Tourniquets and occlusion: the pressure of design.

UNLABELLED

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.