Passenger fitness to fly

Abstract

The COVID-19 pandemic has reduced the amount of international travel, however, the speed and convenience of jet travel is unparalleled and our love of visiting far flung places at low cost will not have gone away for good. Now is an ideal time to review the health considerations of travelling in order to provide safe advice to our patients, who are increasingly elderly and travel with a wider range of medical co-morbidity. The purpose of this article is to consolidate guidance from the Civil Aviation Authority and the International Air Travel Association with supplementary travel information from other specialist organisations to help develop understanding of the issues air travel may pose for patients in primary care.

Clinical case scenario 1

John is a 65-year-old insulin-dependent diabetic patient who is attending for a check-up following a coronary artery bypass graft (CABG) 11 days prior. He has made an excellent recovery and has had no issues with his glycaemic control, maintained by a multiple daily basal-bolus regimen consisting of a long-acting and rapid-acting insulin. His father lives in New York City and has unfortunately been taken ill. John is planning to visit his father next week. What health advice should his GP give and is John safe to fly?

Introduction

Travellers reflect the demographics of the population from which they originate. The UK has an ageing population with a broad range of conditions that are affected by the physiological effects of altitude. Although there are few absolute contraindications to flying, certain conditions need further assessment to ensure flight is safe. Aircraft cabins are pressured to a ‘cabin altitude’ of between 5000 and 8000 feet during commercial flights. In healthy passengers, this will lead to oxygen saturations of around 90% from a reduction in the oxygen partial pressure in the inspired air (Civil Aviation Authority CAA, 2021). This is particularly relevant to passengers with conditions that predispose them to hypoxia, including heart and lung disease. Additionally, gas will expand by 30% in volume at a cabin altitude of 8000 feet, so any obstruction to the free flow of gas in and out of body cavities can result in complications. This can range from minor sinus discomfort to serious post-operative issues if, for example, insufficient time has been allowed for surgically introduced gas to be reabsorbed into the body.

As a general rule, people should not board a commercial flight with acute, unstable or contagious conditions. Patients with conditions that do not fall into these categories need an assessment of the condition to establish how the stress of the aviation environment will affect their condition. Air travel involves navigating complicated, crowded buildings with queues, security checks and signage. In flight, cabin crew can provide basic first aid, but cannot help with other care needs such as toileting, washing or administration of medication. In the unlikely event of an emergency, passengers need to be able to adopt the brace position, don a life jacket and oxygen mask and follow instructions from cabin crew. The environment in the cabin is hypobaric and hypoxic with a low humidity level and very narrow passageways. The seats have limited leg room and the toilets provide little space for manoeuvre. Airports and airlines will provide reasonable assistance if requested in advance, but nevertheless this environment is not one that is suitable for all.

The final decision on a patient’s fitness to fly rests with the airline. However, patients often request a declaration from a doctor to support their travel plans. Such ‘fitness notes’ fall outside the remit of NHS primary care and are chargeable (British Medical Association (BMA), 2020). Any correspondence should be worded with care, so as to avoid providing a guarantee of fitness for the duration of the trip. The BMA suggests phrasing letters thus: ‘Based on information available in the medical notes, the patient appears to be fit to travel with any medical information limited to factual detail about any relevant conditions and their stability (BMA, 2020)'. Where there is doubt, it is acceptable to seek clarification from the patient’s specialist team, the medical department of the airline (if there is one) or the Aviation Health Unit of the CAA. A summary of the role of the CAA is outlined in Box 1. The formal process of requesting advice from the airline is completed using a Medical Information Form (MEDIF) by the traveller and a healthcare professional familiar with the patient, usually the GP. This form can be accessed via the airline or from travel agents. Passengers with stable and long-term chronic conditions can be provided with a Frequent Travellers’ Medical Card (FREMEC) to avoid the need for clearance on every occasion they travel.

Box 1.

The CAA.

The CAA is the organisation responsible for UK aviation safety and regulation

The COVID-19 pandemic has added an additional dimension to ‘fitness to fly’ assessment, as some countries mandate a negative SARS CoV-2 PCR test within a certain timeframe prior to flight. This is not a service offered by the NHS, but can be provided by the private sector. The specific guidance pertaining to COVID-19 can change frequently, and as such, should be consulted prior to each journey and for each country visited.

