Sci fully intended to slide this post in for the Carnal Carnival JUST before the deadline, but events conspired against her, and against Friday Weird Science in general! It was too sad.
And so Friday Weird Science goes up late today as Sci scrambles to catch up on life. But it’s still about vomit. Because vomit is awesome. 🙂
In addition, today’s paper provided to you via the awesomeness of Mary Roach and her extensive bibliography in her new book “packing for Mars”.
Schlegel et al. “Orthostatic intolerance and motion sickness after parabolic flight” Journal of Applied Physiology, 2000.
So first off, this is not just about motion sickness, it’s also about orthostatic intolerance, and how the two are related. So what is orthostatic intolerance? Orthostatic intolerance is a disorder of the autonomic nervous system where you don’t have a compensatory mechanism for certain kinds of stress, specifically rapid changes in cerebral blood flow and blood pressure. When your cerebral blood flow and blood pressure change rapidly, you can’t compensate as well as a normal person. The practical upshot of this is that if you’d been sitting down, and stand up suddenly, you either sit right BACK down or pass out inelegantly on the floor. This is because standing up after sitting for a long time (or otherwise changing position like that) is a bodily stressor (though a small one), and requires quick changes to cerebral blood flow, blood pressure, and heart rate.
Sci doesn’t think she has this (though she may), but I do have a tendency to have to get up SLOWLY after I’ve been sitting a long time, and I do have a tendency to pass out when I’ve been standing at attention for long periods (this made marching band practice…interesting, and probably not a good idea). So I can tell you that this isn’t fun. You really do have to THINK about how you get up, or the next thing you know you’re sitting right back down again, or you’re on the floor and feeling really stupid with everyone looking at you.
Now, you might ask, how is this connected with puking, and what does this have to do with parabolic flight and zero-g? Well, first off, astronauts often suffer orthostatic intolerance. In fact, they suffer it a LOT, and they can experience the symptoms even after as little as 2.5 days in space. This is because changes in gravity are going to affect things like your cardiovascular regulation. Your body can adapt, of course, but some people’s bodies aren’t as fast as others.
And of course another big thing that affects astronauts? MOTION SICKNESS. Lots and lots and lots of motion sickness. Apparently, they used to medicate for it, but for the long missions, they don’t, so as to allow people to adapt as quickly as possible. That said, people often don’t really adapt. I highly recommend reading Mary Roach’s book “Packing for Mars” if you want to hear hilarious and gross stories of people who’ve been up in space for weeks and suddenly vom in their helmets…or in their suits…or in the cabin…in zero G. Where everything FLOATS IN A HUGE BALL OF SPEW. EEEEEWWWWWWWW. But also awesome and kind of hilarious.
Now, of course, why on earth are orthostatic intolerance and motion sickness related? Well, one of the symptoms of orthostatic intolerance is nausea or lightheadedness, and some case reports of astronauts coming back have shown that they suffer worse orthostatic intolerance…after they hurl. Which apparently you do AFTER you return to earth as well as when you’re up in the air.
So what this study wanted to look at was whether orthostatic intolerance affects people on parabolic flights in as little as two hours of microgravity…and how this was affected by whether or not the person ended up tossing cookies. FUN! WHO WANTS TO VOLUNTEER!!!!
(Obviously, Sci was not meant for space, I can’t help but think this sounds really unpleasant)
So they took 16 people (10 men, 6 women), and stuck them on a parabolic flight, where they were “loosely restrained”. A parabolic flight, usually taken on board airplanes, is a way to achieve short time periods (25 seconds) of weightlessness. The plane goes up fast, peaks, and then heads back down. At the top of the peak and just as you start heading down, you get the weightlessness, kind of like that brief feeling you get right when you start the awesome-going-down-WHEEEEE-section of a rollercoaster. Looks like this:
Much as apparently NASA has TRIED to get people to stop, everyone calls it the “vomit comet”. Gee, I wonder why. I do know a couple of people who’ve gone up in this thing and it’s apparently WICKED AWESOME. I would really love to do it (who wouldn’t?!) except I’d probably heave.
The subjects for the study flew four sets of 10 parabolas each, for about two hours worth of flight and a little over 16 minutes of weightlessness. They then got rated on their motion sickness. Apparently these people fall into two groups, those who get motion sick, and those who don’t, which the authors decided to call “vomiters” and “nonvomiters”. Cause you might as well just come out and say it, you know?
They then also looked for signs of orthostatic intolerance in the study participants. And here’s what they got.
(You’ll wanna click to embiggen)
What I love is that instead of calling it “vomiting”, “tossing cookies”, “the vom”, “hurling”, or anything else, the authors (AFTER dividing people into “vomiters” and “nonvomiters”) decided to get all pussy footed and call it “oral fluid loss”. Since they had to specify the oral, Sci really wonders if someone peed themselves.
The authors of this study had MASSIVE findings. They recorded basically everything about these people and measured it: heart rate, blood pressure, full EKGs, CO2 levels, weight loss. And then they analyzed it all six ways from Sunday. The data are great, but Sci’s running late, and most of them relate to symptoms of orthostatic intolerance and how they differ.
And what they found was that people who hurled after the flights were both more likely to have symptoms of orthostatic intolerance, AND That they exhibited different symptoms of intolerance than people who didn’t upchuck. People who went on the vomit comet did have an increased incidence of orthostatic intolerance over all, but what was REALLY interesting was the difference between the vomiters with OI, and the NONvomiters with OI. The nonvomiters with orthostatic intolerance showed pretty standard clinical symptoms, showing changes in blood pressure, heart rate, cerebral blood flow, etc, when they were tilted. The vomiters with orthostatic intolerance, though, were not so easy to characterize, their intolerance appeared to be much more specific and was confined more to changes in cerebral blood flow. This could mean one of two things:
1) Hurling acts to localize the OI changes.
2) Localized OI changes result in hurling.
Sadly, you can’t really tell which, because the hurling happens SO FAST after the vomit comet that they couldn’t give them the intolerance test. Ooops.
One of the things they didn’t address in this, which I think would have been interesting, would be the vomiters and non-vomiters, and how awful they felt about the orthostatic intolerance. Does vomiting make you feel it less? Does it make you feel it more? Does the spewing help, is what I’m saying? And who wants to go into the vomit comet and FIND OUT?!?
Schlegel TT, Brown TE, Wood SJ, Benavides EW, Bondar RL, Stein F, Moradshahi P, Harm DL, Fritsch-Yelle JM, & Low PA (2001). Orthostatic intolerance and motion sickness after parabolic flight. Journal of applied physiology (Bethesda, Md. : 1985), 90 (1), 67-82 PMID: 11133895
PS: I used as many vomit synonyms as possible in the post! Awesome, amirite? Which ones did I miss?
