Page 19 - JSOM Spring 2021

under the tourniquet (physiology and physics). Limb tissue Author Contributions
changes that could result in an increase in tourniquet pressure PW, CB, and EH contributed to concept development and proj-
would be those that decrease tissue compliance or increase tis- ect design. All authors contributed to the acquisition, analysis,
sue volume: an increase in muscle tension under the tourni- and interpretation of data and the drafting and revising of the
quet or changes in muscle diameters that have a net result article. All authors had final approval of the manuscript.
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of an increase in tissue volume under the tourniquet (physics).
References
Along with time-related decreases in tourniquet pressure, 1. Kragh JF Jr, Walters TJ, Baer DG, et al. Practical use of emergency
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decreases in limb muscle tension, and increases in systemic tourniquets to stop bleeding in major limb trauma. J Trauma.
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blood pressure, 4,17 this study shows that passive limb position 2008;64:S38–S50.
changes can also cause tourniquet applications that were ar- 2. Kragh JF Jr, Littrel ML, Jones JA, et al. Battle casualty survival
with emergency tourniquet use to stop limb bleeding. J Emerg
terially occlusive when applied to have arterial pulses present Med. 2011;41(6):590–597.
at later evaluation. In addition to indicating the importance of 3. Teixeira PGR, Brown CVR, Emigh B, et al. Civilian prehospital
tourniquet reassessments during patient care, all of these are tourniquet use is associated with improved survival in patients
reasons for evaluations of tourniquet effectiveness on scene to with peripheral vascular injury. J Am Coll Surg. 2018;226(5):
differ from tourniquet effectiveness evaluations on arrival at 769–776.
medical care facilities. 4. Scerbo MH, Holcomb JB, Taub E, et al. The trauma center is too
late: major limb trauma without a pre-hospital tourniquet has
increased death from hemorrhagic shock. J Trauma Acute Care
In addition to tourniquet pressure and Doppler audible pulses, Surg. 2017;83(6):1165–1172.
this study included looking at the character of the tourniquet 5. Howard JT, Kotwal RS, Stern CA, et al. Use of combat casualty care
pressure trace during each limb position interval. We previously data to assess the US military trauma system during the Afghan-
noted that the presence of a visible, rhythmically pulsatile tour- istan and Iraq conflicts, 2001–2017. JAMA Surg. 2019;154(7):
niquet pressure trace was associated with and often preceded re- 600–608.
turn of a Doppler audible pulse in a study that involved 2-minute 6. Hingtgen E, Wall P, Buising C. OMNA Marine Tourniquet
self-application. J Spec Oper Med. 2020;20(3):52–61.
thigh tourniquet durations. When visible at the graph scale used 7. Wall P. OMNA Marine Tourniquet description [video]. https://
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during data collection, we consider the presence of a rhythmi- vimeo.com/434732616. Accessed 2 July 2020.
cally pulsatile trace as an indicator that arterial occlusion, as indi- 8. Wall P. Sitting, leg bent first, position effects on tourniquet pres-
cated by the Doppler audible signal, either is or will soon be lost. sure [video]. https://vimeo.com/490842933. Accessed 14 Decem-
ber 2020.
9. Wall P. Sitting, leg straight first, position effects on tourniquet
This small proof of concept study has the obvious laboratory pressure [video]. https://vimeo.com/490842998. Accessed 14 De-
setting limitations. Additionally, we knew that stopping tour- cember 2020.
niquet tightening with the ladder tooth advance that achieved 10. Wall P. Laying, leg bent first, position effects on tourniquet pres-
occlusion would result in loss of Doppler-indicated arterial sure [video]. https://vimeo.com/490843296. Accessed 14 Decem-
occlusion in most applications within 200 seconds with no ber 2020.
limb position change. We chose to stop tightening that near 11. Wall P. Laying, leg straight first, position effects on tourniquet
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the arterial occlusion threshold to maximize the likelihood of pressure [video]. https://vimeo.com/490843443. Accessed 14 De-
cember 2020.
having pulse change information to accompany any pressure 12. Wall P. Sitting, arm bent first, position effects on tourniquet pres-
change information. sure [video]. https://vimeo.com/490843614. Accessed 14 Decem-
ber 2020.
13. Wall P. Sitting, arm straight first, position effects on tourniquet
Conclusions pressure [video]. https://vimeo.com/490843642. Accessed 14 De-
Passive limb position changes can cause significant changes cember 2020.
in tourniquet pressure. Therefore, tourniquet adequacy should 14. Hingtgen E, Wall P, Buising C. Characterizing a system for mea-
suring limb tourniquet pressures. J Spec Oper Med. 2020;20(1):
be reassessed after any patient limb position change. 47–54.
15. Rometti MRP, Wall PL, Buising CM, et al. Significant pressure
Disclosures loss occurs under tourniquets within minutes of application. J
None of the authors have any financial relationships relevant Spec Oper Med. 2016;16(4):15–26.
to this article to disclose, and there was no outside funding. 16. Wall PL, Duevel DC, Hassan MB, et al. Tourniquets and occlu-
sion: the pressure of design. Mil Med. 2013;178(5):578–587.
PW and CB are paid by their respective institutions, and the 17. Schroll R, Smith A, McSwain NE, et al. A multi-institutional
other authors were volunteer researchers. None of the authors analysis of prehospital tourniquet use. J Trauma Acute Care Surg.
has stock in any tourniquet companies, and none do any paid 2015;79:10–14.
consulting with any tourniquet companies. The authors talk 18. Wall P, Buising C, Nelms D, et al. Effects of distance between
to and share data with any and all companies and individu- paired tourniquets. J Spec Oper Med. 2017;17(4):37–44.
als who are interested and will not keep any secrets. The lab 19. Wall P, Buising C, Grulke L, et al. Effectiveness of pulse oxime-
equipment belongs to Drake University and UnityPoint Health try versus Doppler for tourniquet monitoring. J Spec Oper Med.
2017;17(1):36–44.
Iowa Methodist Medical Center.

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