Clinical case scenario 2

Alice is a 22-year-old normally fit and well lady who is 28 weeks pregnant with her first child. She wishes to go on holiday to France next week with her husband, but is aware she will need a note from a healthcare professional before boarding the aircraft. Is it safe for her to fly and what information should be provided in the note?

Conditions by system

Acute Illness and COVID-19

Mild and self-limiting conditions make up a significant proportion of the primary care workload and can impact upon the ability of the patient to fly. Patients with upper respiratory tract infections, otitis media and hay fever need to be able to clear their ears before getting on an aircraft. Gas in the middle ear cavity should be able to vent through the Eustachian tube – this usually happens passively as altitude increases but during descent this requires the passenger to yawn or swallow to allow the negative pressure to equalise. A simple (but limited) method of examining this in the clinic is by asking to patient to perform a gentle Valsalva manoeuvre while examining the tympanic membrane with an otoscope. The variation of middle ear cavity pressure should result in corresponding movement of the tympanic membrane. Patients may report the sensation of not being able to clear their ears during the illness and should not fly until this symptom resolves. From a dental perspective, the presence of even tiny gas bubbles in caries can expand at altitude and cause pain, so patient with active dental issues should have them corrected by a dentist prior to flying. Patients with headache should be assessed to ensure they have no ‘red flags’ of a space-occupying lesion, intracranial bleed or meningitis. Migraines can be debilitating, and there is a lot of variation between individuals. Air travel can be a trigger for some, due to the stress of arranging travel, jet lag and sleep deprivation, pressure changes, dry air, dehydration and certain foods or drinks. Travellers with migraines should be mindful of this before flying and plan ahead to reduce the risk of having an episode during the flight.

Passengers should not fly with contagious conditions, potentially indicated by having a fever alongside coughing, diarrhoea, vomiting, headache, rash or confusion. Different infections have different incubation and infectivity periods which should be observed. Aircraft have high efficiency particulate air filters in the on-board air conditioning systems which make airborne or droplet spread throughout the cabin less likely, and means the risk of transmission will be highest to those in closest proximity to the index case. Of particular relevance to this is the overlap between common coughs and colds and COVID-19, which can have almost indistinguishable symptoms. The current NHS guidance is that individuals with a cough, a fever or a change in taste or smell should get tested for SARS-CoV-2 at a nearby testing centre and isolate until they have the result. If the test is positive they should isolate for 10 days or until they have been apyrexial for 48 hours, whichever is later. If they are aware they have been in contact with a case, they should self-isolate for 10 days following the exposure to monitor for the onset of symptoms, and quarantine rules may apply if returning from certain high prevalence countries (UK Government, 2021). A diagnosis of COVID-19, being in self-isolation or being in a quarantine period represents a contraindication to commercial passenger flight. There is no specific published guidance on the long-term effects of COVID-19 (‘long COVID’) and flying. However, if there is concern, particularly regarding hypoxia, then this should be discussed with the airline.

Diabetes

Travellers with diet or oral medication-controlled diabetes can generally fly without restriction, and only need to ensure they have an adequate supply of medication and be aware that other countries may use different units to measure blood glucose (mg/dL instead of mmol/L) (Diabetes UK, 2020). Travelling with enough medication is important, especially if there is an unexpected extension to the stay abroad. Managing insulin across time zones (especially if more than 4 hours difference) can be complicated, and if any doubt exists, the patient should seek advice from their diabetic team. Insulin should not be kept in the hold, as there is a risk it might freeze in transit, and medications or equipment such as hypodermic needles will need to be accompanied by a prescription or note from their doctor. Travellers with medical devices (such as a continuous glucose monitor or an insulin pump) should discuss their equipment with the airline in advance. Users with insulin pumps should not put their devices through X-ray machines or whole body scanners, as the radiation may interfere with the functionality of the motors and therefore safe insulin delivery; these devices should be checked against manufacturer guidance and be accompanied by a letter from a healthcare professional (Diabetes UK, 2020). Other essential equipment and medication can be transported through airport security, but again they may need supporting documentation.

