Altitude sickness prevention

 

grey Altitude sickness preventionIt is really hard to put into words how extreme altitude affects you but I shall try: Imagine waking at 3am inside a refrigerator with the worst hangover of your life. Inside the fridge is a treadmill. Run on this for 12 hours straight…with a plastic bag over your head.

Some of my most vivid memories were formed inside a high altitude torture chamber; climbing Island Peak (my first Himalayan mountain), trekking the Inca Trail with my parents, trekking parts of the Andes with a donkey and finally returning to Nepal to climb Manaslu, all involved various degrees of altitudinal discomfort. Don’t be put off though, I am going back this October for some more high altitude suffering with some good friends so it can’t all be bad news…right? Dealing with altitude can be seen as just a regular part of adventuring at the really good places.

So why does altitude affect the normal functions of your body?

As altitude increases, atmospheric pressure drops, this means that less oxygen is delivered to your body with every gasped breath. After some time the body responds by producing more red blood cells (to transport the limited oxygen) in a process called acclimatisation. There are also some changes in how the body manages its fluid.

grey Altitude sickness preventionGeneral rules for altitude sickness prevention are as follows:

  1. Go up slowly. When above 3000 meters try not to sleep more than 300 meters higher than the previous night and take a rest day every 3 days, or for every vertical kilometre gained.
  2. Take planned acclimatisation walks. On a rest day climb about four to five hundred metres then descend and sleep at your original altitude. This shocks your body into making more red blood cells. It is a proven method and is how climbers can survive at extreme altitudes.
  3. Remember the old adage “climb high, sleep low” Don’t sleep on top of a high pass if there is a chance to sleep lower in a valley. It is the altitude you sleep at which tends to dictate your risk of altitude issues.
  4. Drink lots of fluids. One thing that many people don’t realise is that you will pee a lot at altitude, this combined with exertion and dry air sucking moisture out of your system can lead to dehydration. Maintaining good hydration levels helps the body to acclimatise.
  5. Be honest with yourself and your trekking partners. A niggling headache or slight nausea can be your body’s warning that AMS (Acute Mountain Sickness) is just around the corner. Rest and take it easy if you are feeling poorly.
  6. Have an altitude profile to plan your trek or climb (see image below). This will help you to plan your altitude gains and to factor in rest days at clever intervals.
  7. Drugs. Some people use them, some prefer not to. Diamox (Acetazolamide) is a diuretic drug which is commonly used to treat and prevent AMS. It is generally only used if a person is going straight from sea level to around 3000 meters or if someone is planning to climb (and sleep) at more than 600 meter altitude gains per day. This drug speeds up acclimatisation but takes a day or two for the full effect so is not super helpful in cases of acute AMS. A dose of 125mg once or twice daily is commonly used to aid acclimatisation, starting 3 days before going high. Higher doses are commonly used in cases of acute AMS. More detail can be found in the footnote*.

AMS has stages, almost everyone who visits areas at high altitude will suffer some or many symptoms, I sure haveplenty of times.    The most common symptoms include: Headache, breathlessness, insomnia, nausea and loss of appetite. Keeping a close, honest track of these is very important in monitoring and managing your acclimatisation. There is a great worksheet here which helps in tracking and monitoring progress of symptoms.

If in doubt, descend and don’t push yourself too hard.

Below is the altitude profile of a climb to extreme altitude. It shows a lot of up and down done to shock the system into acclimatising as well as possible. Most treks to high altitude have available altitude profiles where you can plan rest days, acclimatisation walks and see which days to watch closely with regards AMS risk.

grey Altitude sickness prevention

(Reproduced with permission from Mal Haskins @ Speedfly8000)

 

HAPE and HACE

Many of the serious health issues that occur at altitude stem from water’s nasty habit of shifting location as we go up in the world. At sea level much of the body’s fluid spends its time helping out in our circulatory system, moving red blood cells and nutrients about and flushing away toxins. This arrangement is rather agreeable for survival. At high altitude the water can go where it’s not wanted or needed. The fluid not being where it is meant to gives rise to the symptoms many trekkers suffer at altitude. If too much moves to the brain or lung cavity it can cause serious, often fatal, conditions such as HAPE (High Altitude Pulmonary (lung) Oedema), and HACE (High Altitude Cerebral (brain) Oedema). Yes, Australians spell Oedema differently to the rest of the world, deal with it! The mechanism is similar to how ankles can swell on long haul flights but much more serious.

Don’t cancel your adventure just yet though guys, HACE and HAPE rarely occur below 8000 metres and only ever kicks in after you body has given plenty of warning signs. It can occur much lower at altitudes as low as 3000 metres but usually this is due to a rushed or non-existant acclimatisation plan.

I will not go into details here on treatment of HAPE and HACE, treatment involves rapid descent if possible, Adrenaline, Dexmethasone and oxygen given by qualified physicians.

HAFE 

HAFE is another uncomfortable part of trekking at altitude. Gasses expand at decreasing pressure, this also happens in the bowels. This expansion, combined with a trekking diet commonly high in carbohydrates can lead to High Altitude Flatulent Extravaganzas. There is no cure for HAFE. It can be managed by walking separately from the group from time to time and by leaving the tent open a bit at night.

