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Aviation Health News
 

ARRIVE IN BETTER SHAPE

ALCOHOL | ASTHMA | CHILDREN | DIABETES | DIZZINESS AND FAINTING | GAS EXPANSION | HEARING | HUMIDITY | HYPERVENTILATION | MEDICATIONS | MOUNTAIN SICKNESS | OXYGEN DEFICIENCY | PRESSURISED CABIN | SLEEP | AUTOMATIC SLEEP PILOT | STOPOVERS | SUPPLEMENTARY OXYGEN | WOMEN

ALCOHOL   Back to index

One in the air is equivalent to two on the ground – A well known adage among airline crews.

Most passengers are unaware that the cabin environment increases the effect of alcohol on the body.

It has been demonstrated in experiments that drinking two or three cocktails while airborne has the physiological effect of four or five drunk or terra firma.

Alcohol’s principal action is to slow down brain activity by restricting oxygen intake to the brain. When passengers ascend to moderate altitudes while on a plane they are already subjected to the additional oxygen deficiency caused by lower pressure in the cabin. This “double-whammy” makes alcohol have a much more powerful effect than normal.

Some air travellers who are more vulnerable than others to the concentration of alcohol in their bloodstream find that the consumption of only a couple of drinks can produce an “instant hangover” that lasts the duration of the flight.

Using alcohol to induce sleep on board may also backfire. Although step is promoted by alcohol because of its sedative effect, if more than a specified amount is drunk it can cause insomnia. Passengers who are used to an alcoholic nightcap of brandy or whisky may accordingly want to reduce their intake to half a glass of either, or to switch to a glass of wine.

As alcohol has a different potency in the air you may wish to limit your intake during the flight.

  1. Drink wine rather than spirits as a glass of wine has far fewer units than a glass of spirits. Beer, too has less units than spirits but is not recommended because of its gaseous content. Cocktails (such as a Bloody Mary or Martini) have the least number of units per glass.
  2. If you do drink alcohol, make sure it is only when accompanied by a meal.
  3. A drink before take-off may be a good solution because it will not only relax you but reduce stress. A glass of champagne, which is a “euphoric,” is an excellent way to begin a flight.

ASTHMA   Back to index

Some 5 percent of passengers on flights from the U.S. and the U.K. may have asthma, and between 5 and 10 percent may have had asthma in the past. Nevertheless, it is rare for acute asthmatic episodes to occur in the air, although factors such as how anxious the asthmatic passenger is and how stuffy the cabin is do come into play.

In general, air travellers with stable asthma tolerate the moderate oxygen deficiency of the pressurised cabin as long as adequate bronchodilator therapy (with or without corticosteroids) is used. On the other hand, severe chronic asthmatics should have a pre-flight evaluation before a long-haul trip to assess their arterial partial oxygen pressure (PA02). Such a measurement remains a reliable test for predicting their ability to withstand the lower pressure in the cabin. If this is less than the required 70 mmHg, provision can be made for supplemental oxygen on the flight.

As a standard procedure, asthmatics should review their treatment prior to their departure and ensure that they have an adequate supply of routine as well as emergency medications for their journey. This should include antibiotics if the sufferer is prone to chest infections. In addition, they should have a good management plan in the event of their condition deteriorating unexpectedly. All their medication should be readily available in their hand luggage and they should arrange to have a seat well away from the smoking section.

Time zone changes, too, should be taken into account. Passengers with moderate to severe asthma should continue taking their medication at their usual home time. On arrival, the intervals between medications should be adjusted to the local time. For example, if travelling from London to New York, the asthmatic passenger would take his or her medicine at, say, 11am London time, 4pm London time, then 3pm New York time (8pm London time), and so on.

Most major airlines are equipped to deal with asthmatic attacks as their medical kits contain appropriate drugs. Some have nebulizers on board too, such as Air New Zealand, while other airlines such as Cathay Pacific and Virgin can arrange to carry them if given at least 24 hours’ advance notice. If passengers have their own electric nebulizers they will not be able to use them on board because of the high-frequency 115V aircraft system. Oxygen is also on hand from portable canisters should they feel the need for it.

As a last resort, a diversion to the nearest airport can be arranged if necessary. This is costly for the airline, but such a decision is usually deferred to a doctor or physician (in 80 percent of cases there is usually at least one passenger on board who is a doctor).

Stress, which can sometimes precipitate an asthmatic attack, can be minimized on flights.

CHILDREN   Back to index

‘Some babies bark like seals on long-haul flights,” says Robert Hubbard of Delta Air Lines. “They tend to bet out of sorts, crying a lot, and produce a dry cough which is the result of dehydration. The remedy is to get them to breathe oxygen through a moist hand towel.”

Although children generally travel well, there are some points which parents should bear in mind.

Babies may suffer discomfort by pressure changes during aircraft descent; providing them with a bottle or dummy facilitates the equalization of pressure. Howling pitifully is another method of resolving the problem, but is of course a lot harder on the baby, his or her parents, and other passengers. Older children should be given chewing gum or boiled sweets (sucking candies).

An interest in flying is something that parents can encourage at an early age. John Munday is a nine-year-old who has flow to Los Angeles from London to visit his grandparents on 12 occasions since his birth. When he travels, he enjoys looking out of the window at the clouds and visiting the cockpit. As he really likes flying he has already had three flying lessons.

