Any destination over 3500 metres.
Altitude sickness is caused when a person fails to acclimatise properly and therefore does not receive enough oxygen. Although at altitude there is the same amount of Oxygen in the air, the oxygen pressure in the air drops (thin air) and therefore the lungs are unable to take on as much oxygen as the body requires to function normally. The body undergoes many processes to help cope with this change. At first the body will hyperventilate to try and gain more Oxygen, this in turn increases CO2 in the blood. Carbonic Anhydrase converts the CO2 to bicarbonate making the blood acidic. Acidotic blood causes breathing apnoea causing a reduction in extra oxygen intake. The reduction in oxygen intake then stimulates breathing. (Diamox can help in preventing the carbonic Anhydrase working, therefore preventing acidosis of the blood and keeping breathing stimulated without undergoing the apnoea). The body also has an increased cardiac output and an increase of haemoglobin to help transport oxygen.
Be aware of the symptoms of altitude, Acclimatise slowly. Allow rest days every 3 days. Never sleep more than 300 metres higher than previous night and/or in the presence of symptoms of AMS. Drink lots of fluids and minimise exertion. ALWAYS attempt to descend if symptoms of altitude illness worsen at a altitude or if symptoms are severe. Consider Diamox as this will assist in acclimatisation. If you experienced AMS on a previous trip to high altitude it is more likely it will happen on any subsequent visits. If you have visited high altitude previously and did not suffer AMS it does not mean you won’t on subsequent visits.
Some medical conditions increase the likelihood of the traveller experiencing problems at altitude and should therefore see their GP prior to departure. These include: Pulmonary problems (COPD), cardiac disease and pregnancy.