Oxygen is often pumped in through a flexible tube, called an endotracheal
tube, placed in the trachea. Inserting it is often very difficult, especially
at accident sites where a victim may be lying awkwardly.

Normally, the tube is passed down the throat and through the vocal cords
into the trachea. To see the vocal cords, the attendant tips the patient’s
head back-wards and uses a laryngoscope, a rigid L-shaped instrument that
holds the tongue out of the way.

Tipping the head, however, may aggravate any neck injury by injuring
the spinal cord, and the laryngoscope may damage the teeth and soft tissues
of the mouth. Also, the tube may be inserted too far, entering the airway
to only one lung, or be misdirected into the oesophagus, which lies just
behind the trachea, so that oxygen is pumped into the stomach.

The Trachlight is a patented system consisting of three parts: a handle
containing three AAA batteries and electronic circuitry, a plastic sheath
or ‘light wand’ 5 millimetres in diameter with a tungsten filament vacuum
bulb on one end, and a stiff wire that slides inside the light wand. Before
the endotracheal tube is inserted, it is clamped to one end of the handle.
The light wand containing the wire is inserted into the tube and attached
to contacts on top of the handle.

The tip of the tube is bent at 90 degrees and kept in that position
by the wire as it is pushed down. The bend makes the tube’s end large enough
that a laryngoscope is not needed to place the tube at the entrance to the
trachea, and also prevents it going any farther. Once the end is in position,
the attendant withdraws the wire and pushes down the tube containing the
light wand. The bulb on the light wand shines through the skin so the attendant
knows its position.

Withdrawing the stiff wire may change the position of the tube, but
the attendant knows it is still in the trachea as long as a glow is visible
at the front of the neck. If the tube is in the oesophagus, there is no
glow. If, as the tube is pushed down, the glow appears above the sternum
and then disappears behind it, the tube has gone too far and may be in the
airway to one lung. Once the endotracheal tube is in the correct position,
the attendant retracts the light wand.

The circuitry in the handle prevents overheating, and starts the bulb
blinking after 30 seconds – the maximum time it should take to insert the
tube before the patient starts to suffer from lack of oxygen. It also indicates
if the batteries are low or the bulb has burnt out, and regulates current
output to keep the bulb burning brightly as the batteries drain.

Orlando Hung, assistant professor of anaesthesia and pharmacology at
Dalhousie University and staff anaesthetist at the Victoria General Hospital,
both in Halifax, Nova Scotia, and his colleagues have tested the Trachlight
on more than 4000 patients and found other advantages. Heart rate and blood
pressure are less likely to rise than when a laryngoscope is used, and anatomical
irregularities such as abnormally shaped jaws and large tongues do not interfere
with the insertion of the tube. ‘It’s much easier and simpler to teach paramedics
and medical students how to use the Trachlight,’ says Hung. ‘It will significantly
affect emergency care in the field.’

The Trachlight was developed by Ron Stewart, a former emergency room
physician, and Geoff Garth, president of California Medical Corporation,
of Long Beach in California.

Luis Bate of the Atlantic Veterinary College in Charlottetown, Prince
Edward Island, is using microwaves to warm pigs at two critical stages of
their development. The first and more serious period occurs during the first
few hours after birth, because young pigs cannot regulate their body temperature
adequately.

It is common for the temperature of a newborn piglet to drop from its
normal 39 °C to 36 °C through the evaporation of placental fluid.
If its temperature drops to 35 °C it is in danger from hypothermia.
At 30 °C the piglet may be so lethargic it is unable to suckle and
may starve to death. Hypothermia and starvation account for over half the
mortality of newborn pigs and cost farmers millions of dollars every year.

At the moment, hypothermia is treated by putting the pigs under infrared
lamps. Instead, Bate uses microwaves at a frequency of 915 megahertz, compared
to the 2450 megahertz of a kitchen microwave. The lower frequency microwaves
penetrate tissues to a depth of three centimetres, almost twice as deep
as higher frequency microwaves, and can warm piglets with a diameter of
six to seven centimetres. The piglets can be warmed by 1 °C per minute
with no ill effects. He has successfully revived piglets with a temperature
of 25 °C – a stage at which they are usually considered beyond hope.

Though the microwave heater will cost more than an infrared one, it
will be cheaper to run as it consumes only 150 watts of power for a few
minutes. A 250-watt infrared lamp takes up to an hour and is less effective.

Bate has built a larger microwave heater, called a weaner deck, to help
pigs through their next critical period. At the age of four weeks they are
taken from their mother and weaned from liquid to solid food. Their heat
regulation is still not fully developed and the combination of changes again
makes them prone to cold stress, which will not kill them at this stage
but will inhibit their growth.

The weaner deck provides extra heat for the pigs by irradiating them
continuously with microwaves at 915 megahertz for four weeks. No adverse
effects have been found in the pigs or their offspring.

A company called D’Ossone Canada has been set up to make the microwave
machines and intends to have them on the market in about a year.