Abstract
It is estimated that 1 billion people travel by air every year, and this is expected to double in 20 years. For the vast majority, commercial flights are safe and comfortable. All flights, short haul or long haul, impose stresses on passengers. GPs are often asked to advise about or certify patients' fitness to fly. This article aims to provide guidance to enable doctors to provide informed and evidence-based advice for their patients.
The GP curriculum and fitness to fly
The UK Civil Aviation Authority's Aviation Health Unit (AHU) was formed in 2003. It advises the government on passenger and aircrew health issues and now has a statutory role. In February 2009, it developed guidelines about fitness to fly for medical professionals.
Ultimately, it is the airline's decision whether to allow any particular individual to fly on their airline. Most airlines have medical advisors who advise health professionals and can ‘clear’ passengers for travel. Some airlines also request certificates or a completed Medical Information (Med IF) form from the patient's GP, or another doctor who knows the patient, to assist them in making decisions about whether they will carry a patient on their airline or not.
The British Medical Association (BMA) advises to word statements on a person's fitness to fly carefully, indicating the information on which the advice is based rather than positively certifying a person's fitness. For example, ‘on the basis of information provided to me by Mr. X, I know of no obvious reason why this person should not fly’ or ‘there is nothing in Mr. X's medical record held in this practice to indicate that flying is a risk for this patient’. This ensures that the doctor is not ‘guaranteeing’ in any way that this patient can travel without any problem but saying that on the available evidence, there is nothing to indicate a greater risk for this person than for others.
However, whether or not an airline requests information from a GP, GPs have a responsibility to provide travel advice. In doing this, they must consider patients' general health and how this may impact on airline travel and always act to ensure patient safety. GPs often need to balance a patient's right to fly against the possible risk of harm to the patient's health, the flight and other passengers.
The main considerations in determining a passenger's fitness to travel are
Will the passenger's medical condition be adversely affected by air travel? Will the passenger's medical condition adversely affect the comfort or safety of the other passengers or the operation of the aircraft?
A historical perspective
In 1590, the Jesuit priest Acosta noted
… I am convinced that the element of the air is in this place so thin and so delicate that it is not proportioned to human breathing which requires extensive and more temperate air.
Later, Robert Boyle explained that, if the temperature remains constant, reducing the pressure on a sample of gas increases its volume proportionally. Hence, Boyle's law:
where P represents pressure and V represents volume.
Aviation and physiology
A number of factors can potentially have an impact on the traveller's physiology.
Hypoxaemia
Boyles' law explains that with altitude, the volume of a gas expands and so has a lower pressure. Most commercial aircraft cruise at an altitude of between 35 000 and 40 000 feet. However, in practice, the air pressure inside the cabin does not fall below a cabin altitude equivalent of between 5000 and 8000 ft. This allows aircraft to fly at much higher altitudes than might be expected, which is both fuel efficient for jet engines and more comfortable since it avoids too much turbulence.
However, at cruising altitude, even in the aircraft cabin, there is a significant reduction in barometric pressure, compared to the barometric pressure at sea level, and a resulting reduction in the partial pressure of alveolar and thus arterial oxygen (PaO2) rendering the traveller hypoxaemic. At the highest cabin altitude of 8000 ft, this equates to an oxygen saturation of 85–91%, which is equivalent to breathing 15.1% (instead of the usual 20.9%) oxygen at sea level (Fig. 1). Most travellers tolerate this level of hypoxaemia well, but patients with cardiac and/or respiratory disease may develop problems.
Relation between altitude and inspired oxygen pressure.
Gas volume expansion
As explained by Boyle's law, as the aircraft climbs, the cabin pressure decreases compared to sea level and can result in gas volume expansion by up to 30%. These changes in gas volumes do not cause any problems where gas movement can take place freely, such as in the airways, but may cause discomfort or even tissue injury where gas is trapped or restricted (e.g. if recent surgery has introduced gas into the abdominal cavity or the eye). Gas can also expand if it has been trapped in the ear, causing pain and possible perforation of the tympanic membrane.
Humidity
Lower humidity levels in aircraft of 10–20% (compared to 40–50% in buildings) can cause dryness of mucous membranes (e.g. for contact lens wearers) and the skin. Contact lens wearers and others (e.g. keratoconjunctivitis sicca patients) may benefit from wearing spectacles or using artificial tears. Low humidity is difficult to avoid because air is drawn into the cabin from the outside and at high altitude it is completely devoid of moisture. However, the cabin environment does not cause dehydration as there is no evidence of change in osmolality.
