Page 83 - JSOM Summer 2020

had 52% of its time spent and 86% of blood loss ocurring exercises may screen promising ideas for additional develop-
before the tourniquet touched the patient. The finding of how ment toward improving care. For example, if first-aid provid-
much bleeding occurred before the tourniquet touched the ers unwrap their tourniquet in preparation for emergencies,
patient was coherent with the research of the initial model, the deletion of that step may save certain amounts of time and
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where that amount was 406mL of 508mL, or 80%. Here, extra blood, which may inform decisions of doctrine. Geolocation
steps added time and bleeding. Because bleeding rates differed technology awareness among the public, use rates, and appli-
4.16-fold between the prior and present studies yet bleeding cation skills in pulling up GPS coordinates may help inform
proportions differed only 1.15-fold, the idea of proportionate best instructional practices. Knowing that the largest accrual of
loss before the moment of bleeding control may be more ro- losses in this model occurred during the phone-call step may in-
bust than we previously thought. The present findings consol- form the development of dispatching best practices. Dispatch
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idated with those of its predecessor, because patient bleeding time-segment data or its summary estimates could inform the
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came at the cost of steps such as donning gloves and calling selection of data for entry into math models. Time data for
9-1-1 while gloving mitigated risk of pathogen transmission performances among user cohorts, consensus for operational
among people. The step of greatest accrual of simulated blood definitions of steps, bleeding-rate data for limb wounds or spe-
loss, 31%, was in talking with a dispatcher, and this step is cific lesions (e.g., artery, vein, muscle, bone, or combinations),
sometimes recommended to be done before bleeding is con- and bleeding-rate models may aid investigators in developing
trolled. Speed in controlling hemorrhage matters. The design ideas of how math models may be refined for improved valid-
of the task also matters. In this study, the last redesign saved ity and reliability by being better grounded in real data and
little time but much blood. This method of redesigning a task by making the assumptions of the models better understood.
added a tool to the simulation toolkit. A limited proof-of-concept type of work may be routinely ex-
pected next in developing candidate designs, such as in a study
Another consequence of redesigning the task was that the user of manually performed steps upon a manikin comparing results
became hands-free of the tourniquet by earlier control of bleed- of differently designed tasks tested in a randomized order. The
ing. A benefit of being hands-free sooner is that those first-aid development of an autonomous tourniquet may help. Ongo-
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providers may attend more patients or perform additional life- ing coordination between dispatchers and other caregivers may
saving tasks sooner, such as packing another wound or hold- aid in developing doctrinal refinements.
ing compression on another bleeding wound. Also, hands-free
first-aid providers are mobile, such as among mass casualties or Conclusions
around an accident scene, whereas those still applying a tour-
niquet remain at the patient’s limb. Faster tourniquet use may In this study, we developed a mathematical model that gen-
help more people than the first patient and the tourniquet user. erated new knowledge in simulated redesigning the first-aid
On the other hand, a good time to learn how to pull up your task of tourniquet use. Modeled redesigns of the task revealed
global positioning system (GPS) coordinates to report them to risk-benefit tradeoffs between steps and people. Most blood
the dispatcher is not when you are talking on the phone with loss occurred before the tourniquet touched the patient, when
the dispatcher. There are many ways to slow aid, and there are patient bleeding came at the cost of donning gloves and calling
very few ways to speed aid. Both are true because there are 9-1-1, whereas gloving mitigated risk of pathogen transmis-
multiple essentials to skill. Speed is one. The 9-1-1 call is part sion among people.
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of the civilian task that makes the call findings more relevant
to the public than to military personnel, whereas the savings of Funding
time and blood loss are more relevant to the military. This project was funded by the US Army Medical Research
and Development Command.
Limitations of this study are numerous, due to its design. The
knowledge generated is of a low certainty because it tested Disclaimer
a hypothesis in a mathematical model that may be imple- The views expressed in this article are those of the authors and
mentable in manikin research. Within the model itself, only do not reflect the official policy or position of the US Army
in a perfect world are the onset of clinical indication and its Medical Department, Department of the Army, Department of
detection coincidental, yet that is how we train most learn- Defense, or the US Government. The authors are employees of
ers. Coincidence negates bleeding for the onset-to-detection the US Government. This work was prepared as part of their of-
interval to bias feedback as if users perform optimally. For the ficial duties and, as such, there is no copyright to be transferred.
tourniquet task, it is unclear how well first-aid providers ap-
preciate the number and types of steps. In the present model, Disclosure
The authors have indicated that they have no financial rela-
every step and trial was mechanically successful without er- tionships relevant to this article to disclose.
ror. Control achieved was never lost. Research simulations
are not real clinical performances, and readers of research re- Author Contributions
ports should not apply the present findings directly to the real All authors participated in study conception and design. J.F.K.
world. The math model remains in the idea incubator and is resourced, managed, and oversaw the study. J.F.K. generated
not ready for implementation, such as in teaching. The math the study data, and J.F.K. and J.K.A. analyzed the data. All
model used has limited breadth and depth so far, and such authors participated in writing the manuscript and approved
limitations beg additional work. the final version.

Future directions of scholarly work are numerous. By simu- References
lating a redesign of the first-aid task of tourniquet use by ma- 1. Gates JD, Arabian S, Biddinger P, et al. The initial response to the
nipulating its steps, some promising findings may be worthy Boston marathon bombing: lessons learned to prepare for the next
of additional research and development. Tests in manikin disaster. Ann Surg. 2014;260(6):960–966.

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