AMS - Making The Diagnosis

Posted by Jeremy Windsor on Sep 25, 2020

Over the last few years we've written a number posts about different aspects of Acute Mountain Sickness (AMS). But strange as it may seem, one area that we haven't focused upon is how to make the diagnosis! After we returned from Mt Kenya last January, two climbers got in touch to describe their own experience on the mountain. Over the course of half a dozen emails a vivid story of what could best be described as "mistaken identity" emerged. Rather than recognise the symptoms of AMS and turn back, the pair pressed on and found themselves in a life threatening situation. Their story goes some way to showing just how difficult it is to make the diagnosis of AMS and the consequences if you get it wrong...


The South East Face of Nelion (5188m) from the Austrian Hut. Graded at UIAA IV- the route climbs the face and ridge above at a very amenable grade. However at that altitude the climbing can feel much harder if acclimatisation is lacking. The "Gates of the Mist" and Batian (5199m) lie just out of sight behind the summit of Nelion


In the late 1990's Andy and Bob were working in oil exploration off the east coast of Tanzania. Both were keen climbers and decided that with a weeks leave they would attempt to climb the "classic" South East Face of Nelion, cross the "Gates of the Mist" and top out on the summit of Batian (5199m). With limited time and money, they decided to carry their own equipment and "acclimatise on the route". They camped at the start of the Mackinder's Route (3050m) and next morning ascended to 4200m. The following day they stopped briefly at Austrian Hut (4790m) and started the route shortly after 1200.

The ascent profile of Andy and Bob (red) and a BMMS party who visited Mt Kenya in  January 2019 (green). The Wilderness Medical Society recommend an ascent rate of up to 500m per day with rest days taken every 3 to 4 days. Andy and Bob comfortably exceeded these recommendations!


Going slowly, they arrived at Baillie's Bivvy at 1800. They decided to stop for the night and set off early the next day. At 0400 Bob awoke complaining of a "7/10" headache and symptoms of fatigue and lightheadedness. The pair put these down to a combination of tiredness, hangover, caffeine withdrawal, dehydration, anxiety and the onset of a common "cold". With these in mind they decided to rest up for a couple of hours, drink some coffee and Bob decided to take a couple of paracetamol tablets.

The Baillie Bivvy at approximately 5000m. The pair put Bob's symptoms down to a number of conditions including - the after effects of an evening spent drinking a small bottle of whisky and several days of going without their daily dose of caffeine

Two hours later they woke up and decided to set off. From Baillie's Bivvy the route climbs up 100 or so metres left of the obvious ridge line to the De Graaf Variation. For many teams this is the crux of the route -  a steep, well featured chimney that's perhaps 20m long. Despite being only UK 4a or 4b, climbing at this altitude, with a full rucksac, can be strenuous to say the least. By the time Bob seconded up the pitch it was 1300. Bob's headache had now returned and was worse than ever - "10/10". He was also lightheaded, nauseous and moving very slowly. Now, the pair were a little less sure about the reasons for Bob's symptoms. Whilst the previous causes were still possible Andy thought Bob might also be suffering from the altitude. The decision was made to rest for 30 minutes and Bob took two more paracetamol with the remaining water. Andy decided to take over the lead and filled his rucksack with most of Bob's kit, leaving what was left at the belay for when they returned.

The De Graaf Variation. Many consider this to be the crux of the route. Andy and Bob lost several hours trying to find it. Their lack of acclimatisation meant that they found this pitch very difficult to overcome and many more hours were lost

The pair made slow progress, climbing another 100m in 6 hours. By the time they arrived at the Howell Hut it was dark. At the hut Bob collapsed and was unable to stand. In fact, he was barely able to speak or even raise his head to drink. Andy decided that they would both stay the night in the hut. Next morning Bob was unconscious and Andy took the decision to descend alone and organise a rescue. Credit to Andy, he completed the 16 or so abseils in just under 4 hours and made it to Austrian Hut by lunchtime. The ranger at the hut was able to radio down to park headquarters and a rescue team were mobilised. Later that evening they arrived and climbed through the night to get to Bob. On arriving they found him unconscious but breathing. Lifting and lowering, the team were able to get Bob down the route and onto the glacier below. It took almost 24 hours - almost as long as it took Andy and Bob to climb the route. A helicopter from Nyere arrived the next morning and evacuated the pair to safety. Landing at an altitude of 1700m, Bob quickly regained consciousness and was able to walk unaided to the awaiting ambulance. After a quick check up Bob was discharged from hospital an hour or so later. There wasn't a scratch on his body! Bob's symptoms had been due to AMS. The higher partial pressure of oxygen at Nyere had rapidly reversed the symptoms and quickly restored Bob to good health.  

Andy spent the night at the Howell Hut. Situated just below the summit of Batian (5188m) this is the highest hut in Africa

So how could Andy and Bob have made the diagnosis sooner? Above all they needed to know about the symptoms of AMS and what would happen if these were ignored. By their own admission, they hadn't heard of AMS or any of the life threatening complications seen at high altitude. If they knew that headache, fatigue, dizziness and gastrointestinal symptoms were consistent with AMS then they would have put it in their list of possible causes. With a few more pieces of knowledge they would have put it right at the top! Symptoms of AMS are commoner in those who ascend quickly and are more likely the higher you go. Reaching 4800m and the start of the route in less than 2 days is unlikely to lead to good acclimatisation. Physical and mental processes will be slow. Guidebook times will be stretched and the majority of climbers will suffer from AMS. The answer is to ascend slowly and watch for the symptoms of AMS. If they occur, stop and rest, take painkillers and wait for improvement. If they don't - descend! The mountain's not going anywhere...

Thanks to Andy and Bob for getting in touch. We have changed their names for this post. 

For more on AMS take a look at this. Thinking about taking Gingko Biloba to prevent AMS? Read this!

If you're interested in climbing Mt Kenya why not take a look at this

Robyn Johnston's brilliant account of being an expedition doctor on Mt Kenya can be found here

2 thoughts on “AMS - Making The Diagnosis

David Hillebrandt commented 1 month ago
Chris, Thanks for publicising this HRA video. Well worth watching. Interesting that the pilgrim evacuated by the army team was carried prone. Dave H
Chris commented 1 month ago
There is a great little vcd distributed by the Himalayan Rescue Association Nepal - 'Trekking Wisely, The Atitude for Altitude' which shows the things people will blame when they get ill at altitude, even when they know about AMS.

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