There is also a category of young flyers known by the airlines as unaccompanied minors (UMS). They hang out in a special executive lounge, the Sky Flyer, at Heathrow and are more assured than other children of the same age. On board, these young flyers roll their eyes throughout the safety demonstration, are experts with the seat controls and sometimes even try to order a Bloody Mary! But however blasé they appear to be, most are still accompanied by their favourite cuddly toy.

As infants have a higher water content than adults (some 70 percent compared with 50-60 percent), they should be given small amounts of water at regular intervals during the trip. This will ensure that they do not become dehydrated. Children with bad colds or problem ears should not be taken on long-haul flights as they may be in great discomfort or even pain. The use of a decongestant may be helpful.

DIABETES   Back to index

Although two to three passengers on board aircraft tend to have diabetes, some are too embarrassed to announce the fact.

As a result, it is not surprising to find that diabetes is in a list of seven of the most frequent in-flight medical problems. “Some typical incidents happen when passengers with diabetes drink alcohol, particularly white wine,” says Robert Hubbard of Delta Air Lines. “They become aggressive and demanding, only later to confess their condition.”

There is no need for this to occur if passengers with diabetes plan well in advance of their trip. The difficulties that long-haul flights present include irregular meals, alcohol and insufficient exercise, resulting in inappropriate amounts of insulin and/or inappropriate snacks. This can give rise to hyperglycaemia (where the blood sugar level is too high) and perhaps serious problems on arrival, or to hypoglycaemia (a fall in blood sugar).

The medical kits of most major airlines do contain drugs to treat hypoglycaemia in case this problem arises during a flight. However, it is important for passengers with diabetes to ensure that their medications have been packed in their hand luggage.

Passengers with diabetes who undertake journeys over several time zones should remain on home time throughout as regards meals and medication. This can be achieved with good planning through the cooperation of the airline or when the passengers include their own food together with their medications in their hand luggage.

An additional factor to consider in westward or eastward travel is that the insulin regimen will have to be adjusted slightly. For westward travel, the shift in time zones should be covered by one or two extra injections of short-acting insulin. The additional dose should be about 20 to 30 percent of the total daily dose. A decrease in dosage, by a similar amount, on eastbound flights maintains sound glycemic control. This is achieved by slightly reducing normal doses during the flight.

Keep well hydrated during the flight, as some people with diabetes can be prone to dizziness on board. A quick fix for a hypoglycaemic passenger, according to a Lufthansa purser, Christine Behmer, is either a Coke or an apple juice because of their sugar content.

DIZZINESS AND FAINTING   Back to index

“The “Coke fix” is the tried and tested method to prevent fainting on board,” says Woody Watkins of American Airlines who has been flying since 1968. “As soon as passengers complain of being hot and giddy, I get a Coca-Cola down them as fast as possible.”

The most common problem for passengers on long-haul flights (noted specifically in those seated at the rear of aircraft such as the Airbus 340 and Boeing 767) is dizzy spells, which usually result in fainting. This temporary loss of consciousness through deficient blood supply to the brain can occur after a meal and/or when a passenger rises after prolonged sitting. There are also instances of passengers who wake up after several hours of sleep to find that they feel hot and sweaty, who then faint as soon as they move around.

The digestion and absorption of food results in a rise of blood flow to the intestines, which is compensated by an increase in the heart rate. Consequently, blood-pressure and the flow of blood to the brain are not compromised. There are exceptions, however, such as in the case of elderly passengers and those with cardiovascular conditions or non-insulin dependent diabetes mellitus. In these cases, eating may cause a fall in blood pressure and lead to feelings of dizziness, light-headedness and even to fainting. An additional factor which may have a bearing on the condition is the oxygen deficiency of the cabin, whereby a small drop in blood pressure may have a significant effect on cerebral function. Alcohol, too, raises the blood flow to the intestines and the heart rate.

According to Pat Evans, a flight attendant on Virgin Airlines, the majority of those affected are overweight and male. On Lufthansa flights, the candidates vary in age from 25 to 40 and are mainly the result of ground stress and aerophobia. A flight attendant from the airline also advised placing a cold Coke bottle behind the ear to prevent fainting.

The standard procedure on board is to wait for the passenger to faint before raising his legs to return the blood to the brain as quickly as possible.

These incidents can be also ascribed to vasovagal fainting. In such an instance, all the arteries dilate, draining blood from the head and, finally, the cranial nerve (the vagus) slows down the heart rate. It is a result of the failure to maintain an adequate venous return of the blood to the heart due to its pooling in the feet after prolonged standing or sitting. This common cause of fainting, which is associated with symptoms of sweating, nausea and pallor, is also likely to happen through fear or anxiety and because of oxygen deficiency. It is a well-known phenomenon among aircrew.

The moment you feel dizzy, you need to get some volume in fast. Any liquid intake (with the exception of alcohol) will do, whether cola, juice, plain mineral water, etc. There is also the other remedy of lowering your head between your knees to increase circulation if you are feeling hot or nauseated. In the case of elderly passengers, it may be prudent to eat lightly on board or to have a meal high in carbohydrates with coffee. There is evidence that drinking coffee at the end of such a meal prevents the drop in blood pressure.

The risk factors for the condition include dehydration, hypoxia (oxygen deficiency), changing position from seated to upright, prolonged sitting, alcohol, and medications for high blood pressure (such as beta-adrenergic blockers).

Douglas Adams, author of The Hitchhiker’s Guide to The Galaxy, fainted during the dramatic cardiac injection scene in Pulp Fiction on a flight to Australia. An additional factor, such as strong emotion, can tip some individuals into syncope and consequently they should avoid watching violent films on aircraft.

