Page 36 - JSOM Winter 2023

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Tourniquet Applications Time data were organized in Microsoft Office Excel 2003
The dorsal pedal artery Doppler signal was audible before ( Microsoft Corp., www.microsoft.com). Graphing and statisti-
starting applications. Each application was videoed from two cal analyses were performed with GraphPad Prism, version 7.04
angles at 90 frames per second with GoPro Hero 5 Sessions for Windows (GraphPad Software Inc., www.graphpad.com).
(GoPro Inc., www.gopro.com). One-way analysis of variance (ANOVA) with Tukey’s or Sidak’s
multiple comparisons tests and unpaired, two-tailed t tests were
After watching training videos, 2,3–10 appliers knelt beside the used for time comparisons. P-values of .15 or less are reported.
recipient’s leg and waited for the director to say “Go” before
picking up the tourniquet. Each tourniquet was presented Results
threaded or clipped in a closed loop and folded in approx-
imately quarters with the (primary) redirect buckle as the Applier and application process information is detailed in the
1
location of the center fold. 11–18 Each tourniquet was on the companion paper. In brief, 33 of 64 appliers had no prior
same side of the applier as the recipient’s feet and oriented tourniquet experience of any sort, 33 appliers (13 appliers
with the (primary) redirect buckle away from the recipient’s with some prior tourniquet experience and 20 appliers with
leg. 3–10 Appliers had to unthread or unclip the tourniquet to no prior tourniquet experience) had at least one application
place it around the limb; lifting the recipient’s foot to slide an process problem in each of their eight tourniquet applications
intact tourniquet loop up the leg was not allowed (considered (only 66 applications had no application process problems), 68
a trapped limb). Applications were considered complete when of 512 applications were not occluded at “Done” (55 because
the applier was hands off and stated “Done” or the director the applier stopped use of the tightening system prematurely),
stopped the application 5 minutes after saying “Go.” and 109 applications were not correctly secured at “Done.”

Application Timing Orientation
Total times were determined real time with a stopwatch Times to “strap secured” and to “touch tightening system” are
started by the director when saying “Go” and stopped when shown for each orientation in Figure 2 and for only the good
the applier removed his or her hands from the tourniquet and orientation in Table 1. Fifty-one applications (10.0%) started
said “Done” or at 300 seconds (5 minutes). Application-step- with strap/redirect orientations other than those shown. 2–10 In
related times (described in Appendix A) were determined later seven, appliers took time to change to the video-shown ori-
from a video-captured online stopwatch display (minutes to entation. Times from these seven are included in tightening
thousandths of a second displayed on a screen with a 60Hz system-related figures and analyses. Times from the 44 appli-
refresh rate). VLC media player version 3.0.16 (VideoLan, cations that remained in the alternate orientation are not in-
www.videolan.org) was used for playback (60 frames per sec- cluded in tightening system-related figures and analyses.
ond, interactive zoom, and the ability to play at 0.25 speed
with audio or advance frame-by-frame). Research assistant Strap/Redirect System
pairs provided consensus times; a researcher, CB, determined For each tourniquet, applications without strap/redirect prob-
final application-step-related times from videos. lems generally reached “strap secured” and “touch tightening
system” faster than applications with problems (Figure 2).
The timed segments in the application process are shown in Among applications without strap/redirect problems, self-
Figure 1 and relate to the y-axis times in Figures 2–5 and to the securing redirect systems had the fastest (clip and slider of
x-axis events shown in Figure 2 of the companion paper. The SOFTTW5) and slowest (no clip and overlapping rectangles
1
scoring criteria and definitions of major groupings are detailed Tac RMT) “strap secured” and “touch tightening system” times.
in Appendices B and C of the companion paper. 1 Threading/clip problems, minor and major understanding
problems, opening hook-and-loop problems, and hook-and-
Times of 300 seconds were used for strap/redirect system event loop interference during pulling (“bad pull hook-and-loop”)
failures and for tightening system event failures with no times as- resulted in slower “strap secured” and “touch tightening sys-
signed to events following the failure: 1) The six applications that tem” times. Bad pull technique had slower median times for all
did not reach strap security because of a broken (SOFTTW5)or tourniquets except the CAT7, but the p-values were all >.15.

incorrectly threaded (4 Tac RMT) redirect buckle or pulling at Tight applications were not slower than loose applications of
the wrong strap redirect (X8T) received “Go” to “strap secured” the same tourniquet. Applications with bad strap security were
and “Go” to “touch tightening system” times of 300 seconds. generally slower than applications with good strap security.
2) The CAT7 application that never went to rod rotation re-
ceived a “Go” to “touch tightening system” time of 300 seconds. For applications without strap/redirect problems, the median
3) The two CAT7, one SOFTTW3, and one RST applications times from strap secured to “touch tightening system” were
that never reached occlusion because of failure to understand <1.2 seconds. A bad, minor understanding problem, that re-
the tightening system received “touch tightening system” to “oc- sulted in slower times from “strap secured” to “touch tight-
clusion” times of 300 seconds and did not receive “occlusion” ening system” was appliers wondering what to do with what
to “Done” times. Applications that never reached occlusion be- they perceived as extra strap length.
cause the applier simply stopped tightening prematurely did not
receive “touch tightening system” to “occlusion” times. Among applications with good orientation, the fastest median
time from “Go” to “touch tightening system” was with the
Statistical Analysis SOFTTW5, as was the fastest median time for tight strap ap-
To control for order effects, the orders of watching applica- plications and secure strap applications (Table 1). The slowest
tion videos 3–10 and of tourniquet applications were separately median times for good orientation applications, tight strap ap-
randomized with 8x8 Latin Squares using www.hamsterand- plications, and secure strap applications were with the TMT
wheel.com. (Table 1).

34 | JSOM Volume 23, Edition 4 / Winter 2023