Time zone changes
‘Jet lag’ or circadian dysrhythmia is due to desynchronization between the individual's internal clock and the external environment. Important factors affecting jet lag include:
The number of time zones crossed The direction of flight—westward flights are usually tolerated better than eastward flights The degree of environmental stimulation—light, the presence of social contact and knowledge of clock time The cumulative sleep loss—quantity and quality Individual differences (e.g. age)
Time differences may also complicate medication times, for example, with insulin administration or the oral contraceptive pill.
Physical stressors
Preflight stresses include carrying baggage and walking long distances. The seating of passengers in smaller spaces than normal with less opportunity to walk may predispose them to ‘traveller's thrombosis’.
Psychological stressors
A number of psychological stressors may occur when flying. These range from fear of flying, through worry and frustration over flight delays, to anxieties about arriving at an unknown and unfamiliar destination. Alcohol may exacerbate these symptoms.
Cardiovascular disease
Reduced oxygen saturation level during flights may affect some patients with cardiovascular disease. However, with the exception of the conditions listed in Box 1, most patients with cardiac conditions can travel safely.
Cardiovascular contraindications to airline flight
Unstable angina, uncontrolled hypertension, uncontrolled cardiac arrhythmia, decompensated heart failure, severe symptomatic valvular disease: Uncomplicated myocardial infarction: no flying within Complicated myocardial infarction: no flying within Coronary artery bypass graft: no flying within Percutaneous coronary intervention, e.g. angioplasty: no flying within Cerebrovascular accident: no flying within Pacemakers/implantable cardiac defibrillators—patients may travel when stable. Interaction with airport and aircraft electronics/security devices is unlikely.
In patients with low cardiac reserve, lower oxygen levels (together with tachycardia in response to this) increases myocardial oxygen demand and thus may cause cardiac decompensation. For these travellers, in-flight oxygen may be required. The indications for in-flight oxygen in cardiovascular disease include:
Need for oxygen at baseline altitude Congestive heart failure New York Heart Association (NYHA) class III—IV or baseline PaO2 less than 70 mmHg Angina of Canadian Cardiovascular Society (CCS) class III—IV Cyanotic congenital heart disease Primary pulmonary hypertension Other cardiovascular diseases associated with known baseline hypoxia
Respiratory disease
The new British Thoracic Society Recommendations for ‘Managing passengers with respiratory disease planning air travel’ will be published in autumn 2010.
Chronic lung disease
The majority of in-flight medical oxygen requests are for chronic respiratory disorders, such as chronic obstructive pulmonary disease (COPD), emphysema, bronchiectasis and pulmonary hypertension. Significant hypoxaemia may develop in such patients because they start with a low PaO2. Fitness to fly depends on the type, reversibility and severity of the respiratory illness, assessment of tolerance of cabin altitude and oxygen concentrations and anticipated duration of flight.
The following assessment is recommended in respiratory patients:
History and examination with particular reference to cardiorespiratory disease, dyspnoea and previous flying experience. Patients with an acute exacerbation of chronic respiratory disease should wait until their respiratory condition improves before flying. Spirometry (in non-tuberculous patients only) Measurement of oxygen saturations by pulse oximetry. If saturation is greater than 95%, oxygen is not needed and respiratory referral is not required. If hypercapnia is known or suspected, then specialist referral for arterial blood gas (ABG) measurement is preferable
The simplest fitness-to-fly test is whether the potential traveller can walk 50 m unaided at normal pace, or ascend one flight of stairs, without becoming severely breathless. If accomplished, the person is likely to tolerate the aircraft environment.
Potential travellers with oximetry saturations of less than 95%, those who are breathless at rest or those who have additional risk factors (Table 1) or complex disorders should be referred for specialist respiratory assessment. Lung function tests, ‘hypoxic challenge’ testing and ABGs may be needed to decide if a person with chronic lung disease can fly or if in-flight oxygen is needed.
Results of initial assessment of respiratory function (BTS)
Additional risk factors: hypercapnia, forced expiratory volume in 1 second (FEV1) less than 50% predicted, lung cancer, restrictive lung disease involving the parenchyma (fibrosis), chest wall (kyphoscoliosis) or respiratory muscles, ventilator support, cerebrovascular or cardiac disease, within 6 weeks of discharge for an exacerbation of chronic lung or cardiac disease.
