Abstract

Respiratory problems account for 10% of inflight medical emergencies; this is usually due to the acute physiological stress induced by hypobaric hypoxia on board aircraft. During a typical commercial flight, the cabin pressure is the equivalent of breathing 15% oxygen at sea level, as opposed to 21% (~ 15.2 kPa versus 21.2 kPa FiO₂). The response to this hypobaric hypoxia is mediated by the autonomic nervous system; it is characterised by an increased rate and depth of breathing, mild tachycardia, and hypoxic pulmonary vasoconstriction. Patients who are able to walk 50 metres without developing shortness of breath are generally “fit to fly” from a respiratory perspective, and those with resolved pneumonia may fly if they are clinically stable. Military patients with asthma and COPD are generally safe to fly, as they must have stable airways disease to remain medically fit for service. A recent or unresolved pneumothorax is an absolute contraindication to air travel. Other absolute contraindications for air travel include tuberculosis, major haemoptysis and an oxygen requirement of ≥4 l/min. If there is any doubt regarding a patient’s fitness to fly, an opinion from a respiratory physician should be sought. All patients flying with a respiratory condition must carry their medications onboard, have up-to-date vaccinations and seek advice from their doctor should they have any concerns over their fitness to fly. This review article will explore the effect of air travel on the respiratory diseases most likely to be seen in the UK military population: airways disease (COPD and asthma), respiratory infections, pneumothorax, and spontaneous pulmonary embolism.