Preflight screening

• All patients should undergo careful initial evaluation with history and physical examination by a clinician who is competent. The history should include:

  • Review of symptoms, baseline exercise capacity, recent exacerbation history, treatments and previous experience of air travel.

  • Consideration of the logistics of the intended journey, to include (if known):

    • Number and duration of flights, including whether daytime or overnight,

    • Location of stop-over(s) and destination: these determine air quality, altitude and available medical facilities,

    • Time away from home

    • Return journey.

• Further assessment by a respiratory specialist is advised for those in whom screening raises concerns, and HCT may be advised.

The following clinical practice points are specific to infants and children

• For infants born at term (>37 weeks) it is prudent to delay flying for 1 week after birth to ensure they are healthy.

• Infants born prematurely (<37 weeks) with or without a history of respiratory disease who have not reached their expected date of delivery at the time of flying should have in-flight oxygen available. HCT may not be a reliable guide of oxygen requirement in this group. If air travel is essential, they should travel with oxygen at a tolerable low flow, recognising that this may be a minimum of 1 L/min depending on equipment.

• Infants under 1 year with a history of chronic respiratory problems should be discussed with a respiratory paediatrician and HCT considered. Those with SpO₂ <85% on HCT should have in-flight oxygen available; paediatrician discretion should be used for infants with SpO₂ 85%–90% recognising that sleep or respiratory infection may further reduce saturations in this group.

• In children with chronic lung disease able to perform spirometry whose forced expiratory volume in 1 s (FEV₁) is consistently <50% predicted, HCT should be considered. This includes children with CF and primary ciliary dyskinesia (PCD). Children with chronic lung disease who are too young to perform spirometry reliably should have a clinical assessment of disease severity and their likely tolerance of hypoxia. In children with CF the disease is rarely severe enough to compromise lung function significantly at this age.

• Infants and children who have required long-term oxygen in the last 6 months should be discussed with a respiratory paediatrician and HCT considered.

The following patients should not require HCT

• Those with stable disease who have previously undergone HCT (no recent hospital admissions, exacerbations, or significant changes to treatment).

• Patients with COPD with baseline SpO2 ≥95% and either MRC score 1–2 or desaturation to no less than 84% during 6 min walk test (6MWT) or shuttle walking test (SWT), should be able to travel without in-flight oxygen.

• Those with previous significant intolerance to air travel, such as mid-air emergency oxygen or diversion. These should have in-flight oxygen available at 2 L/min provided there is no history of hypercapnia.

• Preterm infants who have not reached their due date at the time of travel, as testing is not a reliable guide of oxygen requirement in these infants. These should have in-flight oxygen available, delivered at 1–2 L/min if they develop tachypnoea, recession, or other signs of respiratory distress.

HCT should be considered for the following patients

• Patients with COPD with resting SpO₂ ≤95%, MRC score 3 or greater, or desaturation to <84% on 6MWT or SWT, and in whom there are concerns about hypercapnia.

• Infants and children with a history of neonatal respiratory problems, or existing severe chronic lung disease including those with FEV1 persistently <50% predicted.

• Adults and children with severe asthma, evidenced by persistent symptoms and/or frequent exacerbations despite optimal treatment regardless of resting sea level SpO₂.

• Patients with ILD in whom SpO₂ falls to <95% on exercise, and whose resting sea level arterial oxygen tension (PaO₂) is ≤9.42 kPa or whose TLCO is ≤50%.

• Those with severe respiratory muscle weakness or chest wall deformity in whom forced vital capacity (FVC) is <1 L.

• Those with existing or previous hypercapnia and those at risk of hypercapnia, including those taking medication(s) which can cause respiratory depression.

• Patients with a history of type 2 respiratory failure already on LTOT at sea level. However, if there is no evidence of hypercapnia, it seems reasonable to recommend an increase in flow rate by 2 L/min in-flight, provided the equipment can provide it (see Appendix A)

HCT results

• PaO₂ ≥6.6 kPa (≥50 mm Hg) or SpO₂ ≥85%: in-flight oxygen not required.

• PaO₂ <6.6 kPa (<50 mm Hg) or SpO₂ <85%: in-flight oxygen recommended.

• Where required, titrate oxygen to maintain PaO₂ ≥6.6 kPa or SpO₂ ≥85% in adults, SpO₂ 90% in children aged 1 year or more.

Asthma

• The patient’s condition should be optimised before travel, with attention paid to inhaler technique and smoking cessation referral as required.

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of lost or missing hold baggage.

• Emergency medications, including salbutamol inhalers and spacers, must be immediately accessible.

• Individuals prescribed epinephrine auto-injectors should have them readily available.

• For acute exacerbations on board, the passenger’s own bronchodilator inhaler should be given, with a spacer if needed.

• The passenger should alert the cabin crew if symptoms do not respond rapidly to use of the inhaler, or if they recur after a short interval.

• If the passenger does not have their own inhaler with them, or if it is inaccessible, the airline may carry an inhaler in the emergency medical kit. Spacers are not commonly available.

• Those with severe asthma should consult their respiratory specialist beforehand and consider taking an emergency supply of oral corticosteroid in their hand luggage in addition to their usual medication.

• Passengers with severe asthma are advised to carry copies of their asthma management plan and/or relevant clinic letters. Information can be held securely as scanned copies on a mobile phone, or on a digital platform such as the National Health Service (NHS) App.

• Food allergy affects up to 8.5% of children and adults with asthma and asthma is a risk factor for severe or fatal anaphylaxis. Appropriate precautions for those affected include wiping tray tables and hands, informing the airline beforehand and the cabin crew of allergies, and not eating during flights or bringing known ‘safe’ foods from home.

Chronic obstructive pulmonary disease

• The patient’s condition should be optimised before travel, with attention paid to inhaler technique and smoking cessation referral where appropriate.

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of missing hold baggage.

• Emergency medications, including salbutamol inhalers and spacers, must be immediately accessible.

• For acute exacerbations on board, the passenger’s own bronchodilator inhaler should be given, with a spacer if appropriate.

