Page 47 - JSOM Summer 2019

FIGURE 8 Map of tourniquet fit by limb size. the modification, users were fast. However, the enactment in-
fluenced later steps in the directions. First, users paid attention
to pressing the nondominant (left for both users) thumb down
onto the adherence when turning the rod to mitigate risk of in-
advertent peel-back of the self-adhering fasteners. Speed of use
was also fast, in part, because only one turn was needed for
an infant’s limb, as compared to more turns commonly needed
for an adult limb. During the turn, users were momentarily
distracted during their first use by the dangling excess in the
band dangle and quickly formed a workaround by moving the
dangle away to drape it over a clip. Because this management
of excess band is a difference only in degree from management
for adult limbs, both experienced users intuitively incorpo-
rated the drape move into their troubleshooting skillset. Us-
ers already understood that specific way of troubleshooting
through its mechanical feel, but additional coaching gave it a
wording to aid its communication, comprehension, retention,
and even potential teaching to other people.
How well a tourniquet fit a limb differed by limb circumference. Limbs
more than 35 in. were too big. Limbs less than 4.25 in. were too small. Another influence was in the IFU-step directing: “Secure the
Mid-sized limbs were fitted easily. The 5.25-in. limb was difficult in rod inside a clip to lock it in place.” Here the users aided them-
that it required a modification in technique from the instructions for
use (IFU). Two borders occurred where the fit and no-fit results made selves by pressing the thumb to push the clip toward the rod
a boundary; the bigger boundary was 35 in. and the smaller boundary and to improve their alignment so that the rod would move
was 4.25 in. At these two borders, two modifications to the IFU were more easily into position. This action was impossible in the
required. At 4.25 in., the same modification required at 5.25 in. was 3.25-in. limb because its arc was most severe. The space be-
also made, plus there was another modification securing the rod by
figure-8 wrapping of the band. At 35 in., the first modification was tween the clips available for securing the rod became less when
that the user had to add manual compression to the self-adherence the band was self-adhered, as when a room’s ceiling looks
zone, which was extremely short and adhered tenuously. The second lower when its floor becomes carpeted. Although users no-
modification at 35 in. was that the user applied duct tape to the tour- ticed less space, their performance was unaffected. The excess
niquet for security. To aid the reader in putting the information into band was secured by wrapping it around the limb three or four
context, some cues may help. Robert Newhouse was a Dallas Cowboy
football player with 44-in. thighs—the size of a common medicine times and then placing it under the time strap. The duration
ball. The 35-in. border is the practical limit of the C-A-T self-adhering of such wrapping was longer than for adult-sized limbs, be-
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band if it is to self-adhere over a 2.25-in. length from the apex of the cause smaller limbs required more wrapping.
red tip to the buckle, and we used a plastic bucket to find that limit.
The 25-in. thigh is a common girth at the gluteal furrow of Soldiers
(65th percentile for women, 60th for men), and this matches a vol- The first minor finding was about vexing fits. Fits of tourni-
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leyball. The 5.25-in. infant limb was simulated by a handrail and is quets to infants brought forth several implications for care-
a common size for grips such as a dumbbell or gymnasium bar. The giving knowledge. In the smaller simulated limbs of infants
4.25- and 3.25-in. infant limbs were simulated by a pipe and pole, re- (i.e., 4.25 and 3.25 in.), tourniquet use was harder than for
spectively, and because dumbbells and bar grips are commonly scaled the large limb (i.e., 5.25 in.), likely because a second technique
to their weights, both sizes are also commonly seen in gymnasiums.
modification from the IFU was required by the user. Among
national anthropometric reference data for all ages of the US
Discussion population, our 5.25-in. limb approximates a 25th percentile
for mid-arm circumference of male babies 3–5 months old.
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The major finding of this study was that, on average, ease As it turned out before and after collection of the study data,
of mechanical use of a tourniquet on a simulated limb of an we felt this size was a testy challenge for us as experienced
infant was practicable. The ease of fitting a tourniquet to a tourniquet users but easy enough for systematic practice. Re-
limb that was 5.25 in. in circumference was evidenced among garding fit, some caregivers may intuit when treating an infant
100 uses by two users. However, the technique required a spe- that the guideline to place a tourniquet 2–3 in. above a wound
cific modification from the tourniquet’s IFU. The IFU states, might be scaled down. Also, the 2–3 in. above a wound may
“Pull the band tightly and fasten it back on itself all the way risk having the tourniquet override a proximal joint if the limb
around the limb, but not over the clips.” The modification segment is too short to accommodate both the guideline and
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was necessary because the limb circumference was so short the width of the device. For example, upper arms of male in-
that no length in the band was leftover to routinely self-adhere fants 3–5 months old at the 25th percentile of the limb seg-
it anywhere but between the clips. In other words, the band ment’s 4.69-in. length may need 64% (i.e., 3/4.69) of that
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slack was pulled out to the extent that the clips and buckle length for the 3 in., another 32% for the 1.5-in. width of the
eventually abutted one another. Abutment entailed that no tourniquet, leaving only 4% (100% minus 64% minus 32%,
fastener surface remained between the clips and buckle in the or 0.19 in.) available for the wound.
routine zone for self-adherence. A new zone of adherence was
between the clips, at 1.38-in. long. That length ended where The second minor finding was that ease of use was associated
the fastener surface stopped, where its opening exposed the with accrued experience through deliberate practice by a tour-
inner band, thus allowing inner band passage through the niquet user while under coached learning. By such practice, the
rod. This new zone is also crossed by a bar in the stabiliza- user perceived that, on average, the task became easier. Partic-
tion plate, which further limits the area available for contact ularly, faster and easier performance was graphically coupled
between the fastener surfaces. Despite these details of enacting to show speed and ease concurrently. To us, these aspects of

Tourniquets on Simulated Infant Limbs | 45