Central nervous system disorders

Patients who have had a transient ischaemic attack (TIA) should wait at least 2 days with proper investigation following a TIA, and those who have had a stroke should wait 5–14 days prior to flying (International Air Travel Association (IATA), 2020). If within 2 weeks post-stroke these patients should receive in-flight oxygen in conjunction with the airline’s medical department. At least 10 days should elapse following brain surgery providing the cranium is free of air and the patient is clinically well and without any new neurological signs or symptoms, however, it would be sensible to seek advice from the airline and the specialist if there is any uncertainty. Patients who have had a grand mal seizure should wait at least 24 hours (IATA, 2020), but if control is poor and there is the risk of an in-flight episode, then that will impact their ability to board the aircraft. Airlines will typically wish to know the type of seizure, their frequency including when the last seizure occurred and if they are controlled on medication.

Circulatory disorders

For patients with a stable and mild cardiac history, the physiological changes associated with commercial flight are not a barrier to travel. Flying restrictions are primarily for those with more severe cardiac disease where there is concern over the stability and deterioration of the condition. The baseline cardiac function of the patient should at a minimum allow them to ‘walk 50 meters on the flat or go up a flight of stairs at normal pace without breathlessness’ (IATA, 2020). Airline medical departments will wish to know the functional ability of the patient, the results of relevant investigations (such as electrocardiograms), the details of any prescribed medication, symptomatic control and details of any syncopal episodes.

Patients who have had an acute coronary syndrome can be individually risk stratified according the characteristics of the episode. However, as a general rule, patients who are clinically stable and who have been fully investigated and treated should not fly within 10 days. However, if they are unstable, or have investigations and treatment outstanding, flying should be deferred until this has been addressed. Acute heart failure patients should wait until 6 weeks before flying if they are stable (Smith, 2010). Chronic heart failure and pulmonary hypertension patients need to be assessed according to their New York Heart Association (NYHA) classification (IATA, 2020): patients NYHA Class I can fly without restriction, Class II and III will require specialist assessment and may require in-flight oxygen and Class IV will require in-flight oxygen and airport assistance (if they are allowed to fly) and this would need to be under a special protocol, due to being at a very high risk of deterioration in the flight environment. Similarly, severe symptomatic cardiac valve disease is a relative contraindication to flying (CAA, 2021). Supplementary oxygen during flight is reserved for patients with debilitating circulatory disease (for example, severe angina, severe heart failure, or home oxygen use) and this may come at an additional cost and requires assessment by a doctor with aviation medicine experience to ensure it is safe for them to board the aircraft.

Travellers are restricted for 10 days post cardiac surgery such as a coronary artery bypass graft (CABG) as any residual trapped air in the thoracic cavity will require a period of time to be fully reabsorbed. Implantable cardiac devices in a bipolar configuration are safe for flight, provided that more than 2 days have elapsed since insertion, there has been no pneumothorax and the rhythm is stable (IATA, 2020).

The otherwise well traveller with a haemoglobin level greater than 8.5 g/dL can fly without issue (especially if the condition is chronic in nature), however, if it is less than 7.5 g/dL, the patient should be considered for in-flight oxygen (IATA, 2020). The concern with severe anaemia is that the oxygen-carrying capacity of the blood is reduced, and in the hypoxic and hypobaric aviation environment, this can lead to poor oxygenation of end organs, including the myocardium. This can present as chest pain, shortness of breath and dizziness. Travellers with sickle cell anaemia will need to travel with oxygen and should avoid flying for 10 days after a sickling crisis for the same reason (IATA, 2020).

Respiratory disorders

Patients with lung disease can be particularly susceptible to the aviation environment, due changes in cabin oxygen partial pressure leading to hypoxaemia. Contraindications for commercial air travel are listed in guidance published by the British Thoracic Society (Ahmedzai, 2011) as infectious tuberculosis, ongoing pneumothorax with persistent air leak, major haemoptysis and a requirement of more than 4 L/min oxygen at sea level. Patients with conditions such as mild chronic obstructive pulmonary disease (COPD), emphysema, pulmonary fibrosis, and small pleural effusions can generally fly without specialist assessment if they have an exercise tolerance of over 50 meters without shortness of breath and have recovered from any exacerbations (IATA, 2020).