GAS EXPANSION   Back to index

Delta Air Lines, which carries 87 million people a year, has noticed an increase in the incidence of gas pain among its passengers.

The body contains a number of gas-filled cavities such as the ears, sinuses, lungs and stomach, which communicate with the surrounding atmosphere. In accordance with Boyle’s Law, the gas will expand on ascent in an aircraft by some 30 to 35 percent, and while there is unrestricted access between the cavities and the surrounding atmosphere, this expansion will occur unnoticed. However, if this pressure build-up cannot be relieved it may cause considerable pain.

The most common site in the body for trapped gas is the middle ear, where a condition called otitic barotraumas can arise. Here, inadequate ventilation causes pain in the middle ear, particularly if an infection is present. It can also result in temporary deafness, tinnitus or vertigo. The effects of pressure changes on the middle ear cavity is a good example of this. The cavity of the middle ear is separated from the outside by a thin diaphragm, the eardrum, which communicates with the back of the throat through the Eustachian tube, comprised of soft walls that collapse together.

During ascent, the expanding air easily escapes along the Eustachian tube and pressure is maintained equally on both sides of the ear drum. (The popping sensation sometimes experienced is due to the air escaping down this tube).

During descent, the collapsed walls of the Eustachian tube tend to act as a valve preventing air from flowing back into the middle ear cavity. The resultant pressure build-up on the outside of the eardrum distorts the drum inward. As the degree of distortion increases with descent the pressure differential across the drum causes a sensation of fullness in the ear, a decrease in hearing and local pain. If the descent continues without equalization of pressure, the eardrum may perforate. In some passengers the rapid increase of pressure in the middle ear cavity can affect their organs of balance and cause vertigo.

When Leslie Lefkowitz of the Ritz-Carlton flew at the age of 16 for the first time, she experienced a sharp pain in an upper left tooth. What frightened her was that it came from nowhere. She begged for an aspirin from the flight attendant to relieve her discomfort. Ever since she has always taken one on a flight in case that intolerable pain returned.

  1. Pressure changes: Sometimes it is necessary to perform a manoeuvre to open the Eustachian tubes, such as yawning, swallowing or (in the case of babies) screaming. A more soothing alternative for the latter is to offer them a dummy or bottle. Should these actions fail to clear the ears, the Valsalva manoeuvre should be attempted. Here you inhale and then close your nose with a thumb and forefinger and exhale – keeping your mouth closed.
  2. Colds: In the case of inflammation of the middle ear or otitis media, it is advisable not to fly. For head colds (which may cause congestion and swelling of the lining of the Eustachian tube) or sinusitis (in which the lining of the sinus is swollen), a nasal decongestion spray may help to ease the pain. However, again it is better not to fly with such conditions. If you do fly and your hearing does not return to normal, you should seek medical advice urgently to prevent the risk of permanent damage to the middle ear. Parents often do not appreciate the damage that a child can suffer as a result of otitis barotrauma.
  3. Infected cavities: As a general principle, any cavities or semi-cavities of the body that are either infected or inflamed are likely to cause pain and should be treated beforehand. These include loose deep-seated dental fillings, intestinal infections and any areas where air circulates or has access, such as the thoracic cavity.
  4. Surgery: Air enters the body during surgery and you should not travel until this air has been reabsorbed into the bloodstream. Otherwise, the gas may expand and cause a haemorrhage. Factors that delay healing include advanced age, steroid treatment, diabetes, obesity and smoking. Allow a reasonable period (at least a week) before considering air travel.
  5. Plaster casts: Passengers with limbs in casts should consider having them split if they undertake long-haul flights. Air trapped within the cast can expand and compress the underlying tissue, causing a circulatory obstruction.
  6. Stomach: A common semi-cavity that is usually overlooked is the stomach, where gas can expand by about 30 percent during a flight. For this reason, carbonated drinks and foods such as peas, beans, roughage, cabbage and cauliflower should be avoided.

HEARING   Back to index

Temporary hearing loss is an unusual consequence of flying, as some passengers may be vulnerable to noise (such as that of the jet engines) on board an aircraft.

Prolonged moderate-to-high noise levels are well known for producing a phenomenon called Temporary Threshold Shift (TTS). This consists of a decrease in auditory sensitivity which can last from minutes to days or even weeks depending on the nature of the noise and the length of time a person is exposed to it. The stimuli that have been known to induce hearing loss have usually consisted of very high intensity, spectrally simple signals such as pure tones or broad band noise over relatively short periods of time (up to a few hours). The condition can be debilitating, particularly if a passenger has to attend a meeting or other important engagement soon after arrival.

If your hearing is sensitive it is best to wear earplugs on board and to ensure that your seat is well forward of the engines, where the noise levels are lower. Some airlines, such as JAL, supply Sony earphones which neutralize back-ground noise.

HUMIDITY   Back to index

A component of cabin air that is usually overlooked is the moisture content, as few passengers realize that it helps prevent infections.

The humidity level within the cabin tends to be low, partly because the outside air at high altitude contains 66 percent less water than at sea level (about 0.15 g/kg of dry air compared to 10 g/kg respectively) and partly due to the fact that the air, which enters at a temperature of about 54ºC/65ºF below zero, has to be heated.

The relative humidity in aircraft, which can vary from 2 to 23 percent, is far from the comfort zone of between 30 and 65 percent recommended by both the Association of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) and the National Institute of Occupational Safety and Health (NIOSH). Low levels of humidity, together with contributing factors such as tiredness, stress, age (the elderly, children and babies seem to suffer most) and antibody status increase our susceptibility to infection.

