INTRODUCTION

As air travel has become more common, travel opportunities have increased for people with serious medical conditions. This includes passengers with lung disease who require supplemental oxygen during air travel. Commercial air carriers' policies regarding in-flight oxygen vary considerably, potentially leading to a great deal of confusion for travelers.

This topic review provides an overview of the potential effects of air travel; measures to determine who may require in-flight oxygen; and steps to help patients plan ahead so that traveling with oxygen can be achieved safely, comfortably, and relatively easily.

EFFECTS OF AIRLINE TRAVEL

Traveling by airplane exposes people to decreased air pressure and lower than normal oxygen levels. For most people, these changes are not noticeable. However, for patients with certain underlying lung conditions, small atmospheric changes can have significant and potentially severe effects.

Cabin pressure — Air pressure drops as altitude increases. Thus, as an airplane ascends, the air pressure inside the plane is reduced. Inside commercial airplanes, pressurization of the cabin limits the fall of pressure. This allows the airplane to cruise at altitudes up to 40,000 feet without exposing travelers to dangerously low levels of air pressure.

Cabin pressurization levels vary by the type of airplane. The United States Federal Aviation Administration (FAA) requires that the cabin pressure on commercial airplanes be maintained at levels equivalent to the atmospheric pressure below 8,000 feet. The FAA allows for brief drops in air pressure for safety purposes only, such as to avoid bad weather conditions. The minimum air pressure to which travelers could be exposed for short periods of time is equal to that encountered 10,000 feet above sea level.

Risks of exposure to low air pressure — The effects of increased altitude and associated reductions in air pressure can result in expansion of the air or gas trapped within the body. Trapped air or gas can be located in many different places, including:

• Nasal sinuses
• Tubes within the ear
• Abnormal pockets within the lung (bullae)
• The space between the outer layer of the lung and the inner layer of the chest wall; air trapped in this region is referred to as a pneumothorax
• Internal organs in the abdominal cavity

As atmospheric pressure drops, trapped air expands. This explains the "ear-popping" with which most travelers are familiar. When air is trapped in the chest, gas expansion can be life-threatening.

Low air pressure during air travel also decreases the amount of oxygen in the air. This effect is modest and generally not noticeable for healthy travelers. For patients with significant lung disease, a small decrease in available oxygen can cause significant symptoms, especially with exercise. Although air travelers usually remain sitting and are relatively inactive during flight, even modest exertion (eg, walking to lavatory) under these conditions can cause low oxygen levels in up to 80 percent of people with lung disease.

Despite the theoretical risks associated with air travel, studies indicate that medical emergencies and deaths are uncommon in people with long-standing (chronic) lung disease who fly. Most studies suggest that medical emergencies occur in about one in every 19,000 to 40,000 travel episodes and that deaths occur in approximately one in every 3,200,000 travel episodes.

WILL I REQUIRE IN-FLIGHT SUPPLEMENTAL OXYGEN?

Patients with diseases that can cause low oxygen levels, particularly chronic obstructive pulmonary disease (COPD), may need oxygen supplementation in-flight. This is true even if the person does not use oxygen at home. (See "Patient information: Chronic obstructive pulmonary disease (COPD), including emphysema (Beyond the Basics)".)

Predictive tests — The evaluation often includes measurement of the blood oxygen level using a finger oximeter and general tests of lung function. If you require supplemental oxygen on a daily basis, you may need an increased flow rate in-flight. If you do not require oxygen on a daily basis, but have borderline lung function, other tests may be recommended to calculate oxygen requirements during in-flight conditions. These include:

• Breathing a gas mixture with lower than normal levels of oxygen
• Testing in a special chamber where air pressure is lowered to simulate flight

Experts generally recommend supplemental oxygen for any patient whose in-flight oxygen level is predicted to fall below a certain point and for anyone who is known to have low oxygen levels on the ground.

PREPARING FOR AIRLINE TRAVEL

Visit your doctor — People who are at risk for low oxygen levels should discuss their condition with a clinician well in advance of the planned departure date. Here are some suggestions to make this process as efficient as possible:

• Determine if supplemental oxygen is needed several weeks to months before leaving. The studies necessary to determine the need for oxygen are best performed when your health is stable, within several weeks before the actual travel date. Most airlines require notification of the need for in-flight oxygen at least 48 hours before the trip, making it necessary to undergo such testing at least three days before travel.
• Learn what your oxygen requirements will be while flying, as well as during layovers and at the final destination (for those who require supplemental oxygen on the ground). Airlines do not provide oxygen for ground use. Speak with your doctor or other members of the healthcare team about arrangements to supply oxygen for each part of the trip. A local oxygen provider might be able to help with such arrangements.
• Obtain documentation of the need for oxygen from your doctor. Most airlines require a letter on the doctor's letterhead with his or her name and contact information, your specific underlying lung condition, approval for air travel, verification of need for in-flight oxygen, and information specifying the required oxygen flow rate in liters per minute, as well as duration of use (figure 1). Be sure to bring enough copies of this letter for all flights.
• Make sure that you have an adequate supply of your usual medications for the trip.
• Some doctors will prescribe an emergency supply of certain medications, such as an antibiotic in case of a bacterial lung infection or an oral glucocorticoid (eg, prednisone) to prevent or reduce inflammation. Keep such medications in their original containers and be sure to pack them in carry-on luggage.
• Gather copies of prescriptions for your medications. You should carry multiple copies in case the luggage is delayed, lost, or stolen. Consider keeping copies in the carry-on luggage rather than in checked baggage.
• Obtain a list of recommended physicians at your destination(s) and along your travel route.

