More and more people are travelling to places of high altitude. For example, Mt. Kilimanjaro (at 5895m above sea level) in Tanzania is a popular tourist destination with over 20,000 people attempting to climb it every year. It’s not just adventure travelers who are at risk. Any city situated at high altitude, like Cuzco ( at 3400m above sea level) and La Paz (at 3700m) are popular with travelers of all ages. Whether you are an experienced mountaineer or a first time traveler to a destination of high altitude, it is important to be aware of ‘altitude illness’ or ‘acute mountain sickness’, and how to manage it.
High altitude is often considered to apply to any location at 2500m or more above sea-level. Anyone who travels above this level is at risk of developing altitude illness. Altitude is related to air pressure. As the altitude increases, air pressure decreases resulting in a decrease oxygen intake with each breath.. Shortness of breath is a normal effect of high altitude. It can take days for the body to adjust to high altitude.
Altitude illness results from a lack of sufficient oxygen to the organs of the body. Symptoms of altitude illness include headaches, dizziness, fatigue, nausea, vomiting and more serious and life-threatening consequences such as cerebral oedema (fluid on the brain) or pulmonary oedema (fluid on the lungs).
Risk factors for the development of altitude illness include how high and how quickly the traveler ascends, and past experiences of altitude illness. Interestingly, physical fitness, alcohol and cigarette smoking do not have any correlation with developing altitude sickness.
1. See your doctor at least 6-8 weeks before you leave. If you have a chronic condition, discuss with your doctor what your risks are when travelling to high altitudes. People with conditions including severe COPD (chronic obstructive pulmonary disease), unstable asthma, severe ischaemic heart disease, severe uncontrolled heart failure, or complicated pregnancies are discouraged from travelling to high altitudes. Caution should be used in people with angina, previous stroke, poorly controlled diabetes and heart rhythm disorders. Uncomplicated pregnant women should not ascend above 2500m, and should not be at high altitude after 36 weeks.
2. Ascend to your destination slowly, and allow plenty of time for acclimatization. Don’t ascend more than 500m per day at altitudes more than 3000m. Stay for at least 48hrs after first arriving in areas of high altitude before ascending further to help acclimatize. Have a rest day every 3-4 days.
3. There are several medications available to help with preventing acute altitude illness. Acetazolamide is one such medication commonly prescribed to help with acclimatization. Talk to your doctor to see if this is an appropriate medication for you, or whether another medication would be more appropriate.
4. Natural remedies such as gingko biloba and coca tea have been suggested to help prevent altitude sickness. The research however is inconsistent and the claims cannot be supported with the current level of evidence.
5. The risk of developing a DVT (deep venous thrombosis) is increased when at high altitude. DVTs are blood clots that form in the deep veins of the legs. They can lead to blood clots in the lungs. Ensure you have plenty of water (avoid tea, coffee and alcohol), do regular leg exercises, wear loose clothing and keep active. Speak with your doctor about compression stockings if you a have pre-existing condition.
6. To treat acute altitude illness, descent is the single best option. Mountaineers will often take supplementary oxygen with them to treat acute altitude illness. Portable hyperbaric chambers are available for serious climbers and certain medications such as dexamethosone can also be used.
7. Avoid alcohol and maintain adequate hydration using water. Be careful not to overhydrate. Continue to do moderate exercise and eat carbohydrate-rich foods, as these are the body’s preferred fuel at high altitude.
Acclimatisation takes time and patience. Following these simple strategies will help reduce the likelihood of developing acute altitude illness.
1. Travelling safely to places at high altitude – Understanding and preventing altitude illness. Volume 46, No.6, June 2017 Pages 380-384
2. Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness. Volume 21, issue 2, June 2010, Pages 146-155