Patients with severe COPD, and those who have a baseline oxygen requirement, will need further assessment and may benefit from bringing an emergency supply of prednisolone in their hand luggage. When being discussed with the airline for consideration of suitability of flight and on board oxygen they will want to know if the patient is a CO₂ retainer and if they have had any recent arterial blood gases (and what the PO₂ and PCO₂ readings were). They may also ask when the patient last was on an aircraft and how they tolerated the flight. Patients who have had pneumonia should not fly if still symptomatic. Asthmatic travellers should not fly if they are having symptoms and should bring their bronchodilator medication on the flight. Patients who have had a non-traumatic pneumothorax should allow 7 days after full inflation is seen on chest X-ray with normal oxygen saturations (Ahmedzai, 2011). If the pneumothorax was traumatic in origin (including if after pacemaker implantation), there should be a 2-week delay before flying, due to potential gaseous expansion and risk of tension pneumothorax (Smith, 2010). Patients who have had a pulmonary embolism should not fly within 5 days and only once they are oxygenating normally and anticoagulated, and deep vein thrombosis (DVT) patients should only fly once asymptomatic and anticoagulated (IATA, 2020).

If oxygen is required following assessment by a doctor with aviation medicine experience, it can be supplied by the airline after being booked in advance. Oxygen is usually ‘pulsed’ (breath-activated) and this may be difficult to operate for the very young or the very frail without a regular breathing pattern. Oxygen would only be supplied for the flight itself and not for any layovers, so this would need to be considered when the flights are arranged. Personal oxygen concentrators require pre-approval from the airline and need to be on an agreed list of devices (CAA, 2021).

Pregnancy

Flying while pregnant is thought to be physiologically safe, but is restricted due to the risk of going into labour during the flight (Greer, 2013). For uncomplicated singleton pregnancies, the patient can fly up until the end of the 36th week, but for uncomplicated multiple pregnancies patients can fly up until the end of the 32nd week (CAA, 2021). Airlines require pregnant travellers to carry with them a note from 28 weeks from their doctor or midwife (see Box 2) and they can be turned away at the boarding gate without this documentation. It should be completed as close to the departure date as possible and if the trip is uneventful the note will also cover the return journey. If the pregnancy is complicated, or there is risk of pre-term labour, these should be assessed on a case-by-case basis and involve the airline. The mother may experience symptoms of fluid retention, sinus discomfort and sickness. The pregnant traveller is at an increased risk DVT during the pregnancy and for 6 weeks postpartum, but for short haul flights (less than 4 hours), this risk is low in the absence of other risk factors, and usually no action is needed (Greer, 2013). On longer haul flights, or if the traveller has other DVT risk factors, they may require further assessment and in some circumstances the prescription of a low-molecular-weight heparin to be accompanied by a prescription or letter. Simple advice can be given to reduce the risk of DVT, for example, mobilising regularly, in-seat calf exercises, staying hydrated, avoiding caffeinated drinks and wearing loose clothing (Greer, 2013). Graduated elastic compression stockings can be considered if there are no contraindications. Airport security scanners are not considered a risk in pregnancy and seatbelts should be worn when required. Additional medical issues that can pose a barrier to flight include conditions that predispose the individual to being anaemic (such as significant vaginal bleeding or sickle cell disease), being at increased risk of premature delivery, or co-existing cardiopulmonary disease. More complicated cases such as this should be discussed with a specialist.

Box 2.

Flying and pregnancy.

A woman should not fly after 36 weeks if they are carrying an uncomplicated single pregnancy, or after 32 weeks if they are carrying an uncomplicated multiple pregnancy. They do not need a MEDIF submitted to the airline. A fitness-to-fly note for a pregnant passenger after 28 weeks is mandatory and should include:

• If the pregnancy is single or multiple

• That the pregnancy is progressing without complication

• The estimated delivery date

Patients who have had a threatened or complete miscarriage should only travel once stable, not bleeding and pain free for 24 hours. Newborns should not fly if less than 48 hours old, but preferably after 7 days (IATA, 2020).

Psychiatric illness

The CAA outlines that the main consideration when assessing the safe flight of mental health patients is if their condition is likely to deteriorate in the flight environment, or if it may impact flight safety – particularly if it could manifest as disruptive or aggressive behaviour. For acute psychosis, 30 days should have elapsed prior to boarding the aircraft (IATA, 2020). Airlines will also want to know if the patient has flown before (and if so, when and if they were alone or escorted). Concerning features could be indicated by a ‘history of delusional, paranoid, aggressive or disinhibited behaviour with disorientation and agitation, wandering and significant anxiety’ (IATA, 2020). Patients with conditions such as Alzheimer’s disease, but who are safe to fly, may benefit from a trusted travel companion and UK airports and airlines can provide special assistance to individuals if requested in advance (Alzheimer’s Society, 2016).

