Page 50 - JSOM Summer 2019

Best Tourniquet Holding and Strap Pulling Technique

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Piper Wall, DVM, PhD *; Charisse Buising, PhD ; Sara Donovan, BA ;
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Connor McCarthy, BA ; Katherine Smith, BA ; Catherine Hackett Renner, PhD 4

ABSTRACT
Background: Appropriate strap pressure before tightening- The processes involved in achieving strap tightness before tight-
system use is an important aspect of nonelastic, limb tour- ening-system use include holding the tourniquet in some fashion
niquet application. Methods: Using different two-handed that prevents tourniquet rotation around the limb while pull-
techniques, the strap of the Generation 7 Combat Application ing the strap in some direction and then also securing the strap
Tourniquet (C-A-T7), Tactical Ratcheting Medical Tourniquet if the redirect buckle is not self-securing. If we define the side of
(Tac RMT), Tactical Mechanical Tourniquet (TMT), Parabelt, the redirect buckle into which the strap feeds as “below,” then
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and Generation 3 SOF Tactical Tourniquet–Wide (SOFTTW) the options for tourniquet holding locations are the following:
was secured mid-thigh by 20 appliers blinded to pressure data (1) above the redirect buckle, (2) the redirect buckle, and (3) be-
and around a thigh-sized ballistic gel cylinder by gravity and low the redirect buckle. The options for strap-pulling direction
23.06kg. Results: Pulling only outward (90° to strap enter- relative to the redirect buckle are a 180° redirection tangential
ing buckle) achieved the lowest secured pressures on thighs to the limb where the strap feeds into the redirect buckle (0°
and gel. For appliers, the best holding location was above the angle), to directly outward from the limb at the redirect buckle
buckle, and the best strap-pulling direction was tangential to (90° angle), or all the way to no redirection of the strap (180°
the thigh or gel (0° to strap entering buckle). Preceding tan- angle, which is counter to the very idea of a redirect buckle
gential pulling with outward pulling resulted in higher secured and results in no strap tightening). Physics indicates that the
pressures on the gel but did not aid appliers. Appliers generally strap should be pulled at a 0° angle relative to the strap feeding
did not reach secured pressures achievable for their strength. into the redirect buckle (a redirected strap pull tangential to the
Of 80 thigh applications per tourniquet, 77 C-A-T7, 41 Tac limb), but not all tourniquet application instructions show or
RMT, 35 TMT, 16 Parabelt, and 10 SOFTTW applications state this. In addition, the use of hook-and-loop strap-securing
had secured pressures greater than 100mmHg. Conclusions: systems creates challenges for tangential pulls (i.e., 0° pulls).
The default for best tourniquet strap-application technique is
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to hold above the buckle and pull the strap tangential to the Most tourniquet redirect buckles are not low friction, and not
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limb at the buckle. Additionally, neither strength nor expe- all appliers are strong. Therefore, determining and training
rience guarantees desirable strap pressures in the absence of people to use a good holding location and a good strap- pulling
pressure knowledge. direction is important for achieving appropriate tourni-
quet-strap tightness and therefore maximizing the probability
Keywords: tourniquet; hemorrhage; first aid; emergency of an arterially occlusive, successful tourniquet application with
treatment use of the tourniquet’s tightening system. The purpose of this
study was to explore the effects of different holding locations
and strap-pulling directions on secured strap pressure without
use of the tourniquet’s tightening system. The first hypothesis
Introduction
was that the best tourniquet-holding position would be below
Limb tourniquets are part of prehospital care, and training the redirect buckle, because it allowed appliers to feed the strap
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with limb tourniquets is part of the national Stop the Bleed up into the redirect buckle. The second hypothesis was that
campaign. Most limb tourniquets currently used in prehos- the best strap-pulling direction would be tangential to the limb
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pital care have a nonelastic strap, a buckle allowing a 180° at the redirect buckle (0° angle) regardless of strap and buckle
strap direction change (strap redirect), a strap securing mech- design (smooth or hook-and-loop for straps and self-securing
anism, and a mechanical advantage tourniquet-tightening sys- or not self-securing for redirect buckles).
tem. Optimal application technique includes achieving secured
tourniquet strap pressures greater than 100mmHg (ideally Methods
greater than 150mmHg) before using tourniquet-tightening
systems to facilitate achieving arterial occlusion, minimize The Drake University Institutional Review Board approved
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tightening-system problems, 7-10 and probably minimize recip- this prospective study. The study took place February through
ient discomfort. May 2018.
*Correspondence to piperwall@q.com
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1 Dr Wall is a researcher in the Surgery Education Department, UnityPoint Health Iowa Methodist Medical Center, Des Moines, IA. Dr Buising
is a professor of biology and the director of the Biochemistry, Cell and Molecular Biology Program, Drake University, Des Moines, IA. Ms Don-
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ovan, Mr McCarthy, and Ms Smith were undergraduate students at Drake University. Dr Renner is associate vice president of Analytic Support
and Institutional Research, Grinnell College, Grinnell, Iowa.
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