Page 43 - Journal of Special Operations Medicine - Spring 2015

heat exposure to the function of tourniquets without The two users were members of the study team (JPD,
heat exposure. JFK) and included a military physician assistant and a
military clinician­scientist. Both the physician assistant
The study group was a set of new tourniquets. The and the clinician­scientist received formal Army training
set included three models: (1) the Combat Applica­ in tourniquet use. Both were familiar with tourniquets,
tion Tourniquet (C­A­T; Generation 6; Composite Re­ especially the C­A­T. The clinician­scientist was expert
sources, http://composite­resources.com), (2) the SOF with all aspects of tourniquets and was more experi­
®
Tactical Tourniquet Wide (SOFTT­W; Tactical Medi­ enced in tourniquet use than the other user.
cal Solutions, www.tacmedsolutions.com), and (3) the
Ratcheting Medical Tourniquet (RMT; M2 Inc; www. The tourniquets were tested on a manikin in the labora­
®
ratchetingbuckles.com). These models are on the list of tory (Figures 1–3). The investigators used a HapMed
those ordered commonly in the defense logistic system; Leg Tourniquet Trainer (CHI Systems, www.chisystems.
the first two are recommended by the Committee on com). A simulated right­thigh body segment (leg num­
Tactical Combat Casualty Care and by the USAISR, and ber 000F) with an above­knee amputation injury was
all three are currently selected for testing (Joint Opera­ the testing apparatus. 10,11 The manikin was designed to
tional Evaluation of Field Tourniquets, Phase 3) by the train users by providing differential performance feed­
US Department of Defense. back. The investigators mechanically tested tourniquet
performance with the manikin. The manikin provides
The study group was exposed to heat for 91 days (rep­ for mechanical stresses to tourniquets, and these stresses
resenting one summer season) in a laboratory oven. realistically mimic those in caregiving; the manikin’s
An oven (Fisher Scientific Isotemp Oven, model 516G; track record is good as a valid assessor of emergency
www.fishersci.com) was used for the study group at tourniquet use. 10,11
130°F (54.4°C). The oven was dry and the humidity of
its air was very low. After heat exposure and a cool­ Figure 1 Manikin used in assessing tourniquet performance.
down period, the tourniquets were tested. Without any Photograph shows the thigh manikin lying on a desk top
available data with which to estimate the temperature with the imbedded touchpad on the right and the amputation
and duration, we selected a value close to the record injury on the left.
high of Baghdad, Iraq, but we used a value slightly
higher, since the shipping containers are out in the sun.
The control group was constituted similarly to the study
group except there was no heat exposure. The control
group tourniquets were purchased at the same time and
from the same manufacturing lots as the study group.
The control group tourniquets were kept indoors at
room temperature (76°F [24.4°C] in an air­conditioned
laboratory with humidity control). The storage closet
was not exposed to heat or bright daylight.

There were five devices per model (three models), for a
total of 15 devices in the control group and 15 in the The medial hip had an embedded computer interface
study group. The number of tests (iterations or repli­ that included a smartphone­like touchpad. Software
cates) per device was 10 per user, with two users in the (version 1.9; CHI Systems, www.chisystems.com) inte­
study. The total number of tests was 600. Ten mechani­ gral to the manikin allowed the thigh to stand alone and
cal loads of each device were intended to stress the com­ be operated by user input through finger touch on the
ponents adequately to assess care; care often involved pad. The thigh was laid on a benchtop in the labora­
multiple mechanical loads applied to the tourniquet tory and was operated in accordance with the manufac­
in one episode of care for one casualty (initial place­ turer’s instructions. The thigh had no fluid to simulate
ment and tightening during Care Under Fire, replace­ blood, but bleeding was represented by red lights that
ment (proximal or distal during Tactical Field care, transilluminated the wound. The number of lights il­
adjustments such as retightening after time periods for luminated represented the bleeding rate—all lights on
issues such as rebleeding, removal and replacement to meant uncontrolled bleeding; no lights on meant bleed­
assess for wound assessment such as for hemorrhage ing had stopped. Intermediate control was indicated by
control confirmation or failure of conversion to a pres­ a few lights twinkling. Arterial pulse was palpable in the
sure dressing); additional loading is often periodically popliteal artery area behind the distal thigh. The touch­
made by users to refresh their own skill in tourniquet pad readout for each iteration included hemorrhage
application. control, the time to effectiveness, the pressure exerted

Testing of Tourniquets Exposed to Prolonged Heat 33