Page 31 - Journal of Special Operations Medicine - Spring 2016

Figure 2 Combat Application Tourniquet Generation 7 Table 1 Design Contrasted for Combat Application
is a prototype in redesign of the prior Generation 6. The Tourniquet Generation 6 and Generation 7
maker entered the prototype shown into production on
3 November 2015. Photograph is used with permission of Combat Application Tourniquet
North American Rescue Products. Trait Generation 6 Generation 7
Buckle Buckle has two slits Has one slit newly
contoured to ease
passage of the tip of
the band
Routing May be routed singly Can only be routed
or doubly singly

Windlass Diameter is smaller; Midshaft diameter is
grip rings are concave wider; grip rings are
convex
Plate Leading edge is Leading edge is
squared; plate is rounded; plate is
thinner thicker
Strap Windlass clip strap is Windlass clip strap
white is gray
Windlass Windlass clip is Windlass clip is thicker
Clip thinner without with buttressed sides
hemorrhage control, their ease of use, and the design buttressed sides
preference of users. Ten users of the two C-A-T de-
signs placed them on a manikin thigh to stop simulated
bleeding. Ten users conducted 20 tests each. The overall Briefly, effectiveness was determined by the cessation of
number of tests performed for the experiment was 200 blood loss (i.e., hemorrhage control). Iterations began
replicates. Data were collected in October 2015. with a tourniquet laid out flat and undone on the bench-
top. Iterations ended when the user touched the touch-
Users included four US Army instructors of medic pad button, assessing that the hemorrhage was stopped.
students, the US Army master instructor of medics, a Both designs had the self-adhering band routed singly
clinician-scientist with expertise in tourniquets, a tour- through the buckle. Users tightened tourniquets until
niquet research associate, and three laboratory person- they perceived that simulated bleeding stopped or until
nel with little to no experience with tourniquet use. The a tourniquet broke. The casualty had a medium build
clinician-scientist and research associate also were the and the setting was Care Under Fire, a setting resem-
trainers and assessors. The trainer-assessors were pres- bling emergency care when under gunfire.
ent during practice and testing to answer questions or
address problems such as in manikin use. Ease of use was assessed by each user and self-reported
using a Likert scale with a range of 5 numbers: 1: very
The control group was the C-A-T 6 tests, and the experi- difficult, 2: difficult, 3: neutral, 4: easy, and 5: very easy.
mental group was the C-A-T 7 tests. Several design traits Preference was self-assessed by users in answering the
of C-A-T 6 were refined in the C-A-T 7 version (Table 1). following question: If you had to go to war today, and
you could only bring C-A-T tourniquets of only one
Users had familiarization training in use of the manikin. type of model (either Generation 6 or Generation 7),
Training also included instruction in C-A-T use, famil- which would you prefer: 6 or 7?
iarization with both C-A-T designs, handling both de-
vices, and one or two practice uses for each tourniquet Descriptive statistics were used to portray results.
design on the manikin before testing began. A mixed-model analysis of variance (ANOVA) was
planned if user effects were large. Categorical data
The tourniquets were tested on a laboratory manikin (hemorrhage control in contingency tables) were ana-
that was designed to train users by providing feed- lyzed with a χ test, and the likelihood ratio p values
2
back on user performance. The investigators used a were reported. For pairwise comparison of designs, a
HapMed Leg Tourniquet Trainer (CHI Systems; http:// nonparametric Wilcoxon method was used. Significance
™
www.chisystems.com/p_medicaltrain.html); a simulated for results was established when p < .05. All statistical
right thigh with an above-knee amputation injury was analysis was conducted using SAS software (SAS Insti-
the testing apparatus. A previous report detailed use of tute; https://www.sas.com) and MS Excel 2003 (Micro-
the manikin in assessing first aid performance. 10 soft Corp.; http://www.microsoft.com).

Comparing C-A-T Gen 6 to Prototype Gen 7 15
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