Home' Defence Technology Review : DTR JUN 2015 Contents 21
DEFENCE TECHNOLOGY REVIEW | ISSUE 10 | JUN 2015
US Army medical researchers have developed a device
which they claim will “revolutionise” triage treatment of
About the size of a matchbox with an attached display,
the Compensatory Reserve Index (CRI) device has been
specifically designed for use during the first few, vital minutes
of casualty treatment.
The CRI clips on to the soldier’s finger, whereupon
it displays his vital signs: body temperature, heart rate,
breathing rate and blood pressure.
“One of the challenges now with triage is that with multiple
casualties on the battlefield, the medic may have a difficult
time determining which patients need to be treated first,” task
area manager for Tactical Combat Casualty Care Research
at the US Army Institute of Surgical Research, Joint Base San
Antonio, Texas, Lieutenant Colonel Richard Carter said during
Lab Day at the Pentagon on 14 May.
He explained that while someone who is bleeding profusely
might obviously need to receive care first, someone else may
be suffering from internal injuries caused by a blast that resulted
in injuries even more severe. But the extent of those injuries
would likely go unnoticed until the vital signs were taken.
Receiving the inputs from the CRI device wirelessly, a
single tablet displays the vital signs of multiple casualties
fitted with CRI. This enables the medic to attach CRI to
numerous patients and read their vital signs on the one
screen, removing the need to leave casualties unattended
whilst he/she deals with each individually. It also permits the
tracking and monitoring of vital signs that can properly inform
If the CRI indicates very poor vital signs, the medic would
The CRI device (blue, bottom right of photo), its attached
display and tablet display. Image: US Army
Device to “revolutionise” casualty treatment
then know to provide blood or resuscitative fluids to the
patient immediately, before it’s too late to resuscitate him.
Already in use by the Israeli Defense Force, CRI is currently
being tested by the US Food and Drug Administration for
certification. The Army is yet to determine whether or not
to field the device. Meanwhile, multiple civilian trauma care
centres and clinics around the US are testing and using the
device, as the Army has decided to share its technology.
– Matthew Mendenhall
THE SCIENCE BEHIND CRI
The most important aspect of CRI is the ‘machine-learning
algorithm’ embedded in its chip that drives its intelligence, COL
That algorithm extracts the patient’s vital signs using “a material
waveform-based photoplethysmography,” or in layman’s terms a non-
invasive, optical method of detecting blood volume changes in the
For example, each time the heart contracts, blood enters the finger
at a maximum rate and as the heart muscle relaxes, the amount of
blood decreases. The algorithm analyses the waveform it produces
over time, in seconds in real time.
If a patient is losing blood, the waveform changes and the
algorithm analyses the rate and type of change taking place. It
predicts how long the patient has before he ‘decompensates’ due to
loss of blood and reaches a dangerous threshold where death is a
risk. – US Army Tactical Combat Casualty Care Research.
ABOVE: The X Mini engine alongside the iPhone 6 for size
LEFT: LiquidPiston’s 70cc X Mini engine (right) next to a 49cc
Honda Metropolitan moped engine. Images: LiquidPiston
New heavy-fuel engine holds promise
Early LiquidPiston prototypes have validated the principles
and confirmed compression ignition of diesel and JP-8 fuels.
The company has built 70hp and 40hp compression ignition
heavy-fuel engine alpha prototypes, and recently unveiled a
70 cubic centimetre (3-5hp) gasoline powered rotary four-
stroke engine prototype known as the X Mini, which will serve
as the test platform for the work with DARPA.
Particularly suitable for portable and small-engine
applications such as that for unmanned aerial vehicles and
other equipment where space and weight restrictions are
common design requisites, an engine with improved fuel
efficiency and power density would also deliver increased
operational range for so-fitted platforms and fuel savings over
The technology also lends itself to in-service equipment
such as diesel/JP-8 generators. Whereas a typical 3kW
heavy-fuel generator weighing more than 135kg requires a
six-man lift, LiquidPiston’s engine technology may enable a
JP-8 generator of similar output to weigh less than 13kg and
be compact enough to fit in a backpack.
– Azar Fatwani
LiquidPiston has signed a US$1 million (AUD$1.29
million) agreement with the US Defense Advanced Research
Projects Agency (DARPA) to develop its compact, power-
dense, heavy-fuel rotary combustion engine technologies for
the US military.
The funds will be used to demonstrate a pathway towards
maturation of a rotary heavy-fuelled engine that could deliver
more than 50 per cent average brake efficiency, 57 per cent
peak brake efficiency and high power density (>1hp/lb),
using a test-bed environment. Such efficiency would reduce
fuel consumption by approximately 50 per cent compared
to today’s conventional piston engines, the company claims.
The effort will demonstrate key enabling components of
the engine technology, as well as enable initial JP-8 fuel
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