Page 90 - JSOM Winter 2023

and accessories useful in the times of turmoil. Using rapid https://nkhome.com/) to ensure all tests were conducted in
manufacturing methods and quick research and development similar conditions, including temperature and humidity.
processes, they have manufactured tens of thousands of parts
for Ukrainian nongovernmental organizations (NGOs), med- Before every test, ambient atmospheric pressure was measured
ical facilities, the army, and many others. Among them is a as a baseline, and this was subtracted from the absolute pres-
3D-printed tourniquet. sure recorded by the transducer to give gauge pressure. The
tourniquet, with the pressure cuff situated underneath, was
Therefore, this study aimed to investigate how the 3D-printed then tightened around a minimally compressible, water-filled
tourniquet compared to the existing and recommended com- bottle representative in the dimensions of a male adult upper
mercially available tourniquets with respect to how effectively limb and recording of pressure commenced. Each tourniquet
it attains and maintains effective pressure for an extended pe- was positioned and tightened by the same expert provider on
riod of time. every occasion. Once correctly in place, we aimed to tighten to a
starting pressure of more than 300mmHg above baseline. This
should be sufficient to stop arterial circulation in humans. 9,10
Methods
Most starting pressures were between 200−400mmHg above
Experimental Overview baseline. When beginning the test, all three tourniquets were
We compared three types of tourniquets for their ability to new and had never been before used. Each was tested 15 times
attain effective arterial occlusion pressure and sustain that for the full 120-minute period.
pressure thereafter. Two tourniquets were commercially avail-
able models and the third was a 3D-printed version based on Tourniquets
an open-source design. Each tourniquet was placed around a Three types of tourniquets were investigated in this project.
minimally compressible cylinder (Nalgene 32-oz Wide Mouth Each broadly consisted of a minimally-elongating, flexible
Tritan Water Bottle (diameter 8.9 cm), https://nalgene.com/) webbing strap used to encircle a limb, and a locking windlass
in accordance with the manufacturer’s instructions for appli- system capable of generating and maintaining tension within
cation. The 3D-printed version was placed according to the the webbing strap.
instructions of the C-A-T as no instruction has been provided
yet. Further, an air-filled cuff (Mindray “Small Infant,” https:// • Ukrainian model (3D-printed model, “Tech Against Tanks”
www.mindray.com/en) and pressure transducer system in- Charity): consisting of Acrylonitrile Butadiene Styrene
terfaced between the cylinder surface and tourniquet strap. (ABS) parts in conjunction with a 3.0-cm wide sturdy
Setup can be seen in Figure 1. Pressure measurements were non-elastic strap of seatbelt type (Type TN-30C-202-K50).
then carried out every 1 second for a continuous 120-minute This tourniquet was named the Ukraine model tourniquet
period. The 120-minute period was chosen based on TCCC and can be seen in Figure 2.
®
guidelines, stating that effort should be made to convert a • Combat Application Tourniquet Gen.7 (C-A-T, North
tourniquet within this timespan if bleeding can be controlled American Rescue, https://www.narescue.com/): consisting
through other means. 7 of a rigid plastic polymer windlass and buckle, in conjunc-
tion with a 2.5-cm wide nylon webbing strap. This tourni-
quet was named the CAT tourniquet in the present study.
®
• SOF Tactical Tourniquet–Wide (SOF TT-W, TacMed Solu-
tions, https://tacmedsolutions.com/): consisting of 6066
aluminum windlass and buckle, in conjunction with 3.0-cm
wide 6.6 nylon webbing strap. This tourniquet was named
the SOF tourniquet in the present study.
The CAT and SOF tourniquets are widely used in many North
Atlantic Treaty Organization (NATO) countries and are rec-
ommended by the CoTCCC. The products are marked CE
11
FIGURE 1 Setup for (conformité européenne), meaning they are tested according
tourniquet testing.
to the European Economic Area manufacturing and safety
standards. 12
Our investigation tested the efficacy of the “Tech Against
Tanks” flag project, a tourniquet developed in response to the
8
war in Ukraine. As of January 2023, the initiative had deliv-
ered over 2,000 tourniquets of their design to Ukraine, making
it thoroughly battle-tested and established (anonymous per-
sonal communication). The tourniquet can be produced closer
to the combat zone, with a prompter resupply line. 3D printers
can be relatively small and can be set up in shelters, cellars,
Procedures and other locations close to the war zone. The description for
The same lab was used for all testing. The lab was not in use the design and 3D printing is freely available. The Ukrainian
8
by anyone but two scientists during the testing period. Door model does not have CE marking, or other approvals or certi-
opening and human movement were restricted to a minimum. fications. Notably, the cost of materials is relatively inexpen-
Environmental data were monitored and continuously re- sive. Our test models have an estimated cost of less than three
corded (Nielsen-Kellerman Kestrel 5400 Heat Stress Tracker; dollars.

88 | JSOM Volume 23, Edition 4 / Winter 2023