Page 53 - Journal of Special Operations Medicine - Spring 2017

Results of time to stop bleeding by model of tourniquet seconds), and the SOFTT-W was slow (mean, 18 sec-
were three tiered, with each model in its own tier. The onds). The order of after-time results was the same as
C-A-T was fast, with a mean time of 21 seconds; the time to stop bleeding except the RMT was first instead
SOFTT-W was intermediate (mean, 29 seconds); and of last. Each pairwise comparison differed significantly
the RMT was slow (mean, 34 seconds). Each pairwise (p < .001, all three pairs; Figure 2). The 0.08-second
comparison differed significantly (p < .001, all three difference in mean after-time between users was not sig-
pairs). nificant (p = .80).
Figure 2 After-time* results by tourniquet model.
†
The respective mean times to stop bleeding for the
unexposed and exposed tourniquets were as follows:
C-A-T, 19 and 23 seconds; RMT, 33 and 35 seconds;
and SOFTT-W, 26 and 29 seconds. Results of mean time
by model and by exposure were five tiered. The slowest
tier included exposed and unexposed RMT devices. The
next-to-slowest tier included unexposed RMT devices
and exposed SOFFT-W devices. The middle tier included
exposed and unexposed SOFFT-W devices. The next-to-
fastest tier included unexposed SOFFT-W devices and
exposed C-A-T devices. The fastest tier included unex-
posed C-A-T devices. Of 15 pairwise comparisons, only
four were not significant: exposed and unexposed RMT,
exposed and unexposed SOFTT-W, unexposed SOFTT-
W and exposed C-A-T, and unexposed RMT and unex-
posed SOFTT-W (p ≥ .056, all four pairs).

Total Trial Time Results: C-A-T, Combat Application Tourniquet; RMT, Ratcheting Medical
Overall and by Tourniquet Model Tourniquet; SOFTT-W, Special Operations Forces Tactical Tourniquet
For the overall study, 9% of the variance of the total Wide version.
*“After-time” was defined included time needed to secure the tour-
trial time results (i.e., sum of time to stop bleeding, time niquet, assess its placement, and assess response of the casualty to its
to secure the tourniquet and assess its placement, and use. After-time was calculated by subtracting time to stop bleeding
time to assess the casualty) could be attributed to the us- from total trial time.
Results of after-time by tourniquet model were three tiered, with
†
ers. Results of mean total time by user were two tiered: each model in its own tier. The RMT was fast (mean, 8 seconds);
user 1 (scientist) was slow (43 seconds) and user 2 C-A-T was intermediate (mean, 12 seconds); and SOFTT-W was slow
(cadet) was fast (37 seconds; p ≤ .001). Among the 256 (mean, 18 seconds). Each pairwise comparison differed significantly
(p < .001, all three). These are the results of 256 tests that had a good
effective tests, the mean total time results for all three outcome. The SOFTT-W took more time than the C-A-T after control-
models of tourniquet was 39 seconds; for unexposed de- ling hemorrhage, in part because it took longer to secure the windlass
vices, 38 seconds; and 43 seconds for exposed models (p into its clip; the RMT had no windlass to secure.
= .003). Results of total time by tourniquet model were
three tiered, with each model in its own tier. The C-A-T Pressure Results:
was fast (mean, 33 seconds), the RMT was intermediate Overall and by Tourniquet Model
(mean, 41 seconds), and the SOFTT-W was slow (mean, For the overall study, 21% of the variance of the pres-
46 seconds). Each pairwise comparison differed signifi- sure results could be attributed to the users. Among
cantly (p ≤ .048, all three pairs). the 256 effective tests, the mean pressure results for all
three tourniquet models was 203mmHg; unexposed
After-Time Results: devices had a mean of 204mmHg, and the mean of
Overall and by Tourniquet Model the exposed models was 200mmHg (p = .03). Results
For the overall study, 9% of the variance of the after- of pressure by tourniquet model were two tiered: the
time (i.e., total trial time minus time to stop bleeding) C-A-T and SOFTT-W were in the high tier, with means
results could be attributed to the users. Among the 256 of 206 mmHg and 204mmHg, respectively; RMT was in
effective tests, the mean of the after-time results for all the low tier at 198mmHg. In pairwise comparison, the
three tourniquet models was 12 seconds; unexposed de- C-A-T and RMT pair and the SOFTT-W and RMT pair
vices had a mean of 11 seconds, and the mean of the differed significantly (p = .0008 and .02, respectively).
exposed models was 14 seconds (p = .04). Results of Results of mean pressure by user were two tiered: user 1
after-time by tourniquet model were three tiered, with (scientist) was low (197mmHg) and user 2 (cadet) was
each model in its own tier. The RMT was fast (mean, high (208mmHg). The 9mmHg difference in mean pres-
8 seconds), the C-A-T was intermediate (mean, 12 sure between users was significant (p < .001).

Tourniquet After Environmental Exposure 31