Page 51 - JSOM Summer 2019

Two tourniquets were donated by their respective compa- under the tourniquet strap approximately 180° from the re-
nies for this or prior studies: the Tactical Ratcheting Medical direct buckle and connected to a gas pressure sensor system
Tourniquet (Tac RMT; 10 November 2015; m2 Inc., www (Vernier Gas Pressure Sensor, Vernier LabPro interface, and
®
.ratchetingbuckles.com) and the Parabelt (Lot PT1116-21- Logger Pro Software; Vernier Software and Technology, www
04, RevMedX, www.revmedx.com). The other three tour- .vernier.com). Pressure was recorded every tenth of a second
niquets were purchased: the Generation 7 C-A-T (C-A-T7, on thighs and every second on the gel. Secured-strap pressure
Lot 120B207; C-A-T Resources Inc., http://combattourniquet was taken with the applier’s hands off the tourniquet. The
.com/), the Tactical Mechanical Tourniquet (TMT; Lot pressure graph was not visible to appliers, and no data were
040517; Combat Medical, https://combatmedicalsystems. shared with appliers during applications.
com), and the Generation 3 SOF Tactical Tourniquet–Wide
®
(SOFTTW; 3 April 2017; Tactical Medical Solutions, www Tourniquet Recipient Thighs and Ballistic Gel
®
.tacmedsolutions.com). Tourniquets were applied to left and right thighs of authors
PW and CB at locations with circumferences of 46.0, 46.5,
Redirect Buckles and Straps and 48.0cm. Recipients were seated with a 90° angle between
Tourniquet features are shown in Figure 1. The C-A-T7 has relaxed thigh and lower leg.
a hook-and-loop strap; a simple, rough redirect buckle that
does not secure the strap; and no specifically built-in holding Tourniquets were also applied to a 57.5cm circumference,
location. The Tac RMT has a smooth strap; a self-securing 20% synthetic ballistic gel cylinder (Clear Ballistics; clear
redirect buckle composed of two overlapping, rough-coated, ballistics.com). 11,12 The cylinder was suspended via a rod
round-stock metal rectangles; and a built-in holding loop through the 2.54cm-diameter central stainless steel tubing.
above the redirect buckle. The TMT has a hook-and-loop
strap; a rough, square-edged, triglide redirect buckle that Tourniquet Appliers
does not secure the strap; and no specifically built-in hold- For thigh applications, 20 volunteers were the tourniquet ap-
ing location. The Parabelt has a smooth strap; a self-securing pliers. Inclusion criteria were age 18 years or older, willing-
slider redirect buckle composed of slider with a ridge that fits ness to practice applying each tourniquet at least once with
a depression in the outer part of the buckle; and a built-in feedback, and completion of a dominant-hand, single-handed
holding loop above the redirect buckle. The SOFTTW has a weight pull greater than 9kg. Exclusion criteria were con-
smooth strap; a self-securing slider redirect buckle composed ditions that would impair use of the tourniquet-holding or
of a U-shaped slider and metal round stock; and no specifi- strap-pulling techniques.
cally built-in holding location. The triglide and slider redirect
buckles of the TMT, Parabelt, and SOFTTW all significantly All appliers did at least one set of practice applications. Nine
impair the conversion of a 0° angle, strap tangential to the appliers had considerable experience applying the Tac RMT
limb, pulling force to circumferential pressure to a consid- to thighs in practice and in past studies (hereafter referred to
erably greater extent than do the redirect buckles of the Tac as experienced appliers). 13,14 One experienced applier also had
RMT and the C-A-T7. 11 considerable prior study experience applying single-routed
generation 6 C-A-Ts 12,15 and some prior study experience
FIGURE 1 Tourniquet buckles, holding locations above the buckles, working with the current C-A-T7, the TMT, the Parabelt,
11
11
11
and straps.
and the current- and past-generation SOFTTW. 11,15 The other
eight experienced appliers had no study experience and only
nonextensive practice experience applying the C-A-T7, TMT,
Parabelt, and SOFTTW.
Six appliers had more than three practice sessions with the
Tac RMT but no experience applying it in studies (hereafter,
novice appliers). Like eight experienced appliers, these six had
no study experience and only nonextensive practice experience
applying the C-A-T7, TMT, Parabelt, and SOFTTW.
Tourniquets from left to right: Generation 7 Combat Application Five appliers were complete novices regarding any limb tourni-
Tourniquet with non–self-securing, simple redirect buckle, windlass quet applications (hereafter, complete novice appliers). These
securing bracket (“windlass clip”), and hook-and-loop strap; Tactical
Ratcheting Medical Tourniquet with self-securing, overlapping rough five watched at least one set of study applications with each
coated metal rings redirect buckle, holding loop (“Tactical loop”), tourniquet and had at least one set of practice applications
and smooth strap; Tactical Mechanical Tourniquet with non–self- with each tourniquet.
securing triglide redirect buckle, windlass clip (“retaining clip”), and
hook-and-loop strap; Parabelt with self-securing, sliding-bar redirect
buckle, holding loop, and smooth strap; and Generation 3 SOF Tac- All appliers were directed to watch a C-A-T instructional
®
16
17
tical Tourniquet–Wide with self-securing, sliding bar and round-stock video and a TMT instructional video. During applications,
redirect buckle, windlass securing triangle, and smooth strap. Red ar- appliers were told the specific technique to use (i.e., holding
rows indicate holding locations. location and pulling direction) and were told to pull the tour-
niquet as tight as possible with each technique.
Pressure Measurements
Pressures under each tourniquet were measured using a No. 1 Applier Pulling Force
neonatal blood pressure cuff (2.2cm × 6.5cm bladder, single Each applier’s single-arm downward pulling force was de-
tube) inflated to 15mmHg above atmospheric pressure. Atmo- termined. Increasing weight increments of 4.56kg were at-
spheric pressure was used as baseline. The bladder was placed tached to one end of the strap, which was run up and over a

Tourniquet Strap Technique | 49