Low humidity causes the filtering functions of the nose and upper airways to be compromised. When air is breathed in, it enters the nose, passes down the trachea and through the upper airways to the lungs. On its way to the lungs the air is heated, humidified and filtered. The important factor in this process is found in the cellular structure of the lining of upper airways. Along this route from the trachea to the bronchi and the bronchioles lies the body’s protection network against infection. The surface of these cells is covered in fine hair-like projections called cilia.

There is a layer of mucus around the cilia which is continually secreted by goblet cells. The cilia beat constantly, much like corn moving in a cornfield, and carry the layer of mucus up towards the back of the throat where it is swallowed. Any inhaled micro-organisms or specks of dust which have escaped the hairs in the nose soon get trapped in this layer of mucus and are returned to the back of the throat, where they are swallowed.

In environments with low humidity, such as aircraft, inhaled air reduces the moisture content from the mucus to such an extent that the layer becomes viscous and concentrated. When this occurs it is more difficult for the cilia to beat and the mucus, rather than being moved along to the back of the throat, remains in the respiratory tract for a longer period, where it can cause infection.

Of the micro-organisms carried by the air, it is viruses – particularly respiratory viruses – which survive better than bacteria in low humidity. This could explain the fact that passengers tend to suffer from upper respiratory infections post-flight. The other reason, of course, is inadequate cabin air filtration.

There are several examples of airborne viruses that cause disease. Influenza, which infects the upper and lower respiratory tracts, can in its mild form cause flu, but in susceptible people this can progress to viral pneumonia. In the case of the common cold, many different viruses can be responsible.

1. The obvious method of preventing infection on board an aircraft through low humidity is to drink water.
2. Fly on crowded flights. Moisture from other passengers’ breathing and perspiration can increase the relative humidity dramatically. In the instance of an eight-hour flight in a CD-10 with 265 passengers, the humidity level can rise to 20 percent; the same flight with only 108 passengers sees this level fall to 2 percent. Aircraft which have recirculated air have a higher humidity level than those with only a 100-percent fresh airflow.
3. Frequent flyers should regularly use rehydration gels or moisturizers, such as Prescriptives Flight Age Cream, to protect their skin from the drying, aging effects of low humidity levels.

HYPERVENTILATION   Back to index

Hyperventilation, which is common among passengers, has an unusual feature (known to those who participate in certain voodoo ceremonies, particularly mutilation): it anaesthetizes the participant.

This condition, which denotes fast or over-breathing, affects a large proportion of pilots during training, as well as experienced flight crew on the occasions when they are under mental stress. The pattern among air travellers is similar, and it is the most inexperienced flyers who tend to breathe too fast.

The most obvious trigger on board is the oxygen deficiency, or hypoxia, that causes increased ventilation, among other things, as the body makes an effort to compensate for the lack of O2. Another trigger which is commonplace on the ground (where the condition is usually described as hysterical panting) is mental and emotional disturbance. However, during a flight there are sufficient environmental influences such as motion sickness, body vibration, air turbulence and a hot, stuffy cabin, as well as the possible contributory factors such as anxiety and emotional stress. To a lesser degree, there are certain drugs that can stimulate breathlessness such as stimulants and oral contraceptives.

The symptoms of the condition are dizziness, palpitations, a tingling sensation in the limbs or face and pain, discomfort or a tightness in the chest. The last symptom can lead to hyperventilation being mistaken for an attack of angina.

When hyperventilation occurs, large amounts of carbon dioxide are exhaled. Low levels of CO2 in the blood upsets the acid-alkali balance and the blood becomes more alkaline, leading to alkalosis. Essentially, the condition inhibits the catalytic activity of enzymes, which can affect the cardiovascular and central nervous systems. The hyperventilator can experience severe chest pain and signs such as blurred vision and dizziness as the blood flow to the brain decreases with the onset of hypoxia (oxygen deficiency).

As a group, hyperventilation affects men and women equally; those who are most prone are meticulous, hard-working perfectionists.

  1. If you find yourself overbreathing, re-breathe the air you have exhaled by breathing into a paper bag. Also, make a conscious effort to breathe more slowly.
  2. As hyperventilation can chalk up losses of moisture, it would be prudent to drink lots of water to rehydrate your body after an episode.
  3. Some air travellers who often overbreathe on aircraft may find that they are breathing incorrectly. Instead of taking deep breaths, they are indulging in shallow, fast breaths. An easy way to check for this at home is to relax either in an armchair or on the floor with one hand on your chest and the other on your abdomen. When you breathe normally your chest rather than your abdomen should rise. Incorrect breathing can be corrected by consulting a respiratory physiotherapist.
  4. On the other hand, passengers whose chronic hyperventilation is associated with anxiety disorders may need sedation before the flight. Check with your doctor or physician.

The so-called antidotes which should be avoided are alcohol and supplemental oxygen, which may sometimes be offered by a flight attendant. Both can aggravate rather than alleviate hyperventilation.

MEDICATIONS   Back to index

The effects and side-effects of drugs can be heightened in the confines of the pressurized cabin. This is due to the interaction between the physiological stresses of flight, particularly oxygen lack; and medicines. As the former alters brain function, the actions of any drugs that affect the brain will be altered, too. Medicines and drugs that fall into such a category include anti-histamines, acetazolamide, fat-soluble beta-blockers, alcohol and psychotropes.

