Page 56 - JSOM Fall 2019

the C-A-T strap; no strap sliding occurred until <18mm to FIGURE 1 Optimal thigh Generation 7 C-A-T application.
41mm of strap hook-and-loop was in contact with itself. The
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other evaluated the influence of strap “slack” on windlass turns
and reported increasing C-A-T wear and tear with slack in the
strap prior to using the windlass versus no apparent wear and
tear with 0mm of strap slack. In addition to C-A-T damage
9
from more windlass turns with the presence of strap slack, the
study showed strap slack increases the time required to reach
a potentially occlusive pressure and would therefore be associ-
ated with greater blood loss. The authors stated, “The present
9
study adds to a growing body of empiric knowledge that the
best tourniquet practice is indeed to remove all slack to make (A) (B)
the strap very tight before turning the windlass.” 9

The third 2013 publication establishing optimal C-A-T appli-
cation technique was a study of recovered tourniquets from
casualties of Operation Enduring Freedom and Operation New
Dawn. C-A-T windlass turns varied from zero to nine with a
8
median of three, indicating many appliers had not achieved
8
ideal strap tightness before engaging the windlass. The authors
stated, “Moderate to severe deformation began at 2 turns, in-
creased in likelihood stepwise with each additional turn, and (C) (D)
became omnipresent at 7 or more turns (Figure 6 [in the publi- (A) The applier should hold the windlass securing clip (not the wind-
cation]).” Data from this study indicate that to have no C-A-T lass rod) and pull the strap as tight as possible through the redirect
8
damage, C-A-T applications should only require one turn for buckle. The direction of strap pull should be parallel to the portion
arterial occlusion. Knowing equipment damage can lead to of the strap encircling the thigh before entering the redirect buckle
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equipment failure and more turns are associated with both (0° angle). Optimal strap-pulling technique uses the applier’s body
weight to advantage. The pulled free end of the strap must then be se-
C-A-T damage and longer times to reach potentially occlusive cured hook-and-loop to hook-and-loop by the applier. (B) An optimal
pressures, the results of one 2011 and two 2013 publications secured strap pull will result in visible tissue indentation and should
7–9
indicate optimal C-A-T application technique requires only one have a secured strap pressure ≥150mmHg (174mmHg for the shown
windlass turn for occlusion. (One windlass turn = a single 180° strap application). The tubing seen under the thigh is part of the pres-
rotation of the windlass rod starting from a position with the sure-measuring system. (C) The windlass rod of the C-A-T should be
rotated such that the slot in the rod remains in a parallel plane to the
rod parallel to the strap encircling the limb.) stabilization plate. The first 90° of turn puts the windlass rod parallel
to the limb encircling strap for the start of windlass-turn counting.
In 2015, data were published concerning strap tightness on With a good secured strap pull, only one or possibly two 180° turns of
the thighs of volunteers and C-A-T turns to reach arterial oc- the windlass will be required to achieve arterial occlusion. The wind-
lass rod must be secured in the windlass securing clip by the applier
clusion. To achieve optimal C-A-T applications of one turn at a rotation beyond that at which bleeding is stopped and the distal
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to arterial occlusion, the study showed that tourniquet appli- pulse is gone. (D) The windlass rod has been rotated one 180° turn and
ers need to attain secured strap pressures ≥150mmHg before secured in the windlass securing clip with the slot remaining parallel
windlass use. 60 to the stabilization plate. This is an arterially occlusive application
with a single windlass turn pressure of 381mmHg. Across 420 adult
34.5cm to 72.7cm circumference thigh applications, the mean ± stan-
Also in 2015, a publication detailed the Tactical Combat Casu- dard deviation pressure required to achieve arterial occlusion was 334
alty Care guidelines change of recommending C-A-T applica- ± 56mmHg (95th percentile of 428mmHg). 24,60–63 Arterially occlusive
tions should be single-routed. This formalized single-routing thigh applications of 3.8cm-wide, nonelastic tourniquets such as the
59
as the optimal technique for Generation 6 and older C-A-Ts C-A-T will have visible tissue indentation. To finish the C-A-T appli-
cation, the free end of the main strap should be placed over the wind-
and relates to the buckle design change of Generation 7 lass rod within the securing clip; the windlass securing strap should
C-A-Ts to a simple redirect rather than offering the possibility be secured across the opening of the securing clip; and the time of
of double-routing through a triglide friction buckle. application should be written on the windlass securing strap.
Images of Optimal Thigh Tourniquet Applications
Figures 1–3 show optimal applications of Generation 7 C-A-Ts, thigh applications ranging from 34.5 to 72.7cm in circumfer-
Tactical RMTs, and SWATTs. C-A-T and Tactical RMT strap ence 24,60–63 ). For the SWATT, arterially occlusive thigh applica-
pulls are 0° angle. SWATT stretch is maintained throughout tions require visible tissue indentation and a mean tourniquet
each wrap. For nonelastic, 3.8cm-wide tourniquets, tissue in- pressure of 233 ± 55mmHg (mean and standard deviation
dentation should be visible before tightening system use (opti- for 29 thigh applications ranging from 39 to 56cm in circum-
mal pressure ≥150mmHg ). The C-A-T windlass rod should ference ). Non–self-securing tourniquet tightening systems
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be rotated with the slot through the rod maintained parallel (C-A-T and SWATT) require a final securing step: The C-A-T
to the stabilization plate. The Tactical RMT ratcheting buckle windlass rod must be placed in the securing clip, and the
7
should be advanced with downward pressure directing the ad- SWATT free end must be tucked under the last circumferential
vancing pawl into the ladder teeth. The wraps of the SWATT wrap. The next steps with the C-A-T are placing the hook-
should be flat and completely overlapping. For nonelastic, and-loop strap free end over the windlass rod in the securing
3.8cm-wide tourniquets, arterially occlusive thigh applications clip and extending the securing strap across the clip’s opening.
require visible tissue indentation and a mean tourniquet pres- For all tourniquets, application time should be recorded, and
sure of 334 ± 56mmHg (mean and standard deviation for 420 bleeding and pulse should be monitored. 25

54 | JSOM Volume 19, Edition 3 / Fall 2019