to bleeding tissue, there was with combat experience) were consulted: three medics,
no advantage relative to the control group in closed- four physicians, and one nurse. Providers were trained
abdomen testing. 14–17 It was hypothesized that pooled on the use of the down-selected device in a classroom
blood formed a barrier to abdominal transport, prevent- setting. Following a 24-hour knowledge decay period,
ing foams from reaching the site of injury. Building on participants operated a foam delivery system prototype
16
these findings, we developed more than 1,300 foam for- using a mannequin. Participants were observed for any
mulations with a range of chemical and physical proper- errors in performance or “near misses” and interviewed
ties. Through in vitro and in vivo testing, we identified after the session for device feedback. Participants were
the target foam formulation based on its superior trans- asked to rate ease of use on an ordinal scale from 1 to
port throughout the abdomen in the presence of blood. 5, with 1 indicating the least favorable (very difficult)
This foam has been investigated in more than 600 swine rating and 5 indicating the most favorable (very easy)
studies to confirm performance. 13,18–25 rating.

The goal of this paper is to summarize the existing pre-
clinical data for self-expanding foam, describe the role Results
of SOF personnel in foam delivery-system development,
and to integrate these together to conceptualize how this Overview of Preclinical Data
novel method for percutaneous damage control could In the swine model, foam conformed to abdominal anat-
be incorporated into SOF medical care. omy but was efficiently removed (Figure 2). Survival
was dose dependent, but all doses demonstrated a sta-
tistically significant survival benefit relative to controls
Methods
at 3 hours (120mL: 90%; 100mL: 72% [Figure 3A];
Preclinical Data Figure 2 In vivo foam appearance in a swine study.
Ten publications were identified as originating from our (A) Foam is removed rapidly as a single block. (B) Shown
research team and describing self-expanding foam ther- following removal, foam topography corresponds with
apy for trauma. These manuscripts have described efficacy, abdominal tissues. (C) It is hydrophobic, absorbing small
safety, dose translation, and risk-benefit analysis of exsan- volumes of blood. Scale bar = 15cm.
guination rescue with percutaneous foam damage con-
trol. 13,18–26 Results from those studies are reviewed herein.

Procedure in Swine Model
We initially tested foam effectiveness in a high-grade,
closed-cavity, hepatoportal injury model (low pressure,

40 Journal of Special Operations Medicine Volume 15, Edition 3/Fall 2015