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Background: The Tactical Pneumatic Tournqiuet 2" (TPT2, 5.1cm-wide deflated) allows total average applied pressure measurement, which should be useful toward development of emergency-use limb tourniquet certification devices., Methods: The TPT2 hand bulb was replaced with stopcocks and syringes, allowing filling with continuous pressure measurement. Forearm and mid-thigh applications involved two sets of five Doppler-based pulse gone/return pairs. Second set pulse gones were chosen a priori for occlusion pressures (preliminary work indicated greater consistency in second sets)., Results: All 68 forearms occluded (30 female, 38 male, median circumference 17.8cm, range 14.6-23.5cm; median second set of pulse gone tourniquet pressures 176mmHg, range 128-282mmHg). Fifty-five thighs occluded (median circumference 54.3cm, range 41.6-62.4cm; median systolic pressure 126mmHg, range 102-142mmHg; median second set of pulse gone pressures 574mmHg, range 274-1158mmHg). Thirteen thigh applications were stopped without occlusion because of concerning pressures combined with no indication of imminent occlusion and difficulties forcing more air into the TPT2 (3 female, 10 male, peak pressures from 958-1377mmHg, median 1220mmHg, p<.0001 versus occluded thighs; median circumference 63.3cm, range 55.0-72.9cm, p<.0001 versus occluded thighs; median systolic pressure 126mmHg, range 120-173mmHg, p<.019 versus occluded thighs). Thigh TPT2 impression widths on five subjects after occlusion were as follows: 3.5cm, occlusion 274mmHg; 2.8cm, occlusion 348mmHg; 2.9cm, occlusion 500mmHg; 2.8cm, occlusion 782mmHg; 2.7cm, occlusion 1114mmHg., Conclusions: Though probably useful to tourniquet certification, the required pressures for thigh occlusion make the TPT2 undesirable for any clinical use, emergency or otherwise.

Background: We investigated emergency-use limb tourniquet design features effects on application processes (companion paper) and times to complete those processes (this paper)., Methods: Sixty-four appliers watched training videos then each applied all eight tourniquets: Combat Application Tour- niquet Generation 7 (CAT7), SOF™ Tactical Tourniquet-Wide Generation 3 (SOFTTW3), SOF™ Tactical Tourniquet-Wide Generation 5 (SOFTTW5), Tactical Mechanical Tourniquet (TMT), OMNA Marine Tourniquet (OMT), X8T-Tourniquet (X8T), Tactical Ratcheting Medical Tourniquet (Tac RMT), and RapidStop Tourniquet (RST). Application processes times were captured from videos., Results: From "Go" to "touch tightening system" was fastest with clips and self-securing redirect buckles and without strap/redirect application process problems (n, median seconds: CAT7 n=23, 26.89; SOFTTW3 n=11, 20.95; SOFTTW5 n=16, 20.53; TMT n=5, 26.61; OMT n=12, 25.94; X8T n=3, 18.44; Tac RMT n=15, 30.59; RST n=7, 22.80). From "touch tightening system" to "last occlusion" was fastest with windlass rod systems when there were no tightening system understanding or mechanical problems (seconds: CAT7 n=48, 4.21; SOFTTW3 n=47, 5.99; SOFTTW5 n=44, 4.65; TMT n=38, 6.21; OMT n=51, 6.22; X8T n=48, 7.59; Tac RMT n=52, 8.44; RST n=40, 8.02). For occluded, tightening system secure applications, from "touch tightening system" to "Done" was fastest with self-securing tightening systems tightening from a tight strap (occluded, secure time in seconds from a tight strap: CAT7 n=17, 14.47; SOFTTW3 n=22, 10.91; SOFTTW5 n=38, 9.19; TMT n=14, 11.42; OMT n=44, 7.01; X8T n=12 9.82; Tac RMT n=20, 6.45; RST n=23, 8.64)., Conclusions: Suboptimal processes in- crease application times. Optimal design features for fast, occlusive, secure tourniquet applications are self-securing strap/ redirect systems with an easily identified and easily used clip and self-securing tightening systems., (2023.)

Background: We investigated emergency-use limb tourniquet design features effects on application processes (this paper) and times to complete those processes (companion paper)., Methods: Sixty-four appliers watched training videos and then each applied all eight tourniquets: Combat Application Tourniquet Generation 7 (CAT7), SOF™ Tactical Tourniquet-Wide Generation 3 (SOFTTW3), SOF™ Tactical Tourniquet-Wide Generation 5 (SOFTTW5), Tactical Mechanical Tourniquet (TMT), OMNA Marine Tourniquet (OMT), X8T tourniquet (X8T), Tactical Ratcheting Medical Tourniquet (Tac RMT), and RapidStop™ Tourniquet (RST). Application processes were scored from videos., Results: Thirty-three appliers had no prior tourniquet experience. All 512 applications were placed proximal to the recipient's simulated distal thigh injury. Thirty-one appliers (13 with no experience) had 66 problem-free applications (18 by no experience appliers). Tightening-system mechanical problems were more frequent with windlass rod systems (26 losing hold of the rod, 27 redoing rod turns, and 58 struggling to secure the rod) versus ratchet systems (3 tooth skips and 16 advance failures). Thirty-five appliers (21 with no experience) had 68 applications (45 by no experience appliers) with an audible Doppler pulse when stating "Done"; causes involved premature stopping (53), inadequate strap pull (1 SOFTTW3, 1 RST), strap/redirect understanding problem (1 SOFTTW5, 1 X8T, 4 Tac RMT, 1 RST), tightening-system understanding problem (2 CAT7, 1 SOFTTW3, 1 TMT, 1 RST), and physical inability to secure (1 SOFTTW3). Fifty-three appliers (32 no experience) had 109 applications (64 by no experience appliers) not correctly secured. Six involved strap/redirect understanding problems: 4 Tac RMT, 1 X8T, 1 SOFTTW5; 103 involved improper securing of non-self-securing design features: 47 CAT7 (8 strap, 45 rod), 31 TMT (17 strap, 19 rod), 22 OMT (strap), and 3 SOFTTW3 (rod)., Conclusion: Self-securing systems have process advantages. Because most emergent tourniquet recipients require transport, we believe tourniquet security is a critical design aspect. Decisions regarding tourniquet choices may become very different when both occlusion and tourniquet security are considered., (2023.)