The art of high altitude sickness13 min read


High altitude sickness, also referred to as acute mountain sickness (AMS), is the effect of the environment at higher elevations (above 2440 meters) on the body. You don’t have to be attempting an 8000-meter peak to experience it. It’s common among skiers, travellers, hikers, and climbers, and should be taken very seriously. I’ve had my fair share of experience with it. In the following article, I’ll share with you some useful information regarding its nature and prevention.


The First Time


Back in 2014, I got high at 5895 meters atop the most common of the 7 summits—Kilimanjaro. The trip was impulsive and back then I did not understand what altitude does to the body. In fact, at that point, I had’t even been to my homeland’s higher mountain tops, which are below 3000 meters. Kilimanjaro is a peak where often inexperienced enthusiasts (like myself) are exposed to the risk of acute mountain sickness, due to short itinerary.


The usual culprit in the onset of either condition (HAPE,HACE) is a sudden ascent from a relatively low altitude. A peak like Kilimanjaro, in Tanzania, is a perfect breeding ground for HAPE or HACE , as hundreds of trekkers each month go from 3,000 feet to 19,000 in a matter of days.

— Ed Viesters


Within less than 48 hours we made an ascent from Horombo Hut at 3700 meters to Kibo Hut at 4750 meters, where we had an afternoon rest and prepared for the summit bid after midnight. Those 1050 meters of altitude gain are considered optimal for a day, even if you are experienced and well- acclimatised. Something I was not. After midnight, we went for the summit and gained another 1145 meters. We were back to the Horombo Hut some 18 hours later. That makes 2195 meters of altitude gain in about 38 hours.


Stubborn as I am, the challenge ahead was one I gladly welcomed. As the night’s chill took a toll on me, so did a rapid heartbeat, dizziness, loss of orientation and one hell of a cough, ripping my ribs from the inside. Thanks to the tight itinerary we were quickly back down. Within a day, I was back to a cheerful mood, ready to celebrate the success of what marked my first of many to come adventures up in the thin air.





On the top

On top of Kilimanjaro, 2014

What Causes AMS?


The higher you go, the lower the levels of oxygen in the air. Air pressure also decreases, so even though the ratio of the oxygen to the nitrogen remains the same, the molecules are spread further apart. Thus, one portion of breath brings in less oxygen. Exertion at higher elevations makes it worse, for as with any other exertion, your body needs to transport oxygen. But since the oxygen is insufficient, you suffer.To compensate, the heart pumps faster, so it can carry blood flow to the oxygen-starved tissues. But that compensation is not limitless. Once the heart reaches its maximum rate, the body shuts any further exertion to preserve itself.


Nevertheless, the human body is complex and smart. Within hours of getting to high altitude, it starts producing red blood cells to accommodate to the environment, which helps transport the increasingly scares oxygen. But this solution is no magic and only works to a point. First of all, new red blood cells take about 7 to 10 days to mature. If the blood gets too thick it can form clots. That, in a worst case scenario, may end up in a deep vein thrombosis. If the thrombosis breaks loose, it may cause a serious problem in the lungs, called a pulmonary embolism, a heart attack or stroke.


Types and Symptoms


Mild AMS


Many people experience Mild AMS during their acclimatisation process. One can feel the effect of the altitude within 12 to 24 hours upon arrival. At night the symptoms worsen due to poor oxygenation. This is because the respiratory drive decreases while we are at rest. Common symptoms are:


* headaches * dizziness * fatigue * shortness of breath * loss of appetite * nausea * disturbed sleep * general feeling of malaise *


It is normal to experience some of those symptoms as you are going up. Even if you gain elevation by the books, it’s probable that at some point you will feel discomfort. As long as it is mild, some rest and either stopping, or going down, may have a miraculously curing effect. Mild AMS is treated with pain medications and should not cause abortion of your trip or expedition.


Nowadays, a drug called DIAMOX is popular in terms of prevention. If you are a trekker or a tourist, you don’t need it. You could manage going high in a way that is controllable and needs no medications. If you are a mountaineer, using DIAMOX is like cheating and it is very disrespectful. I’ve never used it and I would not recommend it.




High altitude image

A bit swollen somewhere high in the tent.