On ABG, PaO2 is considered the best predictor of altitude PaO2 and tolerance—a ground level PaO2 greater than 70 mmHg is considered adequate to allow a person to fly in most cases. The ‘hypoxic challenge’ test simulates the cabin environment in the laboratory using oxygen—nitrogen mixes. If the challenge results in a PaO2 of less than 55 mmHg, in-flight oxygen is required. If oxygen is required, the airline should be informed as early as possible.
Patients suffering from bronchiectasis or cystic fibrosis should ensure that infection is controlled, secretions are loose and that they are adequately hydrated before travel. Medications reducing sputum viscosity may help such as deoxyribonuclease (DNase) in the low humidity environment of the aircraft cabin.
Patients with home oxygen
The majority of home oxygen users use flow rates between 1 and 2 l/minute. Passengers are generally prohibited from carrying their own oxygen and so flow rates 2 or 4 l/minute of oxygen are available from the airline, along with nasal prongs. Passengers should note that oxygen may only be provided in-flight and not from point of departure to destination.
Asthma
Patients with stable asthma can fly but are advised to carry medication in hand baggage.
Pneumothorax
The presence of pneumothorax is an absolute contraindication to air travel as trapped air may expand resulting in a tension pneumothorax. The AHU suggests air travel no earlier than 2 weeks after successful drainage, with full expansion of the lung. The British Thoracic Society (BTS) allows travel 1 week after chest X-ray confirmation of successful resolution of pneumothorax.
Although BTS guidance states that there is no evidence that air travel per se precipitates recurrence of pneumothorax, the consequences of recurrence during air travel may be serious. Recurrence risk only significantly falls 1 year after the index pneumothorax, so in the absence of a definitive surgical procedure, patients with spontaneous pneumothorax in particular may choose to minimize their risk and defer air travel where possible.
Pleural effusion
A pleural effusion, especially if large, should be drained at least 14 days prior to flight for both diagnostic and therapeutic reasons. A post-thoracentesis chest X-ray is indicated prior to flight to assess reaccumulation of pleural fluid or the presence of pneumothorax.
Infection
Patients with active or contagious infection are unsuitable for travel. Those recovering from acute bacterial or viral infection should be clinically improved with no residual infection and have satisfactory exercise tolerance before flying.
Sleep apnoea
Patients with obstructive sleep apnoea syndrome should avoid alcohol before and after the flight. Mild snoring or hypersomnolence do not require continuous positive airways pressure (CPAP) ventilation. Those with significant desaturations, and intending to sleep on the flight or travelling to high altitude destinations, should consider CPAP.
Other respiratory problems
Patients with interstitial lung diseases (e.g. pulmonary fibrosis and sarcoidosis) and malignancy can generally travel safely. Patients with spinal cord injuries, obesity, hypoventilation syndrome, kyphoscoliosis, muscular dystrophy and other types of neuromuscular disorders have limited ability to hyperventilate and clear secretions. These patients may fly but often require some manual assistance, suctioning or ventilator capabilities and medical oxygen—which must be discussed with the airline in advance.
Deep vein thrombosis
The World Health Organisation (WHO, 2007) reported that immobility (being seated for more than 4 hours in a car, bus, train or an aircraft) increases the risk of blood clotting rather than any effect of the cabin environment. Thus, ‘traveller's thrombosis’ may be a more appropriate term than ‘economy class syndrome’. The absolute risk was 1 in 4656 flights greater than 4 hours. The risk increases with the duration of the travel and with multiple flights within a short period. Risk also increases significantly if the individual has other risk factors for venous thromboembolism (VTE). These include
Age greater than 40 years Obesity Smoking Pregnancy Oral contraceptive pill use Prolonged immobility Varicose veins Recent major surgery Trauma or surgery of the lower limbs History of malignancy Family history of VTE Thrombophilia enhancing clotting activity Depletion of body fluids causing increased blood viscosity
The British Committee for Standard in Haematology (BCSH) classify three risk categories for VTE—low, medium and high—and suggest the precautions for continuous journeys lasting more than 6 hours listed in Table 2. Advise all travellers undertaking a long-haul flight to take sensible precautions including
Risk categories for VTE
Ensuring adequate hydration Performing calf exercises during the flight Spending periods out of the aircraft seat Avoiding excess alcohol Avoiding tight-fitting socks or stockings
In medium-and high-risk groups, prophylaxis should be used with graduated compression stockings and/or low-molecular weight heparin. Patients with plaster casts should be considered for a split cast to reduce the risk of compression. There is no evidence to support the use of aspirin in any risk category.
