Page 54 - JSOM Summer 2019

FIGURE 3 Gel tourniquet application with outward pulling TABLE 1 Greatest Thigh Pressure Technique per Tourniquet
direction. Above Buckle
Above Below Out, Then Out, Then
Tourniquet Tangential Tangential Tangential Tangential
C-A-T7 9 4 3 4
Tac RMT 14 3 3 0
TMT 6 6 8 0
Parabelt 5 9 4 2
SOFTTW 7 5 8 0
All
tourniquets 41 27 26 6
combined
χ without row “All tourniquets combined” p = .0109.
2
C-A-T7, Generation 7 Combat Application Tourniquet; Tac RMT,
Tactical Ratcheting Medical Tourniquet; TMT, Tactical Mechanical
Tourniquet; SOFTTW, Generation 3 Special Operations Forces Tacti-
cal Tourniquet-Wide.

TABLE 2 Lowest Thigh Pressure Technique per Tourniquet
Above Buckle
Above Below Out Then Out Then
Tourniquet Tangential Tangential Tangential Tangential
C-A-T7 3 7 4 6
Tac RMT 0 1 1 18
TMT 2 3 2 13
Note the clear space between the gel and the tourniquet strap at the Parabelt 4 4 5 7
redirect buckle. SOFTTW 4 6 0 10
All
secured-strap pressure was to hold above the redirect buckle tourniquets 13 21 12 54
and pull the strap downward, tangential to the limb at the re- combined
direct buckle (0° angle). The worst technique was to hold the χ without row “All tourniquets combined” p = .0119.
2
buckle (Table 2). Preceding the tangential strap pulling with C-A-T7, Generation 7 Combat Application Tourniquet; Tac RMT,
directly outward strap pulling (i.e., out, then tangential) ap- Tactical Ratcheting Medical Tourniquet; TMT, Tactical Mechanical
peared to have secured-strap pressure benefits when done with Tourniquet; SOFTTW, Generation 3 Special Operations Forces Tacti-
cal Tourniquet–Wide.
the gel and the constant strap-pulling force of 226N (50.84lbf,
Figure 2B) but was generally not helpful when done by appli-
ers (Figure 2A, Table 1). To achieve the highest secured-strap in Figure 2A involving human appliers. Looking at data for
pressures, holding the strap below the redirect buckle to feed pulling tangential only, even humans capable of applying more
the strap into the buckle was generally inferior to holding than 226N (greater than 23.06kg weight pull) fail to achieve
above the redirect buckle (Figure 2A, Table 1), probably re- the secured-strap tightness reached with a continuous force
lated to having two fingers between the strap and the limb application of 226N (50.84lbf). Also in the tangential-only
during strap pulling. data, the order of secured-strap pressures achieved for the
TMT, Parabelt, and SOFTTW was reversed for human ap-
As shown in Figure 2A, only the C-A-T7, non–self-securing pliers (TMT highest, SOFTTW lowest) versus static hanging
tourniquet design consistently had secured-strap pressures weight (SOFTTW highest, TMT lowest). Looking at data for
greater than the minimum threshold of 100mmHg (77 of 80 outward then tangential pull in Figure 2B, a secured-strap pres-
applications) and a majority of secured-strap pressures greater sure advantage was gained for the TMT, Parabelt, SOFTTW,
than the desirable threshold of 150mmHg (50 of 80 applica- and even the Tac RMT when an outward pull preceded the
tions). With the ideal application technique of holding above tangential pull during consistent force applications on the gel.
and pulling tangential to the limb (0° angle), the Tac RMT had Table 1 and Figure 2A show that human appliers failed to gain
secured strap pressures greater than 100mmHg for 14 of 20 ap- a secured-strap pressure advantage by preceding the tangential
plications and secured-strap pressures greater than 150mmHg pull with an outward pull.
for 8 of 20 applications. The Tac RMT also had secured-strap
pressures greater than 100mmHg for 14 of 20 applications Applier Force Not Converted Into
and secured-strap pressures greater than 150mmHg for 5 of Secured-Strap Pressure
20 applications, with the application technique of holding Thigh peak strap pressures during active strap pulling were
above and pulling outward and then tangential. Applications considerably higher than the final secured-strap pressures
using the other three tourniquet designs were significantly less (compare y-axis in Figure 4A and Figure 2A). This was also
successful for achieving secured-strap pressures greater than true for gel applications involving only outward pulling: Peak
the minimum threshold of 100mmHg. strap pressures with the hanging weight were considerably
higher than final secured-strap pressures (compare y-axis in
A few interesting items appear when comparing the gel ap- Figure 4B and Figure 2B). Differences between peak strap
plications in Figure 2B involving consistent force application pressures and secured-strap pressures are shown in Figure 4C
via static hanging weight with the thigh applications shown and 4D.

52 | JSOM Volume 19, Edition 2 / Summer 2019