• Passengers with severe COPD are advised to carry a copy of their COPD management plan and/or relevant clinic letters. This information can be held securely as scanned copies on their mobile phone A history of previous pneumothorax or bullous lung disease necessitates assessment by a respiratory specialist to determine the potential risk of complications from reduced cabin pressure.

• Patients with COPD are at greater risk of VTE as a direct consequence of the underlying condition, as well as after an exacerbation. They should be advised accordingly, especially if planning longer flights when the risk is further enhanced.

• Patients requiring long-term oxygen therapy should also plan for oxygen supplementation at their destination (see online supplemental appendix 1).

• Wherever possible, those who have had a recent exacerbation of their condition should not fly until their condition is stable and use of reliever therapy has returned to their usual baseline. If their condition deteriorates while overseas, medical advice should be sought before undertaking the return flight.

Cystic fibrosis

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of missing hold baggage.

• Patients with CF under the age of 6 are likely to be well enough to fly at the paediatrician’s discretion.

• In those with CF who are old enough for spirometry and whose FEV1 is <50% predicted, HCT is recommended. If SpO2 falls below the 90% cut-off, as outlined above, in-flight oxygen is advised.

• In children with chronic lung disease able to perform spirometry whose FEV₁ is consistently <50% predicted, HCT should be considered. This includes children with CF and non-CF bronchiectasis. Children with chronic lung disease who are too young to reliably perform spirometry should have a clinical assessment of assess disease severity and their likely tolerance of hypoxia. For children with CF disease is rarely severe enough to severely compromise lung function at this age.

Non-CF bronchiectasis

• Regular airway clearance is essential for those dealing with overproduction of mucus.

• Advice from a respiratory physiotherapist on adapting airway clearance techniques should be sought for long-haul flights.

• Portable nebulisers and positive expiratory pressure (PEP) devices may be considered, but use of these devices in-flight must be approved by the airline before travel.

Interstitial lung disease

• In patients with comorbidity, including PH and/ or cardiovascular disease, attention should also be paid to the impact of air travel on these conditions.

• Physicians may wish to consider HCT in those whom SpO2 falls to <95% on exercise, and/or in those in whom either Transfer Factor Carbon Monoxide (TLCO) ≤50% or PaO₂ ≤9.42 kPa (if available).

• Patients with TLCO <50% of predicted or PaO₂ ≤9.42 kPa are likely to need in-flight oxygen. If there are no concerns about hypercapnia it may be reasonable to recommend 2 L/min without recourse to HCT. In those in whom there are concerns about CO2 retention, titration HCT is advised to determine the oxygen flow rate.

Thoracic surgery

• The opinion of the surgeon or interventionalist should be obtained before the patient travels by air. Patients, professionals and their carers should be aware that this may result in a delay of 4 weeks for non-essential air travel and 2 weeks for essential air travel.

• Careful clinical assessment of the patient is required. This should include consideration of their baseline status including comorbidities, SpO2, postprocedure complications such as infection and/or pain, flight duration and destination.

Other interventional procedures

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Careful clinical assessment of the patient is required. This should include consideration of baseline status including co-morbidities, SpO2, postprocedure complications such as infection or pain, flight duration and destination.

• Patients with no pneumothorax seen on the postprocedure chest X-ray should wait for 1 week before air travel.

• Patients with a pneumothorax seen on the post-procedure chest X-ray should wait for one1 week after resolution on chest X-ray before air travel.

Trapped lung

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Patients should be assessed carefully and advised on a case-by-case basis.

• Patients should be clinically stable before air travel.

Bronchoscopic procedures

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Patients should be clinically stable before they travel.

• After interventional bronchoscopy including Transbronchial Needle Aspiration (TBNA), Transbronchial Lung Biopsy (TBB), Endobronchial Ultrasound Bronchoscopy (EBUS) and endobronchial valve insertion, those with no pneumothorax seen on the postprocedure chest X-ray should wait for 1 week before air travel.

• After interventional bronchoscopy including TBNA, TBB and EBUS, those with a pneumothorax seen on the post-procedure chest X-ray should wait for 1 week after resolution on chest X-ray before air travel.

Pneumothorax

• Passengers should not travel by air until 7 days after full resolution on chest X-ray.

• Those at higher risk of recurrent pneumothorax should be advised accordingly.

• Higher-risk groups, including those with cystic lung disease such as lymphangioleiomyomatosis (LAM) and Birt-Hogg-Dubé (BHD) syndrome, should be advised accordingly.

• Patients with trapped lung and a chronic air space thought to present a low risk should be evaluated in secondary care before travel.

Upper respiratory infection including otitis media and sinusitis

• In passengers who develop sinus barotrauma after flying, it may be helpful to consider topical and oral decongestants as well as appropriate analgesia. Prolonged use of decongestants is not advised owing to the risk of rebound congestion on withdrawal.

• If there is an allergic component, intranasal steroids used for a week prior to travel, and/or oral corticosteroids may be considered.

• Symptoms and signs of barotrauma should have resolved before flying again. This usually takes between 1 and 6 weeks.

• After an episode of acute otitis media, patients are usually advised not to fly for 2 weeks.

Viral infections

• Patients with highly contagious infections including measles, chickenpox, mumps, SARS, Middle East respiratory syndrome (MERS) or COVID-19 should not be allowed to travel until they are considered non-infectious.

• Passengers should familiarise themselves with current national and international regulations regarding air travel, which should always be observed.

Tuberculosis

• Smear positive patients must not fly until they have provided two smear negative samples on treatment.

• Those starting treatment for pulmonary tuberculosis (TB), where not all the information is yet available, should not travel by air for the first 2 weeks.

• For those who are smear negative and have a fully sensitive organism, treatment would be expected to render them non-infectious after 2 weeks.

• For patients with multidrug resistant/extensive drug resistant (MDR/XDR) TB, travel is prohibited until two negative culture samples have been produced and there is clinical evidence of improvement on treatment.

• Extrapulmonary TB does not usually warrant additional precautions before air travel.