Patients with a history of recent VTE who are on anticoagulant treatment are at low risk of further clots. However, specialist advice should be taken if flying within 2 weeks of a new deep vein thrombosis (DVT) or pulmonary embolus (PE).
Pregnancy
The aircraft cabin conditions are not considered hazardous to normal pregnancy. At cabin altitude, maternal haemoglobin remains saturated at about 90% and so foetal PaO2 remains unchanged. This is due to the increased oxygen affinity of foetal haemoglobin, the Bohr effect (Fig. 1) and increased foetal haematocrit.
Most airlines require a certificate after 28 weeks gestation confirming the estimated date of delivery and that the pregnancy is progressing normally. Most airlines do not allow travel after 36 weeks for a single pregnancy and after 32 weeks for multiple pregnancy due to the increased risk of in-flight delivery or need for diversion.
Pregnancy-related emergencies during airline flights are most likely in the first and third trimester. Women, particularly in the first trimester, are advised not to fly if they are having either bleeding or pain associated with their pregnancy. Women with multiple pregnancies, a history of preterm delivery, cervical incompetence or increased uterine activity that might result in early delivery should avoid prolonged air travel.
Cramped seating and immobility for long periods increase the risk of lower extremity oedema, thrombophlebitis and DVT. Pregnancy significantly increases this risk of VTE due to obstruction of the vena cava from uterine compression, dependent lower extremities and altered clotting factors. Simple DVT precautions should be taken and compression stockings considered. If additional risk factors are present, specialist advice should be taken.
The risk of increased exposure to cosmic ionizing radiation for the foetus is not thought to be significant but is unquantifiable and must be taken at the mother's discretion. The risk may be increased if flying several times a week.
Infants and children
The BTS advises waiting 1 week after birth before flying to ensure the infant is healthy. Premature infants who have had complications should not fly under 6 months post-expected date of delivery due to the increased risk of apnoea. Infants with a history of neonatal respiratory illness and children with chronic lung disease and forced expiratory volume (FEV) of less than 50% should have formal preflight assessment and hypoxic challenge testing.
Gastro-intestinal problems
Gastro intestinal bleeding is a contraindication to flying for at least 10 days after a bleed. Ulcer sites may bleed due to stretching of gastric or intestinal mucosa, although travel may be permitted if there is clear endoscopic evidence of healing.
Surgery
The number of patients wishing to travel very soon after surgery is increasing with the wider use of day surgery and surgery tourism for cheaper cosmetic procedures abroad. Post-operatively, patients have a higher oxygen consumption, increased adrenergic flow and the possible presence of sepsis or anaemia. The AHU recommends avoiding flying after the procedures and circumstances mentioned in Box 2.
Surgical and traumatic contraindications to airline flight
Abdominal surgery: no flying within 10 days Colostomies: no flying unless larger bag ensured Laparoscopic surgery: no flying within 24 hours Colonoscopy: no flying within 24 hours Neurosurgery: no flying within 7 days Retinal detachment surgery: no flying within 2–6 weeks Other ophthalmological surgery or eye trauma: no flying within 1 week Active middle ear infections, effusions or recent ear surgery Tonsillectomy and adenoidectomy, palatoplasty, nasal/facial fracture repair: no flying within 2 weeks After application of plaster cast, avoid flying for 24 hours on flights less than 2 hours and 48 hours for longer flights
General anaesthesia is not a contraindication to flying because the cardiac depressant effects and changes in vascular resistance of anaesthetic agents wear off quickly, before discharge from hospital. However, bed rest is usually recommended for at least 24 hours following all spinal anaesthesia, with gradual return to full activities. Spinal anaesthesia can cause a moderate to severe headache, which is more likely with prolonged sitting or standing after surgery and with the lower air pressures occurring in flight.
