Page 57 - JSOM Fall 2025

one fifth, one sixth, one seventh, two eighth applications. The of the sum-of-processes endpoint of occlusion at “Done”
TMT errors were two instances of balancing the rod on the was insufficient for across-all-tourniquets, first-use learning
wrong side of the rod-securing bracket, one was balancing improvements.
the rod at the open edge of the bracket, and nine had the rod
within the opening of the bracket but not clicked in. One of Providing instructor-origin feedback is crucial for critical
the nine with the rod not clicked in had four 180° rod turns endpoints that lack intrinsic knowledge-of-results regarding
making correctly securing the rod impossible. idealness of achieving the endpoint. Clear examples of the im-
portance of this are the presence of repeatedly inadequate strap
Event System Failures security in two experienced appliers, who perhaps never re-
The event system failures assigned times of 300 seconds were ceived feedback on this, and the lack of improvement in hook-
the following: 1) Four applications that did not reach strap and-loop strap security with second- and third-encounter
security because of a broken (one SOFTTW5) or incorrectly applications by no-experience appliers. The CAT7 and TMT
threaded (two Tac RMT) redirect buckle or pulling at the have rod security as an additional application process clearly
wrong strap redirect (one X8T) and received “Go” to “strap needing instructor-origin feedback regarding idealness of rod
secured” times of 300 seconds and did not receive “touch security. Of course, this also speaks to the training and ap-
tightening system” to ‘”Done’” times. 2) One CAT7 applica- plication advantages of designs that self-secure: no need for
tion that never went to rod rotation and received a “Go” to instructor-origin feedback on something addressed by the
“touch tightening system” time of 300 seconds. Each event design.
system failure occurred with a no-experience applier. One of
the incorrect strap/redirect rethreadings with a Tac RMT hap- Having knowledge-of-results is insufficient for improvement
pened in the last two applications. The other four event system without a clear method to improve subsequent results. Hav-
failures happened in a first tourniquet application (4 of 33 first ing occlusion present with hands off the tourniquet is an
applications versus 1 of 66 last applications, p=.041). The dif- endpoint involving more than one process and potentially re-
ference in event system failures between experienced appliers quiring some deeper understanding when using windlass-rod
and first tourniquet applications of no-experience appliers was tightening systems. Windlass-rod tightening systems required
0 of 30 first and last applications versus 4 of 33 first applica- continuous hands on until the rod was intentionally secured
tions (p=.115). in some fashion while ratcheting-buckle tightening systems in-
volved some natural release of hand pressure between buckle
Summary from Results for No-Experience Appliers advancements, allowing appliers a built-in moment to hear a
Table 1 summarizes the constellation of all the results: times, continued Doppler signal while deciding whether to continue
frequencies of problems, and frequencies of successes of no- tightening. Securing windlass rods took intentional and, some-
experience appliers. times considerable, physical effort that would require reversal
to continue tightening after initial rod securing; rod securing
was different for the four windlass-rod systems; rod securing
Discussion
involves some release of rod rotation; rod securing can easily
The key finding was that beneficial first-use learning occurred, include some hand pressure on the tourniquet, and rod secur-
but only regarding similar designs and simple processes closely ing takes more time than would just letting go of the rod. Con-
linked with knowledge-of-results feedback. Endpoints lacking tinuing the tightening process with a ratcheting buckle was
knowledge-of-results feedback did not improve despite similar simpler (no securing reversal required), was the same for all
designs (for example, correct hook-and-loop strap security). three ratcheting-buckle systems, and did not require any physi-
Additionally, in no-experience appliers, knowledge-of-results cal effort or hand pressure on the tourniquet to secure between

TABLE 1 Summary from Results of Applications by No-Experience Appliers
System Intrinsic knowledge-of-results Support for first-use learning
Strap/redirect (“Go” to “strap secured”)
All 8 tourniquets (1st vs 7th and 8th applications) Yes Yes, 7th and 8th faster (p=.008)
Highly similar, shared-design
CAT7/OMT Yes Yes, 2nd encounter faster (p=.0005)
SOFTTW3/SOFTTW5 Yes Yes, 2nd encounter faster (p=.079)
CAT7/TMT/OMT strap security No No, 2nd and 3rd encounter recurring security problem
Tightening (“touch tightening system” to “Done”)
All 8 tourniquets (1st vs 7th and 8th applications) Yes 7th and 8th faster (p=.236)
Highly similar, shared-design
CAT7/SOFTTW3/SOFTTW5/TMT tightening Yes No
OMT/Tac RMT/RST tightening Yes No
Across-tourniquet-designs
Rod security No* No
Occlusion (excluding preclusive event) Yes No, for windlass-rod systems
Yes, for ratcheting-buckle systems
*There were ways to make the rod not unwind that were not correct rod securing. An unwinding rod would provide intrinsic knowledge-
of- results that the rod was not secure. A rod that did not unwind despite incorrect securing would not provide intrinsic knowledge-of-results
regarding the incorrectness of the securing.

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