Altitude Sickness 101

Don't book a trek until you read this

Altitude Sickness 101

Welcome to Altitude Sickness 101 (Don’t book a trek until you read this).

Travelling at altitude can be a dangerous undertaking for all of us, and understanding the relevant dangers before you reach the mountains is an absolute must.

What is Altitude Sickness?

The term ‘Altitude Sickness’ refers to ailments caused from exposure to high altitude. The most common is Acute Mountain Sickness (AMS), which if left untreated can lead to High Altitude Cerebral Edema (HACE). A parallel condition that can occur after a few days at altitude is High Altitude Pulmonary Edema (HAPE). Without sounding like an old mother hen, make no mistake about it, HAPE and HACE do kill trekkers and climbers at altitude and an understanding of their symptoms and treatment options are a must for all of us travelling at high altitudes.

High altitude – 1500-3500 metres (5,000-11,500 feet).

Very high altitude – 3500-5500 metres (11,500-18,000 feet).

Extreme altitude – 5500 metres and above (18,000 feet).

Number 1 rule is to listen to your body and look out for your fellow trekkers. Never be too proud to act on suspicions of AMS – it could save your life. Your itinerary should allow sufficient time to acclimatise, if you are concerned discuss this with your trek provider before the trek.

Q. What can I do to lesser the chances of my susceptibility to altitude related sickness?
Acute Mountain Sickness or AMS occurs from exposure to the low pressure of oxygen found at high altitudes. Often referred to as mountain sickness, the mountain bends, or ‘soroche’ for those trekking in South America. AMS commonly occurs above 2400m but can arise as low as 2000m. AMS is very common and should be used as a warning sign to the more serious HAPE and HACE. At high altitude your risk and chance of displaying AMS symptoms are high and are equal regardless of your age, gender, high altitude experience, or fitness levels. Everybody traveling at high altitudes (even a Nepalese porter) is at risk of AMS.

Read our article on acclimatisation and preventing altitude sickness for more information.

Q. What are the Symptoms of AMS?
Mild AMS should be assumed if you have a headache occurring at an altitude above 2000m combined with one or more of the symptoms listed below: Loss of appetite, nausea, weakness, ongoing fatigue, dizziness or lightheadedness, trouble sleeping. If you simply have a headache without these symptoms, you may just be dehydrated, drink a litre of water, take simple analgesia, wait about 15 minutes and if the headache does not reside, assume the onset of mild AMS.

Q. I’m showing symptoms of altitude sickness, what do I do?
If your symptoms are only mild don’t panic. Mild AMS will usually subside within a few days as your body adapts, it’s called acclimatisation. Your symptoms will tend to be worse at night. Take ibuprofen to relieve your headache. Tell somebody about it and don’t be alone. Avoid ascending further. Continued ascent may increase symptoms of AMS. Wait for symptoms to ease before you continue ascending at altitude.

Q. I still have these symptoms and they are no longer only mild, and/or I also have one or more of these symptoms: severe headache that isn’t relieved by medication. Nausea and vomiting, severe fatigue, shortness of breath on mild exertion, decreased co-ordination.

You need to seek medical help AND descend. Do not continue to ascend. Tell someone and never be alone. DESCEND in altitude to as low as possible – at least 300 vertical metres or more if you can. If a person cannot walk organise another method for them to descend. Supplementary oxygen will help ease symptoms if available but should not take place over descent. Continue to descend in altitude if symptoms do not improve – the lower the better. Use of acetazolamide (Diamox) may help to increase rate of acclimatisation, read more here.

Remain at lower altitudes until all the symptoms have gone, this may take a few days. Consider re-ascent carefully.

Q. What is High Altitude Pulmonary Edema (HAPE)?
HAPE occurs at high altitude usually after a few days. It can kill within hours. It is the build-up of fluid in the lungs. Because of this, the sufferer’s lungs cannot take in as much oxygen.

Early symptoms of HAPE resemble a chest infection. At high altitude if you notice a person with signs of a chest infection it should be assumed as the early onset of HAPE. Some people who develop HAPE display AMS symptoms as well. Sufferers will show signs of excessive breathlessness on exertion and coughing. This will change to breathlessness at rest. They may also display signs such as blue lips, mildly raised temperature, and/or high resting heart rate.

Q. What is treatment for HAPE?
DESCEND as fast as safely possible; if the victim cannot walk organise another method for them to descend. Descend as much as possible and at least 600m in altitude. Seek medical help, trained professionals may be able to utilise drugs such as Nifedipine, dexamethasone or Sildenafil (Viagra®) to help. This should only be considered a temporary measure for CONTINUED DESCENT in altitude. Yes right Viagra, while potentially helping in the creation some interesting social media posts, it can also save your life. Like Nifedipine, it does this by opening up the blood vessels in the lungs.

Another temporary measure that can be used if available is a Gamow bag, or portable altitude chamber. Supplementary oxygen will also help as a temporary measure for continued descent. Evacuation to a medical facility is a must for follow up treatment.

Portable altitude chamber for altitude sickness
Gamow Bag

Q. What is HACE – High Altitude Cerebral Edema?
The actual cause of HACE remains unknown but it is thought that it results from the swelling of the brain due to damaged blood vessels, which in turn causes fluid leakage. And yes, if left untreated it will kill you very quickly. One of the major red flags to notice in a person developing HACE is strange or irrational behaviour, disorientation, poor coordination, decreasing levels of consciousness.

Q. What is treatment for HACE?
DESCEND as fast as safely possible; if the victim cannot walk organise another method for them to descend. Descend as much as possible and at least 600m in altitude. This is considered necessary to save the person’s life. Seek medical help, trained professionals may be able to utilise the drug dexamethasone. This should be considered a temporary measure for CONTINUED DESCENT in altitude.

Another temporary measure that can be used if available is a Gamow bag, or portable altitude chamber. Supplementary oxygen will also help as a temporary measure for continued descent. Evacuation to a medical facility is a must for follow up treatment.

Learn this info about altitude sickness and have it handy on your trek or climb. That way you can trek easy, knowing what to look for and how to deal with it. Nobody has ever been too prepared for the mountains.

To learn more on AMS, HACE and HAPE and Other High Altitude problems visit Altitude.org

Guest post by Nathan Sharp, Sub edited and approved by our Expedition Medicine Advisor Dr. Andrew Peacock.

We interviewed Dr Andrew Peacock about physically preparation and altitude sickness, you can read the transcript by downloading our free guide. 

Free Guide Avoiding Altitude Sickness

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