Health Advice From The Flight Surgeon #1

Over the years, flying has developed into the safest form of transportation and the most popular, with more than one billion people travelling every year on aeroplanes. More and more passengers with chronic or latent (hidden) illnesses are also using this means of transport.

It was recently estimated that one case of in-flight illness will occur for every ten million Passenger Revenue Miles (PRM - one PRM being equivalent to one passenger being transported one mile), and that one flight diversion for medical emergency reasons will occur for every three billion PRM.
Let me emphasize from the start that flying is an extremely safe form of transport and safe also as regards the health.

Only a very few people will be unable to tolerate the stresses the body is exposed to when flying. Even passengers with severe chronic illnesses can fly safely - they just need to take some basic advance precautions, which require a little extra planning, These passengers are advised to contact their General Practitioner for advice and information prior to flying.

Most modern passenger aeroplanes fly at an altitude of 30-40,000 feet. To make high altitude flight possible for humans, modern airliners are equipped with pressurised cabins, This means that even though the aeroplane is flying at 40,000 feet, a pressure equivalent to an air pressure of 6 - 8,000 feet altitude is maintained in the cabin. In other words: the air pressure outside the cabin is only ¼ atmosphere whilst the pressure inside the cabin is ¾ atmosphere and therefore contains enough oxygen for passengers to function normally. Cabin air pressure at this altitude therefore poses no risk to healthy people.

In - Flight Problems

The main problems are those caused in particular by the thinner air (lack of oxygen) and the expansion of the air (in the middle ear, sinuses and stomach). But the dry atmosphere, confined space, lack of activity, and low fluid intake can also cause symptoms of illness to appear during the flight.

Strobe effects, or 'flicker', caused by the reflection of light from the aircrafts propellers, or the reflection when flying through layers of cloud can cause 'seizures' in some passengers who are predisposed to that. Passengers with this predisposition should avoid glare, perhaps by lowering their window visor or by wearing sunglasses.

Heart and Lung Diseases

If a passenger suffers from certain heart or lung diseases or from a low blood count, this may mean that not enough oxygen can be absorbed into the blood for distribution to the organs of the body. Signs of illness may then appear, depending on which organ is not being adequately supplied with oxygen.

If the heart is starved of oxygen, Angina Pectoris (heart cramp) may occur. If the brain is affected, this may cause confusion, paralysis or loss of consciousness. If suffering from a fever, the body's need for oxygen is increased significantly due to symptoms, which may appear at a very early stage in the flight. Passengers with fever are advised to avoid flying until the fever has subsided.

Passengers suffering from asthma must be in a stable state without recent attacks. Any medication should always be hand-carried.

For passengers with heart and lung diseases the rule of thumb is: "if you can walk the stairs to the first floor and back with no great difficulty, then you can stand the reduced pressure in the cabin during flight".

Middle Ear, Sinuses and Stomach

You can feel air expanding in the middle ear during take off, and contracting during landing. The air from the middle ear can only enter and exit through the Eustachian Tube, the channel that connects the inner ear to the back of the naso-oral cavity. Because of the shape of the Eustachian Tube, it is easier for air to get out of the middle ear than to get in. It often needs a helping hand, by holding the nose and breathing out gently with the mouth closed (this is called the Valsalvas manoeuvre).

It is important to do this all the time the aeroplane is descending, since the negative pressure in the middle ear can increase to the point that it causes the Eustachian Tube to collapse. If the mucosa is thickened, as when you are suffering from a common cold, for example, pressure- equalization may be impeded or even be impossible, the condition may become very painful and require treatment from a medical specialist, It is therefore advisable not to fly when the middle ear and sinuses are blocked due to an infection.

Some people, mainly children, have difficulties in carrying out the Valsalva Manoeuvre. If you have problems, you could use "Otovent", a balloon with a special mouthpiece, which is placed on the nose and blown. Otovent is available from good chemists.
When having difficulties in equalising pressure in the middle ear or sinuses during the flight, nasal spray or drops should be taken as early as possible during the decent. Most airliners carry a doctor's or attendant's kit from which this medication can be issued on an emergency basis.

Enjoy your flight!

By Steffen Lyduch, MD, Senior Medical Consultant to IHI Danmark Specialist in Aviation Medicine. Courtesy of IHI Danmark.

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