When we flew on the

When we flew on the Vomit Comet in 1999, my pre-flight training ride in the hypobaric chamber was interesting — after a couple minutes of breathing air at a simulated 25,000 feet, I put down my pencil, looked up, and completely zoned out. I have a hazy memory of the test conductors helping me put my mask back on, and regaining my senses on the 100% oxygen it provided. I expected a similar reaction yesterday. So imagine my surprise when my hypoxia symptoms this time around were totally different!
After pre-breathing 100% oxygen for half an hour to rid our bodies of some nitrogen and lower the risk of getting the bends (yep, just like a scuba diver), we went from sea level to 25,000 feet in a mere five minutes. This is accomplished, of course, by sucking air out of the chamber with a big vacuum pump. The percentage of oxygen doesn’t change, but the partial pressure does. Your body can’t get as much oxygen and you start to feel, well, drunk. Yep, breathing the air at 25,000 feet has about the same effect as drinking a six pack!
The people on the other side of the chamber took off their masks first, so I got to laugh and point at Becca, who was sitting across from me and exhibits the classic symptom — euphoria. It was fun egging her on in her hypoxic state. Mwa ha ha.
After that it was my turn to drop my mask and instantly go to the level of Mt. Everest. I expected to feel dizzy quickly, and then start to zone out. Instead, and surprisingly, I can honestly say that I never really lost track of where I was or what was going on. I was breathing more deeply, a little dizzy, a little happy, and a little slow, but I stayed coherant for the entire five minutes. I lost some awareness — for instance, I didn’t notice that the teacher next to me was totally cheating by looking at my worksheet (which has simple math problems and questions to test your reasoning as you get more and more hypoxic). And at three minutes, I wrote down that my symptom was “hot cheeks,” which amused everyone later on as we descended back to sea level.
It took me a little while to realize that my difference in symptoms is probably due to the fact that between 1999 and 2006, I became a runner. I raised my level of fitness. I am in far better shape now than I was seven years ago, and I think it showed in the hypobaric chamber.
It’s funny that it took a hypobaric chamber run to make me realize that even when I’m berating myself for having been a lazy bum over the past few months, I’m still so much farther ahead than I once was.