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APEX 5 Bolivia 2017 was a high altitude medical research expedition to Huayna Potosi (4,700m) near La Paz, Bolivia successfully completed in June 2017.




The expedition was led by a group of medical students at the University of Edinburgh. Following in the footsteps of previous APEX expeditions, APEX 5 carried out scientific research exploring the impact of altitude and hypoxia (low oxygen) on coagulation, immunology, genetics, cognitive function and vision. This research has the potential to affect millions worldwide.

Our expedition gave 30 Edinburgh University students a unique cultural and professional experience, whilst experiencing exciting research in the beautiful Bolivian Andes.

See our expedition blog for expedition tales!


Scientific Background

Every year, 100 million individuals go above 2500m: high altitude dwellers, pilgrims, travellers, and climbers. People are susceptible to altitude illness above 2500m.

High altitude is particularly stressful for lowlanders. At high altitude, there is less oxygen available for the body, and rapid physiological adjustments are needed to prevent harm. This proc  ess of adjustment, known as acclimatisation, is highly variable.

During an acute exposure to altitude, some individuals adjust sufficiently while others can develop altitude illnesses. These include acute mountain sickness (AMS), high-altitude cerebral edema (HACE; swelling of the brain tissue), and high-altitude pulmonary edema (HAPE; fluid build-up in the lungs). You can find out more about altitude illness here.

A greater knowledge of the mechanisms that lead to altitude illness is needed to improve the wellbeing of the millions of individuals who ascend to high-altitude each year.

Importantly, knowledge gained from high-altitude research can also be applied much more widely, as many patients who are extremely unwell due to acute trauma or severe disease will also have low blood oxygen concentration. Therefore, our exciting research has the potential to improve our understanding of conditions that affect millions of people around the world.

Our Research

Our expedition will follow in the footsteps of four previous successful APEX expeditions to Chacaltaya, Bolivia. Our ascent profile will match that of previous APEX expeditions. The expedition is led by six senior medical students at Edinburgh University, with the support of University clinicians and researchers.

Aims & Objectives

The main scientific aims of our expedition are to investigate the impact of altitude and low oxygen (hypoxia) on blood clotting, the immune system, cognitive function, the eye and vision, and genetics.

Alongside our scientific aims, we aim more broadly to inspire our volunteers, allowing them to get involved in exciting research. We hope APEX 6 will develop from our volunteers.

Around 30 volunteers may take part in research studies involving:

  • Blood samples investigating white blood cells (the immune system), blood clotting, and genetic changes at altitude

  • Vision tests

  • Eye imaging

  • Oxygen saturations

  • Altitude illness questionnaires

Jason, Gordon, and Chris are research leads for this expedition. More information on their research is detailed below.

The research


Hypoxia and Blood Clotting

It is known that hypoxia (low oxygen) causes platelets to become more active and likely to aggregate (a key step in blood clot formation). Research from the previous APEX 4 expedition has highlighted the role of a particular signaling pathway in this process. In the coming expedition, Gordon will be exploring this pathway in greater depth.

Clinical Relevance If this process can be understood, it could be vitally important in the understanding of strokes at high altitude, deep vein thrombosis (DVT) on flights and may explain why patients with hypoxic lung diseases are more likely to have strokes and heart attacks.

Hypoxia and the Immune System

Jason is leading this part of the research, with additional in-country support from Joe Willson, a PhD student. Neutrophils are a type of white blood cell that play a crucial role in the acute inflammatory response. Sites of inflammation are typically oxygen deplete (hypoxic); therefore, neutrophils tolerate hypoxia well. In fact, hypoxia promotes neutrophil survival. Despite neutrophilic inflammation playing a key role in several lung diseases associated with systemic hypoxia, such as the acute respiratory distress syndrome (ARDS), and chronic obstructive pulmonary disease (COPD), treatment options are limited to date. A greater understanding of neutrophil responses to hypoxia is therefore warranted.

We aim to investigate these responses in human volunteers on the expedition, with a particular interest in changes to neutrophilic gene expression that are induced by hypoxic exposure.

Clinical Relevance: Understanding the pathophysiology of inflammatory, hypoxic conditions, e.g. COPD.

