November 10, 2014

Flying High or Possibly Low on Oxygen?

Sharon Lagan BSc CRFS, Respiratory Scientist, Department of Pulmonary Physiology & Sleep Medicine, Sir Charles Gairdner Hospital, Perth, WA

Dr Ivan Ling MBBS FRACP, Respiratory and Sleep Physician, Department of Pulmonary Physiology & Sleep Medicine, Sir Charles Gairdner Hospital, Perth, WA

 

Flight has become an accepted form of travel for so many of us in Australia. If your lungs and heart are in reasonable shape, then the conditions within the aircraft cabin are something our bodies can deal with. However, if you have respiratory or heart disease, the environment in a plane can pose a potential problem.

The concentration of oxygen that we breathe at sea level is around 21%. Unless you were born at high altitudes (e.g. the Sherpa near Everest), your body tends to work best with this oxygen level. With altitude, the pressure (and effectively the amount) of oxygen available in the air rapidly diminishes. The human body could not survive at the heights that planes travel at – between 9,000-12,000 metres (30-40,000 feet). To overcome this, plane cabins are pressurised, making the conditions around the same as standing at an altitude of 2,400m (approximately 8,000ft). This equates to breathing an oxygen concentration of around 15%. This is not ideal, but in response our hearts and lungs work
a bit harder to pump enough oxygen around our bodies to allow us to happily wander around the cabin. Not all planes are the same and the cabin pressure (and therefore the available oxygen level) will alter over the course of the flight. In addition, newer planes do not necessarily have better cabin pressures, although commercial aircraft must adhere to a minimum standard.

When measured using an oximeter, your oxygen levels (SpO2) whilst on a flight are ideal if maintained above 90%. If you have severe lung or heart disease then the additional work to maintain adequate oxygen concentrations may put your body under undue stress. At an SpO2 of significantly less than 90%, things can get hard, particularly on long haul flights when you will need to move from your seat. Mild exercise may cause your oxygen levels to fall rapidly, leaving you feeling unwell or extremely short of breath.

For those who need oxygen during air travel, there are options to help you on your journey. If pre-arranged, some airlines can provide supplementary oxygen. Some also let you take your own oxygen concentrator on board, which can be very useful if you think you may need supplementary oxygen at the other end of your journey.

So how do you know how your body is going to respond to these low oxygen levels?

Before undertaking a flight, it is a good idea to speak to your doctor or specialist and if needed, they can arrange for a High Altitude Simulation Test (HAST) to be performed at a lung function laboratory. During this test, you will be fitted with a mask and will breathe the same oxygen level (approximately 15%) as you would during air travel. Your oxygen saturation level (SpO2) will be monitored with an oximeter to see how your body responds. Some labs may also perform blood tests to ascertain the amount of oxygen in your blood stream. If your oxygen levels fall too low during this test, then supplementary oxygen can be added to see if that helps to maintain a healthy SpO2. When completed, the doctors overseeing the test will provide a recommendation of whether additional oxygen will be of benefit to you in flight. In some cases, doctors may recommend that a person should not undertake air travel.

If supplementary oxygen is suggested, then that is the time for you to spring into action and listed below are a number of things you will need to do:

  • Contact your airline to find out their policy on flying with oxygen. Some airlines e.g. some budget airlines will not supply oxygen, nor allow you to take concentrators on board.
  • There are forms available from each airline that will need to be completed with the assistance of your referring doctor. These forms must be submitted BEFORE travel.
  • Remember to ask about any additional charges involved.
  • Organise oxygen well in advance and follow up with the airline before travel to make sure that everything is in place.
  • Ask to be seated as close to the toilets as possible to minimise the distance needed to walk there.
  • Take your own nasal prongs as well as spare batteries, chargers and adaptors if using a concentrator.
  • Arrive at the airport early and allow extra time to clear check points in case someone has a query about your concentrator.
  • Remember, you cannot use the drop down oxygen masks they talk about during the safety demonstration, as these are strictly for emergencies.

Air travel and more importantly your destination can be fun, but it is important to recognise that you might need a little more assistance than you have previously. Before you book a ticket for air travel, ask your doctor if he/she thinks you may need additional oxygen inflight. Allow enough time before travel to have a HAST test (there may be a wait time for an appointment at lung function labs) and research which airlines will accommodate your needs. When you have the recommendation from your doctor, contact the airline well in advance and follow up just before travel. Lastly…don’t forget your passport and to have a great trip!