Almost all the antihistamines produce side-effects such as drowsiness, vomiting, diarrhea, fatigue, dry mouth and tinnitus, and are commonly prescribed for “cold cures,” motion sickness, hay-fever and urticaria (nettle rash). Perhaps the gastrointestinal symptoms are mistaken by passengers for food poisoning.

Acetazolamide is used to treat glaucoma and to regularize breathing at altitude. Among the psychotrope group are hypnotics and sedatives, tranquilizers and antidepressants, marijuana, LSD and opium. Therefore, if the passenger is under medication or plans to use over-the-counter medicines on board he or she should consultant a physician beforehand. His or her doctor may want to decrease the patient’s dosage for the duration of the flight, because of the cabin environment’s effect on medications, that is, to increase their potency.

The interaction between oxygen lack and drugs can also have other effects on the brain. For example, there have been cases of memory loss when the hypnotic traizolam (0.5gm) was taken on board to encourage sleep and minimize jetlag. This benzodiazepine, which has a short half-life of 2.6 hours, caused transient global amnesia that lasted for several hours after landing. In each case, a moderate amount of alcohol, such as a glass of wine, was consumed. Consequently, the National Westminster Bank have excluded sleeping tablets from their travel kit. “The other reason,” says Dr. David Murry Bruce, “is that under the influence of a hypnotic you won’t be alert enough in an emergency.”

Such episodes suggest that it is best to exercise caution when using this medication to avoid jetlag, particularly if alcohol is imbibed during the flight. A more common experience with tranquilizers taken for aerophobia on board is severe depression, which cannot be shaken no matter how idyllic the passenger’s destination.

There are a couple of other examples that illustrate the unusual relationship between drug dosage and the flight environment. Diabetic passengers should increase their dose of insulin when flying west and decrease it when they are eastward bound on long-haul, to bring their insulin levels into line with the time zone they are flying to. Another factor that they should take into account is that the consumption of excessive alcohol can precipitate hypolgycemia.

On the other hand, epileptic passengers may well have to increase their dosage because oxygen lack, over-breathing, fatigue and stress can provoke seizure. In fact, those whose condition is poorly controlled should be advised to increase their medication 24 hours before take-off and maintain a high dose until they arrive at their final destination. Thereafter, there should be a gradual reduction of the dosage. Certain drug groups, such as salicylates, female sex hormones, catecholamines and alaeptics have been found to cause hyperventilation.

A final reminder for all passengers on medication is to consult with their doctor and to take it regularly during the flight based on home time, and to adjust the regimen only after they arrive in the new time zone.

MOUNTAIN SICKNESS   Back to index

The connection between mountain sickness and air travel may not be apparent and may even seem odd, but the former can inadvertently be provoked by the latter.

The first link arises from the fact that there is an analogy between flying and mountaineering. Both activities occur at altitude. As modern aircraft are pressurized to altitudes of between 5,000 and 8,000 feet, passengers can be whisked to the height of a minor peak in the Alps without moving a limb.

However, there is a corresponding increase in blood pressure, heart rate and respiration. This physiological effort can account for the inexplicable fatigue some passengers feel, even after short flights. Additional factors, such as the amount of alcohol consumed or food eaten, or stress experienced at the airport, can also be contributory factors.

Mountain sickness, or acute mountain sickness (AMS) as the benign syndrome is known, is characterized by nausea, headache, loss of appetite, dizziness and sleep disturbance. The condition is quite harmless but the symptoms should not be ignored in case it develops into a more serious form characterized by cerebral or pulmonary oedema (water on the brain or lungs).

It seems to be caused by the alkalinity of the blood and the presence of nitrogen bubbles. As our bodies adapt to compensate for the low oxygen pressure at altitude, we breathe more quickly and therefore expel more carbon dioxide. One of the functions of carbon dioxide is that it keeps the blood acidic, and so the loss of this gas can cause the blood to be more alkaline. There is also a release of nitrogen bubbles on ascent, and some experts believe that these small bubbles are responsible for increased blood-clotting and certain other complications of mountain sickness. The small and large blood clots often found in the blood vessels of high-altitude victims may be the result of nitrogen bubbles and may affect the blood vessels’ permeability.

But people do not have to ascend to a great height to be affected by AMS, as it can equally occur at levels of 8,000 feet or below. A 1989 survey of 400 people at U.S. ski resorts located at 6,600 feet demonstrated that the condition affected 25 percent of skiers. The illness was short-lived, however, and the symptoms disappeared within the first 72 hours.

Factors such as age or physical fitness are no guarantee against the condition. Studies on several thousands of visitors who come to the resorts in the Colorado Rockies have shown that men are more vulnerable than women because they tend to be more active, while children (rather than adolescents) and adults are more susceptible to the malignant form of the illness than are the elderly, unless the latter have a condition that predisposes them to it (such as cardiac or pulmonary complications). This may in part be due to the fact that the elderly tend to climb more slowly. The rate of ascent is a crucial factor in preventing mountain sickness.

Passengers who fly direct on long-haul routes to mountain resorts and go at once into the mountains may be at greater risk than those arriving more slowly by ground transportation. They are likely already to be slightly hypoxic (oxygen-deficient) and exhibiting symptoms such as headache, fatigue, mental sluggishness and perhaps oedema (water retention in tissues) and breathing difficulties. Some evidence suggests that when established circadian rhythms are altered by crossing several time zones, susceptibility to hypoxia (oxygen deficiency) is increased, perhaps not only during a long-haul flight but for several days after arrival as well.

