For the next several months I’ll be engaging in various training programs with the idea of getting me “spun up” to be a fully functional flight surgeon. The first indoctrination of this training pipeline is a six-week course at Brooks City Base in San Antonio known as the aerospace medical primary course.
The purpose of the course is to basically teach me all the fundamentals about the unique challenges faced in aerospace medicine as well as an introduction to aviation itself. The majority of the course is basically death by powerpoint covering a variety of topics from aviation history to current treatment strategies of decompression sickness. Although the majority of the lectures are fairly interesting, there are those of us who have lost the well groomed ability to sit through 8-10 hours of lectures a day.
The “sleep deterrent device” issued for this course is a spare tire off of a T-38 jet that will find its way around the neck of anyone dosing off. When I’m not learning fun facts like if a U2 pilot takes off his flight suit above 63,000 feet his blood will boil I do get to do some pretty cool stuff. To recap the first couple of weeks, I got certified in the altitude chamber, saw the decompression chambers, learned how to fly a small Cessna, and logged my first flight as a budding pilot.
Obviously flying was amazing, but the altitude chamber was pretty surreal. The purpose of the chamber is to expose future aircrews and flyers to some of the physiologic extremes that came come with zipping in between various atmospheres. We all know that at higher altitudes such as above 25,000 feet there is significantly less oxygen. However, outside of a hole being punched through the wall of your next 747 flight, or being dropped off on the top of Everest most of us will never know what it feels like to go rapidly between these worlds. The altitude chamber can literally suck the pressure out of the room to basically create conditions at any altitude.
The chamber itself is a small metal room inside a larger room. There is a big door that clanks shut sealing up to 16 people inside. Portholes line the room so trainers on the outside can monitor and communicate with the victims on the inside. Before entering everyone gets fitted for an oxygen mask and helmet. Once inside everyone quickly gets cozy with their neighbors. Now I think there is a natural tendency not to look your neighbor in the eye, as most of us know what’s coming. To understand what I mean it helps to know that before going in the chamber we got a refresher lecture on all the wonderful things your body can do while quickly depressurizing, most notably; expanding gases. For example, the gas in our bowel could potentially expand to over three times its original size causing some rather debilitating abdominal pain. The solution to this is to toss modesty aside and just let it loose. So with everyone shying away, I put an arm around my neighbor and told him that I had something nice saved up for him. In addition to wet gas like the gas in your colon, there is also dry gas like potential small gas pockets that could be say trapped in a filling, or a cavity.
So by the way your tooth might explode. Kind of wish they would have kept that one to themselves. To further illustrate the point of expanding gases there are a variety of latex gloves on the ceiling that blow up as the chamber ascends that remind everyone to fart, and make some of wish we would have dealt with that toothache sooner.
After the initial ascent to 25,000 feet, which is only a few thousand feet shy of the top of Mount Everest we take turns taking our oxygen masks off so we can feel the effects of hypoxia. This is basically the purpose of the chamber, pilots and actually anyone with an aeronautical rating which I will soon have needs to periodically go in the chamber and feel what hypoxia feels like. The reason is that everyone has different symptoms of hypoxia so the only way to understand what your symptoms actually are is to experience them. This might seem crude, but there is a very real chance that anyone of us could be flying someday in an aircraft with an insidious leak causing the environment to slowly lose oxygen. The idea would be to feel hypoxia and acknowledge what was happening before it was too late.
So after taking off my mask and cutting off my flow of oxygen I started to get a tingling sensation in my hands, quickly followed by numbness, then I got really hot and dizzy, and my vision started to gray, so I threw my oxygen back on. The whole point of it is to recognize your symptoms and then correct by putting the mask back on. It took me only about a minute before wussed out, my pulse ox reading got down to 74%. There were a couple of Sherpa reincarnations in our chamber that sat there chilling for about 10-15 minutes before they felt anything, one guy’s pulse ox got down to 51%. Another one just started to get loopy. The reality is that at 25,000 feet most people only have about 1minute or so of useful consciousness. After that time without any prior acclimation most people either get disorientated so they can’t reliably perform tasks, or they pass out. Neither which are optimal when flying a multimillion dollar plane.
The practical lesson to take away here is its probably a good idea to quickly put that little orange cup on your face the next time a meteor punches a hole through your 747 while cruising at 35,000 -40,000 feet, as you really only have about 10-12 seconds before you pass out at that altitude. Actually, truth be told it might not even matter. It was explained in one lecture that the average Joe enjoying a cocktail and watching a movie on a commercial jet at 38-ish thousand feet would take about 8 seconds from the time the plane ripped apart to the time he actually comprehends what was going on. From there the poor fella has about 2-3 seconds left before he passes out from hypoxia. Let's say for good sportsmanship he manages to get the little orange mask on just as he loses it. When he passes out he’s going to slump over or at least bend his neck. Problem is there must have been a critical shortage on plastic tubing the day every airline installed oxygen masks because all the tubes are only long enough to work if your sitting up nice and straight, slump down at all and it comes right off your face, and its permanent lights out. Sorry if I ruined anyone’s future airplane naps. By the way that Ambien isn’t going to help with your two-second reaction time window either 🙂 …isn’t aerospace medicine fun!!