Right up until the saturday night before, I had been looking forward to my chamber experience. Then, in the pub on the final team training weekend up in North Wales I heard all the tales of horror... sticky tape, sickness and stretched out hours. Comments like ‘you’ll look forward to that bit Jess...ha’ and ‘oh yes, that was horrendous’ don’t inspire much confidence!
And so dawned Test Day. After 12 hours of fasting and 24 of no caffeine, alcohol, exercise or oranges I arrived bright and early at the Glamorgan campus. Those yet to know me well, will soon discover that I definitely don’t function at my full potential with a lack of food! The day was an opportunity to test expedition members in the environmental chamber at the university. I was going to undergo a whole barrage of tests, first in our normal, fine South Welsh atmosphere (21% oxygen), and then after spending 6 hours in the chamber set to 12% oxygen, in order to simulate the oxygen levels found at 4500m. The data being collected both in Wales and when we are in South America is forming part of a number of research projects looking into the human response to hypoxia.
And so the tests began, and kept coming... and coming. First I was subjected to mental testing: put the pegs in the holes, dot-to-dot, 15 word memory lists and number recall. Then I underwent a 12 lead ECG for 5 minutes to establish my heart rate and pattern at rest. Then I became something of a sci-fi lookalike with wires everywhere: a 3 lead ECG, a blood pressure probe on my finger, oxygen sensors on my forehead looking at the oxygen levels going to and from my brain, a doppler (ultrasound) probe on my temple looking at the blood flow to my brain and a mouth piece wired up to measure my breathing pattern and gas levels. I was then subjected to 40 minutes of challenges: sitting still, standing up, doing squats, breathing high levels of carbon dioxide, hyperventilating and having both my legs tornequéd. All of these looked at how my brain and it’s oxygen levels were responding to each onslaught. Following this I then got to lie down for a while whilst, surprisingly, more tests were done. The response of the blood vessels in my arm were looked at using flow mediated dilatation: a blood pressure cuff was inflated for 5 minutes just below my elbow and then released whilst an ultrasound probe measured what happened to an artery above my elbow. They then used the doppler probes to look at the velocity of my circulation between my heart, radial, carotid and femoral arteries. A canula was then inserted and tube after tube of blood was taken, but by no means was that the worst bit. No, without a doubt that was the finger pricks! I’m not proud to admit it but the anticipation of what is about to happen coupled with the actual pricking of the end of my finger with a sharp implement made me yelp. But it had to happen so that they could gather info on blood glucose and lactate. The final test required skills in breathing out to look at nitric oxide levels.
This all took three and a bit hours, and so as the oxygen levels in the chamber were being reduced down to 12% I was informed I was allowed to eat! This was very exciting as the previous day I’d bought loads of sugary and delicious danish pastry reduced from my local Co-op (other supermarkets are available). Filled with sugary goodness and anticipation I entered the chamber and the door was shut.
Being in the chamber was a bit like being in a giant, noisy, silver lift. It was larger than I’d imagined, big enough to hold a bed, examination couch, exercise bike, and some testing equipment. I settled down to watch some downloaded nature documentaries having been tipped off by my fellow adventurers that the hours would drag. Almost immediately I felt the effects of the lower oxygen, I could feel my heart racing a little, considering I was sitting down. 10 minutes in and I was feeling exhausted, quite happy just sitting there doing nothing. After an hour in there my observations were taken: heart rate 80 bpm, oxygen levels 72%. And then, all of a sudden, I didn’t feel so good. With little warning I was sick, then I quickly felt entirely normal, had a chat with one of the Phd students in the lab who had come to sit with me for a bit, and then I settled down to a second episode. 30 minutes late...bleergh...sick again out of the blue! I felt a bit disheartened, imagining how terrible it would be on the expedition if I was going to be sick all the time. Apart from sickness I wasn’t suffering any other symptoms, no headache, no funny vision. I now had about 2 hours left before the next lot of tests would begin again. It was a long two hours, filled mostly with feeling nauseas, calming myself down, feeling nauseous again, worrying about how I hadn’t eaten anything since the night before, and worrying about how embarrassing it would be if I was sick mid-testing with the mouth piece in.
Then my time was up and testing began again in the chamber at the 12% oxygen to measure my results in hypoxic (low oxygen) conditions. Mentally I didn’t feel too sluggish and I only really struggled when having to do the squats, which made me feel very faint and sick. After all the tests were complete and another puddle of my blood had been taken (more finger pricks), I had the final hurdle to get over: the ‘exercise test to exhaustion’. Exhaustion comes quickly at altitude, and after 3 minutes on a reclining exercise bike my legs could take no more. More blood was taken (and finger pricks) and the nitric oxide breathing test was repeated. Then came the second most unpleasant part of the day, the removal of all the extremely sticky sticking tape and ECG pads, with an audience. I was then free to go, and just under 8 hours after entering the chamber I breathed ‘normal’ air, which felt very thick, and feeling slightly groggy I returned home.
So did the altitude chamber live up to all those horror stories? Well it was definitely an experience, and it certainly had its unpleasant moments (finger pricks), but it was also very interesting (as were the nature documentaries) and I must admit, it’s a pretty cool thing to have done.
By Jess Christley (Expedition Team Member)
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