At the RSM Sports and Exercise Medicine Section on the evening of the 28th September, the talk was all about Extreme Medicine.
Dr Daniel Martin
is the Director at the UCL centre for altitude space and extreme environment medicine based at ISEH (CASE).
He is a member of the Xtreme Everest
Executive board. He also is involved in educating undergraduate physiology students – and runs the most popular physiology course in the department at UCL.
These are the notes I took from Dr Martin’s fascinating talk.
It covers a run through of XtremeEverest and some interesting experiences and anecdotes Dr Martin had to share with the audience. I’ve also put some links in that may be of interest. If you’re game, carry on!
What Was Xtreme Everest?
Xtreme Everest was a project intending to study the effects of altitude and hypoxia on healthy volunteers to benefit critically ill patients and to further understand mechanisms of survival in an ITU population.
Hypoxia in critical patients can be caused by trauma, airway obstruction, increased metabolic rate and oxygen consumption through sepsis etc.
Mountaineers at altitude experience a similar (if greater) level of hypoxia!
For example, the summit of Mt. Everest has 1/3 the amount of oxygen than at sea level. Even Mt. Everest’s “base camp” has only half of what we breathe here in the UK!
This low oxygen concentration results in low partial pressures in the lung and profound hypoxaemia – with oxygen saturations (SaO2, the amount of oxygen carried in the blood) of 79% at 5300m of elevation, continuing to decrease to 62% Sa02 at 6400m. To maintain adequate oxygen delivery to the tissues, the resting individual’s heart rate had to beat at 116 BPM.
Dr Martin’s Acclimatisation Period.
Acclimatisation to altitude is very important before progressing to higher elevations.
– People with high oxygen sats and haemoglobin don’t necessarily do well at altitude.
– Many people suffer from Acute Mountain Sickness- individuals feeling off their food, experiencing poor sleep, feeling grumpy – AMS is said to feel like a hangover.
– There are more serious side effects of being at altitude, with dangers of High Altitude Cerebral Oedema (HACE
) and Pulmonary Oedema (HAPE
), each carrying mortality rates of 50% and 44%
– Anyway, forget the dangers of hypoxia and AMS. Dr Martin said “The most difficult part was hauling the tonnes of equipment up the mountain”!
Why Did They Have To Climb A Mountain/ Why can’t they do it in the ITU?
It’s too difficult to find two similar critical care patients – the population is too heterogeneous. The possibility just doesn’t exist. Thus the paradigm of altitude and ICU was proposed.
First, the team had to reach Everest Base Camp.
The journey was fraught with danger.
To approach Base Camp, the team flew in via Lukla Airport.
Lukla is the world’s most dangerous airport, with at least a fatal crash every year for a number of years! The airstrip is only 576 metres long, with a 12 degree upslope. Mountain weather conditions change rapidly, allowing harsh winds to enter the equation. Furthermore, mountain clouds and fog drift into view, obscuring visibility. To finish off, it’s bordered by raw cliff and brick walls. If you’re so inclined there are many videos of planes taking off and landing treacherously on YouTube
The project required 26 metric tonnes of expensive equipment, totalling over a million separate items detailed on spreadsheets, all of which had to be hauled up the hill as the Everest helicopters can only go up 3500m. At the time of presentation Dr Martin informed us that none of these original helicopters are still in existence after crashing.
The approach by air to Everest certainly sounds beautiful. Any threat danger may have been consoled by Dr Martin recalling Rhododenron forests down by the river, slowly changing scenery, mountains appearing in the sky with lunar like landscapes at 5000m of elevation.
When you arrive, the danger has not passed. The Base Camp is situated atop a moraine
which is a shifting bit of glacier and travels a little further down the valley each day. The previous two seasons have seen over 25 deaths due to avalanche.
The project ran from February 2013 to June 2013, a period in which over 15000 blood samples taken. After the tough ordeal of rigorous scientific pursuits and living at altitude, the next challenge was to return all the samples and equipment to the UK! It was a challenge to keep them consistently cold, a task needing 100 gallons of liquid nitrogen.
The team left for the summit at 9pm to make the descent in daylight hours. “When the sun comes up you realise you’re balanced on a knife edged ridge with no-one coming to rescue you”
When the sky clears and surroundings appear, the elevation provides an incredible vantage point – you can even make out the curvature of the earth. The elevation and bare exposure of the climbers mean plummeting cold and difficult winds. Dr Martin’s summit was during temperatures of -20 with winds of 20mph.
On the summit at 8400m, the crew took blood gases from four climbers. These samples had mean values of PaO2 3.28 kPa ! and Sa02 54% !!
The lowest reading from a climber was of 2.5kPa and SaO2 of 34% !!!
– This reading is the lowest ever recorded partial pressure in a human being!
To finish off – On their descent from the summit, the Xtreme Everest team made the highest ever rescue.
Thanks for reading! Long post I know, but I hope this provided valuable anecdotes from one man’s rare experience. I highly recommend you check out the Xtreme Everest Blog here