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TABLE 5 Algorithmic implications of tradeoff among results in conversion of a field tourniquet to a pneumatic tourniquet.
tourniquet interventions Even if in the future the field tourniquet is converted to an-
Personal Protective Equipment Use other field tourniquet on the manikin, it will still have the
No Yes problem of flashing lights when bleeding is controlled to start
• Less time to stop • More time to stop each conversion trial. We likely could not see these problems
Donning bleeding bleeding in the prior study because gauze covered the wound and its
• Less blood loss • More blood loss lights. Perhaps a software input overrides the mechanical in-
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• Higher risk of injury or • Lower risk of injury or put, since the manikin’s purpose is to train a user to control
disease spread disease spread hemorrhage, not to convert types of control. Should such an
• Other than to stop • Other than to stop
Wearing optimal manikin be developed, researchers and makers should
bleeding, times and bleeding, times and
blood losses are blood losses are provide input into its requirements in order to eventually ful-
affected little affected little fill the needs of the operational health community.
Limitations of this study are numerous because its design dealt
The minor finding of this study is that the conversion process with one caregiver and narrowly simulated health care. Simu-
was inadequately realistic because the manikin was not de- lation of multiple people might offer team or group data that
signed to simulate conversion. The stepwise conversion proce- are more representative of caregivers. The PPE that were se-
dure was workable, as a caregiver could learn its steps in order, lected were readily available, but also similarly not diverse.
but the hard manikin provided too firm a hand-feel. In addi- The manikin is passable as a limb segment to practice the con-
tion, it did not allow the pneumatic tourniquet to deform and version step order, but as a task trainer, the manikin poorly
realistically indent the limb surface, which distributes compres- suits conversion because it is nearly incompressible and pro-
sive forces into the deeper, underlying tissues. Under a 6mm vides incorrect feedback.
layer of silicone-like skin, the manikin has thin piezoelectric
transducers undergirded by a layer of hard plastic. Such hard- Conclusions
ness may protect transducers from high bending forces and
allow reliable readings with flat tourniquets. However, pneu- This study developed a method of simulating PPE donning ef-
matic bladders are rounded. The EMT inflatable bladder has fects on tourniquet use. How long it took to don equipment
two stacked layers—one toward the limb and one away from delayed the time to stop bleeding and increased blood loss, but
the limb. The nylon layers are heat-sealed together at their wearing PPE slowed down neither field tourniquet application
edges to form a long, wide band, which also has sealing exten- nor its conversion.
sions that incompletely cross for air to flow lengthwise. Sealing
extensions are evenly spaced lengthwise along the band. The Funding
sealing stabilizes the band on the limb as layers are bonded This project was funded by the US Army Medical Research
together only at sealed areas, which dimple the bladder on in- and Development Command.
flation to limit rounding. Otherwise, a bladder without sealing
extensions or dimpling takes the form of an inner tube, which Disclaimer
rolls down a conically shaped limb to migrate distally as pres- The views expressed in this article are those of the authors and
sures lessen because the limb is narrower. In use, one can see do not reflect the official policy or position of the US Army
the EMT band is initially uninflated and flat on the limb. With Medical Department, Department of the Army, Department
each pump of the hand bulb to inflate the bladder, the EMT of Defense, or the US Government. The authors are employees
incrementally rounds up on its topside away from the skin. The of the US Government. This work was prepared as part of
bottom-side rounds similarly, but radially inward toward the their official duties and, as such, there is no copyright to be
skin. The pumping-rounding increments separate the bladder’s transferred.
topside and bottom-side layers, except where they are sealed.
Disclosure
The authors have indicated that they have no financial rela-
On a nearly incompressible manikin, such layer separation
leaves the sealed areas suspended between the topside and bot- tionships relevant to this article to disclose.
tom-side to leave gaps between the sealed areas and the skin.
The adjacent areas to the sealed areas round to lift the sealed Author Contributions
JFK participated in study conception and design. JFK and
areas from the skin and offload transducers. In real patients, MAD resourced, managed, and oversaw the study. While JFK
the computerized tomography of limbs with applied EMTs collected data, both JFK and TDL analyzed data. All authors
showed no gapping from the skin because the human limb participated in writing the manuscript and approved its final
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is more compressible than the manikin. However, the manikin version.
is nearly incompressible, so its transducers detect lower pres-
sures at gaps where the sealed areas have less contact. Thus, References
when sampled over multiple transducers, there are some low 1. Kragh JF Jr, Dubick MA, Aden JK, McKeague A. U.S. military use
pressures resulting from this design artifact in the manikin. Be- of tourniquets from 2001 to 2010. Prehosp Emerg Care. 2015;19
cause of the hardness, an algorithm such as averaging nearby (2):184–190.
pressures would under-sample clinically relevant pressures. 2. El Sayed MJ, Tamim H, Mailhac A, et al. Trends and predictors of
Because the manikin is unrealistically stiff, such undercount- limb tourniquet use by civilian emergency medical services in the
ing underappreciates EMT capability. The manikin was pre- United States. Prehosp Emerg Care. 2017;21(1):54–62.
viously shown to be suboptimal as a platform or a tool to 3. Kragh JF Jr, Aden JK 3rd, Dubick MA. Tourniquets last to tourni-
quets first. J Spec Oper Med. 2020;20(2):20−21.
simulate conversion of a field tourniquet to a pressure dress- 4. Military Health System. Emergency Preparedness Response
ing. Likewise here, the manikin was suboptimal in simulating Course. https://www.health.mil/Training-Center/Defense-Medical
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