Page 28 - JSOM Fall 2021

had was not significant (median, 90 vs 91 seconds; p = .18; Limbs compressed differently for their indentation (squeeze
Figure 5). However, times were shorter for CT (median, 115 effect). Plastic pipes, glass bottles, a rain downspout, and a
vs 155 seconds; p < .0001) and TTT (median, 212 vs 278 sec- cardboard poster tube were hard and had no indent. One’s
onds; p = .02). hand-feel of forces varied—for example, limbs without indent
were stiffly hard and not lifelike. Limbs with intermediate in-
FIGURE 5 Time results by conversion type. dents were firmer than lifelike by hand-feel. The maximum in-
dent depth was in the noodles, the softest limb material used.
The indent looked similar among four noodle diameters at a
sixth of the limb diameter, a realistic fraction.

Among limb surrogates, hard and smooth surfaces led to
spontaneous slips of tourniquet displacement during loop
tightening. A common but not omnipresent displacement was
on smooth-bottle surfaces that sloped, such as toward a bot-
tleneck. On surfaces that were hard and smooth, tightened
TT is T→T, a tourniquet–tourniquet type of conversion (n = 83). PD loops resisted pushes upslope toward greater girths. However,
is pressure dressing as in T→PD, a tourniquet–dressing type of con- tightened loops could often be pushed downslope. In the fore-
version (n = 17). Only for tourniquet application time was the mean arm-sized glass bottle that was smooth, downslope pushes eas-
difference not significant. ily displaced the loop until reaching the waist. Further pushing
became harder upslope until progress stopped where the girth
Measured by whether the T1 to be converted was also used
as the conversion device, 80% were not, while 20% were, in equaled that of the original site. At the waist, loops could easily
hasty TCs from its highest site to another site at 2–3 inches slip circumferentially when pushed but resisted such displace-
above the wound. There was no statistically significant differ- ment on both slopes. Circumferential displacements occurred
ence between TAT and CT whether the T1 was also used as only with force: either a push by hand or a tourniquet–gurney
the conversion device (yes vs no; median, 95 vs 82.5 seconds; contact during limb movements. Cylindrical pipes and bottles
p = .08, and 125 vs 115.5 seconds; p = .39, respectively), but a allowed loop displacement by similar push efforts in four di-
marginal difference in TTT was observed (median, 239 vs 197 rections (axially proximal or distal, and circumferentially left
seconds; p = .05; Figure 6). or right). Yet no slip occurred on a noodle or a frosted texture.
Conversion concepts identified for development include top-
FIGURE 6 Results by whether an initial tourniquet (Tourniquet 1) ics from doctrine and materials (Table 2). Materials may need
applied was also used in its conversion.
research and development to see which users prefer. Conver-
sion metrics of performance may be developed. Conversions
grouping and typing may aid categorization and classification.
IT versus FT uses (simulated application and conversion) may
differ for blood loss. Simulations of conversion steps may gen-
erate time and blood loss results to inform doctrinal choices
about techniques.

TABLE 2 Conversion Concepts Identified for Development
Conversion materials may need development, research, or user
Initial tourniquet was applied in conversion (No, n = 80; Yes, n = 20). preference studies.
Only for total test time was the mean difference significant. Simulation of conversion steps may generate time and blood loss
results.
Regarding whether a visual wound check was performed be- Simulated application and conversion of IT and FT may test blood
fore siting the conversion device, results between check (54%) loss results.
or no check (46%) were not statistically significant (TAT, me- Conversion metrics (time, blood loss, ease of use, user
dian, 90.5 vs 89 seconds; p = .47; CT, median, 128.5 vs 112.5 performance) may be developed.
seconds, p = .29; and TTT, median, 228 vs 218 seconds, p = Conversions can be grouped and typed to develop categories and
.34; Figure 7). Wound checking cost little time and garnered classifications.
useful information but risked additional bleeding. Conversion concept names, symbols, abbreviations, and glossaries
may aid communications.
Conversion advice sought by caregivers may vary by their skill
FIGURE 7 Time results by whether a wound check was performed. level, novice to expert.
A tourniquet task may include subtasks (application,
reconfiguration, conversion).
Prompt, realistic feedback may aid learning by developing user
mechanical intuition.
Sizes of tourniquet loop opening may not fit over large limbs, big
boots, or some garments.
Clinical practice guidelines for conversion may be developed for
different settings.
Certain conversion types may suit some but not all levels of user
skill, novice to expert.
A wound check was performed (No, n = 46; Yes, n = 54). No mean dif-
ference was significant. A wound check by glance took minimal time. FT, field tourniquet; IT, improvised tourniquet.

26 | JSOM Volume 21, Edition 3 / Fall 2021