Surgery, ophthalmology, ear nose and throat, and orthopaedics

Surgical interventions can impact on ability to travel, as it can involve introducing gas into parts of the body that are unable to equalise pressure. Surgery can also increase venous thromboembolism risk and result in post-operative anaemia and infection. At a cabin altitude of up to 8000 feet gas will expand by 30%, which can cause increased stress on suture lines causing bleeding, tearing or perforation. Following major abdominal surgery without evidence of obstruction, the traveller should wait at least 10 days prior to flying (CAA, 2021). Following other procedures such as laparoscopic surgery or appendectomy the traveller should wait 5 days (IATA, 2020). For colonoscopy or investigative laparoscopy, the traveller should wait for 24 hours, as these procedures involve the introduction of large volumes of gas into the gastrointestinal tract (CAA, 2021). Specific guidance for ophthalmological conditions should be reviewed on a case-by-case basis, due to the potential for eyesight compromise secondary to the expansion of trapped gas. Cataract or corneal surgery patients can fly after 24 hours, but intra-ocular surgery (or penetration) patients may need to wait between 1 and 6 weeks depending on the procedure or injury sustained (IATA, 2020). Ear nose and throat (ENT) patients will have advice specific to their condition given how sensitive the anatomy is to flight and this can vary from simply being able to clear their ears (such as in otitis media) to requiring an escort with wire cutters (or quick release wiring) if the jaw is wired following a mandible fracture (to ensure their airway can be secured, for example if they were to vomit). Patients will need to wait at least 10 days following middle ear surgery with a letter from their ENT specialist (IATA, 2020).

If a full plaster cast has been applied, the traveller should avoid flying for 24 hours (flights shorter than 2 hours) or 48 hours (flights longer than 2 hours) (see Box 3) (IATA, 2020). This is because of the risk of circulatory compromise secondary to tissue swelling, which can be reduced with the use of a bi-valved (split) cast or a back slab. Similarly, if a pneumatic splint is used, some air should be released prior to flight to allow for expansion. Patients who have received major orthopaedic surgery and are not anticoagulated should avoid flying for at least 6 weeks unless essential due to increased DVT risk (IATA, 2020). Finally, if the patient has had any surgical intervention and lost a significant amount of blood causing them to become anaemic they may need to wait until this improves and they cannot travel while actively bleeding. Airlines will want to know details of the procedure, relevant vital signs and investigation results (including haemoglobin level) and if there are any complications with recovery.

Box 3.

Flying and plaster casts.

If the flight is shorter than 2 hours, the traveller should delay flying by 24 hours. If the flight is longer than 2 hours, the traveller should delay flying by 48 hours

Conclusion

Clearance to fly is ultimately at the discretion of the airline with the role of the GP being to help provide adequate information ahead of time to help facilitate a safe decision. This can be done by telephone or more formally by use of a MEDIF. This is to be completed where there is doubt about the passenger’s fitness to travel (for example, due to acute or chronic illness, surgery, or hospitalisation) or when additional help or equipment is required. Patients with stable, long-term disability can apply for a FREMEC to avoid them having to gain medical clearance on every occasion they fly.

There are multiple medical considerations when assessing a patient’s fitness to fly as a passenger in a commercial aircraft. Aviation can be physiologically and psychologically stressful and directly impact the health of the passenger, especially if there are co-morbidities. Furthermore, the health of the passenger could also impact on the safe, appropriate and comfortable completion of the journey for the crew and other passengers; if a diversion is made it comes at a significant financial cost to the airline. There are internationally agreed guidelines on passenger fitness to fly and in the first instance there is plenty of information available for primary care clinicians on the CAA website.

International travel has taken a backseat to other world affairs in recent times. Nevertheless, travel health and fitness-to-fly assessments will gradually return to being a regular staple of the GP workload and now is a good time to think about how the commercial flight environment may impact upon the health of our patients in order to provide safe and appropriate flying advice.

KEY POINTS

Flying is generally very safe, but some patients will need specialist assessment

The aviation environment is dry, hypoxic and hypobaric

The decision to ‘clear’ a patient to fly is at the discretion of the airline

Additional advice and support to primary care clinicians is available using a MEDIF form

The CAA and IATA publishes guidance for different medical conditions and their suitability to fly

Footnotes

ORCID iD

Andrew Godden

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