If you have COPD and you are considering travel that specifically involves airline travel, there are some facts that you should know. If you currently use oxygen, then your needs may change when you travel by air. How you manage the need for oxygen (or not) once airborne depends on a few factors.
In order to understand what happens in higher altitudes, you have to first understand how oxygen is obtained from the environment. We breathe air in, and when it reaches the lungs (alveolar) air sacs, it has to cross over to the blood vessels that surround the sacs. Then the oxygen is carried by red blood cells, so that it can be used for energy by all the organs in your body. Oxygen, like all gases, will travel in the direction of the highest pressure to lower pressure.
At sea level, the air pressure is 760 mm of mercury (mmHg). Since the air you inhale contains 21 percent oxygen, the pressure of oxygen in the air is 159 mmHg. The partial pressure of the blood in your body that is carried by the veins into the lungs is only 40-50mmHg. That means that there is enough of a differential in the pressures to allow oxygen to naturally move from the lungs into the bloodstream, so that the arteries that leave the heart are carrying oxygenated blood.
This scenario just described is what occurs in healthy individuals. In the case of COPD this transfer of oxygen is not as efficient. COPD causes anatomic changes in the lungs resulting in areas (called bullae) where air doesn’t circulate, and areas where the air sacs don’t make contact with blood vessels. As a result of these issues, these patients may not have sufficient oxygen in their blood. If the level of oxygen is low enough, they can ameliorate the problem with supplemental oxygen. You may have seen patients who have these tanks of oxygen, or you yourself may have a prescription for supplemental oxygen.
In high altitudes, matters get complicated. The air pressure decreases as we go higher up in altitude, like on a plane. That means that the partial pressure of oxygen will be lower, and the impact of that additional difference in pressures means that internally, the flow of oxygen will be further lowered.
Commercial airplanes limit the fall of the pressure to a certain extent by pressurizing the cabin. This allows planes to reach altitudes as high as 40,000 feet. The FAA requires that the airlines keep the cabin pressure equal to 8,000 feet, with some allowances for unexpected bad weather.
This in itself may be a significant change for those with COPD. At 8,000 feet, the barometric pressure drops to 574 mm Hg and it means that there is actually a level of 76 percent of the oxygen normally available at sea level. In the typical patient with COPD this will likely require supplemental oxygen.
The FAA, however, does not allow travelers to carry their own oxygen tanks or liquid oxygen aboard commercial aircraft. Patients are only allowed battery-powered oxygen concentrators. If you require oxygen on a regular basis, then you will need to increase the flow by 2 liters per minute (lpm) to a maximum of 4 lpm, which is the upper limit of what a battery-powered concentrator can deliver.
If you don’t use oxygen regularly, but are borderline status, meaning the limit of oxygen saturation in your blood is 90 percent, you are a patient who will also need supplemental oxygen on the plane.
Oxygen concentrators are available as short-term rentals from an oxygen supply company. There are several brands of concentrators. In my experience, the company that makes the smallest unit with a battery pack that lasts 12 hours is a company by the name of Inogen.
Here are the steps that you should take when considering air travel:
- Obtain a letter from your doctor saying that you will need oxygen on the flight. He will need to either test your oxygen saturation or measure the pressure of oxygen in your blood, by obtaining blood from your artery (arterial blood gas) prior to travel.
- Call the airline and ask about its rules regarding oxygen containers. Some airlines may have forms that the physician needs to fill out prior to your travel with the concentrator, and some airlines have their own concentrators.
- Ask your doctor for the company he recommends and then contact them directly. They may also require a prescription from your doctor.
- Fax or email your physician’s note and the oxygen prescription to the airline, ahead of travel.
- Go to the airport early and proactively inform the TSA agent about your oxygen (remember he does not work for the airline), and be prepared to show both the doctor’s note and the separate prescription.