The Minster Practice, Lichfield

Page updated 25/08/2008

Key areas for health issues regarding flying

All passengers should avoid excess alcohol before and during a flight but especially those with obstructive sleep apnoea (OSA) or at risk of thrombosis. Special assessment may be required before air travel for those with obstructive or restrictive lung disease including muscle weakness and conditions worsened by low oxygen such as cerebrovascular disease, angina or heart failure. Some operations may require a postoperative recovery period before flying.
If medication is not carried in hand baggage, patients should check with their pharmacist whether medication could be spoilt by exposure to the temperature range in the hold. Important medication must be in hand baggage.

Lung diseases

In 2001, lung problems were the fourth commonest (10%) in flight medical emergencies and third commonest (9%) reason for medical diversions. Advice for lung specialists was published in 2002:
British Thoracic Society recommendations. Managing passengers with respiratory disease planning air travel. Thorax 2002;57:289-304.

Modern aircraft cabins are pressurised to the equivalent of an altitude of 8,000ft. At this altitude the partial pressure of oxygen falls equivalent to breathing 15.1% oxygen at sea level resulting in oxygen sats (SaO₂) of 85-91% in healthy passengers. Those passengers with impaired lung function may not cope with a reduction in oxygen saturation. If someone is unable to walk more than 50 metres without getting breathless, they will probably be unable to tolerate the relative hypoxia.

We have an oximeter for measuring oxygen sats and those with SaO₂ >95% should be able to fly without oxygen.
Those with SaO₂ 92-95% will probably be OK unless there are additional risk factors such as hypercapnia, FEV₁ <50% predicted, lung cancer, restrictive lung disease (lung fibrosis, kyphoscoliosis, respiratory muscle weakness), cardiovascular disease, and those within 6 weeks of discharge for an exacerbation of chronic lung or cardiac disease. Assessment (hypoxic challenge testing) in a lung function laboratory may be required.
Patients with SaO₂ <92% will require in flight oxygen. Oxygen supply has to be arranged with the airline, usually at significant extra cost. Some airlines (e.g. Britannia in 2002) only supply oxygen for periods too short to cover a transatlantic flight. The oxygen need not be switched on until cruising altitude is reached and may be switched off at the start of descent.

 Preventer and reliever inhalers should be carried in hand luggage. Spacers on inhalers are as effective as nebulisers for asthma.

Deep Vein Thrombosis, Pulmonary Embolism and Travel

Hospitals near Heathrow airport admit 2 long haul passengers per week with deep vein thrombosis (DVT). Hospitals around Gatwick airport recorded 142 deaths from DVT in a one year period. Long haul passengers on flights lasting 6 hours or more are particularly at risk with an overall risk of 1 in 2000). The cause is blood flow in the legs being slowed by immobility, dehydration and cramped conditions (not low cabin pressure and low oxygen). About half have symptoms of pain & swelling of the calf but others show no sign of a clot until a serious problem develops. The clot usually forms in the legs or pelvis and may affect 10% of airline travellers. If the clot moves through the bloodstream it can cause a fatal pulmonary embolism (PE) where the blood flow through the lungs is blocked.

It used to be thought that only economy passengers were affected as the room between seats is so restricted but it has been reported even in first class. Similar problems can occur on coach and train journeys and even office workers** ; British Airways prefers the term "Travellers thrombosis". The thrombosis seems to start after about 2 - 3 hours and progressively increases.

If you are travelling back in plaster, e.g. after a skiing injury, ask your overseas doctors about the possibility of protection using injections of low molecular weight heparin or formal anticoagulation with warfarin.

The Civil Aviation Authority has confirmed that its role in seat sizing is limited to safety standards related to evacuation. It has no remit to consider passenger health.

The Lancet published a New Zealand study suggesting the frequency of venous thromboembolism associated with travel was 1·0% (9/878, 95% CI 0·5-1·9), which included four cases of pulmonary embolism and five of deep venous thrombosis. Six patients with venous thromboembolism had pre-existing clinical risk factors, two had a recognised thrombophilic risk factor, two travelled exclusively in business class, five used aspirin, and four wore compression stockings.  http://www.thelancet.com/journal/vol362/iss9401/full/llan.362.9401.original_research.28136.1

Flight socks have been shown to reduce the risk of DVT. A review of 9 studies covering 2,800 passengers showed a risk reduction of 90%. They also control the postural leg swelling which is a common cause of discomfort. Ensure that the correct size is purchased and they are worn correctly.

** Research published in 2007 suggested office workers who spend all day sitting in front of computers could be at greater risk of developing potentially fatal blood clots than passengers on long-haul flights. In a study of 62 patients aged up to 65 who were admitted to hospital with blood clots, 34 per cent had been seated at work for long periods.

*+* Exercising on flights: http://www.wikihow.com/Do-an-In-Flight-Fitness-Workout 

Risk factors for thrombosis and embolism

Slight increased risk:

Moderately increased risk:

High risk (in this group, if flying is unavoidable, risk may be reduced by injections of low molecular weight heparin or formal anticoagulation with warfarin and INR result 2-3. Treatment should be continued throughout the vacation and continued until normal activity resumed after the return journey.):

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Homepage last modified: August 25, 2008.