The answer is to let your body acclimatize, because the kidneys can adjust over a few days to the lack of oxygen. For those who cannot or will not take time to acclimatize, acetazolamide (diamox) offers protection against AMS. This drug increases arterial oxygenation during sleep and consequently decreases mountain sickness symptoms in the morning. Another method is to use the Gamow or pressure bag, which will increase oxygen pressure in the lungs within one minute.

OXYGEN DEFICIENCY   Back to index

Oxygen lack has fascinated many scientists over the years. Joseph Barcroft from Cambridge was so curious that he lived for six days in a glass box where the oxygen supply was gradually depleted until on the last day it was down to 10 percent of the atmosphere – the equivalent of being at an altitude of 19,000 feet. It was termed a heroic experiment and he felt quite ill at the end.

Although the proportion of gases such as oxygen, nitrogen and carbon dioxide remains the same in the atmosphere no matter the altitude, as you go higher the partial pressure of each decreases. Oxygen deficiency, which is technically known as hypoxia, occurs when there is a decrease in the partial pressure of inspired oxygen (PIO2 ), such as happens in an aircraft or on a moutaintop. The PIO2 at sea level is 150 mmHg; at altitude it can fall to 60 mmHg, decreasing the oxygen level in the blood to 89 percent or below.

Most passengers at rest in an aircraft with cabin altitudes between 5,000 and 8,000 feet will experience little discomfort, with blood oxygen levels of 95 to 93 percent. Such a small degree of oxygen deficiency is termed mild hypoxia.

But at levels of 89 percent or less (equivalent to altitudes of about 10,000 feet and above), the effects of hypoxia become more apparent. Of all the tissue cells, the brain cells are the most sensitive to lack of oxygen. The areas of the brain most affected at low cabin altitudes are those associated with the powers of judgement, self-criticism and accurate performance.

Hypoxia in passengers is usually a short-term condition. As soon as they are back on the ground and a normal oxygen supply is restored, it disappears.

There are some individuals who may have lower blood oxygen saturation levels than average because of either their health or personal habits. Passengers with cardiovascular and respiratory disease, blood disorders or neurological conditions would fit into this category. They should consult their physician or the medical department of the airline before flying.

Other passengers who are likely to experience some discomfort are smokers, drinkers (particularly those who regularly drink large amounts of alcohol), the overweight, and those on medication for a cold or allergy.

Smokers can decrease their blood oxygen levels by between 4 and 8 percent before they even take off. The reason is that carbon monoxide, the chief component in tobacco smoke, has 300 times greater affinity for haemoglobin than oxygen, and therefore will displace it readily to form carboxy-hemoglobin. The effects of alcohol and other drugs, such as antihistamines, also contribute to oxygen deficiency. Obesity causes a person to be more sensitive to low blood oxygen levels because a greater volume of tissue has to be supplied with blood than is true of people at a more desirable weight.

PRESSURISED CABIN   Back to index

It adds six tons in payload or the equivalent of the weight of 60 passengers to pressurize a Boeing 747-400.

Whenever we travel by air, the space we inhabit must be pressurized. The procedure is similar to blowing air into a balloon or using a bicycle pump to inflate a tyre. The pressure inside the cabin must be higher than that outside, because the outside pressure is so low that breathing would be impossible. The difference between the two pressures, outside and inside an aircraft cabin, is called the cabin pressure differential.

Piston-engined planes and turboprops have air compressors to maintain a supply of pressurized air, while the engines of jet airliners compress air as part of their operation. The air, which is bled form each engine, enters the fuselage throughout the flight to keep the pressure constant. There are outflow valves to control the expulsion of air and to protect the aircraft itself from excessive differential pressures. (Such pressurisation is essential: too great a difference in the outside and inside pressures and, as in the case of the balloon or bicycle tyre, the plane would either burst or crumple in on itself).

There is a general belief that the pressure in the cabin (or, as it is known, cabin altitude) is equivalent to that at sea level. This is not the case. Cabin altitude can fluctuate from 5,000 to 8,600 feet in cruise levels and is dependent on many variables, including the load factor, fuel burn, the aircraft’s age and model and , above all, the airline or captain’s preference.

In the instance of an aircraft cruising at an altitude below its operational ceilings, there is a choice. The pilot can either select the maximum cabin differential pressure (about 5,000-6,000 feet) to increase the comfort of the passengers, or make things easier on the cabin structure (what is known as “prolonging the cabin’s fatigue life”) by keeping the differential pressure at a setting of around 8,000 feet.

The optimum cabin altitude for the 747-400 at flight levels of 29,000-41,000 feet is 8,000 feet, according to Bob Fletcher, Head Flight Operations Engineer of Air New Zealand. The Concorde was an exception because its cabin altitude could be maintained at 5,000 feet due to its high cabin pressure differential.

The most obvious sign of pressurization on aircraft is the size and thickness of the windows. These are smaller than are found on surface transport. The largest civilian aircraft, the 747-400, has rectangular windows measuring 30 cm/12in wide and 40 cm/16in in diameter. There are three layers: an outer pane, an inner pane and a scratch pane on the passenger side. The first two panes are strengthened with laminates; they are made to withstand the pressure load pushing outwards from within the cabin.

If cabins of aircraft were pressurized to seal level, penalties for carrying too much fuselage weight and fuel would be incurred.

