High altitude sickness is a condition commonly seen in trekkers. It happens because the body doesn’t have enough time to adapt to the lower air pressure and lower oxygen level in the air at high altitudes.
Altitude sickness typically only occurs above 2,500 meters (8,000 ft), though some are affected at lower altitudes. Risk factors include a prior episode of altitude sickness, a high degree of activity, and a rapid increase in elevation. Diagnosis is based on symptoms and is supported in those who have more than a minor reduction in activities. It is recommended that at high-altitude any symptoms of headache, nausea, shortness of breath, or vomiting be assumed to be altitude sickness.
Types: Acute mountain sickness, high altitude pulmonary edema, high altitude cerebral edema, chronic mountain sickness.
|Gastrointestinal||Loss of appetite, nausea, or vomiting, excessive flatulation|
|Nervous||Fatigue or weakness, headache with or without dizziness or lightheadedness, insomnia, “pins and needles” sensation|
|Locomotory||Peripheral edema (swelling of hands, feet, and face)|
|Respiratory||Nose bleeding, shortness of breath upon exertion|
|Cardiovascular||Persistent rapid pulse|
Symptoms that may indicate life-threatening altitude sickness include:
The drug acetazolamide (trade name Diamox) may help some people making a rapid ascent to sleeping altitude above 2,700 metres (9,000 ft), and it may also be effective if started early in the course of acute mountain sickness. Daimox can be taken before symptoms appear as a preventive measure at a dose of 125 mg twice daily. Diamox, a mild diuretic, works by stimulating the kidneys to secrete more bicarbonate in the urine, thereby acidifying the blood. This change in pH stimulates the respiratory center to increase the depth and frequency of respiration, thus speeding the natural acclimatization process. An undesirable side-effect of Diamox is a reduction in aerobic endurance performance. Other minor side effects include a tingle-sensation in hands and feet.
In high-altitude conditions, oxygen enrichment can counteract the hypoxia related effects of altitude sickness. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms.
Increased water intake may also help in acclimatization to replace the fluids lost through heavier breathing in the thin, dry air found at altitude, although consuming excessive quantities (“over-hydration”) has no benefits and may cause dangerous hyponatremia.
Ascending slowly is the best way to avoid altitude sickness. Avoiding strenuous activity such as skiing, hiking, etc. in the first 24 hours at high altitude reduces the symptoms of acute mountain sickness. Alcohol and sleeping pills are respiratory depressants, and thus slow down the acclimatization process and should be avoided. Alcohol also tends to cause dehydration and exacerbates acute mountain sickness. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.