FORT LAUDERDALE, FLA. – Your patients with cystic fibrosis or other pulmonary conditions may ask you if and when it’s safe for them to fly on an airplane.
How you respond can depend in part on their travel history, how long they will be exposed to increased cabin pressure, and if they are immunocompromised or have other risk factors for infection that are related to airborne pathogens, Dr. Susan L. Millard said.
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Air travel for patients with pulmonary conditions can be difficult. Physicians may have to recommend supplemental oxygen, provide travel letters, or administer hypoxia inhalation or walking tests prior to travel.
Severe respiratory insufficiency, right heart failure or hemodynamic instability, and active pneumothorax are absolute contraindications to air travel, according to 30 experts who wrote a consensus statement for traveling with cystic fibrosis (J. Cyst. Fibros. 2010;9:385-99).
These first-ever European recommendations are useful because they address preparations for travel (for example, vaccinations and packing medication), important considerations during travel, and issues specific to the immunocompromised, Dr. Millard said at a pediatric pulmonology seminar, which was sponsored by the American College of Chest Physicians and the American Academy of Pediatrics.
Air travel for pulmonology patients can be difficult, Dr. Millard noted, because "the environment is very dangerous." The cabin is pressurized, alveolar partial pressure falls with increasing altitude, and the partial pressure of oxygen is inversely proportional to altitude. Because the Joint Aviation Authorities stipulated that mean cabin pressure match an altitude of 8,000 feet, "this means they want us to all have an oxygen saturation of about 90%."
Supplemental oxygen during air travel can help patients, but identification of appropriate candidates varies. Guidelines from the American Thoracic Society and British Thoracic Society (Thorax 2002;57:289-304)recommend that patients with chronic lung disease be able to maintain an arterial oxygen tension greater than 50 mm Hg or 6.6 kilopascals (kPa), Dr. Millard said. However, because they tend to be younger than COPD (chronic obstructive pulmonary disease) patients and generally have no increased cardiovascular risk, use of such a cutoff value could be an oversimplification for patients with cystic fibrosis, said Dr. Millard, a pediatric pulmonologist at Helen DeVos Children’s Hospital in Grand Rapids, Mich.
Dr. Susan L. Millard
Hypoxia during flight is a major concern. Consider whether your patient will be able to sustain hyperventilation that is spurred by hypoxia while on the airplane. Significant bronchospasm, for example, could impede prolonged hyperventilation, Dr. Millard said.
Consider a hypoxia inhalation test in advance of travel. This test requires that patients breathe a hypoxic mixture of 15% oxygen with nitrogen for 20 minutes to predict their reaction to hypoxia at 8,000 feet. Supplemental oxygen is recommended if their arterial oxygen tension drops below 50-55 mm Hg or 6.6-7.4 kPa.
"The hypoxia inhalation test is found to be safe," Dr. Millard said. Applicability outside the clinic setting is a concern, however: "The problem is, they are sitting. This may not fully represent the physical stress and environmental variability of air travel," including Transportation Security Administration screening and walking long distances.
For this reason, some experts advise also screening patients with a walk test prior to their trip, Dr. Millard said. The American Thoracic Society provides guidelines for conducting a functional exercise evaluation called a 6-minute walk test, for example (Am. J. Resp. Crit. Care Med. 2002;166:111-7).
Patients who require supplemental oxygen are permitted to use their own approved portable oxygen concentrator (POC) on all airlines that operate in the United States. POCs weigh 8-10 pounds and batteries last an average of about 4 hours, Dr. Millard said. Also, some POCs are pulse generated, meaning the patient must be able to inspire strongly enough to get oxygen.
Advise your patients or their families to check in advance if their airline requires approval from a physician for POC use, Dr. Millard said. "I had a patient who gave me 48 hours notice that they were going to fly. I had to fill out a form ahead of time for the airline."
Pulmonology patients also may request a travel letter, "which is especially important if they are going through customs," Dr. Millard said. Include their insurance information, your contact information, the telephone number for the clinic, and a list of medications (and approximate quantities required).
Airborne infection risk is another major concern. Most commercial aircraft recirculate 50% of the air delivered to the passenger cabin, Dr. Millard said. Ideally, the aircraft features HEPA (high-efficiency particulate air) filters, although the U.S. Federal Aviation Authority (FAA) and the U.K. Civil Aviation Authority do not mandate this level of filtration.