Breathing easier aloft

Among the nearly 2 billion people who travel in commercial airliners each year are growing numbers who don’t want to be sidelined by their respiratory or heart problems.

Doctors urge such passengers to do their part, which means checking in for a preflight assessment from their physician that will determine not only their fitness for flying but also whether they need supplemental oxygen or a change in medication.

Hypoxia -- insufficient oxygen in the blood or tissues -- is a primary hazard of altitude for those who suffer heart and lung problems. Decreased oxygen, in turn, can lead to such medical problems as hyperventilation and constricted blood vessels in the lungs, which can decrease blood flow to the brain and heart.

Anyone with severe lung disease or asthma, cystic fibrosis or a history of respiratory problems such as chest pain or fainting while flying should have a preflight assessment, says Dr. Mark J. Eisenberg, a cardiologist at Jewish General Hospital in Montreal and an associate professor of medicine at McGill University. His review paper on altitude-related problems for those with lung and heart problems was published in the September issue of Aviation, Space and Environmental Medicine.

Others who need to be evaluated before flying include those with tuberculosis, anyone who has been hospitalized for acute respiratory disease within six weeks of the departure date, those who need supplementary oxygen for lung problems and those with uncontrolled high blood pressure or abnormal heart rhythms, Eisenberg says.

Those who need supplemental oxygen on the ground also will need it aloft, says Dr. Henry Gong, a volunteer spokesperson for the American Lung Assn. of California and a professor at the University of Southern California’s Keck School of Medicine. They probably will need more of it on board than on the ground.

The more difficult challenge, Gong and Eisenberg agree, is identifying those who don’t need supplemental oxygen on the ground but who might need it aloft. “A common misconception is if you don’t need supplemental oxygen on the ground, you don’t need it at altitude,” Eisenberg says. Not true.

The best way to evaluate a person’s response to altitude, Eisenberg says, is to place him in a hyperbaric chamber, drop the pressure to the equivalent of the airplane cabin and measure the blood’s oxygen saturation using a blood gas test or pulse oximetry, which involves attaching a probe to the person’s finger or earlobe. (The hyperbaric chamber is the gold standard, but it’s not often used for this purpose, Gong says, because of the expense and lack of availability of the chambers.)

“If the oxygen saturation is less than 92% ... at ground level, oxygen is required at altitude,” Eisenberg says. “The partial pressure of oxygen gets lower the higher you go. As the partial pressure lessens, the amount of oxygen that gets into your blood decreases.”

A typical airplane cabin, he says, has air pressure equivalent to that at 5,000 to 8,000 feet, and that sometimes can cause breathing problems.

Passengers who need oxygen aloft must plan for it. For safety reasons, Federal Aviation Administration regulations forbid passengers from taking their own oxygen for use in flight, says Alison Duquette, a public affairs spokesperson for the FAA, but the regulation doesn’t require airlines to provide it, she adds. “It’s up to the airline.”

Those who need oxygen also should get a note from their doctor about how much they need and at what flow rate, Duquette says.

It’s best to inquire about the availability of oxygen before you make reservations and to reserve it when you book. Don’t assume it will be available on all airlines; some don’t provide it. And don’t assume it will be available on connecting flights. Some airlines, for instance, offer it on their flights, but their partner airlines offering connecting flights may not. Be sure to inquire about the availability of oxygen on each flight leg. Most airlines that provide it require at least 48 hours’ notice.

Fees vary, but a charge of $100 per flight leg is typical.

Airlines don’t provide supplemental oxygen to passengers while they are on the ground during a layover, so passengers must make their own arrangements.

Some nationwide suppliers that provide patient oxygen to a traveler’s home will also arrange to have it delivered to an airport during a layover. Again, planning is crucial.

At the destination, passengers also must arrange for oxygen tank delivery. Their home oxygen supplier can usually help with this.

Gong advises those with respiratory or heart problems to fly nonstop when possible, to avoid layovers and the need for oxygen on the ground, and he advises travelers to carry their doctor’s summary of their problem, along with a list of their medications and doses.

Certain heart and lung problems suggest a traveler should delay or cancel a trip. Those with newly diagnosed angina (the chest pain that indicates insufficient blood flow to the heart) or poorly controlled congestive heart failure are at higher risk for problems at altitude, Eisenberg says.

Healthy Traveler appears twice a month. Kathleen Doheny can be reached at kathleendoheny@earthlink.net.