Sun Smart 

grey Altitude sickness prevention

Recent research has confirmed a long held belief that people get sunburn more readily at high altitudes. UV-B levels, the most damaging UV band, have been proven to be around 60% higher at 2500 meters than at sea level. Higher UV-B levels combined with snow reflecting the sun’s rays can lead to sunburn in some interesting places, like under the earlobes! I once ended up with a seriously sunburnt and swollen tongue after an extended climb at altitude. It happened after gasping with my mouth open for too long. I could hardly talk let alone eat properly and it was absolute agony. This is one experience I certainly do not want to repeat. It is crucial to cover up and regularly apply a high SPF (Sun Protection Factor) sunscreen while up high.

The dry air and harsh sun can lead to cracked lips so buy, and regularly use, a high SPF lip balm as well. I have a special top with a little pocket in the sleeve near my wrist which just fits a lip balm. Remember guys, it is not seen as dorky to use lip balm above altitudes of 2500 meters.

 

 

 

Above: The author being very sun smart after suffering a sun burnt tongue.

Altitude affects everyone differently. Some unfit people will spring along without an issue while some super-athletes can struggle at the slightest elevation. One person’s response to altitude can differ from trip to trip as well. Once I was in the Andes trekking at around 4500 meters and had to spend an excruciating 24 hours in my tent, curled in a foetal position with a pounding headache, nausea and no chance of descent; yet the next time I went high I got to 7000 meters before even getting a slight headache. The main rule is to be gentle with yourself and to descend if in doubt.

So, if you are smart, plan your height day by day and don’t push yourself too hard, you can have a healthy and most importantly fun time playing in the world’s high places.

Much more detailed information on this topic can be found here: Medex Book English Version and Guide to High altitude medicine

Thanks to Mal Haskins for his input into this post. Mal does loads of cool stuff in extremely high places. Check him out here: Vertical Resources 

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*Acetazolamide.

Action: This drug works by forcing the kidneys to excrete bicarbonate which leads to a slightly more acidic blood. Our bodies monitor levels of (the slightly acidic) Carbon Dioxide (CO2) by detecting the blood’s acidity. Making the blood more acidic fools the body into thinking that CO2 levels are higher than they actually are. This triggers an unconscious deeper and faster baseline breathing rate. By breathing deeper and faster more oxygen is taken in.

Acclimatisation: I eluded in the text above that a low dose of Acetazolamide can be used to aid acclimatisation. The normal dose is 125mg twice daily. This only speeds up normal acclimatisation processes, hence if acclimatising to a certain height normally takes 24-48 hours, Acetazolamide can reduce the time by 50%. Stopping the drug will not reverse acclimatisation, the rate will just return to pre-dose speeds. Being a diuretic or fluid pill Acetazolamide also ‘concentrates’ the blood, that is, less fluid in circulation means there are more oxygen carrying red blood cells in every millilitre of blood.

AMS While the mainstay of AMS treatment is rest and descent if possible, Acetazolamide can be used in higher doses to treat the condition. The dose is much higher than for prevention at 250mg every 4-6 hours. The diuretic effect reduces over the course of a few days (by which time you should be feeling comfortable again)

Cheyne Stokes Breathing: Gasping rapidly at altitude means the lungs are clearing CO2 faster than Oxygen is being taken in. As mentioned above, the body ‘listens’ to CO2 levels more closely than to oxygen levels when setting baseline respiration rate. Having the body clear CO2 so efficiently can lead to a drop in respiration rate to nil in some climbers during sleep (as the body reads a low CO2 level and assumes a relative high oxygen level). When the breathing stops during sleep a climber will wake up desperately gasping for air and rather upset about the while situation, not to mention tent-buddies waking to find a friend lying there peacefully not breathing! By artificially increasing respiration rate, a low (125mg) dose of Acetazolamide before sleep can counter this whole scenario.

Random fact: When you drink a carbonated soft drink whilst on Acetazolamide you can feel but not taste the bubbles (which are CO2 and acidic). I have no idea exactly why this is but guess it is due to the blood being more acidic, closer to the pH of the bubbles of CO2 and harder for the taste buds to pick up. It is a really, really weird sensation, try it if you get the chance!

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8 Responses to Altitude sickness prevention

  • Vanessa West via Facebook says:

    God it sounds awful! You’ve put me off haha xo

  • Catherine West via Facebook says:

    Ari van Eysden how does this fit with your Kilimanjaro experience?

  • Ari van Eysden via Facebook says:

    Yeah it certainly brought back some vivid memories! Stuck in a fridge with a massive hangover just about describes it exactly!! Wish I’d had access to all this information before we went to do Killi – all in one place and easy to read like this is.

  • Catherine West via Facebook says:

    Well now you know it’s here you can recommend it hey? BTW Good work on your Killi climb

  • Thanks for the thumbs up Ari :-)

  • Ha ha, this is the best description of what climbing at high altitude is like I have ever seen. I got AMS twice (mild symptoms whilst climbing Cotopaxi and proper illness with vision loss and everything during the Everest Base Camp trek). Traveling really slowly and acclimatising at each altitude level for a bit def. works best for me.

  • Gosh dealing with altitude sickness sounds like such a challenge. I can’t say the thought of being hungover in a fridge excites me! Although perhaps the view from the top of the mountain does. Fair trade? I’m not sure!!

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