Page 55 - JSOM Fall 2020

FIGURE 1 OMNA marine tourniquet. snug against the limb with the inflated bladder correctly posi-
tioned and the redirect on the marked location. The number
of ladder teeth advanced (clicks) for occlusion and comple-
tion was recorded. Secured was defined as hands off after the
tourniquet was pulled tight and the hook-and-loop was se-
cured. Occlusion was defined as hands off following loss of
audible distal Doppler pulse (Ultrasonic Doppler Flow Detec-
tor Model 811 with 9.5MHz adult flat probe; Parks Medical
Electronics, www.parksmed.com). Completion was defined
with hands off one-tooth advance (one click) past occlusion.
During experiments, appliers did not receive information
regarding pressures. Data collection for each condition was
done in triplicate.

Thigh Applications
The involved thigh was parallel to the floor with the lower leg
at a right angle. Three thigh applications involved pulling the
strap down; three involved pulling the strap up. For down-
ward pulls, the ladder was on top of the thigh; both hands
were used to pull the strap down from the redirect buckle;
the dominant hand was close to the redirect; the nondominant
hand passed under the thigh to grasp the strap below the dom-
inant hand. For upward pulls, the ladder was on the bottom
Two OMNA Marine Tourniquets are displayed: one topside and one of the thigh; both hands were used to pull the strap up from
bottom side. The labeled parts are: A, Simple, smooth, round, low- the redirect buckle; the dominant hand was close to the redi-
friction redirect buckle. B, Tightly rolled hook-and-loop bite strap. rect; the nondominant hand passed over the thigh to grasp the
C, Self-securing ratcheting buckle. D, “Lift to open” release lever of
the ratcheting buckle. E, Toothed ladder. F, Hook-and-loop strap. G, strap above the dominant hand. The strap was secured (hook-
Neoprene-backed sleeve. and-loop to hook-and-loop); the subject’s hands were off the
tourniquet for 5 seconds; the subject advanced the ratcheting
buckle one-tooth at a time with hands off between advances to
above atmospheric pressure (baseline) secured beneath the occlusion, waited 5seconds with hands off, then advanced one
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tourniquet with the bladder starting 1cm away from the neo- more tooth to completion. After 5seconds, the subject released
prene sleeve, placing the bladder on the medial aspect of the the tourniquet by disengaging the hook-and-loop. Thigh down
thigh and arm. The bladder was connected to a Vernier Gas first or thigh up first was randomized in blocks of 12 for 60
Pressure Sensor, Vernier LabPro interface, and Logger Pro total subjects.
Software (Vernier Software and Technology, www.vernier.
com). Pressures were recorded every tenth of a second and Arm Applications
marked at secured, occlusion, and completion of application. Arms with circumferences <23.0cm were too small for the
tourniquet, and, to avoid pulling the bladder into the redirect
Tourniquet Applications buckle, only subjects with arm circumferences ≥30.0cm had
We conducted pilot work to decide on the directions of strap the pressure measuring system in place. Applications were by
pulling. Because we use the medial thigh as the pressure mea- the nondominant hand to the dominant arm. The ladder was
suring location, thigh strap pulling direction options were on the back of the arm. The strap was pulled across the chest.
with the redirect positioned on the lateral aspect of the thigh The strap was secured (hook-and-loop to hook-and-loop); the
and the strap pulled down or up (the study uses both). For subject’s hands were off the tourniquet for 5seconds. The sub-
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the arm, we investigated three strap pulling directions: redi- ject advanced the ratcheting buckle one-tooth at a time with
rect positioned laterally and strap pulling across the chest; re- hands off between advances to occlusion, waited 5seconds
direct positioned medially and strap pulling dorsally through with hands off, then advanced one more tooth to completion.
the armpit; and redirect positioned laterally and strap pulling Ratcheting buckle advances with the subject’s nondominant
dorsally (with pulling arm passed through the armpit). We hand were done by reaching between the body and around the
achieved the highest secured pressures pulling medially across backside of the dominant arm or by reaching across the front
the chest with the redirect buckle positioned on the lateral as- of the dominant arm. After 5seconds, the subject released the
pect. This technique allows splinting of the arm against the tourniquet by disengaging the hook-and-loop.
body. No techniques involved the bite strap, so we tightly
rolled and secured the bite strap to prevent it from interfering Statistical Analysis
with the hook-and-loop of the main strap during threading Double data entry with crosscheck was used for organizing
through the redirect. pressure data from LoggerPro into Microsoft Office Ex-
®
cel 2003 (Microsoft Corp., www.microsoft.com). Graphing
For all applications, subjects sat upright and were instructed and statistical analyses were performed with GraphPad
to maintain the involved limb in a relaxed state. Tourniquets Prism, version 7.04 for Windows (GraphPad Software Inc.,
were applied to dominant-side thighs and arms with the redi- www.graphpad.com). Unless otherwise stated, values in text
rect located mid-lateral on the limb. The location of the redi- are medians, minimums to maximums for means of replicates.
rect on each limb was marked for consistent tourniquet starting Fisher’s exact test was used for contingency data. Paired and
location. The pre-pull condition was with the tourniquet strap unpaired t tests were used to compare thigh down versus thigh

OMNA Marine Tourniquet Self-Application | 53