As cabin pressure decreases, gas volumes increase. This can be a problem if gas is introduced into any body cavity during surgery or after abdominal surgery:
Intestinal gas is thought to expand by 30% at cabin altitude. After abdominal surgery, patients may have a relative ileus, thus posing a risk of tearing sutures, bleeding or even perforation. Passengers with colostomies should use a larger bag as intestinal distension may increase faecal output Following procedures where gas is introduced into the abdominal cavity or gut, such as laparoscopy or colonoscopy, it is advisable not to fly for 24 hours in case of residual gas from the procedure Some ophthalmological operations such as retinal detachment surgery involves intraocular gas injection, which transiently increases intraocular pressure. Travel should be delayed, if sulphur hexafluoride is used for 2 weeks and for 6 weeks with perfluoropropane. There is no flying restriction after cataract or corneal laser surgery. Travel after any neurosurgery should be delayed for at least 1 week due to the risk of trapped gas in the skull.
Fractures
After application of plaster cast, the majority of airlines restrict flying for 24 hours on flights less than 2 hours and for 48 hours for longer flights. These restrictions do not apply if the cast has been bivalved to allow swelling without increased pressure within the cast.
Ear, nose and throat
During ascent, air in the ear, nose and throat (ENT) cavities expands. This can cause a problem if the entrance/exit to these cavities is blocked.
In the sinuses, blockage of the entrance/exit passages by nasal polyps or as a result of sinusitis can result in headache and facial pain during flight. Unless it is absolutely necessary, advise patients not to fly until their symptoms have resolved. If flying is a necessity, decongestants, steroid nasal sprays and/or antibiotics may prevent these symptoms from occurring. Those with chronic problems, such as recurrent sinusitis or large nasal polyps, may need specialist ENT assessment prior to flight.
In the ear, the air in the middle ear expands but the pressure within the space does not increase because air is able to escape along the eustachian tube. On descent, air must pass back along the eustachian tube to equalize the air pressure as the air contracts. This process can be facilitated by yawning, swallowing or techniques such as the Valsalva manoeuvre.
The process of adjustment of pressure in the middle ear depends on patency of the eustachian tube. If the eustachian tube is blocked, for example, secondary to inflammation resulting from an upper respiratory tract infection, then pressure equalization cannot occur. The tympanic membrane will then be sucked inwards (usually on descent of the aircraft), causing pain, dizziness or even bleeding and perforation of the membrane. Therefore, patients with significant upper respiratory tract infections or active middle ear infections should be advised not to fly until their symptoms have resolved. Patients with chronic middle ear effusions may need specialist assessment prior to flying.
Similarly, if a bubble of air is trapped in the outer ear between the eardrum and impacted wax in the external ear canal, between the eardrum and swelling, pus and debris resulting from otitis externa or even just between the eardrum and a tight-fitting hearing aid or ear plug, it will not be possible to equalize the air pressure in this bubble of air with the air pressure in the middle ear. This can also result in pain and barotrauma to the eardrum. Earplugs and hearing aids should be loosened before take off and landing and where possible external auditory canal wax or otitis externa should be treated preflight.
ENT surgery
Recent ear surgery (tympanoplasty, mastoidectomy, stapedectomy, endolymphatic shunt, labyrinthectomy, acoustic neuroma removal, nerve section via middle cranial fossa or other otologic surgery) and jaw wiring for any reason are contraindications to flight, unless deemed fit to fly by an ENT specialist. Following tonsillectomy and adenoidectomy, palatoplasty or nasal or facial fracture repair, patients can fly once post-operative bleeding risk has passed (after about 2 weeks) and they have been cleared to fly by a relevant specialist.
Haematology
If they have no other coexisting medical condition, passengers with a haemoglobin greater than 8 g/dl can usually travel by air without problems. Those with a haemoglobin under 7.5 g/dl are at risk of hypoxia and a formal assessment of their fitness to fly should be carried out and the use of in-flight oxygen considered.
Adaptation to anaemia will affect the likelihood of problems. Patients with chronic anaemia (e.g. as a result of chronic renal impairment) will tolerate hypoxia better than those with anaemia of acute onset (e.g. after a recent haemorrhage).
Patients with sickle-cell disease can fly as long as they have access to in-flight oxygen but should not travel for 10 days following a crisis. Patients with sickle-cell trait can travel without restriction.
Neurological problems
AHU recommendations state that patients should not fly for 10 days after a cerebrovascular accident. However, if patients are stable and flight is absolutely necessary, some airlines may allow patients to fly 3 days after the event.
Patients with controlled epilepsy can generally fly safely. Potential seizure threshold-lowering effects include fatigue, delayed meals, mild hypoxia and hyperventilation, and disturbed circadian rhythm, and therefore, care should be taken with medication compliance. Travel should be delayed for 24 hours after a grand mal seizure.