Moderate AMS


While the Mild AMS does not interfere with your normal activity, this one does. Ibuprofen won’t do the magic here. Been there, done that. Your head is like a ticking bomb. Your eyelids are swollen. Someone is giving you pasta and not only do you feel like vomiting, you may just do so. Appetite? There is no appetite. Sleeping is a serious problem. We are talking about the next level of feeling shitty. The symptoms are:


* severe headache * nausea * vomiting * increased weakness * fatigue * shortness of breath * loss of coordination * irritability * rapid heartbeat * swelling of limps and face


If you are experiencing a moderate altitude sickness, it will be challenging to walk in a straight line. You know, the heel to toe test. You will probably look like someone completely different. I tend to have my face swollen at altitude. If you are in one such situation, it’s best to descend. Some 300 to 600 meters can make a huge difference and will ensure you get down before you become incapable of walking. A day or two at a lower elevation should make you feel better. Give yourself time to recover and acclimatise before going back up.


Descend 500m or more; if descent is not possible, use a hyperbaric chamber or administer low-flow oxygen (1-2 lts/min); if descent is not possible and oxygen is not available, administer acetazolamide (250 mg BD), or dexamethasone (4 mg PO or IM q 6 hourly), or both until symptoms resolve.

Severe AMS


This is HAPE (High Altitude Pulmonary Edema) and HACE (High Altitude Cerebral Edema). If you are suffering from any of those conditions, you need to get down NOW! When you’re experiencing a Moderate AMS, your ego and power of will may help you with your ascent. But when you’re experience HAPE or HACE, you feel the urgency to descend.


High Altitude Pulmonary Edema (HAPE) is caused when hypoxia increases both the arterial flow, and the blood pressure to the lungs to a point when fluid leaks from the capillaries. It’s something like drowning in your own fluids. The symptoms are:


* difficulty breathing at rest * moist cough * severe weakness * drowsiness * cyanosis * tachycardia * tachypnea rales


Administer oxygen (4-6 lts/min until condition improves, and then 2-4 lts/min to conserve supplies); descend as soon as possible, with minimal exertion, or use a portable hyperbaric chamber; if descent is not possible or oxygen is not available, administer nifedipine (10 mg PO initially and then 30 mg of extended release formulations PO q 12-24 hrs); add dexamethasone if neurological deterioration occurs.





Altitude sickness

Normally, I look better 😉


High Altitude Cerebral Edema (HACE) is like HAPE, except the leakage is in the area around the brain, and not in the lungs. As the fluid leaks out because it’s entrapped within the rigid structure of the skull, it creates pressure to the soft tissue of the brain. It may have devastating results. Symptoms include:


* hallucinations * extreme mental confusion * ataxia (loss of full control over the body)


Initiate immediate descent or evacuation; if descent is not possible, use a portable hyperbaric chamber; administer oxygen (2-4 lts/min;) administer dexamethasone (8 mg PO or IM or IV initially and then 4 mg q 6 hourly); administer acetazolamide if descent is delayed.

The Second Time


They say the first time is the worst. Yet, with altitude sickness, one can never predict. AMS does not necessarily affect the unfit or inexperienced ones. If you have suffered ones, it doesn’t mean you are likely to experience it again. If you’ve never had any problems, that doesn’t mean you won’t.


My second exposure to altitude was in the Alps on the classic climb of Mont Blanc. While the story had its own twists and turns, I felt no symptoms. My acclimatisation was by the books and I felt strong.Same goes for my first visit of the Khumbu region when I did the EBC trek with a hike up to Kalla Patar (5644m). During this first Himalayan adventure of mine, I even took part in a focus group which aimed to examine the effects that altitude has on humans. It turned out that my memory and sharp mind became duller above 5000 meters. Despite that scientific fact, I’ve had some great ideas up there! But other than being slower (in both my moves and thinking capacity), I suffered no other symptoms.


Himalayan views

Himalayan views


As I already mentioned, there are no guarantees with AMS. The second I suffered from it was as epic as the scenery in which it took place. Even though I felt great during the acclimatisation, what came after was as closest I’ve gotten to Hell. Funny enough, it was also as closest I’ve gotten (not in a plane) to Heaven, as well. That is, of course, if you associate Heaven with up, clouds, etc. Stuck at 6000 meters for 5 nights and 6 days, I developed HAPE. Trust me when I say, this is torture.


