title: Tourniquets and occlusion: the pressure of design.
abstract: Nerve injuries result from tourniquet pressure. The objective was to determine arterial occlusion and completion pressures with the 3.8-cm-wide windlass Combat Application Tourniquet (CAT) and the 10.4-cm-wide Stretch, Wrap, and Tuck Tourniquet (SWAT-T).
  
  
  METHODS
  Sixteen volunteers self-applied and had tourniquets applied to their thighs and arms (CAT and SWAT-T, random order, then blood pressure cuffs).
  
  
  RESULTS
  Occlusion (Doppler signal elimination) pressures were higher than predicted (p < 0.0001), highest with the CAT (p < 0.0001), and often lower than completion pressures (completion median, range: CAT 360, 147-745 mm Hg; SWAT-T 290, 136-449 mm Hg; cuff 184, 108-281 mm Hg). Three CAT thigh and 9 CAT arm completion pressures were >500 mm Hg. Pressure decreases and occlusion losses occurred over 1 minute (pressure decrease: CAT 44 ± 33 mm Hg; SWAT-T 6 ± 8 mm Hg; cuff 14 ± 19 mm Hg; p < 0.0001; loss/initially occluded: CAT 17 of 61, SWAT-T 5 of 61, cuff 40 of 64, p < 0.01). CAT pressures before turn did not have a clear relationship with turns to occlusion.
  
  
  CONCLUSIONS
  Limb circumference/tourniquet width occlusion pressure predictions are not good substitutes for measurements. The wider SWAT-T has lower occlusion and completion pressures than the CAT. Decreases in muscle tension lead to decreases in tourniquet pressure, especially with the nonelastic CAT, which can lead to occlusion loss.
authors.affiliation: Division of Trauma Services, Surgery Education Department, Iowa Methodist Medical Center, 1415 Woodland Avenue, Suite 140, Des Moines, IA 50309, USA.
authors.forename: Piper L
authors.initials: PL
authors.lastname: Wall
authors.forename: David C
authors.initials: DC
authors.lastname: Duevel
authors.forename: Mohamed B
authors.initials: MB
authors.lastname: Hassan
authors.forename: John D
authors.initials: JD
authors.lastname: Welander
authors.forename: Sheryl M
authors.initials: SM
authors.lastname: Sahr
authors.forename: Charisse M
authors.initials: CM
authors.lastname: Buising
mesh_terms: D000328:Adult; D004632:Emergency Medical Services / Q000379:methods*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D059348:Peripheral Nerve Injuries / Q000517:prevention & control*; D011312:Pressure; D011446:Prospective Studies; D013997:Time Factors; D014111:Tourniquets; D055815:Young Adult