Psychiatric illness
Fear of flying is estimated to affect 10–25% of the population. Symptoms range from mild anxiety to avoidance behaviour, with no borderline between ‘normal’ and ‘pathological’ fear. Those who seek help are those whose lives are severely affected by their avoidance behaviour. An anxiolytic medication may be prescribed if the patient has used it before with good results and without undue side effects. Some potential air travellers with a fear of flying opt to go on courses involving cognitive behavioural therapy, often combined with simple relaxation techniques, and educational information about the mechanics of flying, pilot training and aircraft noises and movements (e.g. turbulence). Such courses may also include an aircraft flight.
For those potential travellers with established psychiatric illness, fitness to fly is best considered on an individual basis and with expert advice if there is uncertainty. The freedoms of the individual to travel need to be balanced with the safety of the other passengers. In most cases, the underlying condition should be stable and medication taken regularly. Patients with behavioural problems, such as unpredictable, aggressive, disorganized or disruptive behaviour, should not travel. Acutely disturbed or psychotic patients should not travel without an appropriately trained medical escort with access to suitable sedation.
It is important to note that many medications prescribed for psychiatric disorders have anticholinergic side effects that may slow digestive processes, increasing intestinal gas formation. The resulting symptoms may be aggravated at altitude.
Diabetes mellitus
There is no restriction on flying for patients with well-controlled diabetes. There are no particular precautions for patients with diet-or tablet-controlled type 2 diabetes.
Insulin-dependent diabetics
Insulin-dependent diabetics may be required to have a letter of authorization from their doctor to allow carriage of blood sugar testing sticks, needles and insulin in their hand luggage. Insulin should be carried in a cool bag or pre-cooled vacuum flask. It should not to be stored in the hold (checked baggage) as temperatures may cause it to freeze and denature.
Special consideration should be applied to insulin dosing regimens on long-haul flights, depending on the direction of travel and movement across time zones. Advice from a diabetes specialist may be needed. As a general rule
When travelling east, the travel day will be shortened and if more than 2 hours are lost, it may be necessary to take fewer units of intermediate or long-acting insulin When travelling west and the day is extended by more than 2 hours, supplemental short-acting insulin or an increased dose of intermediate-acting insulin may be needed
It is recommended to remain on one time system during the flight and only attempt to readjust to local time on arrival at the destination. It is important that patients check their blood sugar before meals at 4–6 hourly intervals, during the flight. Sugar tablets and snacks to prevent hypoglycaemia should also be carried in hand luggage to cover contingencies, such as delayed flights or meals.
Decompression illness
Scuba diving is increasingly popular with many people taking diving holidays. The amount of nitrogen dissolved in body fluids and tissues is dependent on the atmospheric pressure. Decompression illness or ‘the bends’ is caused by nitrogen bubbles forming in the blood or body fluids when one travels from a high-pressure environment to a low-pressure environment. This can happen when surfacing from a dive or ascending to altitude in a plane. The most common symptoms are joint or muscle pain but more serious sequelae are due to occlusion of blood vessels.
Decompression illness rarely occurs below 25 000 ft (7600 m) and so does not affect most passengers at normal cabin altitudes. However, it does occasionally occur in those who have been exposed to hyperbaric conditions prior to flight, e.g. divers and tunnel workers. Recommendations vary, but typically divers are advised to wait a minimum of 12 hours between diving and flight or 24 hours if the dive required decompression stops.
Contagious infectious disease
Infectious disease is a relative contraindication to travel depending on the nature of the condition and its transmissibility at that phase of the illness. It is particularly important to note that most airlines will not carry children with chickenpox until they are non-infectious (5 days after appearance of the rash). Always seek advice from the airline. Any passenger with known tuberculosis should have had adequate treatment and be non-infectious prior to the flight.
Key points
Most healthy travellers tolerate air travel well For those with medical problems, fitness to fly depends on nature of condition, its severity, its stability at sea level and the impact physiological changes at altitude may have The final decision regarding carriage of the patient is made by the airline, but they require as much information as possible from health professionals in order to make a fair and safe decision regarding the patient's fitness Most airlines have medical advisors and provide advice to ‘clear’ passengers fit to fly. Clearance may be assessed by phone or by formal Med IF form. Further guidance is available from the AHU (e-mail: