Page 49 - Journal of Special Operations Medicine - Spring 2017

Cat on a Hot Tin Roof

Mechanical Testing of Models of
Tourniquet After Environmental Exposure

Daniel K. O’Conor; John F. Kragh Jr, MD;
James K. Aden 3rd, PhD; Michael A. Dubick, PhD

ABSTRACT

Background: The purpose of the present study was to Introduction
mechanically assess models of emergency tourniquet Emergency tourniquet use to stop bleeding from limb
after 18 months of environmental exposure to weather wounds has changed since 2001 from a means of last
to better understand risk of component damage. Ma- resort to a means of first aid. Widespread fielding of
1–3
terials and Methods: An experiment was designed to tourniquets to deploying US Military Servicepersons
test tourniquet performance on a manikin thigh. Three since 2005 was made in tandem with their training.
4
tourniquet models were assessed: Special Operations Many Servicepersons eventually became comfortable
Forces Tactical Tourniquet Wide, Ratcheting Medical with tourniquets and wanted them nearby even to the
Tourniquet, and Combat Application Tourniquet. Un- point of routinely hanging tourniquets on the outside
exposed tourniquets formed a control group stored in a of their military uniform. This has been discouraged
5,6
laboratory; exposed tourniquets were placed outdoors because it is outside the recommended place—inside the
on a metal roof for 18 months in San Antonio, Texas. first aid kit, where, in a crisis, other people will look
Two users, a military cadet and a scientist, made 300 for tourniquets to use—and it exposed tourniquets to
assessments in total. Assessment included major damage the environment. Experienced medics thought such ex-
(yes–no), effectiveness (hemorrhage control, yes–no), posure may cause problems, such as increased risk of
casualty survival (alive–dead), time to stop bleeding, damage to some components of the tourniquet. Subse-
pressure, and blood loss. Time, pressure, and blood loss quently, studies were performed to better understand
were reported in tests with effectiveness. Results: Ex- this risk, but the specific type of exposure, such as heat,
posed devices had worse results than unexposed devices light, or humidity, that might increase risk of damage
for major damage (3% [4/150] versus 0% [0/150]; p = remained unknown. 7–10 One study was made after ex-
.018), effectiveness (89% versus 99%; p = .002), and posure to a simulated summer in Baghdad, Iraq, for 91
survival of casualties (89% versus 100%; p < .001). In days in an oven at 54°C, and its finding of no increased
tests for effectiveness, exposed devices had worse re- damage risk led us to consider environmental exposure
sults than unexposed devices for time to stop bleeding that more closely simulates risk in the field, including
(29 seconds versus 26 seconds; p = .01) and pressure diurnal variation of sunlight, temperature, and humid-
(200mmHg versus 204mmHg; p = .03, respectively), ity. We also wanted a longer exposure, to improve the
but blood loss volume did not differ significantly. Con- likelihood of detecting problems. The purpose of this
clusion: Compared with unexposed control devices, en- study was to mechanically assess tourniquet models
vironmentally exposed tourniquets had worse results in after prolonged environmental exposure to weather to
tests of component damage, effectiveness, and casualty better understand risk of component damage.
survival.

Keywords: first aid; damage control; hemorrhage/preven- Materials and Methods
tion and control; shock; tourniquet; resuscitation; emer- This study was conducted under an approved proto-
gency medical services
col. The study group included environmentally exposed
tourniquets; the control group consisted of similar but
unexposed tourniquets.

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