Obtaining oxygen for air travel — The Federal Aviation Administration does not allow travelers to carry their own oxygen tanks or liquid oxygen aboard commercial aircraft. Instead, most patients can use a Department of Transportation approved battery-powered portable oxygen concentrator. Airlines landing in the United States are now required to allow use of these devices throughout the flight.

You can get portable oxygen concentrators for short-term rental from an oxygen supply company. Examples of portable oxygen concentrators include AirSep Free Style, AirSep Life Style, Inogen One, Inogen One G2, Respironics EverGo, Sequal Eclipse, Delphi Medical Systems RS-00400, Invacare Corporation XPO2, DeVilbiss Healthcare iGo, International Biophysics Corporation Life Choice, and Oxlife Independence Oxygen Concentrator. You can use these on the ground and carry them onto the plane. These machines are battery-operated, so you need to bring enough 12-cell batteries for one and half times the anticipated duration of the flight. While you are in the airport waiting for boarding, you might be able to plug the portable oxygen concentrator into an electrical outlet to save your battery power.

Alternatively, some airlines provide oxygen that is supplied in an oxygen canister packaged in a flame proof "super box."

"Shop around" for an appropriate airline — Oxygen policies and charges can be very different, depending upon the airline. It is important to obtain the most up-to-date information about an airline’s specific requirements to make sure that your needs will be met. The Airline Oxygen Council of American web site (www.airlineoxygencouncil.org) lists various airlines' policies regarding in-flight oxygen use and equipment. The European Lung Foundation has compiled information on European airlines, whose rules and charges regarding in–flight oxygen may differ from those of American carriers (www.european-lung-foundation.org).

When contacting the airlines, begin by asking if they have a special services office, medical department, or a help desk to help travelers who need in-flight oxygen. The following is a list of suggested questions that may be helpful in clarifying a specific air carrier's oxygen policies:

• Does your airline accept passengers who require supplemental oxygen?
• Are portable oxygen concentrators acceptable or is oxygen supplied by the airline?
• How much notice do you require before the flight? Many airlines require 48- to 72-hour advance notice. However, some air carriers may require several days, one to two weeks, or as much as one month advance notice. This is particularly true of international flights.
• What documentation is required from my doctor? All carriers require some notification from the passenger's personal doctor concerning oxygen needs, usually a written prescription or an airline authorization form, although sometimes verbal notification is sufficient.
• Do you allow passengers to bring their empty oxygen equipment? Due to safety reasons, the Federal Aviation Administration (FAA) prohibits travelers from carrying their own partially- or completely-filled oxygen tank or liquid oxygen tank aboard commercial aircraft. However, some air carriers permit passengers to bring empty personal oxygen equipment on board or as checked baggage.
• Are there specific seat requirements? Some air carriers assign certain seats to oxygen-using passengers to accommodate their equipment.

If the airline will be supplying the oxygen:

• What do you charge for supplying in-flight oxygen and how is the charge determined? Specific price structures vary among carriers. Some carriers supply oxygen for free, while others charge varying rates, often ranging from about $100 to $250. However, fees may be as low as $50 or as high as $1,500. Charges may be based on a flat fee, the number of travel legs, the number of oxygen cylinders needed, or total air time. It is important to be aware that airlines may charge for each separate flight. Because health insurance may not cover such charges, it is important to consider the expense of in-flight oxygen when selecting among air carriers that serve the same destinations.
• Are passengers required to purchase an additional seat if they will need more than a certain number of oxygen cylinders?
• What liter flow options are available? The liter flow capability offered among different air carriers varies. For example, liter flow options may range from only one or two choices (eg, either 2 or 4 liters per minute) to an adjustable range of 1 to 15 liters per minute.
• Do you provide nasal cannulas or masks? A nasal cannula is a device that delivers oxygen via two small tubes inserted in the nostrils. Air carriers may offer nasal cannulas or masks only, or a choice between the two. In addition, they may allow you to bring and use your own cannula or mask.

Verify the arrangements — After deciding on an appropriate airline, be sure to make reservations as far in advance as you can. If there are any questions or concerns about the information you received while originally talking with the airline, call again to verify the information. In addition, make it a point to confirm your in-flight oxygen arrangements a few days before your flight, and be sure to arrive early.

Take appropriate precautions when aboard — Before your plane leaves the gate, you should also take certain additional precautions. You should make sure that:

• The oxygen equipment is working properly
• You have plenty of batteries for your portable oxygen concentrator; you need enough to last the whole flight comfortably
• For oxygen canisters in a “super box,” check that the cylinders are full
• The flow meter has been set to the proper liter flow per minute
• You have access to all of your medicines, including inhalers

If you have any questions or problems, notify a flight attendant immediately.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient information: Staying healthy when you travel (The Basics)
Patient information: Chronic obstructive pulmonary disease (COPD), including emphysema (The Basics)
Patient information: Chronic bronchitis (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Chronic obstructive pulmonary disease (COPD), including emphysema (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Ear barotrauma
High altitude, air travel, and heart disease
Overview of the causes of venous thrombosis
Patient assessment for air travel
Traveling with oxygen aboard commercial air carriers

The following organizations also provide reliable health information.

• National Library of Medicine

     (www.nlm.nih.gov/medlineplus/healthtopics.html)

• American Lung Association

     (www.lungusa.org)

• Alpha-1 Foundation

     (www.alphaone.org)

• Airline Oxygen Council of America

     (www.airlineoxygencouncil.org)

• European Respiratory Society

     (www.ersnet.org)

• American Association for Respiratory Care

     (www.aarc.org)

• National Home Oxygen Patients Association

     (www.homeoxygen.org/airline-travel-with-oxygen)

• Transportation Security Administration

     (www.tsa.dhs.gov/travelers/airtravel/specialneeds/editorial_1374.shtm#2)

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