Design For Maritime Disaster

HRV – Hypothermia Re‐warming Vest

The HRV is a product to quickly re‐warm hypothermia victims in maritime disaster situations. The vests
work by heating a threaded wire element that is concentrated for maximum effectiveness.

The human body loses heat 25 times faster in water. Even in 26 degree water hypothermia can develop
after prolonged exposure. When the body goes into hypothermic shock, blood rushes away from the
limbs and skin to warm the vital organs.

Re‐warming is not simply the process of heating the body. If the limbs are warmed at the same rate as
the torso, blood can rush to them, causing a dramatic drop in blood pressure known as re‐warming
collapse. Thus the heat must be targeted to the torso, in particular the main arteries in the armpits
(brachial), neck (carotid) and groin (femoral).

Using electric blanket technology one is able to create a precisely targeted network of heat elements
for the most effective re‐warming scenario.

Use of the product is simplified so that the rescuers can deal with many people in a short amount of
time. As such the neck is opened and can be Velcro‐ed. The arms wrap under the armpits and the groin
piece is simply wedged between the victims thighs.

The liner material is a fine microfiber fleece which has excellent wicking capabilities as well a superb
warmth retention and comfort. This is knitted with a special electric blanket loom that creates the
tunnels throughout. Another machine specially designed for electric blankets then pushes the wire
through the tunnels.

The outer material is GORE‐TEX which is water and wind proof, locks in heat and allows moisture to
escape.

It is important to note that the vest is designed to be used in conjunction with an emergency blanket.
Emergency blankets are highly effective at insulating heat (97%) and are already in wide use.
Furthermore they are extremely compact. Should a rescuer not have access to an emergency blanket,
any spare blankets or clothes to insulate the vests heat as well as protect the rest of the users body. This
is simply wrapped around the rescue to insulate the heat coming from the blanket.

The live system is completely insulated from water – the connection points are kept in the front pouch
which has taped seems for extra protection. This pouch incorporates the control through a window so
that the vest can be easily activated without its removal.

The battery is currently used in motorcycle heated jackets and can provide the wires with 60 degrees
heat at full power. It is flexible and waterproof.

The system does not require a thermostat as the wires have a positive temperature coefficient. That is,
their electrical resistance increases with the temperature which means they are self regulating.