Dr Trevor Day, Cardiovascular Physiologist

Taking physiology to new heights

Creative approaches in high altitude research

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James Elworthy, Multimedia Designer at ADInstruments and Kait Mikes, Biomedical Sales Engineer at ADInstruments, joined Dr Trevor Day on an intrepid journey to Mt. Everest Base Camp. Here is James' account.

It’s three in the morning and I’ve woken up, unable to breathe.

Ordinarily, you’d think this predicament would provide some cause for concern, but at an altitude of over 5000 metres (approximately 17,000 feet) I’ve been reassured this “periodic breathing” is a normal physiological response for someone like me who usually lives at sea level. So a little unnerving, yes, but typical nonetheless. After a few moments and a deep, forced inhale, I’m breathing quietly again and able to drift back to sleep.

We are staying in a place called Gorak Shep, at the head of the Khumbu Valley in Nepal. It may as well be the moon – we are surrounded by dust and rock, our lodgings aside a frozen lake. Everest Base Camp is less than two kilometres away, and later (but still before dawn) our troop of twenty three hikers, mostly physiology students who are doubling as researchers and study participants, will climb to Kala Patthar (5643 metres, 18,514 feet), a landmark overlooking Base Camp with views of the Everest summit. Before we depart, however, we are all required to have our weight, blood pressure, resting heart rate, oxygen saturation, respiratory rate and end tidal CO2 measured and recorded.

This battery of measures is the brainchild of cardiorespiratory researcher Trevor Day, Associate Professor of Physiology at Mt Royal University, Canada and the overseer of this expedition to the top of the world – a 120 kilometre round trip from Lukla at the base of the valley to Everest Base Camp and back.

Peculiar things happen when you’re up this high, where the partial pressure of oxygen is a little more than half that at sea level – several compensatory physiological mechanisms are required to maintain adequate oxygen supply to the tissues. As we trudge up the mountain, Trevor gives me the rundown on acclimatization...

“As we ascend, we sensitize our receptors that detect low oxygen, so therefore we breathe more when we are exposed to a low oxygen stimulus.”

“We make more red blood cells, so the ratio of red cells to our total plasma goes up as well and that helps with our oxygen carrying capacity. Our blood pressure goes up, our cardiac output goes up”.

Excess CO2 is also expired as a side effect of the increased breathing. Curiously, this molecule serves as a trigger for the impulse to breathe, and its paucity leads to the strangely contrary periodic breath-hold phenomenon I’ve been experiencing.

This normal acclimatization process is fairly well understood but what Trevor is really interested in is how such a response begins to unravel at these altitudes.

When the body can’t acclimatize well, the result is Acute Mountain Sickness (AMS). Symptoms of AMS include headache, dizziness, nausea and fatigue. If not kept in check (usually by descending to a lower altitude) it can deteriorate into life-threatening cerebral or pulmonary oedema.

Understandably, this has severe implications for climbers and mountaineers.

Nobody really knows how or why AMS manifests like it does – it does so in some people but not others – although it is thought exertion, hydration, food intake, genetics and rate of ascent are all factors. Interestingly, AMS risk doesn’t appear to be dependent on fitness, age or gender.

On each day of our ascent, every member of our cavalcade ranks any AMS-like symptoms they might have on a standardized scale

(known as the Lake Louise score) and adds up these numbers to get a final tally (this being an indicator of the severity of their AMS). However, there’s a problem with the Lake Louise score in that it’s a) self reporting and b) that it doesn’t really seem to correlate with the development of symptoms. Trevor’s research goal is to see if there’s a way of improving the score by seeing how things like oxygenation levels relate to AMS and whether or not his measures will make it easier to ascertain who is really getting sick.


“The big question in high altitude physiology is trying to make some predictions about who is going to do well and who isn’t. What we are interested in looking at is the relationship between some of these physiological responses and the development of acute mountain sickness, and whether or not we can make any predictions between people that get sick, or get sicker than others, and some of these other variables that we are measuring, like carbon dioxide levels, like oxygen saturation levels. That’s the big, overarching question that we are all trying to answer.”

Intrepid explorationIntrepid exploration

Intrepid exploration

Conducting scientific experiments in this sort of environment does have its challenges. Power in the lodges can be fickle, some equipment has proven to be unreliable at altitude and other gear was misplaced by the airline – it arrived days late and arrangements had to be made for a friendly porter to run it up the valley to us – all 40 kilograms of it.

Trevor, as always, is cheerfully unfazed: “field work is inherently full of curveballs, and I know this, I’ve seen it before but you’re never quite prepared for the possible kinds of curve balls you are going to get.”

