Air Travel and Cardiovascular Disease

Stephen E. Possick, MD; Michèle Barry, MD, FACP

Disclosures

J Travel Med. 2004;11(4) 

In This Article

Pathophysiology: Cardiac Ischemia and Arrhythmias During Air Travel

Air travel impacts on patients with cardiovascular disease in several ways. Patients with cardiovascular disease can be more sensitive to changes in arterial oxygen saturation. Airline cabins are not pressurized to provide an altitude that mimics sea level. Cabin altitude may vary during an individual flight, although the FAA mandates an effective cabin altitude of 8,000ft at maximum flying altitude.[8] The effective cabin altitude of a plane flying at 40,000ft approaches 7,500ft if the cabin pressure is maintained at 585mmHg.[9] The net effect of such pressure changes is to decrease arterial oxygen tension, which could provoke ischemia and arrhythmia in those most susceptible. The arterial oxygen tension in a healthy individual, with a resting PaO2 of 98 at sea level, may fall to less than 60mmHg at such pressures during a routine commercial air flight.[10] One can estimate that inspired PO2 will fall by 4mmHg per 1000ft above sea level.[10]

Patients with concomitant pulmonary disease and even those without pulmonary compromise may require supplemental oxygen during air travel.[10] It is recommended that any passenger with a partial pressure of arterial oxygen of less than 70mm at sea level at rest should receive supplemental oxygen during air travel.[10] Oxygen should be requested well in advance, and is typically only available at 2-L or 4-L flow rates. Most airlines will also require a letter of medical clearance from the patient's physician at least 48h prior to the flight. US air carriers will require a prescription for oxygen. Charges for in-flight oxygen vary widely.[11] There are no specific data to support the routine use of in-flight oxygen in travelers who have suffered a recent myocardial infarction (MI) or have cardiac disease.

Several studies have either demonstrated or suggested increased sympathetic activity at altitudes of 1,500 to 3,000m.[12,13] This is believed to be secondary to hypoxia at higher altitudes. Angina and ST segment depression have been documented to occur at lower workloads in subjects at high altitude.[12] Whereas one might expect an increase in anginal symptoms during air travel, studies of this patient population during air travel have not been performed. The relative inactivity during air travel may mitigate the decreased work capacity seen at altitude. Similarly, although arrhythmia might be expected to occur more commonly at altitude, given the increased sympathetic activity and increased hypoxia noted above, this has not been borne out in one very small study evaluating the response of elderly subjects to an altitude of 2,500m.[13] Levine et al.[13] examined the response of 20 subjects with a mean age of 68 years to an altitude of 2,500m. Two of the 20 had a history of significant arrhythmias. Estimated mean pulmonary artery pressure increased by 43% with acute exposure to altitude, probably secondary to hypoxia and sympathetic activation. No significant arrhythmias were noted in the study group at altitude, although the investigators did find an increase in ventricular premature beats. The very small study size limits the broad application of these results to the air traveler with cardiovascular disease.

The increase in pulmonary artery pressure noted by Levine et al. suggests that travelers with depressed ejection fractions might suffer from increased symptoms of right- or left-sided heart failure during air travel. No study has addressed this issue. Whereas measurement of pulmonary artery pressure during flight might be impractical, a retrospective survey of such patients addressing in-flight symptoms would be relatively easy to undertake.

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