Pneumonia

• All but essential travel should be postponed for 7 days in those who have reduced baseline sea level SpO2 (<94%).

Obstructive Sleep Apnoea (OSAS) and Obesity Hypoventilation Syndrome (OHS)

• Daytime flights are advised wherever possible.

• The patient should be advised to carry their continuous positive airway pressure (CPAP) device as hand luggage, and a hospital letter to advise that the patient uses CPAP.

• Careful planning and preparation are required, and use of the patient’s own CPAP device is advised.

• Alcohol and sedatives should be avoided in the 12 hours before, and during, airline travel.

• Patients should use their CPAP device on board if they are travelling overnight, and avoid sleeping during daytime flights.

• Consideration should be given to device settings and whether adjustment is required for operation at altitude.

• Airline approval for carriage and use of device, including battery specification, must be gained before travel.

• Consideration should be given to the whole journey. If driving is required the following day, an overnight stay at destination may be advisable. Patients are advised to refrain from driving if tired and sleepy.

Respiratory muscle and chest wall disorders

• HCT is recommended for all adult patients with FVC <1 L, pending further data, and may be considered in others thought to be at particular risk, including children with reduced FVC due to respiratory muscle or chest wall disorders.

• If patients are unable to perform spirometry reliably, a walk test may be considered as an alternative.

• Patients should be advised to take daytime flights where possible.

• Further planning and support are required for those established on non-invasive ventilation (NIV) (see Appendix A). (online supplemental appendix 2

Prevention of VTE during air travel

See table 1.

• Limit the risk of dehydration with adequate fluid intake.

• Avoid alcohol.

• Keep mobile, if possible, by walking around or doing seat-based exercises once an hour.

• Consider graduated compression stockings (class 1 with 15–30 mm Hg).

• Low molecular weight heparin (LMWH) or a Direct Acting Oral Anticoagulant (DOAC) are advised for both outward and return long haul flights (long haul defined as flights of 6–12 hours) in high-risk patients including those with a history of VTE; local policy should be followed regarding liaison with primary care and/or haematology services to teach the patient how to administer the injection and dispose safely of the equipment. There is no formally recommended dose, but enoxaparin at a dose of 40 mg or weight based 1 mg/kg injected once 4–5 hours before the flight has been suggested.

• The prophylactic doses of the DOAC may also be used.

• All patients with a recent (<6 weeks) history of VTE, especially any who presented with significant right ventricular strain and decompensation should be reassessed before air travel.

Air travel after VTE

• Air travel should be delayed for 2 weeks after a diagnosis of DVT or pulmonary embolism (PE).

Pulmonary hypertension

• Those in New York Heart Association (NYHA) WHO functional class 3 or 4 are usually advised to have in-flight oxygen. If there is no evidence of hypercapnia it seems reasonable to suggest 2 L/min by nasal cannulae. If there are concerns about hypercapnia, HCT should be considered if available.

• Those eligible for LTOT (sea level PaO₂ <8 kPa at rest on air) should have in flight oxygen at double the flow rate recommended at sea level, provided there is no evidence of hypercapnia.

Lung cancer and mesothelioma

• Patients undergoing chemotherapy should not travel while they are at increased risk of infection or suffering from significant side effects, such as vomiting.

Hyperventilation and DB

• Patients with DB, inducible laryngeal obstruction (ILO) and/or vocal cord dysfunction (VCD) should be referred to a respiratory physiotherapy specialist for advice on symptom management before travel.

• Those with anxiety disorders should be reviewed before travel; compliance with medication assessed; and use of short acting anxiolytics encouraged.

• Other life-threatening conditions presenting with dyspnoea should be excluded on board as far as possible.

• Supplemental oxygen should be given on board if the cause of breathlessness is unclear

• Rebreathing via a paper bag is not recommended.

Preflight respiratory screening

Clinical practice points

• All patients should undergo careful initial evaluation with history and physical examination by a clinician who is competent. The history should include:

  • Review of symptoms, baseline exercise capacity, recent exacerbation history, treatments and previous experience of air travel.

  • Consideration of the logistics of the intended journey, to include (if known):

    • Number and duration of flights, including whether daytime or overnight.

    • Location of stop-over(s) and destination: these determine air quality, altitude and available medical facilities.

    • Time away from home.

    • Return journey.

• Further assessment by a Respiratory Specialist is advised for those in whom screening raises concerns, and hypoxic challenge testing may be advised.

Clinical practice points

• For infants born at term (>37 weeks) it is prudent to delay flying for 1 week after birth to ensure they are healthy.

• Infants born prematurely (<37 weeks) with or without a history of respiratory disease who have not reached their expected date of delivery at the time of flying should have in-flight oxygen available. HCT may not be a reliable guide of oxygen requirement in this group. If air travel is essential, they should travel with oxygen at a tolerable low flow rate, recognising that this may be a minimum of 1 L/min depending on equipment.

• Infants under 1 year with a history of chronic respiratory problems should be discussed with a respiratory paediatrician and HCT considered. Those with SpO₂ <85% on HCT should have in-flight oxygen available; paediatrician discretion should be used for infants with SpO₂ 85%–90% recognising that sleep or respiratory infection may further reduce saturations in this group.

• In children with chronic lung disease able to perform spirometry whose FEV₁ is consistently <50% predicted, HCT should be considered. This includes children with CF and PCD. Children with chronic lung disease who are too young to perform spirometry reliably should have a clinical assessment of disease severity and their likely tolerance of hypoxia. In children with CF the disease is rarely severe enough to compromise lung function significantly at this age.

• Infants and children who have required long-term oxygen in the last 6 months should be discussed with a respiratory paediatrician and HCT considered.

Clinical practice points: patient selection for HCT

See figures 1 and 2

The following patients should not require HCT

• Those with stable disease who have previously undergone HCT (no recent hospital admissions, exacerbations, or significant changes to treatment).

• Patients with COPD with baseline SpO2 ≥95% and either MRC score 1–2 or desaturation to no less than 84% during 6MWT or SWT, should be able to travel without in-flight oxygen.

• Those with previous significant intolerance to air travel, such as mid-air emergency oxygen or diversion. These should have in-flight oxygen available at 2 L/min provided there is no history of hypercapnia.

• Preterm infants who have not reached their due date at the time of travel, as testing is not a reliable guide of oxygen requirement in these infants. These should have in-flight oxygen available, delivered at 1–2 L/min if they develop tachypnoea, recession, or other signs of respiratory distress.

HCT should be considered for the following

• Patients with COPD with resting SpO₂ ≤95%, MRC score 3 or greater, or desaturation to <84% on 6MWT or SWT, and in whom there are concerns about hypercapnia

• Infants and children with a history of neonatal respiratory problems, or existing severe chronic lung disease including those with FEV1 persistently <50% predicted (see page 7).

• Adults and children with severe asthma, evidenced by persistent symptoms and/or frequent exacerbations despite optimal treatment (see BTS/SIGN Asthma Guideline75) regardless of resting sea level SpO₂.

• Patients with ILD in whom SpO₂ falls to <95% on exercise, and whose resting sea level PaO₂ is ≤9.42 kPa or whose TLCO is ≤50%.

• Those with severe respiratory muscle weakness or chest wall deformity in whom FVC is <1 L.

• Those with existing or previous hypercapnia and those at risk of hypercapnia, including those taking medication(s) which can cause respiratory depression.

• Patients with a history of type 2 respiratory failure already on LTOT at sea level. However, if there is no evidence of hypercapnia, it seems reasonable to recommend an increase in flow rate by 2 L/min in-flight, provided the equipment can provide it (see Appendix A).

Clinical practice points: HCT results

• PaO₂ ≥6.6 kPa (≥50 mm Hg) or SpO₂ ≥85%: in-flight oxygen not required.

• PaO₂ <6.6 kPa (<50 mm Hg) or SpO₂ <85%: in-flight oxygen recommended.

• Where required, titrate oxygen to maintain PaO₂ ≥6.6 kPa or SpO₂ ≥85% in adults, SpO₂ 90% in children aged 1 year or more.

Air travel may be contraindicated in infrequent cases when supplementary oxygen, at the flow rate needed to maintain PaO₂ ≥6.6 kPa or SpO₂ ≥85%, causes significant changes to pH and pCO₂. The 2015 BTS Guidelines for Home Oxygen Use in Adults19 consider that a pH <7.35, and a PaCO₂ increase >1 kPa from baseline (within 20 min) is significant. Specialist respiratory physicians should use their discretion to determine the risk in individual cases and advise accordingly. Where hyperventilation is suspected, especially in response to anxiety rather than hypoxaemia, results should be interpreted with caution as there is a risk of false negative results.76

Chronic airflow obstruction including asthma and COPD

Most adults and children with well-controlled mild or moderate airflow obstruction and no other co-morbidities should have no problem with commercial air travel, but they should be prepared for the possibility of an exacerbation of their condition. Air travel presents a theoretical risk of bronchospasm because of mucosal water loss due to low cabin humidity.

Cigarette smokers are at a physiological disadvantage during exposure to altitude.81 Every opportunity should be taken, when reviewing travel plans, to take a smoking history and offer brief intervention and smoking cessation referral as appropriate.

Asthma

While asthma is prevalent and has the potential to be life-threatening, most episodes are not.82 83

Most passengers with asthma will have relatively mild disease and do not require HCT. HCT should however be considered for those with severe asthma, regardless of baseline sea level oxygen saturation. In a retrospective study of 37 adults with severe asthma (as defined in the BTS/SIGN Asthma guideline75) undergoing HCT, two-thirds who fulfilled the criteria for in-flight oxygen on HCT had baseline sea level oxygen saturations of >95%.84

The role of HCT has not been studied in children with severe stable asthma. A study in 51 children aged 2–12 years requiring transient oxygen therapy during an acute asthma attack (SpO2 <92%) showed that although 5% failed HCT within 24 hours of discontinuing oxygen therapy, all passed the HCT when retested at 48 hours.85

Food allergy affects up to 8.5% of children and adults with asthma,86 and asthma is a risk factor for severe or fatal anaphylaxis.87 Appropriate precautions for those affected include wiping tray tables and hands, informing the airline beforehand and the cabin crew of allergies, and not eating during flights or bringing known ‘safe’ foods from home88

Clinical practice points

• The patient’s condition should be optimised before travel, with attention paid to inhaler technique and smoking cessation referral as required.

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of lost or missing hold baggage.

• Emergency medications, including salbutamol inhalers and spacers, must be immediately accessible.

• Individuals prescribed epinephrine auto-injectors should have them readily available.

• For acute exacerbations on board, the passenger’s own bronchodilator inhaler should be given, with a spacer if needed.

• The passenger should alert the cabin crew if symptoms do not respond rapidly to use of the inhaler, or if they recur after a short interval.

• If the passenger does not have their own inhaler with them, or if it is inaccessible, the airline may carry an inhaler in the emergency medical kit. Spacers are not commonly available.

• Those with severe asthma should consult their respiratory specialist beforehand and consider taking an emergency supply of oral corticosteroid in their hand luggage in addition to their usual medication.

• Passengers with severe asthma are advised to carry copies of their asthma management plan and/or relevant clinic letters. Information can be held securely as scanned copies on a mobile phone, or on a digital platform such as the NHS App.

• Food allergy affects up to 8.5% of children and adults with asthma and asthma is a risk factor for severe or fatal anaphylaxis. Appropriate precautions for those affected include wiping tray tables and hands, informing the airline beforehand and the cabin crew of allergies, and not eating during flights or bringing known ‘safe’ foods from home.

Chronic obstructive pulmonary disease

Patients with COPD planning air travel need careful evaluation, not only because of their respiratory disease, but also because of their high levels of comorbidity.71 89

Respiratory symptoms in those with COPD are common during air travel, but Edvardsen et al have shown that HCT does not predict respiratory symptoms during air travel in patients with moderate to very severe COPD.71 They suggest that exacerbation of comorbidities such as cardiovascular disease (the most common cause of death in COPD) is the most threatening consequence of severe hypoxaemia. This is consistent with data showing a risk of cardiac arrhythmias and ischaemic chest pain in patients with COPD unable to respond to the physiological stressors of air travel.55 70 Work by Robson et al shows that resting sea level saturations alone do not predict HCT outcome.28

Spirometry does not reliably predict hypoxaemia or complications in COPD.29 It seems prudent to avoid air travel within 6 weeks of an exacerbation although there are few data to support this recommendation. Patients with COPD are at greater risk of VTE as a direct consequence of the underlying condition, as well as after an exacerbation. They should be advised accordingly, especially if planning longer flights when the risk is further enhanced (see section on VTE).90–92 See Figure 1.

Clinical practice points

• The patient’s condition should be optimised before travel, with attention paid to inhaler technique and smoking cessation referral where appropriate.

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of missing hold baggage.

• Emergency medications, including salbutamol inhalers and spacers, must be immediately accessible.

• For acute exacerbations on board, the passenger’s own bronchodilator inhaler should be given, with a spacer if appropriate.

• Passengers with severe COPD are advised to carry a copy of their COPD management plan and/or relevant clinic letters. This information can be held securely as scanned copies on their mobile phone A history of previous pneumothorax or bullous lung disease necessitates assessment by a respiratory specialist to determine the potential risk of complications from reduced cabin pressure.

• Patients with COPD are at greater risk of VTE as a direct consequence of the underlying condition, as well as after an exacerbation. They should be advised accordingly, especially if planning longer flights when the risk is further enhanced.

• Patients requiring long-term oxygen therapy should also plan for oxygen supplementation at their destination (see online supplemental appendix 1).

• Wherever possible, those who have had a recent exacerbation of their condition should not fly until their condition is stable and use of reliever therapy has returned to their usual baseline. If their condition deteriorates while overseas, medical advice should be sought before undertaking the return flight.

Clinical practice points

• All medications and spacer devices should be carried in hand luggage to mitigate the risk of missing hold baggage.

• Patients with CF under the age of 6 are likely to be well enough to fly at the paediatrician’s discretion.

• In those with CF who are old enough for spirometry and whose FEV1 is <50% predicted, HCT is recommended. If SpO2 falls below the 90% cut-off, as outlined above, in-flight oxygen is advised.

• In children with chronic lung disease able to perform spirometry whose FEV₁ is consistently <50% predicted, HCT should be considered. This includes children with CF and non-CF bronchiectasis. Children with chronic lung disease who are too young to reliably perform spirometry should have a clinical assessment of assess disease severity and their likely tolerance of hypoxia. For children with CF disease is rarely severe enough to severely compromise lung function at this age.

Clinical practice points

• Regular airway clearance is essential for those dealing with overproduction of mucus.

• Advice from a respiratory physiotherapist on adapting airway clearance techniques should be sought for long-haul flights.

• Portable nebulisers and PEP devices may be considered, but use of these devices in-flight must be approved by the airline before travel.

Clinical practice points

• In patients with comorbidity, including PH and/or cardiovascular disease, attention should also be paid to the impact of air travel on these conditions.

• Physicians may wish to consider HCT in those whom SpO2 falls to <95% on exercise, and/or in those in whom either TLCO ≤50% or PaO₂ ≤9.42 kPa (if available).

• Patients with TLco <50% of predicted or PaO₂ ≤9.42 kPa are likely to need in-flight oxygen. If there are no concerns about hypercapnia it may be reasonable to recommend 2 L/min without recourse to HCT. In those in whom there are concerns about CO2 retention, titration HCT is advised to determine the oxygen flow rate.

Thoracic surgery and other interventional procedures

There is no high-quality evidence in this area and further research and/or data collection are needed. The following are suggested time periods before which a medically unaccompanied commercial flight can safely be undertaken after the specific thoracic interventions described below. The advice is conservative. Shorter recovery periods may be appropriate in individual cases, but only if approved by the doctor/surgeon carrying out the procedure. It is also important to note that the potential risks of travel are not just those associated with a postprocedure pneumothorax, but include wound infection and pain, which could require medical attention at destination and would need approval by the travel insurer.

Thoracic surgery, including VATS procedures

In the absence of published evidence, we advocate a conservative and safe minimum time interval, with the caveat that flying sooner after such procedures may be possible and/or desirable, but that this should be agreed with the surgeon and discussed with the airline. At least two UK centres independently advise against non-essential air travel for 4 weeks after removal of drains (Jon Naylor, personal communication). If air travel is essential, a minimum delay of 2 weeks is advised, depending on the type of surgery and the surgeon’s advice.

Clinical practice points

• The opinion of the surgeon or interventionalist should be obtained before the patient travels by air. Patients, professionals, and their carers should be aware that this may result in a delay of 4 weeks for non-essential air travel and 2 weeks for essential air travel.

• Careful clinical assessment of the patient is required. This should include consideration of their baseline status including comorbidities, SpO2, postprocedure complications such as infection and/or pain, flight duration and destination.

Clinical practice points

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Careful clinical assessment of the patient is required. This should include consideration of baseline status including comorbidities, SpO2, postprocedure complications such as infection or pain, flight duration and destination.

• Patients with no pneumothorax seen on the postprocedure chest X-ray should wait for 1 week before air travel.

• Patients with a pneumothorax seen on the postprocedure chest X-ray should wait for 1 week after resolution on chest X-ray before air travel.

Clinical practice points

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Patients should be assessed carefully and advised on a case-by-case basis.

• Patients should be clinically stable before air travel.

Clinical practice points

• The opinion of the interventionalist should be obtained before the patient travels by air.

• Patients should be clinically stable before they travel.

• After interventional bronchoscopy including TBNA, TBB, EBUS and endobronchial valve insertion, those with no pneumothorax seen on the postprocedure chest X-ray should wait for 1 week before air travel.

• After interventional bronchoscopy including TBNA, TBB and EBUS, those with a pneumothorax seen on the postprocedure chest X-ray should wait for 1 week after resolution on chest X-ray before air travel.

Pleural effusion

Patients with stable pleural disease and normal resting oxygen saturations should be able to fly without further precautions. Those who have indwelling long-term drainage catheters should be reminded that the manufacturers do not advise air travel. Those who choose to travel should be encouraged to take a supply of drainage bottles for their time away.

In those with a recent onset pleural effusion, investigation should be delayed if air travel is planned within 2 weeks, since intervention may increase the risk of pneumothorax. The risk of delaying investigation should be discussed with the individual to determine whether travel plans can be modified.

Pneumothorax

The prevalence of in-flight pneumothorax in passengers with existing lung disease appears low overall, being zero in the UK Flight Outcomes Study.4 It increases, however, in those at increased risk: 3.6% in a study of 276 patients with LAM101; and 9% within 1 month of air travel in a retrospective survey of 145 patients with BHD syndrome.102

Most individuals with an untreated, closed pneumothorax should not travel by air. In exceptional cases where the pneumothorax is long-standing and thought to present a low risk, secondary care evaluation is strongly advised before travel.

In individuals with a treated pneumothorax, exposure to altitude poses a risk of recurrence. The 2010 BTS Pleural Disease guidelines state that patients ‘…should be cautioned against commercial flights … until full resolution of the pneumothorax has been confirmed by a chest X-ray”.103 These guidelines state that patients should wait a week after pneumothorax resolution before flying. There is limited, more recent evidence to suggest that in the case of traumatic pneumothorax, air travel as early as 72 hours after chest drain removal with full lung inflation may be safe.104 A prospective observational study of 20 patients with a small residual traumatic pneumothorax, exposed to hypobaric hypoxia for 2 hours suggested no significant clinical effects despite expansion of up to 171%.105 The data should, however, be interpreted with caution given the small numbers involved, the small size of the pneumothorax in each case, and the limited duration of hypobaric exposure. They are not sufficiently robust to justify overriding current BTS guidance.

In those who have undergone thoracotomy and surgical pleurodesis, the recurrence rate is so low that no subsequent restriction on travel is necessary.1 The recurrence rate has been reported to be four times greater after video-assisted thoracoscopy,106 suggesting that this procedure may not be as definitive. The risk of recurrence is greatest in those with pre-existing lung disease, cigarette smokers and taller men.1

Clinical practice points

• Passengers should not travel by air until 7 days after full resolution on chest X-ray.

• Those at higher risk of recurrent pneumothorax should be advised accordingly.

• Higher-risk groups, including those with cystic lung disease such as LAM and BHD syndrome, should be advised accordingly.

• Patients with trapped lung and a chronic air space thought to present a low risk should be evaluated in secondary care before travel.

Upper respiratory infection including otitis media and sinusitis

During air travel with acute infection of the upper airway, the main risks are unpredictable, but may reflect previous experience. They are of pain and potential rupture of the tympanic membrane. Those with significant symptomatic viral upper respiratory tract infection may wish to delay travel because of the risk of pain and disseminating infection to others.

Barotrauma, characterised by otalgia, is a consequence of inability to equilibrate the pressure differential between the external and middle ear. This is usually more severe during landing than take-off. Most passengers, including older children, can equilibrate the pressure through yawning, swallowing, chewing or a Valsalva manoeuvre (eg, pinching the nose and blowing). Infants and young children may be unable to perform these manoeuvres, but swallowing may be encouraged by drinking. It is also more frequent when the child is awake and/or crying.

It has been estimated that 10% of adults and 22% of children may have changes to the ear drum after a flight, although perforation is rare and symptoms usually resolve spontaneously.107 108

Historically, oral (and to a lesser extent topical) decongestants have been recommended for adults with risk factors for sinus or middle ear barotrauma.1 The evidence is very weak, and there is no evidence in children. Treatment with intranasal steroids (commenced at least a week before the flight) can however improve symptoms, as for inflammatory rhinosinusitis. After an episode of acute otitis media, patients are usually advised not to fly for 2 weeks107

Clinical practice points

• In passengers who develop sinus barotrauma after flying, it may be helpful to consider topical and oral decongestants as well as appropriate analgesia. Prolonged use of decongestants is not advised owing to the risk of rebound congestion on withdrawal.

• If there is an allergic component, intranasal steroids used for a week prior to travel, and/or oral corticosteroids may be considered.

• Symptoms and signs of barotrauma should have resolved before flying again. This usually takes between 1 and 6 weeks.

• After an episode of acute otitis media, patients are usually advised not to fly for 2 weeks.

Clinical practice points

• Patients with highly contagious infections including measles, chickenpox, mumps, SARS, MERS or COVID-19 should not be allowed to travel until they are considered non-infectious.

• Passengers should familiarise themselves with current national and international regulations regarding air travel, which should always be observed.

Clinical practice points

• Smear positive patients must not fly until they have provided two smear negative samples on treatment.

• Those starting treatment for pulmonary TB, where not all the information is yet available, should not travel by air for the first 2 weeks.

• For those who are smear negative and have a fully sensitive organism, treatment would be expected to render them non-infectious after 2 weeks.

• For patients with MDR/XDR TB, travel is prohibited until two negative culture samples have been produced and there is clinical evidence of improvement on treatment.

• Extrapulmonary TB does not usually warrant additional precautions before air travel.

Clinical practice points

• All but essential travel should be postponed for 7 days in those who have reduced baseline sea level SpO2 (<94%).

Clinical practice points

• Daytime flights are advised wherever possible.

• The patient should be advised to carry their CPAP device as hand luggage, and a hospital letter to advise that the patient uses CPAP.

• Careful planning and preparation are required, and use of the patient’s own CPAP device is advised.

• Alcohol and sedatives should be avoided in the 12 hours before, and during, airline travel.

• Patients should use their CPAP device on board if they are travelling overnight, and avoid sleeping during daytime flights.

• Consideration should be given to device settings and whether adjustment is required for operation at altitude.

• Airline approval for carriage and use of device, including battery specification, must be gained before travel.

• Consideration should be given to the whole journey. If driving is required the following day, an overnight stay at destination may be advisable. Patients are advised to refrain from driving if tired and sleepy.

Clinical practice points

• HCT is recommended for all adult patients with FVC <1 L, pending further data, and may be considered in others thought to be at particular risk, including children with reduced FVC due to respiratory muscle or chest wall disorders.

• If patients are unable to perform spirometry reliably, a walk test may be considered as an alternative.

• Patients should be advised to take daytime flights where possible.

• Further planning and support are required for those established on NIV (see Appendix A).

Prevention of VTE during air travel

The risk of VTE during air travel appears low overall, and prophylaxis is unnecessary for most travellers. Prolonged travel (exceeding 6 hours) and/or the coexistence of another risk factor for VTE increase the risk. The incidence of symptomatic VTE has been estimated at 0.5% on flights over 12 hours, but asymptomatic rates may be higher.128–130 The reasons for the increased risk are not entirely clear. Potential contributory factors include prolonged immobility and dehydration, but these are not conclusively proven. Other risk factors for VTE such as obesity, recent surgery, pregnancy, malignancy and previous VTE all increase the overall risk for travel-related VTE and may necessitate additional prophylaxis.

General measures, including getting up and walking around where possible every 2–3 hours; ankle and calf exercises and avoidance of alcohol or sedating drugs; are advisable for most travellers. Although there is no conclusive evidence that flying causes dehydration, the fall in cabin humidity along with alcohol consumption and reduced fluid intake, may increase the risk on long haul flights. Remaining well hydrated is, therefore, advisable. Wearing graduated compression stockings during travel may reduce the incidence of deep venous thrombosis.131 Data are sparse regarding the method or duration of pharmacological prophylaxis, and recommendations rely on consensus expert opinion. Physicians may wish to recommend pharmacological prophylaxis for those at higher risk of VTE, for example an obese patient planning a flight exceeding 6 hours with a history of recent surgery. The risks of prophylaxis are thought to be low. There is limited evidence for LMWH as prophylaxis.132 There is no formally recommended dose, but enoxaparin 40 mg at a dose of 40 mg or weight based 1 mg/kg injected once 4–5 hours before the flight has been suggested.132 The use of factor Xa inhibitors is off-licence in this situation and currently has no evidence base.

Clinical practice points

• Limit the risk of dehydration with adequate fluid intake.

• Avoid alcohol.

• Keep mobile, if possible, by walking around or doing seat-based exercises once an hour.

• Consider graduated compression stockings (class 1 with 15–30 mm Hg).

• LMWH or a DOAC are advised for both outward and return long haul flights (long haul defined as flights of 6–12 hours) in high-risk patients including those with a history of VTE; local policy should be followed regarding liaison with primary care and/or haematology services to teach the patient how to administer the injection and dispose safely of the equipment. There is no formally recommended dose, but enoxaparin at a dose of 40 mg or weight based 1 mg/kg injected once 4–5 hours before the flight has been suggested.

• The prophylactic doses of the DOAC may also be used.

• All patients with a recent (<6 weeks) history of VTE, especially any who presented with significant right ventricular strain and decompensation should be reassessed before air travel.

Air travel after VTE

Although the risks of prolonged air travel and development of VTE are well known, there are fewer data on the risks associated with flying after a diagnosis of VTE.

A patient with a confirmed diagnosis of PE is highly likely to start anticoagulation, with the aim of preventing the formation of new deep venous thrombi and further PEs. There is a general acceptance that flying immediately after a diagnosis of PE/DVT should be avoided. It appears reasonable to assume that the sooner air travel occurs after a PE the greater the likelihood that hypoxic pulmonary vasoconstriction will exacerbate ventilation-perfusion mismatch and raise pulmonary pressures, affecting cardiac output.

Some authors, but not all, suggest that most clots are resolved after 14–21 days.133 Consensus opinion is to delay air travel, if possible, usually for at least 2 weeks, although there are no concrete data to support a safe time interval. Clearly the risk-benefit ratio needs to be assessed if more urgent air travel is needed. Clot resolution depends principally on in vivo fibrinolysis. Consideration should be given to the severity of the initial presentation. It is good practice, before any proposed air travel, to reassess clinically a patient who has presented with significant right ventricular strain and decompensation.

The probability of recurrent VTE while anticoagulated is extremely low. Recovered, stable patients who remain on anticoagulation should be reassured accordingly and advised to follow the above general measures.

Clinical practice point

• Air travel should be delayed for 2 weeks after a diagnosis of DVT or PE.

Clinical practice points

• Those in NYHA WHO functional class 3 or 4 are usually advised to have in-flight oxygen. If there is no evidence of hypercapnia it seems reasonable to suggest 2 L/min by nasal cannulae. If there are concerns about hypercapnia, HCT should be considered if available.

• Those eligible for LTOT (sea level PaO₂ <8 kPa at rest on air) should have in flight oxygen at double the flow rate recommended at sea level, provided there is no evidence of hypercapnia.

Clinical practice point

• Patients undergoing chemotherapy should not travel while they are at increased risk of infection or suffering from significant side effects, such as vomiting.

Clinical practice points

• Patients with DB, ILO and/or VCD should be referred to a Respiratory Physiotherapy Specialist for advice on symptom management before travel.

• Those with anxiety disorders should be reviewed before travel; compliance with medication assessed; and use of short acting anxiolytics encouraged.

• Other life-threatening conditions presenting with dyspnoea should be excluded on board as far as possible.

• Supplemental oxygen should be given on board if the cause of breathlessness is unclear.

• Rebreathing via a paper bag is not recommended.

Oxygen

Passengers requiring oxygen and travelling overseas will usually need to lease a POC privately, since UK companies do not generally allow equipment provided through the NHS to be taken out of the country. Furthermore, most airlines have moved away from supplying routine medical oxygen.

Where battery powered mechanical devices are required in-flight, including a POC, sufficient batteries should be carried for 1.5 times the anticipated duration of the journey to cope with delays or diversions. For example, a patient using a POC on a 4-hour flight should have 6 hours of battery life. Any spare batteries must be correctly packaged and should be carried in cabin baggage. The airline must be notified in advance of these plans, or airline staff can refuse to allow the equipment to be taken on board.

Pulse-dose oxygen may not be suitable for patients with a fast and shallow respiratory pattern, or during sleep.154 155 Pulse-dose settings do not equate to the equivalent continuous flow rates,74 and not every POC functions well at altitude.156 In contrast, pulse-dose oxygen functions reliably when provided by a cylinder and conserving device.156 One author found significantly lower PaO₂ values when using a POC, compared with compressed oxygen with a conserving device. Acceptable in-flight values are achievable with POCs, but the dose may need to be increased.56

Pulse-dose delivery systems can complicate determination of the flow delivered; and may not be well tolerated. The effects of mouth-breathing, speech, snoring and/or sleeping should be considered. HFNO cannot be delivered on board commercial aircraft.

Pulse-dose oxygen has not been studied in infants and children; and should not be used unless they have been shown to trigger the device’s inspiratory flow.

Currently available POCs that do supply continuous flow oxygen cannot provide flow rates above 3 L/min. Passengers must refer to POC documentation to check that the equipment meets their requirements before they lease it for air travel.

For all these reasons, assessments would ideally take place using the same equipment as that which will be used on board the aircraft. This is only likely to be possible when the patient has leased or purchased a POC for their own long term, private use.

Continuous positive airway pressure

Few airlines, if any, allow any medical device to be powered via the aircraft power supply. An appropriate battery must, therefore, be used. The device and battery specifications must be approved for use by the airline before travel. Battery performance should be checked by the user beforehand, so there is an understanding of operating times on their usual settings.

Further consideration needs to be given to CPAP use during flight and at high altitude destinations, as it requires a machine that will perform adequately at low ambient pressure. The 2011 BTS guidance1 reported that a fixed-pressure CPAP machine without pressure compensation, set to deliver a pressure of 12 cm H₂O at sea level, may deliver only 9 cm H₂O at 8000 ft. The machine may therefore require adjustment to ensure a safe level of treatment throughout the flight. If continuous flow oxygen cannot be provided by the airline or by POC, oxygen and CPAP cannot be used simultaneously. The availability of distilled water for humidifiers may be restricted.

Non-invasive ventilation

For patients established on NIV, further planning and advice are required to support the use of NIV during flight. If continuous flow oxygen cannot be provided by the airline or by POC, oxygen and NIV cannot be used simultaneously. A decision around whether NIV or supplementary oxygen is of greatest physiological importance to the patient is then required on an individual basis. Previous travel history, current clinical condition and the presence or absence of overnight travel should also be considered. The level of clinical and personal dependency must be considered in the context of requirements for trained supervision and assistance by the caregiver.

HCT methods

The HCT uses an inspired gas mixture containing 15% oxygen, which gives an approximate similar PO₂ to breathing air at the maximum allowable cabin pressure altitude (2438 m or 8000ft).53 54 HCT is usually performed in a specialist respiratory physiology unit. The provision of a 15% oxygen gas mixture can be achieved as follows:

• A premixed cylinder containing a 15% oxygen gas mixture can be obtained from medical gas providers, or Douglas bags can be mixed with air and nitrogen to reduce the percentage of inspired oxygen to 15%, both to supply a tight-fitting face mask in a closed circuit.1

• Pure nitrogen can be introduced into a sealed chamber such as a body plethysmograph for paediatric or mask-intolerant patients, removing the need for a face mask.17 Paediatric patients can be sat in a body plethysmograph on an adult’s lap throughout;1 the adult should also undergo SpO₂ monitoring to avoid excessive hypoxaemia. A body box is generally used for children, although some paediatric laboratories use masks

• A 40% Venturi oxygen mask can be used with pure nitrogen as the driving gas, giving a resultant gas mixture containing approximately 15% oxygen.11 58

• A hypoxic gas generator, like an oxygen concentrator, can be used to provide a continuous supply of variable hypoxic gas mixtures to supply a mask or closed chamber. This can be the most cost-effective method for centres with a high demand for HCT.12

The patient usually breathes the hypoxic gas mixture for 20 min, or until SpO₂ reaches 85%. Although this is shorter than the briefest commercial flight, oxygenation equilibrium is usually reached within this time.134 157 The patient is advised to have in-flight oxygen if PaO₂ falls below 6.6 kPa (<50 mm Hg) or SpO₂ remains <85%1 17 (see page 11).

HCT with oxygen

If PaO₂ or SpO₂ values meet the criteria, in-flight oxygen is recommended.1 The flow rate required can be assessed as part of the HCT.17 Previous BTS recommendations advised in-flight oxygen to be supplied at two or 4 L/min via nasal cannulae, which were for many years the only fixed flow rates routinely available on commercial aircraft. As airline-supplied in-flight oxygen becomes less common and greater numbers of patients travel with flight-approved POCs delivering a wide range of continuous and intermittent flow rates, these figures are less critical. The HCT should ideally be performed with the modality that is intended for use in-flight.

Most airlines have moved away from supplying routine medical oxygen. In-flight oxygen is thus now likely to be supplied by an FAA approved POC, leased by the patient. These are mostly pulse-dose delivery. It is, therefore, advisable to conduct a titrated HCT with pulsed dose oxygen to maintain PaO₂ at ≥6.6 kPa or SpO2 ≥85%, using setting 2 as the starting point. This approximates to the 2 L/min originally stated. If pulse-dose oxygen at higher settings is insufficient to maintain PaO₂ at ≥6.6 kPa or SpO2 ≥85%, then continuous oxygen should be considered. It should be noted that POC models supplying continuous flow are limited, and they do not currently supply >3 L/min.

Pulse-dose delivery is not suitable for young children, for use during sleep154 155 or for certain adults. Not all POCs function as expected under conditions of simulated altitude156 and pulse-dose settings may not equate to equivalent continuous flow rates 74 (see Appendix A).