Altitude sickness is a common name that is given to the physiological and symptomatic reactions in the human body when it is exposed to low oxygen pressure, which occurs at high altitude. Altitude Sickness is a common condition that occurs when you climb to a high altitude too quickly, so your body is unable to adjust or adapt to new conditions. It is more common at heights greater than 2,500 metres, the higher you climb the thinner the air becomes, therefore your body adjusts and your breathing rate increases, as well as your pulse rate, your heart's pumping efficiency and the number of red blood cells, which are responsible for your blood oxygen carrying capacity.
How Do I Get Altitude Sickness?
For the majority of people, the symptoms of altitude sickness are mild and can improve when time is spent at altitude so their bodies can adjust. However, in some cases, serious symptoms can occur, which can soon become life-threatening, especially if the individual is unaware of the risks and continues to climb altitude. Roughly 20% of climbers will experience mild cases of altitude sickness at around 2,500 metres above sea level, which is common among ski resorts. More extreme cases of altitude sickness occur in places such as the Andes mountains, which are around 3,000 to 4,000 metres above sea level.
The rate at which altitude sickness symptoms occur, directly relates to the rate of ascent, and is also directly related to how long a person stays at the particular height. The most common symptoms to look out for are headaches, dizziness, nausea and exhaustion, these symptoms occur mainly due to the decrease in atmospheric pressure, which makes breathing difficult as you are not able to take in as much oxygen as you would normally.
Mild symptoms usually occur due to the fact that your body has yet to acclimatise to the new altitude. After a couple of days rest at the new height, if your symptoms have improved and your body has adapted, you can continue to climb. Altitude sickness can affect everybody, it has nothing to do with your current fitness levels, it can bring on symptoms in even the most experienced athlete. When oxygen pressure decreases your body starts to adjust so you are able to survive, breathing rates increase, as well as pulse rates. Red blood cell level is increased so more oxygen can be carried around the body.
Altitude Sickness Prevention:
There are a number of measures to prevent altitude sickness, the most common way is to climb to higher altitude slower as this gives your body more time to adjust to new conditions and adapt to lower oxygen levels. If you begin to feel ill at a particular height, then it is ideal to come down to the height you were last acclimatised until you feel symptoms have calmed. You will need to drink around 3 litres of re-hydration liquids per day, and avoid drinking alcohol.
To help cope with symptoms of Altitude Sickness, there are prescription tablets available, Travelpharm supply acetazolamide (Diamox), which is a weak diuretic belonging to the group of drugs called carbonic anhydrase inhibitors. Its ability to acidify the blood increases ventilation of the lungs which in turn helps prevent altitude sickness symptoms from developing. These tablets are usually taken for one or two days before the highest altitude is reached and continued for a further 3 days. Acetazolamide is not a substitute for acclimatisation, serious illness or death is still possible.
Danger Signals & Serious Symptoms of Altitude Sickness:
If you climb to a high altitude too quickly, danger signals will start to occur within the first 35 hours and will affect more than 50% of travellers that are above 3,500 metres, and almost all of travellers that climb above 5,000 metres. Common symptoms would be headache, nausea, dizziness and difficulty sleeping; if you feel yourself having these symptoms above 3,500 metres then it is advisable to move down 300-500 metres for 48 hours so your body can acclimatise again before attempting any other ascents. If you get worse or fail to improve after this amount of time then you should descend again by at least another 500 metres.
Acute Mountain Sickness can bring on two different types of life-threatening complications, both of these conditions often occur when an individual is over 3,500 metres:
High Altitude Pulmonary Oedema (HAPE) – Water on the lungs.
High Altitude Cerebral Oedema (HACE) – Fluid on the brain.
For more information on Altitude Sickness, please visit the NHS Choices website.