Air travel in people with respiratory disease

The British Thoracic Society's updated guidance on air travel for people with respiratory illnesses provides a valuable resource for practice nurses who offer travel advice

In 2007, the International Air Transport Association (IATA) predicted that the air transport industry would handle 2.75 billion passengers by 2011.¹ The world, it said, wants to fly and needs to fly, for a whole host of reasons, not least, economic. As passenger numbers increase, so does the age of the traveller. Approximately 30 years ago, around 5% of airline passengers were thought to have a pre-existing medical condition. That number is rising as chronic disease is managed more effectively and people are travelling with increasingly complex medical conditions. One such condition is respiratory disease. New guidance published in September 2011 by the British Thoracic Society (BTS)² not only provides an expert consensus view for respiratory specialists in secondary care, but also hopes to provide a valuable reference for practice and specialist respiratory nurses. Although the guidelines refer to the respiratory care of both adults and children, this article will look at the issues relating only to adults and the reader is referred to the original guidance for more explicit details relating to child travellers with respiratory disease.

PRE-FLIGHT ASSESSMENT

If there is any doubt about the traveller's fitness to fly or there are comorbidities affecting fitness such as cardiovascular disease, pre-travel assessment by a respiratory specialist is recommended. Box 2 details the conditions that should be assessed before travel and Box 3 lists the contraindications to commercial air travel. There are three recognised ways to assess a traveller's fitness to fly: the walk test, predicting hypoxaemia from equations and the Hypoxic Challenge Test (HCT). The guidelines state that whilst HCT can be reliably used to identify those travellers requiring supplemental oxygen, there is a need to define the role of the walk test or a symptom-based approach e.g. the MRC dyspnoea scale.

Walk tests

In order to assess whether travellers are fit to fly, airlines have traditionally favoured the 50m walk test i.e. the ability to walk 50 metres without distress. Although there is no evidence to validate the walk test, it is simple, easily administered and a good test of cardiopulmonary reserve.

Hypoxic Challenge Test (HCT)

The HCT, as described in the literature, assumes that the maximum cabin altitude of 8,000 ft (2,438m) can be replicated by asking patients to breathe in a gas mixture containing 15% oxygen in nitrogen for 20 minutes. Saturation is monitored throughout and arterial blood gases or SpO2 are measured beforehand and on completion. A patient would be judged to require in-flight oxygen if the PaO2 fell below 50mm Hg or SpO2 falls below 85%. There is a suggestion that all patients with a sea level SpO2 <95% should undergo HCT; however, a recent study³ suggested that simple SpO2 measurement is insufficient in COPD to identify travellers who require in-flight oxygen. In addition, several studies have confirmed that neither a resting sea level oxygen saturation, nor an FEV1, reliably predict hypoxaemia or complications in those with chronic respiratory conditions during air travel.

DISEASE SPECIFIC RECOMMENDATIONS

Airways Disease (Asthma and COPD)

Commercial flights do not usually pose problems for those travellers with well-controlled asthma. Research indicates that although asthma attacks do occur on flights, approximately a third of these are due to the traveller either forgetting their inhalers, or leaving their medication in their hold baggage. Travellers with airways disease should always be reminded to carry their inhalers (and spacer if appropriate) in their hand luggage. Travellers with COPD are potentially at risk from reduced partial pressure of oxygen and expansion of gases within closed bullae. Traditionally, airlines have preferred the 50m walk test to ascertain a traveller's fitness to fly. However, there is research to indicate that the validated 6 minute walk showed a significant relationship with the HCT SpO2 in predicting altitude hypoxaemia. Overall, the frequency of severe adverse events in patients with COPD who fly appears to be low, although there is evidence of a high rate of respiratory tract infection up to 4 weeks post travel.

Cystic Fibrosis (CF)

Owing to the risk of cross-infection from other CF patients, the CF Trust strongly discourages group travel. The Guidelines suggest that although travellers with CF do become hypoxaemic at altitude, they are rarely symptomatic. Those with a low FEV1 <50% appear to be at increased risk, but there is no data to date to suggest a reliable method of predicting hypoxaemia at altitude for this group of travellers.

