Page 51 - JSOM Fall 2022

Performance Evaluation of the Solo-T and the

Combat Application Tourniquet in a Perfused Cadaver Model

George J. Holinga, PhD *; John S. Foor, MD, FACS, RPVI ;
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Steven L. Van Horn ; James E. McGuire, BS 4

ABSTRACT
Purpose: We evaluated a 10.2­cm­wide, minimally elastic, of an analogous patient benefit from tourniquet education
adhesive wrap–based tourniquet (Solo­T or ST) alongside a and use amongst the civilian community has also begun to
3.8­cm­wide windlass­based tourniquet (Combat Application emerge. Nonetheless, some ambivalence about tourniquets
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Tourniquet Generation 7, or CAT) to determine if the tension has remained in the civilian medical community. This ambiv­
wrap­tightened ST could deliver hemorrhage control equiva­ alence is often attributed to concerns about risk of permanent
lent to the windlass­tightened CAT. Methods: A cadaver model damage to nerves and soft tissue in treated limbs.
was used to simulate lower­thigh femoral arterial hemorrhage
at “normal” (146 ± 5mmHg) and “elevated” (471 ± 3mmHg) There is a broad range of emergency tourniquet designs which
perfusion pressures (mean ± standard error). Three study par­ have been commercialized for use in the pre­clinical treatment
ticipants used the ST and CAT to control hemorrhage during of life­threatening limb hemorrhage. One of the most com­
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48 timed trials. Arterial occlusion was established by Doppler mon emergency tourniquet designs utilizes an inelastic, flexi­
ultrasound and tourniquet performance was quantified by un­ ble strap which is looped around the limb and then tightened
der­tourniquet pressure cuffs. Results: Participants achieved with a mechanical advantage system such as a windlass or
100% (24/24) occlusion success rates and reported similar rachet that permits shortening of the strap’s looped circumfer­
ease of use for both tourniquets. Occlusion and application ence. 14–17 Another common design is the Esmarch­style tour­
times (mean ± standard error) were similar (p > .05) for the niquet which typically utilizes a highly elastic strap, tube, or
ST and CAT under “normal” (occlusion, ST: 25 ± 2 seconds, band which is stretched and tightly wrapped around a limb
CAT: 22 ± 2 seconds; application, ST: 27 ± 2 seconds, CAT: multiple times under tension before being secured by tuck­
26 ± 2 seconds) and “elevated” (occlusion, ST: 24 ± 7 seconds, ing or tying off the free end. 18–20 The adhesive wrap­based
CAT: 24 ± 7 seconds; application, ST: 25 ± 7 seconds, CAT: tourniquet design shares some similarities with Esmarch­type
25 ± 7 seconds) perfusion alike. The ST mean completion pres­ devices, yet it differs most notably in being constructed of a
sures (mean ± standard error) were > 40% lower than the CAT tape­like, polymer material with minimal elasticity, an adhe­
under both “normal” perfusion (ST: 110 ± 20mmHg; CAT: sive coating on its inner surface, and a limited­stick, release
210 ± 30mmHg; p = 0.009) and “elevated” perfusion (ST: coating on its outer surface. When applied, the adhesive
190 ± 50mmHg; CAT: 340 ± 30mmHg; p = 0.03). Conclusion: wrap tourniquet is repeatedly wound around a limb under
The adhesive wrap­based ST tourniquet delivered equivalent tension in a process resembling that of the Esmarch tourni­
hemorrhage control performance at significantly lower com­ quet. However, the bonding interaction between the adhesive­
pletion pressures than the CAT. and release coated­surfaces of the adhesive wrap tourniquet
functions to circumferentially self­secure it around the limb
Keywords: first aid; hemorrhage control; perfused cadaver; during application, while permitting subsequent unwinding,
tourniquet; tourniquet pressure; trauma care adjustment, and re­securement. As a result, the end of the ad­
hesive wrap tourniquet is not required to be tied or tucked at
the conclusion of the application process. Several additional
emergency tourniquet designs beyond those briefly mentioned
Introduction
above have been developed and commercialized, but summary
Over the past few decades, a significant body of research has descriptions of these have been excluded from this report for
emerged demonstrating that the tourniquet is one of the most brevity. 13,21–24
fundamental and important tools available for delivering
life­saving prehospital treatment following traumatic injury. The purpose of this study was to evaluate the performance of
1–6
These findings have led to substantial progress in awareness, the Solo­T (ST; Entrotech Life Sciences Inc., San Francisco,
first­aid protocols, and emergency preparedness surrounding CA, USA, www.entrotechlifesciences.com), an adhesive wrap­
trauma­associated hemorrhage control in both military and based tourniquet and the Combat Application Tourniquet
civilian populations. 7–10 Consequently, the military community Generation 7 (CAT; C •A •T Resources, LLC, Rock Hill, SC,
has reported significant benefit from its sustained efforts to USA, www.combattourniquet.com) a hook­and­loop strap,
educate and train servicemembers to apply tourniquets to bat­ windlass­based tourniquet. A perfused human cadaver model
tlefield casualties when medically appropriate. 3,11,12 Evidence was used to simulate a patient with serious limb hemorrhage
*Correspondence to holinga@entrotech.com
1 Dr George J. Holinga, CMDCM (Ret) Steven L. Van Horn, and James E. McGuire are affiliated with Entrotech Life Sciences, Inc., San Fran­
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cisco, CA. Dr John S. Foor is a practicing vascular surgeon at Mount Carmel Medical Group, Columbus, OH.
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