Medical advice to those with respiratory disease on fitness to fly depends primarily on:
- the type, reversibility and functional severity of the underlying respiratory disease
- an assessment of the likely tolerance to the cabin altitude and ambient oxygen concentration
In patients with significant disease, the relative hypoxia encountered in the aircraft cabin may be easily correctable by therapeutic oxygen. The partial pressure of oxygen in the cabin at normal cruising altitude is considered to be equivalent to an oxygen concentration of approximately 17% at sea level. Some respiratory physicians have carried out assessments in a laboratory using oxygen-nitrogen mixes to simulate this cabin environment. If this results in a PaO2 less than 55 mm of mercury, medical oxygen is indicated.
Guidelines on this approach to assessment can be found at the British Thoracic Society website.
However, the single, most practical, fitness to fly test, which has stood the test of time, is to assess whether the patient can walk 50 yards/metres at a normal pace or climb one flight of stairs without severe dyspnoea. If this can be accomplished, it is likely that the patient will tolerate the normal aircraft environment.
The normal aircraft cabin environment does not represent a specific challenge to those suffering from asthma that is stable. The key issue is to ensure that all medication is carried in hand baggage. It may be prudent that patients with asthma, other than the mildest cases, should take a course of oral steroids with them, in order that they could intervene early if there is any deterioration in their condition.
Chronic Obstructive Pulmonary Disease (COPD)
The walking test and/or hypoxic challenge may be appropriate to determine the passenger’s requirement for supplemental oxygen in flight. Oxygen can be provided by most airlines with prior notification, although a fee may be charged for this. Flow rates of 2 or 4 litres per minute are usually available and some airlines may be able to offer a wider range of flow rates using cylinders with pulse dose delivery systems. Some airlines may permit passengers to carry and use their own oxygen cylinders and passengers who wish to do this should contact the airline for information on their policy. Passengers may also be able to use approved portable oxygen concentrators and again those wishing to do so should discuss this with the airline.
Bronchiectasis and cystic fibrosis
Control of lung infection measures designed to loosen and clear secretions are important aspects of medical care, both on the ground and during travel. Appropriate antibiotic therapy, adequate hydration and medical oxygen may be required for both conditions. Medication to decrease sputum viscosity is helpful e.g. deoxyribonuclease in the low humidity of the aircraft cabin.
Patients with active or contagious infection are obviously unsuitable for travel until there is documented control of the infection and they are no longer infectious. Those recovering from acute bacterial infection e.g. pneumonia should be clinically improved with no residual infection and satisfactory exercise tolerance before flying. Patients with respiratory viral infections e.g. influenza, may infect those sitting adjacent to them and they should postpone air travel until the infection has resolved.
The presence of a pneumothorax is an absolute contraindication to air travel as trapped air may expand and result in a tension pneumothorax. In general, it should be safe to travel approximately 2 weeks after successful drainage of a pneumothorax with full expansion of the lung. If there is a need to travel earlier, safe travel is possible using a one-way Heimlich valve attached to the chest drain.