Staying healthy in the air
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Despite an ever-increasing number of people taking to the skies to travel distances both short and long, health issues during air travel are still surprisingly infrequent, at least for most healthy individuals.
Some people travelling on long-haul flights, however, can and do experience health concerns that might well involve serious and even life-threatening conditions. The good news is that many of these can be avoided or least minimised simply by being aware and taking the necessary precautions.
During the flight, three main factors can affect our bodily functions: modifications of oxygen concentration, changes in cabin air pressure, and lengthy immobility while remaining seated.
At cruising altitude of about 12,000 metres, the cabin in commercial planes is pressurised to maintain a pressure equivalent to 2,500 metres. This level of air pressure leads to lower oxygen absorption and results in about a four-percentage-point decrease in oxygen saturation in the blood, a condition known as hypoxemia. The vast majority of passengers do not feel this minor decrease in blood oxygenation but a few may develop symptoms similar to moderate altitude sickness with light-headedness, headache, difficulties in sleeping and nausea. However, in people suffering from blood disorders or any respiratory or cardiac condition, the effects of hypoxemia can trigger more severe manifestations such as accelerated heart rate, shortness of breath and even decreased consciousness.
In addition, the air pressure variations during the climbing and descending phases lead to significant changes in the gases volume present in some cavities in the body such as in the middle ear. The pressure difference between the air in the middle ear and the external atmosphere usually causes minor discomfort in the ear (a “popping” sensation) but may in some cases lead to an acute traumatic inflammation of the ear that is referred as otic barotrauma. Occurring mainly during descent, the manifestations include sudden pain, temporary hearing impairment and dizziness. The difficulty or the failure to equilibrate the pressure between ambient air and the air in the middle ear via the Eustachian tube (a small canal that links the middle ear to upper part of the throat) is responsible for the symptoms. Prevention includes swallowing, chewing or using the Valsalva method (a brief vigorous expiration against closed nose and mouth) to relieve the pressure in the middle ear. Decongestant nasal drops may be helpful. Importantly, people affected by an ongoing upper respiratory tract infection should not take a flight because of the risk of otic barotrauma due to obstruction of the Eustachian tube by the infection.
The third health concern is related to the prolonged immobility during flight that favours blood flow retention in the legs leading to swelling and discomfort. In some people, this slowing down in blood flow triggers the formation of clots in the veins in the legs, a condition known as deep vein thrombosis or DVT. Most clots are small and the body gradually breaks down the clot within a few days. However, some clots could suddenly detach from the vein and travel up through the circulatory system to become wedged in a pulmonary artery leading to a pulmonary embolism (PE). A large clot may result in a massive embolism of one of the main pulmonary arteries causing severe disturbance in blood oxygenation and possibly cardio-respiratory shock that could be fatal. Fortunately, in most PE cases, the clot is small and leads to much less impressive symptoms such as chest discomfort, cough with blood sputum, sweating and agitation. If pain suddenly occurs in a swollen leg during a flight, the person should lie down to avoid the clot from detaching until the medical team arrives.
During such a prolonged immobility, it is recommended to stand up and walk as often as possible (the contraction of leg muscles helps the blood flow) and at least every couple of hours, drink a lot of water to prevent dehydration and limit or refrain from alcohol or coffee, both of which cause dehydration. Compression stockings can also help and an anticoagulant may be proposed for those at high risk of blood clots.
People with existing medical conditions would do well to |consult their doctor or a travel physician before taking a |long-haul flight.
DR GERARD LALANDE is managing director of CEO-Health, which provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at [email protected].
