Thursday, January 26, 2006
25,000 Feet Without Oxygen
Week five of API has been the most fun so far; lots of good information and a couple of cool exercises. Nothing in the military can go on without an excruciatingly boring PowerPoint slideshow first, so we did have to pay our dues in boredom. No big deal, after TBS I have an amazing tolerance for the death by PowerPoint torture.
We stated out on Friday with a very painful first aid class. I've had so many first aid and CPR classes by now I could practically teach the damn thing. I would enjoy it if there was something new they were going to teach me but I was relatively certain that they weren't going to. There was a rumor that the Marines were excused from the class due to the training that we get at TBS, but I wasn't getting my hopes up yet. When we got there I found out that the Marines did indeed usually get the opportunity to test out of the class but since there weren't enough instructors we couldn't do that.
The class was, as expected, excruciatingly boring. The material was dated and presented in the most boring manner possible. It seems like they change their minds every year about how to perform CPR and administer first aid; every time I take a class something changes. It gets annoying keeping up with the changes so I don't even bother. The basics never change, let the pencil pushers worry about the minutia. The instructor was an unbelievably fat Navy chief petty officer. At first glance I didn't even think he was military, but then I recognized the shirt he was wearing as one of the enlisted staff. He was so fat that he did that wheezing thing that fat people do when they move around and their breathing rate increases above resting rate. I thought we might wind up having to prac app our CPR skills on this tub of lard.
Thankfully that class ended early, we took the written and practical application tests and we got out around 1330 for an early weekend.
Monday started up with a very short land survival class. A couple of videos, a little discussion, and we were on our way. Done by 0930. Nice. Our day does start at 0700 every day, but that's a nice, short day.
Tuesday was aviation physiology. It's pretty cool learning about the effects of altitude and g forces on the body; it really is a different world when you mix high altitude, high speeds, and high angles of bank. Good shit, it makes me want Hornets that much more.
Wednesday was the last of the classes, the altitude chamber, and the MSDD (Multi Space Disorientation Demonstrator), affectionately known as the spin and puke. The class was divided into two groups; one to the chamber, one to the MSDD.
My group did the high altitude chamber first. We got fitted for helmets and oxygen masks then on to the chamber. The chamber simulates altitude by dropping the air pressure at the standard lapse rate of the atmosphere (1in Hg per 1,000' of elevation) First we did a quick ascent to 5k (5,000') MSL (mean sea level) at a rate of 2.5k per minute. It's a rapid ascent and you have to continually swallow or yawn to equalize your ears. Then a rapid descent back to sea level. Again you have to equalize your ears, but this time you do so by squeezing your nose or putting your tongue against the roof of your mouth and blowing air into the eustachian tubes to increase the pressure behind your eardrums.
Once that is done and everybody gives the thumbs up that they are OK, we have to begin our 30 min oxygenation period for safety. We breathe 100% oxygen (the atmosphere regularly contains 78% nitrogen, 21% oxygen, and 1% other gases) for 30 min in order to increase the oxygen level in our blood so that we don't get really hypoxic really quickly. While we waited, we listened to an F-18 pilot talk about his experience with hypoxia in his jet. It's scary stuff if you don't know the symptoms and you let it get out of control. When you are hypoxic, you feel great; you are on top of the world. There are signs (numbness, tingling, fatigue, weakness) that occur before you are too bad to help yourself but they are easily written off as being the effects of something else. You are becoming more and more confused but you think you have your shit together. Eventually you will pass out, and that is a bad thing when you are piloting an aircraft at 35,000 feet.
So then we rapidly ascended to 35,000 feet. You are breathing oxygen under pressure, so you don't feel the effects of hypoxia, but your body is under ever decreasing pressure. If you have any gas in your system, it's gonna come out one way or the other. I'll leave that to your imagination. We hit 35k and then rapidly back down to 25k. That's when the fun starts.
One half of the chamber at a time takes off their masks and begins playing patty cake, working on one of those shape balls that they give three year olds, or doing some other very basic task that doesn't take much intelligence to do. Within about two to three minutes of being off oxygen, people start to become confused, slow, and they start to turn blue/white. It's funny to watch.
I didn't really feel that many effects when I did it. I went about three minutes before I started to become confused, tired, and slow. I never felt euphoria and didn't really feel hot or cold flashes. My fingers did start to turn blue though. Before I got too hypoxic the corpsman in the middle of the chamber motioned for me to put my mask back on and I did. Once you are back on oxygen you recover quickly. We got to watch the video later, which was good for a few laughs, but I was disappointed that I didn't really feel all of the effects of hypoxia.