Cancer

Cancer patients are living longer and therefore travelling more. Some are visiting friends and family or going on holiday post treatment, others may be travelling for medical, surgical or complementary treatment abroad in the later stages of their disease. Such travellers may be systemically more unwell, with the potential for serious complications. Travellers need to be aware of their increased risk of venous thromboembolism (VTE) and should have correctable causes of dyspnoea e.g. anaemia, corrected prior to travelling. They should be reminded about the regulations relating to carrying Schedule A controlled drugs. The UK Home Office advises a doctor's letter should be carried to facilitate easy exit from the UK. Travellers also need to be aware of any potential restrictions from their destination country and should be advised to check the Foreign and Commonwealth Office website (see sources of information) and the relevant destination's government website for current entry requirements. Travellers undergoing chemotherapy should be reminded of the increased risk of infection, should be advised to delay travel and to discuss their travel plans with their supervising specialist or oncologist. Finally, travellers and carers should be reminded that medical insurance may be refused, and that the repatriation costs in any event (including death abroad) will be significant.

Obesity

Obesity is increasing worldwide in both developed and developing nations and may contribute to Obstructive Sleep Apnoea Syndrome (OSAS), dyspnoea, chronic hypoventilation, complicate COPD, and is an independent risk factor for VTE. Obese passengers may have difficulty fitting into a standard seat size and should check in advance with the airline that one seat is sufficient. In addition, those with a BMI of >30kg/m2 should be considered at moderate risk of VTE and should be offered appropriate advice.⁴

Obstructive Sleep Apnoea Syndrome (OSAS)

Little is known about the effects of air travel on travellers with OSAS. Travellers with OSAS should be advised to avoid alcohol, sleeping tablets and sedatives before and during the flight, and should carry a doctor's letter stating their diagnosis. This letter should also state that the traveller's CPAP machine should travel in the cabin as extra hand luggage. If the traveller needs to use their CPAP during the flight, they must notify the airline before travel. Power supplies are not available on all flights, sockets may not be available at every seat and not all airlines will allow them to be used for such equipment. If the traveller requires the CPAP machine to be used in flight or at a high altitude destination they must check if their machine will work adequately at low ambient pressures. Machines with pressure sensors deliver accurate pressures across a range of pressure and altitude combinations. Travellers should be reminded that in order to use their equipment at their destination they will need to bring appropriate extension cables/adaptors.

TRAVELLING WITH OXYGEN

Oxygen-dependent travellers can fly with adequate precautions and preparation. Travellers may be able to take their own small, full oxygen cylinders on board the aircraft, if the airline agrees and this is arranged in advance. Travellers must be advised strongly that it is NOT possible to arrange this when they arrive to check in. In addition, travellers should ensure that their equipment is insured against loss and/or damage. If oxygen is required during the flight, this is usually supplied by the airline and MUST be booked in advance. The airline medical department will issue a MEDIF form (see sources of information) or their own medical form. This is completed by the patient and a GP or hospital specialist with details of the patient's medical condition(s) and oxygen requirements. In-flight oxygen is prescribed at a rate of 2l/min or 4l/min via nasal cannulae.

Many airlines now allow passengers to use lightweight battery-operated portable oxygen concentrators (POCs), but again the airline MUST be informed before travel. The traveller should ensure they have a sufficient supply of batteries for the flight and any potential delays encountered. Finally, the traveller should consider the need for oxygen on the ground and while changing flights. Airlines do not supply oxygen for use at airports and separate arrangements have to be in place via the main oxygen international distribution network. A charge is likely for this service.

CONCLUSION

Despite the current economic situation, patients with respiratory illness continue to travel in increasing numbers. However, some patients will be travelling to destinations with no perceived risk of vaccine-preventable infections, such as Northern Europe or the US. Therefore these patients will not necessarily seek pre-travel advice. The challenge for practice nurses is to provide information and advice (see sources of information) for patients who may travel at some point in the future. Annual review appointments or flu immunisation clinics may provide suitable opportunities. The recent BTS guidelines provide a sound basis for the information and advice which healthcare professionals can give to individual with underlying respiratory conditions, to help them to make informed decisions about any future travel plans.

Conflict of Interest: the author has previously been a member of both the Sanofi Travel Health Vaccine and the GSK Hepatitis B Advisory Boards and has accepted honoraria from both Sanofi Pasteur MSD and GSK.

REFERENCES

1. International Aviation Transport Authority (IATA) Passenger numbers to reach 2.⁷⁵ billion by 2011, 2007. http://www.iata.org/pressroom/pr/2007-24-10-01.htm

2. British Thoracic Society Air Travel Working Group. Managing passengers with stable respiratory disease planning air travel: British Thoracic Society recommendations. Thorax 2011;66(suppl 1):1-30

3. Akere A, Christensen CC, Edvardsen A et al. Pulse oximetry in the pre-flight evaluation of patients with chronic obstructive pulmonary disease. Aviat Space Environ Med 2008;79:518-24

4. National Travel Health Network and Centre (NaTHNaC). Travel Health Information Sheets: Travel Related Deep Vein Thrombosis (2007) www.nathnac.org