Tourniquet Pressure Magnitudes and Distribution During Limb Applications

Effective limb hemorrhage control depends on understanding how tourniquet pressure develops and is maintained. Prior work has emphasized overall occlusion pressure rather than pressure distribution, which influences tissue safety and device performance. This study examined SOF™ Gen 5 tourniquet pressure distribution and torque during key phases of tourniquet use.

Tourniquets were self-applied by novice participants on the upper arm and professionally applied on the thigh for 60 seconds.

All 34 applications (n=17) achieved and maintained arterial occlusion; four arm applications reached occlusion, but could not secure the windlass rod. Median occlusion pressures were ~320mmHg (upper arm, 260.68mmHg; thigh, 335.56mmHg). Pressure decreased minimally during securement (upper arm, 314.24mmHg; thigh, 343.88mmHg) and pre-release (upper arm, 297.80mmHg; thigh, 340.88mmHg). Pressure distribution across the 3.8cm tourniquet width (upper arm P=.305; thigh P=.428) showed a "bell-shaped" pattern with approximately 15% lower edge pressures than central pressures. Median windlass rod occlusion torque was 2.50Nm for upper arm applications and 3.31Nm for thigh applications, substantially lower than the participant maximum hand torque (median 10.70Nm).

This study described a human-limb method to characterize emergency-use tourniquet pressure distribution and torque behavior.