Hypoxia and its impact on the eye, vision and brain function

Chris will lead this research. There are three studies, which all involve the eye:

  1. We will perform a vision test on a handheld device, evaluating the eye's macula (the specialised part of the eye that gives sharp vision). We will determine whether macular function is impaired at high altitude, and the degree of this impairment. We will also evaluate how the macula adapts to altitude

  2. To test saccadic eye movements, which are rapid, simultaneous movements of both eyes controlled by the brain. We will investigate whether these movements are impaired at altitude, reflecting impaired cognitive function. We will be able to determine whether brain function is impaired at high altitude and the degree of this impairment

  3. We will image the fundus (a specialised area of the eye), assessing for changes to the eye's blood vessels and seeing if there are any signs of disease in the eye. We will use a high resolution, handheld camera

Clinical Relevance: this research may reveal a cognitive or visual deficit, relevant to climbers, pilots, and other high-altitude visitors whose health and safety may be compromised by high altitude. We may also learn more about high-altitude retinopathy, a recognised altitude illness.

Copies of the research protocols are available upon request.


The APEX 5 expedition started in La Paz on the 19th June 2017 where the team spent four days acclimatising in La Paz (3,700m) before ascending to Huayna Potosi (4,700m) for a further eight days.

Throughout the expedition we collected blood samples, performed vision tests and fillout symptom questionnaires.



APEX 5 is delighted to be endorsed by leading figures in both mountaineering and altitude medicine circles.


Sir Chris Bonington CVO, CBE

Sir Chris Bonington is one of Britain's most accompished mountaineers.

"Over the last few years, APEX has carried out worthwhile research into the impact of high altitude on man. APEX 5 will give young students the opportunity to experience a new culture, bond as a team in the Bolivian Andes, and then explore South America together. APEX 5's research is important: relevant not only to high altitude dwellers and visitors, but also to patients worldwide with low blood oxygen, such as the critically ill. APEX 5 deserves every encouragement and the expedition team have my full support."


Professor Moira Whyte

Prof. Whyte is the Head of the Medical School at the University of Edinburgh.

"Edinburgh Medical School is delighted to support this excellent student led initiative. I wish you every success with the expedition itself and also in performing the exciting research studies you have planned relevant to cardiorespiratory disease, vision and other important physiological questions."


Professor Jim Milledge

Prof. Milledge is a pioneering figure in the field of altitude medicine and physiology. 

"I am happy to endorse the "APEX 5 Expedition" to Bolivia. This, the latest in a series of such expeditions from Edinburgh Medical students to this research station above La Paz City, Bolivia. I know this site. It is reachable by Jeep and there are good facilities for carrying out the proposed physiological research on the effect of altitude hypoxia on various body systems. The altitude of Chacaltaya is 5,431m which is higher than anywhere in the European Alps and results in very significant hypoxia. I wish the expedition every success."



The team of Medical Students from the University of Edinburgh who organised the APEX 5 Expedition.




Expedition Leader 

Chris is a fifth-year medical student at the University of Edinburgh. Alongside leading the expedition, Chris will be researching the impact of altitude on the eye and vision. Chris loves travel and the great outdoors, and can't wait to return to South America to explore some more, having been a volunteer during APEX 4. As the previous Senior President of the Royal Medical Society, he enjoys the challenges and rewards of leadership. Chris is thrilled to have such a great team alongside him organising the expedition, and can't wait for all the hard work to pay off as we get stuck into exciting, meaningful research in beautiful surroundings!



Research Coordinator 

Gordon is a fourth year medical student who will be coordinating part of the APEX 5 research. His research interests are focused around the impact of hypoxia on blood clotting, specifically platelets. Being a volunteer on the last APEX 4 expedition sparked Gordon's passion for travel and he is constantly planning his next adventure. In his spare time he enjoys running and swimming (whenever he has time!) and can also be found teaching swimming at pools across Edinburgh.



Research Coordinator

Jason is a fourth year medical student who was a member of the plasma team on the APEX 4 expedition. He can also be spotted in the APEX 4 music video making a right hash of the choreography! On APEX 5, he is leading a research arm investigating the effects of hypoxia on neutrophils. He is a keen pianist and in his spare time and goes for the (increasingly) occasional run or two. Undoubtedly, the biggest challenge for him during the expedition will be avoiding Game of Thrones spoilers!!



Logistics Coordinator

Greig, another fourth year medical student at Edinburgh, is the logistics coordinator for APEX 5. He will be making sure everything is ready for us flying out, and that the expedition runs safely and smoothly. Whilst his academic interests lie in acute and emergency medicine, he is also passionate about wilderness and expedition medicine. When he is not playing hockey, Greig is usually doing something with his Scouts: be it hiking in the Highlands, camping in remote far flung locations or planning their next international expedition.



