Saturday, November 11, 2006

Ears and Pressure

One of my readers asked that I address the problem some people have with their ears when flying on airplanes. So...I'll try to oblige!

As anyone who actually listens to the flight attendant announcements knows, airplanes are pressurized. What that means is that the atmospheric pressure inside the airplane is kept at a level that human beings can tolerate. None of us would last very long at all if we were exposed to the pressure of 39,000 feet. It's not that there isn't enough oxygen there...the percentage is the same as at sea level. The problem is the partial pressure is so low that the oxygen molecules aren't pushed through the lung membranes into the bloodstream.

All that is beside the point of the question, though...

The planes are built to withstand a pressure difference between the inside and the outside of about 8 pounds per square inch. That translates to an altitude in the cabin of about 8,000 feet when the airplane is at 39,000 feet. So the most your body would have to endure is a pressure change from sea level to 8000 feet and back. Unfortunately, that's a lot...especially if your ears aren't clearing.

If your eustachian tubes and your ears are normal, and you don't have a cold, then the trip up and down is typically no big deal. But if you have any blockage of the eustachian tube, then you start to have a problem. Because of the way the tube is designed (it connects the inner ear to the throat, which equalizes the pressure between the outer and the inner ear), as you go up, the pressure on the inner ear increases relative to the outer ear. Even when the tube is constricted due to a cold, the pressure can escape. Think of it like a balloon and you are letting the pressure out. The problem comes when it is time to go down again. Now the pressure on the outer ear increases. With a normal tube, the pressure goes back into the inner ear as well, keeping them equal. But if there is any blockage, that pressure can't get back in...sort of like air trying to get back in the balloon by itself. That's where the pain occurs. In very serious cases, it can actually rupture the eardrum.

So what to do? (Keep in mind this isn't medical advice!!!)

Chewing gum sometimes helps in minor problems. Children crying actually helps as well. Pilots (and scuba divers) are taught to "valsalva." That means to hold your nose, close your mouth, and exhale strongly and forcefully. This forces the air through your eustachian tube and into the inner ear. When successful, you will feel the "pop" as well as the relief as the pressure is equalized. You will need to do this several times as the plane descends. If you can catch it before the pressure builds too high, it is far easier. One of the downsides is that a valsalva maneuver will also press some of the "guck" from your cold into the inner ear. You stand a much better chance of coming up with a subsequent ear infection.

Obviously a small child isn't going to be able to do the valsalva...so he has to just deal with the pain and cry, which might help. But if you understand what is going on, it helps you to have compassion on him during the descent and put up with the screaming (it's very, very painful).

Of course, if he's throwing a fit at any other time, then it's time to have compassion on the parent!!!

[P.S. (posted 12 Nov) There seems to be a misconception that smaller airplanes have a greater problem with ear difficulties than larger ones. Actually that's not the case. Both types of planes have similar pressurization ranges. A more reasonable generalization is older versus newer models of planes. As with everything else, newer planes have improved pressurization controllers, so the transition between the cabin pressure at altitude and the pressure at field elevation is smoother. Another reason this myth might persist is that most people fly on smaller planes far more than they fly on the larger ones, thus increasing their chances of having an ear issue when flying on a smaller plane.]

1 comment:

Darya said...

Thanks Charley :) Great explanations!