Page 50 - Journal of Special Operations Medicine - Spring 2015

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Figure 1 (A) Combat Application Tourniquet (Composite Resources, Inc.; combattourniquet.com). (B) Tactical Ratcheting
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Medical Tourniquet (m2 Inc.; www.ratchetingbuckles.com).
(A) (B)

the tourniquet strap and accompanying folding of the UnityPoint Health–Des Moines Iowa Methodist Medi­
limb tissues. The amount of strap bunching is expected cal Center. Two RMTs were previously requested from
to be directly related to the amount of mechanical ad­ and donated by m2 inc. An additional RMT was re­
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vantage system use (windlass turns or ladder distance quested from and donated by m2 inc. during the study.
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traveled). Lower tourniquet pressures prior to engaging The two CATs were purchased.
the mechanical advantage system require more mechani­
cal advantage system use and, therefore, are expected to Tourniquets
be associated with more strap bunching. If strap bunch­ This study used tourniquets with two different me­
ing significantly affects pressure transduction to the ar­ chanical advantage systems: the windlass CAT and the
tery, then changing the tourniquet pressure present at ratcheting Tactical RMT (Figure 1). Issues encountered
the beginning of use of the mechanical advantage system during the study led to the use of two CATs and three
should change the tourniquet­applied skin surface pres­ Tactical RMTs. Those issues are described in the Results.
sure at which arterial occlusion occurs.
The two CATs used in this study were of the same man­
The objective of this study was to examine the influence ufacturing generation. The CATs had a 3.8cm­wide,
of the initial secured pressure on tourniquet variables at 92.5cm­long, hook­and­loop covered fabric strap con­
occlusion and completion with two different mechani­ taining a 2.5cm­wide inner strap. The friction buckle
cal advantage systems. The initial secured pressure of each CAT was a two­slot, flat, plastic friction buckle
is the skin surface pressure when the strap is secured with grip­slot edges. The mechanical advantage system
through the friction buckle with no use of the mechani­ of each CAT was the running of the inner 2.5cm strap
cal advantage system and is defined as Friction Pressure through a slot on the windlass, the turning of which
in this study. The two different mechanical advantage would wind the inner strap around the windlass, result­
systems are the windlass and the ratchet. With the ing in pulling of the inner strap through the hook­and­
windlass system, strap bunching against skin can occur loop covered 3.8cm strap. The 2.5cm inner strap was
everywhere except under the firm area present under attached inside the free end of the 3.8cm strap in one
the Base (Figure 1A). With the ratchet system, strap direction and around the friction buckle on the other
bunching against skin can only occur under the firm side of the 9.3cm­long base plate. Shortening the inner
area present under the Ladder (Figure 1B). The over­ strap, therefore, resulted in increasing applied pressure
all hypothesis was that Friction Pressure would have on the surface of the limb. Both CATs had the follow­
a consistent influence on the amount of pressure that ing discomfort­reducing modifications made by the au­
must be applied by the tourniquet to the skin surface to thors: The bare hook surface of the hook­and­loop on
achieve arterial occlusion. the skin side of the rod locking clip was covered, and
the sharp corners of the base on the end near the friction
buckle were covered with the tape securing the pressure
Methods
monitoring size #1 neonatal blood pressure cuff.
This prospective study investigated the effects of Fric­
tion Pressure on tourniquet­applied skin surface pres­ The three Tactical RMTs were from three manufactur­
sure at arterial occlusion when using CATs and Tactical ing generations (identified as versions A, B, and C in
RMTs, and was approved by the UnityPoint Health– this study). Each had a 3.8cm­wide fabric strap with an
Des Moines Iowa Methodist Medical Center Institu­ attached toothed ladder (linear rack with teeth) and a
tional Review Board. The study was conducted at the friction buckle composed of a pair of overlapping metal

40 Journal of Special Operations Medicine Volume 15, Edition 1/Spring 2015