Breathing is painful, and every breath is followed by a horrific cough that tears your torso from the inside. Sleep is absolutely impossible. Darth Vader could only envy your vocal complexity. Going down became the most important thing. I have been coughing for days, suffocating, until a doctor at base camp alleviated some of my suffering with steroids. Together with my quick descent, this helped for a rapid recovery.


What happens to the body at altitude?

* Your respiratory rate increases.

* Your resting heart rate increases.

* You body initiates the production of red blood cells.

* The higher you go, your maximum heart rate is reduced. The body turns on preservation mode.

* Your heart stroke volume drops.

* For any given workload, your heart must beat more to deliver sufficient oxygen to the working muscles.

* The higher you go, the less oxygen is available to the red blood cells.

* Plasma volume decreases.

* Blood pH shifts to become more alkaline.


Tips & Tricks


1. Train the diaphragm. At altitude, the respiratory muscles—primary the diaphragm—require a greater portion of your cardiac output than the muscles being used for locomotion. The best way to train the muscles of your diaphragm is by doing long duration aerobic efforts. Higher volumes of heavy breathing over long periods is what you should focus on before your trip or expedition.     


2. Climb slowly. If you are not acclimatised, avoid flying to or driving to high altitudes. One reason the Everest View Hotel at 3880 meters shut down in the past, was due to the death of those who went there by helicopter. This is one of the reasons behind the oxygen masks you will find in the rooms of the hotel. While on your trek or approach up, do not exceed 500 meters of elevation gain per day. It is advisable to have a rest day after ascending 1500 meters for the body to adapt. Here, too, it’s the rest that makes the champion. If you feel Mild AMS symptoms, slow down or stop. 


3. All-in on carbs. Yep! No low-carb diets while you are up high. You need calories, as at altitude everything is magnified, including your need for eating well. Try to eat light but often. Every two hours is ideal. Appetite is a great indicator of good acclimatisation. Eat simple foods that are palatable and easy to digest.       


4. Hydration. I go for at least 3 litters a day. I know people who manage with 1 litter, and others who need 5 or even 6 litters a day. While the amount is individual, it’s important to stay well-hydrated. Alcohol does not fall into the proper hydration process, even though it’s liquid.   


5. Caffeine? I love coffee. A high altitude Tzvetichino is my specialty. And so, I embark on a mission to find an excuse for what otherwise is thought to be bad at altitude—coffee. Altitude expert Dr. Peter Hackett concludes:

Fears of dehydration from caffeine are exaggerated. Its effect on ventilation and cerebral circulation and its action as a psychostimulant are likely to be helpful at altitude. Caffeine may also help exercise performance at altitude. Importantly, habitual caffeine users should not discontinue caffeine because of travel to altitude. 


6. Sleep lower. Depending on how high you are going and the essence of your expedition, it is better to go higher during the day and sleep at a lower altitude. As mentioned, altitude sickness gets worse at night and having a good night rest is vital for your well-being.


7. Drugs and supplements. I will not get into the serious stuff such as Dexamethazone and other steroid drugs. What could be crowned as the most universal drug ever is the Aspirin protect. Having one a day helps to thin the blood. Ibuprofen can help with altitude headaches. It is also good to have an anti-nausea drug. I use Degan, but in different countries, the name of the drug differs.


Ginger and garlic are the two foods all altitude adventurers swear by. There is no scientific evidence of their efficacy, but I can tell you that altitude sickness has some sort of a vampire root because garlic does miracles in keeping it away from you.


Electrolytes are a good way to stay hydrated and to give some extra taste to the liquids you drink.


More Himalayan views

More Himalayan views



Acclimatising to altitude is a wondrously complex process. Despite the suffering, it is also accompanied by breathtaking views which have nothing to do with HAPE. Going high requires that one summons up all reserves of will he has stacked. Only true motivation can resist high altitude atrophy. I guess, in an alien-like environment, it’s only natural for one to experience extraterrestrial sensations. And one such is to admire the beauty of an alpine setting.


As you prepare, emphasise on increasing your ability to deliver oxygen to the muscles, and on increasing the efficiency with which those muscles use the oxygen. There is no single formula for that, since we all have a different training background and no two physiologies are exactly the same. The important thing is to enjoy the process and stay healthy!



Sources: Training for the New Alpinism by Scott Johnston & Steve House; No Shortcuts to the Top by Ed Viesturs;

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