Page 38 - JSOM Summer 2018

New and Established Models of Limb Tourniquet
Compared in Simulated First Aid

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John F. Kragh Jr, MD *; Nicola J. Newton ; Andy R. Tan ;
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James K. Aden 3d, PhD ; Michael A. Dubick, PhD 4

ABSTRACT

Background: The performance of a new tourniquet model (e.g., direct wound pressure) fails to control severe external
was compared with that of an established model in simulated limb bleeding” and (2) “[t]he task force strongly believes that
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first aid. Methods: Four users applied the Combat Application education in first aid should be universal: everyone can and
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Tourniquet (C-A-T), an established model that served as the should learn first aid.” In line with these notions, the US
control tourniquet, and the new SAM Extremity Tourniquet Government, in 2015, integrated tourniquet use into public
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(SXT) model, which was the study tourniquet. Results: The health policy so inventors and educators pivoted to focus on
performance of the C-A-T was better than that of the SXT for users such as law enforcement officers and civilian laypersons
seven measured parameters versus two, respectively; metrics who had little training with tourniquets.
were statistically tied 12 times. The degree of difference, when
present, was often small. For pretime, a period of uncontrolled Concurrently, technology continued to evolve, and tourni-
bleeding from the start to a time point when the tourniquet quet studies since 2004 have shown that some models were
first contacts the manikin, the bleeding rate was uncontrolled both safe and effective. 9,10 With later refinements in various
at approximately 10.4mL/s, and for an overall average of 39 tourniquets, some design features, such as rods and bands,
seconds of pretime, 406mL of blood loss was calculated. The have become popular, and such favored features have tended
mean time to determination of bleeding control (± standard to become more similar over time among different models.
deviation [SD]) was 66 seconds (SXT, 70 ± 30 seconds; C-A-T, For example, a wide band became a favored feature. 10–12 In
62 ± 18 seconds; p = .0075). The mean ease-of-use score was 4 fact, developed commonality of favored features can occur as
(indicating easy) on a scale of 1 to 5, with 5 indicating very easy technologies converge. Since 2015, designed refinements have
(mean ± SD: SXT, 4 ± 1; C-A-T, 5 ± 0; p < .0001). C-A-T also shifted to address practical traits like ease of use, whereas be-
performed better for total trial time, manikin damage, blood fore 2005, safety and effectiveness were questioned and subse-
loss rate, pressure, and composite score. SXT was better for quently addressed. 9,13,14 The purpose of the present study was
pretime and unwrap time. All users intuitively self-selected the to compare the performance of a new tourniquet model with
speed at which they applied the tourniquets and that speed was that of an established model in simulated first aid.
similar in all of the required steps. However, by time segments,
one user went slowest in each segment while the other three Methods
generally went faster. Conclusions: In simulated first aid with
tourniquets, better results generally were seen with the C-A-T This experiment was conducted within the protocol guidelines
than with the SXT in terms of performance metrics. However, set forth at the Institute of Surgical Research in 2017. The de-
the degree of difference, when present, was often small. sign was a performance comparison between tourniquet mod-
els: An established model served as the control tourniquet and
Keywords: tourniquet; manual skill; psychomotor perfor- a new model was the study tourniquet (Figure 1).
mance; first aid device comparison/education/standards;
hemorrhage/prevention and control Data grouping was by model. The established model was the
Combat Application Tourniquet (C-A-T; generation 7; C-A-T
Resources, www.combattourniquet.com). The new model was
Introduction the SAM Extremity Tourniquet (SXT; SAM Medical Products,
www.sammedical.com). Both were designed principally for
First aid in emergencies may include limb tourniquet use to easy use (Figure 2). For example, the C-A-T refinements from
stop bleeding. In 2005, the emphasis was mainly on training its prior version were not about safety or effectiveness but
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deployed Servicemembers. However, subsequent to the pub- about making use easier. Similarly, the SXT design aimed to
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lication of military reports, civilian use of tourniquets became make steps such as slack removal easier.
more common overall albeit unevenly from place to place. 5–7
In 2015, first-aid authorities upheld, in part, the following Four persons used the tourniquets individually. All users were
notions: (1) “the evidence supports the use of tourniquets in familiar with the C-A-T but not with the SXT. The four us-
the civilian setting when standard first aid hemorrhage control ers were, in order, a clinician-scientist, an associate researcher,
*Correspondence to 3698 Chambers Pass, Joint Base San Antonio Fort Sam Houston, TX; or john.f.kragh.civ@mail.mil.
1 Dr Kragh is a researcher of bleeding control at the Institute of Surgical Research (ISR) and an associate professor in the Department of Surgery,
Uniformed Services University of the Health Sciences, Bethesda, MD. Cadets Newton and Tan are undergraduate students of mechanical engi-
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neering at the US Military Academy at West Point, NY. Dr Aden is a statistician at the Brooke Army Medical Center, Fort Sam Houston, TX.
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4 Dr Dubick is a resuscitation researcher and manager of the Damage Control Resuscitation task area at the ISR, Fort Sam Houston, TX.
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