SLEEP   Back to index

Sleep disruption caused by jetlag is a common experience among most passengers, even frequent flyers. Judy Moon of Delta Air Lines, who has worked as a flight attendant for 25 years, has a perfect solution; she eats crackers. “Whenever I wake up at 2am in a hotel or at home,” she says “and can’t go back to sleep, I eat something light like a piece of bread or crackers. I never touch protein. And I go back to sleep without fail.”

Sleep, which leads to the restoration of the body’s energy, is the best antidote against the less positive effects of air travel. Passengers who cannot sleep on board may want to build up “sleep credits” prior to departure. Essentially, if you normally sleep eight hours, by getting slightly more than this in the days before you fly you will be “in credit”.

On the other hand, there will be a proportional decrease in how long you can stay wakeful if your sleep is reduced to less than you normally get in the days before you depart. As a result, a sleep deficit will be registered. Passengers can add to their sleep store by having a nap (of an hour or more) before they take off. Another method is to gear yourself up to your new time zone several days before your flight by going to sleep either earlier each evening (if you are going to be travelling east) or alter (if journeying west).

There are some useful techniques for inducing sleep. Some flight attendants swear by taking an aspirin before bedtime. A sleep research laboratory in the U.K. has discovered two novel ways of promoting sleep. The first is to warm the brain slightly during the day, for example, by sitting under a hair dryer. There are other means of obtaining the same results, such as taking a warm bath, lying quietly in a warm room or exercising. The second solution is to increase your brain’s “visual load” by window-shopping, sightseeing or visiting an art gallery for an hour or two before you fly or once you land. Watching television or a film, unless it’s on a wide screen at a cinema, will not work as the colours and/or dimensions are not complex enough to get your brain going.

The obvious way of adapting the first method on board is to wear a woollen cap or balaclava. The latter would also serve as an excellent safeguard against moisture loss.

A final suggestion about sleeping on an aircraft is to upgrade to Business Class or First. Ian Webster, Senior Manager Relationships Marketing at British Airways, offers by way of illustration an event that happens often on flights throughout the world:

A business group goes on a conference to, say, Toronto, from the U.K., and returns on a night flight a couple of days later. As the aircraft is full, they are spread between the three cabins. On arrival the next morning the senior executives (who were in First go straight back to work, those in middle management (who were in Business) return to their offices at lunch time, and the junior staff (who were placed in Economy) came in the next day.

Swissair provides their transient passengers with beds at Swiss airports if they have to wait for four hours or more for a connecting flight. The unique service is offered to all passengers, regardless of the cost of their ticket.

Whenever James Bond, a.k.a. Pierce Brosnan, flies he travels in Coach but always manages to arrive looking good. His secret is to get the studio to buy four seats together so that he can sleep comfortably throughout the trip.

TV personality Anneka Rice set a new around-the-world record in 43 hours, 43 minutes by scheduled aircraft. A key element in achieving this was the fact that she took along a goosedown pillow which enabled her to sleep on board.

AUTOMATIC SLEEP PILOT   Back to index

An original method for sleeping on aircraft has been advised by a British Airways 747-400 Senior First Officer, Ann Peacock.

“It was a desperate measure,” she says, “as I find it difficult to sleep, particularly during the day while I’m on my three-hour rest break.” The long-range aircraft that she flies on has two bunks behind the cockpit for use by both relief and operational crew. This is necessary as the flight can vary from nine to 15 hours.

“One day, I finally managed to nod off and I have had no trouble since. The technique I use is what I describe as modified self-hypnosis. I lie on the bunk with my eyes closed and begin breathing in and out slowly for a period of four seconds. I repeat this for three or four times as it relaxes me.

“Then I start to recall a story of a book I’ve read. It’s not just any book as it can’t be too exciting or horrifying. That produces bad dreams; But one you can’t put down once you’ve started. It usually has a plot that is very involved. A good example is Dick Francis or The Golden Deed by Andrew Garve.

“This routine has worked so well that now I simply lie in the bunk and I go to sleep. Sometimes I have to repeat a story but mostly I just make a note of the time I need to wake and I’m asleep.”

STOPOVERS   Back to index

I’m not afraid of flying, I’m afraid of arriving.
Helene, Hanff, 84 Charing Cross Road

Nonstop flights, which save us the time and trouble of interconnections on the ground, are popular in intercontinental travel. But as these flights make additional demands on the body and mind, passengers in Economy Class may benefit from stopovers. At a simple level, they should fly during the day and spend the evening at a hotel. A night at the Pierre, in New York, for example, where the guest is cosseted with goosedown pillows, silky Frette sheets and a soft bed, is incomparable to the extra hours spent in cramped quarters on board. They wake refreshed, perhaps take in some sightseeing and continue their trip.

Long-distance flights can be turned into pleasurable events much the same way as cruises can when stopovers with interesting sights and hotels are included in the itinerary. One of the masters of this game was the British fashion designer the late Sir Hardy Amis. He spreads a non-stop trip of 26 hours over ten days. Each stop over is calculated to prolong his enjoyment. “My favourite long-haul journey which I have made frequently over the years, is to Sydney, Australia.” He enhances his pleasure by flying with different airlines across various sectors, using Concorde when it use to fly on the first leg from London to New York. He spends a week in New York before taking a day flight to Los Angeles. Whenever possible he chooses a carrier that serves his preferred delicacy, caviar.

Sir Hardy finds L.A. a good stopover destination, for it has Disneyland and Hollywood – and its well-kept secret, Redondo Beach. Located only seven miles south of the airport, this scenic location has not only an excellent beach and marina with the Crowne Plaza Hotels and Resorts situated next to it, but also 18 miles of coastal trails for biking, jogging, roller-skating, and walking.