Play videoEXTRA: Conducting field research in Nepal

Despite the difficulties encountered, the schedule is a busy one. Trips like this don’t come around every day, so as much science as possible has been crammed into every leg of the journey. As well as Trevor’s studies testing new, “fast and light” portable methods for measuring a myriad of physiological functions, investigators from the University of British Columbia Okanagan and University of Victoria are looking at EEG and cognitive function in buddhist monks. There’s also PhD student Jeremy Walsh testing our cognition

before and after strenuous bouts of exercise at altitude. Everyone has wrist-worn accelerometers to ascertain sleep disturbances. The group has even seconded some of our sherpa guides (renowned for their phenomenal physiology) to record their real-time ECG and breathing rate during trekking days using equivital LifeMonitor recording systems.

As if all this wasn’t enough, Trevor has taken on the roles of both dad and doctor – consoling home-sick young scientists and

issuing diamox and oxygen to the altitude-sick amongst us – even while suffering from a bout of gastroenteritis himself. Nepal is certainly a wild and wonderful landscape, but one wonders why Trevor didn’t choose a place that was just a little bit easier. But this choice of location, like everything Trevor does, was carefully considered:

“It’s a beautiful place of course, but that also makes it a bucket list destination that people [study participants] will self-fund to come to, so we can keep the overall research costs down. The other reason is that it gets quite high – base camp is 5,300m – and many of us actually trekked up to Kala Pattar at 5,600m afterward. Now that’s a significant high altitude stress, but you don’t need technical skills – this is long walk of trails really. We are staying in villages along the way so it is relatively comfortable – you’re not in tents. And the cool thing about staying in lodges is that you have access to power. On our scheduled rest days we can make measurements in the lodges using the PowerLabs. And so all of those things kind of come together to make this a really special location to do this kind of work. And of course, the Nepalese people are wonderful.”

OxygenTrevor Day

The self-effacing hero

The ‘science hero’ moniker doesn’t sit well with Trevor. He tells me on multiple occasions that he really would prefer if the article was much less about him and more about the students. He has secured funding to bring nine members of his lab along to help conduct the experiments and when they return to Calgary, they will continue to be hands-on, collating and interpreting the data. It’s a remarkable opportunity for the students to see and experience what primary research in the wild actually looks like. And they are relishing the experience. They unanimously describe this as the trip of a lifetime and they’re grateful to Trevor for making it happen.

“It’s not a cliche, it really is about the students for me. The research is interesting and it’s important, it’s how we know things, but to be able to bring that passion for science back to the students is really important to me. Every paper that potentially comes out of this trip is going to represent a training experience for a group of people that took a risk and took a chance to come to this place and try and do some research with me. And so I think if anything it’s been the training environment I’ve been able to provide for students, and what that means for their CVs, how that helps them get into professional graduate programs, how that challenges the way they see the world, and sends them off into whatever career choices they are going to make afterward.”

Trevor’s advocacy for education and teaching and the way he nurtures the young scientists under his tutelage is obvious on this trip. Reflecting on my own science career (something I ultimately abandoned, after my PhD), I am a little envious of the encouragement these young researchers are receiving: Trevor provides plenty of zeal whilst fostering an element of resilience – the stuff required to cope with the many obstacles that science puts in one’s path.

“In terms of what I hope my students get out of this, I just hope it’s a really rich training experience in terms of understanding how science is done in really austere conditions. Science is hard as it is, but it’s harder still when you’re in a place like this where you are worried about things like power and cleanliness and people’s well-being. All the things we normally control for in the lab are very difficult to control for here. And so I hope they get a sense for improvising and problem solving and really moving toward independence. And being able to ask questions and make measurements in strange and interesting locations.”

This is what strikes me the most about Trevor and perhaps what many non-scientists don’t appreciate about the profession – it’s about being creative, it’s about pushing forward and constantly reinventing your work to make it work. For Trevor, science doesn’t fit around the rest of his life – it is a living, breathing thing that is with him always. The entire way up the mountain, he is strategizing and cognizing (mostly with his colleague, Professor Ken O’Halloran, University College Cork) in between heavy breaths in the thin air - What would happen if we try this? What if the data were to show that? What does this mean? There is not a waking second that Trevor is not thinking about the work. For me, this is the difference between someone who is interested in science and a person who is born to do it.

Attempting to fly off the mountain from Lukla at the end of the trek, we are hemmed in by days of bad weather, with the very real possibility of missing our connecting flights home. Everyone is exhausted, dirty, and growing increasingly tetchy. With the scientific aspect of the trip by now packed away, one might have expected Trevor to have let himself unwind a little, but instead, in his enduringly enthusiastic way, he rallies our tired troop once more. As much as Trevor would protest at the use of the hero label, it is here that he truly deserves it.

To catch a glimpse of life on the trip as it happened, check out James and Kait’s blog: ADIntrepid.com.

Trevor Day

Helping researchers collaborate

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James' daily measures