Volunteer Coordinator

Ellie is a 5th year medical student with a love for travel, photography and all things outdoors. Ellie took part in APEX 4 in 2014 spiking her interest for expedition medicine. Ellie will be volunteer coordinator for APEX 5 and a friendly face whilst at high altitude in Bolivia. She is extremely excited for the trip and recruiting an excellent team of volunteers. If she has her way you'll all be converted yogis by the end of the trip!



Funding Coordinator

Becky is a fifth year medical student who also captains the Edinburgh University Women's Hockey Club 1st team. She's the "mature" one of the team, having studied at Stanford University for four years, where her passion for the Spanish language began (she minored in Modern Languages), and where she learned about the thrill of adventure. Now she spends any spare day she has in the mountains of Scotland, and in the summer you can find her anywhere that isn't home: Peru, Bolivia, California, and Madagascar to name a few! Becky is keen to foster a tight-knit APEX 5 expedition, especially if she can do this by beating group members at a game of Settlers of Catan or two!



Expedition Doctor

Ailsa is a GP, currently working in Edinburgh as a locum and out of hours doctor. She trained at Edinburgh University, did 2 years of paediatric training in Australia and 2 years of A&E in Scotland, before studying for the Diploma of Tropical Medicine and Hygiene in Liverpool and working for MSF in Pakistan, South Africa and Ethiopia. She then returned to Edinburgh for GP training, and completed her Diploma in Mountain Medicine. She has organised and participated in a cycling expedition to Everest Base Camp in Tibet, and recently led a charity trek up Mt Kilimanjaro. She is also a part-time lacrosse coaching, and plays for the Scotland lacrosse team who are aiming for World Cup glory this summer...So will be taking her lacrosse stick to Bolivia!



Expedition Doctor

Nick is an ACCS Anaesthetic trainee at Bart's & The London School of Anaesthesia. He has worked in a number of remote and challenging environments from rural aid posts in the highlands of Papua New Guinea to high altitude rescue posts in the Everest region of Nepal. As an expedition doctor he coordinated the first successful wheelchair ascent of Kilimanjaro by a patient with Friedreich's Ataxia (FRDA) and has worked on larger expeditions in the Himalayas. As a result of research on Kilimanjaro he is now part of an on-going research project at The Institute of Sport, Exercise & Health (ISEH), UCL investigating a possible therapeutic relationship between hypoxia and FRDA. He has the UK Diploma in Mountain Medicine and the Gorgas Diploma in Tropical Medicine and Hygiene.




Joe is a fourth-year PhD student at the University of Edinburgh. The main research focus of his PhD is the effect of hypoxia on immune cells, specifically neutrophil function and survival. Having studied the effects of hypoxia in the lab, Joe is particularly excited to get some real-world experience of altitude and further pursue his research interests in the field. In his free time he enjoys playing the guitar and piano, cycling and running.


Following a round of interviews and medical checks - the final APEX 5 crew has been confirmed! We will meet a number of times to chat through all things APEX as well as fundraising, an awesome weekend away and baseline testing. This will ensure we are all one big happy family by the time we isolate ourselves up a mountain for 10 days for the sake of altitude medicine...

Seriously though, APEX is incredible and on this page we will try and give you a bit of insight into what it's like up there. Our South America experience starts off with a few days in the capital of La Paz. It's a great place to wander around, eat and acclimatise. The city has a real buzz and the cable car ride allows you to see the epic backdrop of many South American cities for the first time.

On day 4 we will then take mini buses up to our home at Chaclataya. This is a stunning ride and climbs almost 2000m. At this point there is a great mix of excitement and nerves, then you arrive to an incredible view.

Day-to-day life consists of chilling with friends, taking part in research and taking in the amazing scenery all around you.Some of us also became extremely talented at cards and many used this down time to plan their up coming South America travel adventures. APEX 5 is the perfect gateway to exploring South America. It combines a genuine interest in medical research with a love for travel and adventure. You will not be short of travel companions and incredible bucket-list places to see!

It's a pretty simple life up the mountain and with being at such high altitude you'll need to be taking things slow. With a great group, come great ideas with how to keep our minds occupied. THIS for example was filmed and edited in its entirety whilst at Chaclataya..

APEX 5 has recruited a fantastic team of volunteers! ​Here is a bit about life as an APEX volunteer and favourite Chaclataya memories shared by the committee.

Volunteer life


APEX 5 has been fortunate to be sponsored by the following organisations. We thank all of our sponsors for their continued support for our expedition.

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