One in Sydney, Sir Hardy stays at the Sebel Town House “which,” he comments, “is like staying with friends. But of course, friends are better because they are cheaper.” Another hotel recommended for Sydney’s King’s Cross area is the Nikko, which offers superb harbour views.

A stopover is not only an innovative way to travel which can prolong the pleasure of a trip but also provides a bonus in terms of a passenger’s physiological and psychological wellbeing. Even businessmen can benefit after a successful tour by spending the odd night somewhere. “During the two decades I flew intensively,” says Sir Peter Walters, the top British industrialist, “I would always stop for a game of golf in Singapore. Otherwise, I would be like a tiger pacing a cage.”

Iceland, for example, is an ideal layover on the busy North Atlantic route, as everything in the country is special – from its natural light, its hot springs and unusual horses which move at a unique pace, to the variety of sports including jet-skiing, fishing and golf, even at midnight during the summer. Icelandair has excellent connections to and from Europe and the USA and offers complimentary stopovers to full-fare Business Class passengers. Airlines, such as Qantas, Emirates and Cathay Pacific, also encourage passengers to break up their long-haul flights with stops, and offer special excursions at destinations along the way.

Some people who are particularly sensitive to the lower cabin pressure during intercontinental travel would also gain from stopovers. These include the elderly, people with chronic obstructive lung disease or asthma, highly trained athletes, smokers and those who are overweight.

SUPPLEMENTARY OXYGEN   Back to index

Oxygen is the elixir of most problems encountered on board; in a survey of medical incidents it was found to be effective in 60 percent of cases.

Airlines are required by civil aviation authorities to carry oxygen supplies in the event of an emergency such as a decompression. The supplies are in the form of drop-down masks and portable oxygen canisters. The latter, which are for passengers use, each contain a sufficient quantity of the gas (120 litres) to allow either a 30-minute high flow or a 60-minute low flow. The number of units on board varies according to the aircraft model and the seat configurations.

In particular, passengers with stable medical conditions, blood disorders such as anaemia or sickle cell disease, or those who are recovering from illness may require supplemental oxygen on board.

Delta Airlines, which offers a pre-flight medical screening for such passengers, found that 80 percent required or requested in-flight oxygen. The customer service department of the airline routinely refers air travellers with known medical conditions, needs or uncertain health status to its 24-hour medical advisory service for evaluation. An analysis of pre-flight screenings found that this service was worthwhile in the planning of safe, comfortable flights, since commercial air travel poses environmental and non-environmental stresses for such passengers.

Although on-board oxygen is available for medical incidents, the airline should be notified at least 48 hours before departure for any supplemental requirements, particularly for continuous oxygen throughout the flight. Most of the airlines charge a supplement for providing these additional facilities, which in the case of US carriers can vary form US $40 to US $200. Air Canada, which offers a special oxygen medipak, has found that most requests for such a service come from people with sickle-cell anaemia.

Your doctor should alert the medical department of the airline beforehand of your particular requirements. He or she may be asked to supply a written prescription and complete an INCAD form, which is the standard requisition form used by the International Air Transport Association (IATA).

WOMEN   Back to index

A female journalist who works for a national newspaper and travels a lot in the U.S. complains about the treatment she receives from hoteliers as a single woman. She always seems to end up with the odd room in the hotel, particularly when she checks in with a female receptionist. She gets the one with the leaky faucet or near the elevator, which is usually allotted to families who would never kick up a fuss. However, she reappears at the reception area and quietly asks for another room. She always wins in the end.

There are several other aspects of flying which are of interest to women.

  1. Water retention: Angela Rossi, an art dealer, uses an herbal diuretic whenever she flies. Another method, according to Vicki Bramwell, a journalist, is to exercise off the excess water. She goes for a gentle jog or swim post-flight as she prefers not to use chemicals in her body.
  2. Menstruation: It is common for women to either miss their periods when they fly a lot or to suffer from heavy periods. As air travel can disrupt the menstrual cycle, it is best to always be prepared. “I was in the middle of my cycle,” says bestselling author, Rosalind Miles, “but when I arrived at my destination I had my period. As I had a problem finding tampons even in shops in five-star hotels, I always take them with me.” For regular periods, Lufthansa purser Christine Behmer recommends a high-dose pill as the low-dose is ineffective.
  3. Constipation: As the metabolism tends to slow down on long-haul flights, some female frequent flyers take along laxatives such as tybogel. Kiwi fruit is also effective.
  4. Nail repair kits: Women with long nails tend to find that flying causes brittleness and they might tear, flake or break easily. It is recommended that a nail repair kit containing Krazy Glue be put into a travel kit.
  5. Homeopathy and aromatherapy: Marguerite Littman, founder of the AIDS Crisis Trust, always travels with aromatherapy oils such as lavender which she pats around her neck and nasal area to ward off infection such as colds. It contains a natural antiseptic and antibiotic, and was used as a disinfectant for hospital floors in the past.
  6. Diet: A long-haul flight is an ideal time to begin a fast or diet. Marie Helvin, international model, goes on a detox diet whenever she flies. She only eats one kind of fruit and drinks a lot of water. “It helps me to beat jetlag,” she says.
  7. Beauty treatment: Some female travellers give themselves a facial on board the aircraft. They make sure that they get a window seat so they can face away from fellow passengers and apply their creams and gauze in semiprivacy. “I survive long-haul trips,” says Tracey Ullman, “through using lots and lots of moisturiser.”
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