Page 29 - Journal of Special Operations Medicine - Winter 2014

Tourniquet Pressures:
Strap Width and Tensioning System Widths

Piper L. Wall, DVM, PhD; Ohmar Coughlin, MD; Mary Rometti, BS; Sarah Birkholz, BA;
Yvonne Gildemaster, BS; Lisa Grulke, BA; Sheryl Sahr, MD; Charisse M. Buising, PhD

ABSTRACT
Background: Pressure distribution over tourniquet width and occlusion changes beyond 1 minute would be of
is a determinant of pressure needed for arterial occlusion. interest.
Different width tensioning systems could result in arte-
rial occlusion pressure differences among nonelastic strap Keywords: tourniquet, hemorrhage control, first aid,
designs of equal width. Methods: Ratcheting Medical emergency treatment
Tourniquets (RMTs; m2 inc., http://www.ratcheting
®
™
buckles.com) with a 1.9cm-wide (Tactical RMT) or 2.3cm-
wide (Mass Casualty RMT) ladder were directly com- Introduction
pared (16 recipients, 16 thighs and 16 upper arms for
each tourniquet × 2). Then, RMTs were retrospectively Arterially occlusive emergency tourniquets are life-
compared with the windlass Combat Application Tour- saving tools with nerve damage as a survivor risk asso-
niquet (C-A-T [“CAT”], http://combattourniquet.com) ciated with applied pressure. Current theory suggests
1-3
with a 2.5cm-wide internal tensioning strap. Pressure was that increased tourniquet pressure may increase risk of
measured with an air-filled No. 1 neonatal blood pressure neuropathy. Among effective designs, pressure for arte-
cuff under each 3.8cm-wide tourniquet. Results: RMT rial occlusion relates to tourniquet width: wider tourni-
4
circumferential pressure distribution was not uniform. quets achieve arterial occlusion at lower pressure. This
Tactical RMT pressures were not higher, and there were suggests that a wider tourniquet could carry a lower risk
no differences between the RMTs in the effectiveness, of neuropathy following application. Some tourniquet
ease of use (“97% easy”), or discomfort. However, a dif- designs require tensioning beyond arterial occlusion to
ference did occur regarding tooth skipping of the pawl secure the mechanism. As a result, a tourniquet’s final
during ratchet advancement: it occurred in 1 of 64 Tac- application pressure may be higher than necessary for
tical RMT applications versus 27 of 64 Mass Casualty arterial occlusion depending upon the design for secur-
RMT applications. CAT and RMT occlusion pressures ing the tourniquet. 5
were frequently over 300mmHg. RMT arm occlusion
pressures (175–397mmHg), however, were lower than The Combat Application Tourniquet (CAT) is the tour-
RMT thigh occlusion pressures (197–562mmHg). RMT niquet currently deployed and most used by the US
effectiveness was better with 99% reached occlusion and Military. The CAT is a nonelastic 3.8cm-wide strap-
6
1% lost occlusion over 1 minute versus the CAT with based tourniquet with a windlass mechanism. Tighten-
95% reached occlusion and 28% lost occlusion over 1 ing is accomplished by winding an internal 2.5cm-wide
minute. RMT muscle tension changes (up to 232mmHg) ribbon strap. The CAT windlass is not self-securing and
and pressure losses over 1 minute (24 ± 11mmHg arm must frequently be secured at a pressure beyond arterial
under strap to 40 ± 12mmHg thigh under ladder) sug- occlusion.
gest more occlusion losses may have occurred if tourni-
quet duration was extended. Conclusions: The narrower The Tactical Ratcheting Medical Tourniquet (RMT)
tensioning system Tactical RMT has better performance and the Mass Casualty RMT are nonelastic, 3.8cm-wide
characteristics than the Mass Casualty RMT. The 3.8cm- strap-based tourniquets with self-securing ratcheting
wide RMTs have some pressure and effectiveness similar- mechanisms. Tightening is accomplished by pawl ad-
ities and differences compared with the CAT. Clinically vancement along a toothed ladder. Ladder widths are
significant pressure changes occur under nonelastic strap 1.9cm for the Tactical RMT and 2.3cm for the Mass
tourniquets with muscle tension changes and over time Casualty RMT (both narrower than the 2.5cm internal
periods as short as 1 minute. An examination of pressure ribbon of the CAT).

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