What is Acute Mountain Sickness (AMS)or Altitude Sickness?

Altitude sickness is a pathological effect of high altitude on humans, caused by acute exposure to the low partial pressure of oxygen at high altitude.  It is also popular as acute mountain sickness (AMS), altitude illness, hypobaropathy, "the altitude bends", orsoroche. It commonly occurs above 3000 meters above sea level.  It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover" and  hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can ascend to 3000 Meters without difficulty. Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which are potentially fatal.  

The main causes of altitude sickness are the low amount of oxygen to sustain mental and physical alertness as it decreases with altitude, dehydration due to the higher rate of water vapor lost from the lungs at higher altitudes and rapid ascent.

Normal Symptoms of AMS

Altitude Sickness is a serious problem for those getting to the higher altitude too quickly. There are several symptoms that Acute Mountain Sickness shows up that can result from normal to a serious one. For this, Headaches are the primary symptom used to diagnose altitude sickness, although a headache is also a symptom of dehydration. A headache occurring at an altitude above 3,000 meters combined with any one or more of the following symptoms, may indicate altitude sickness:- Lack of appetite, nausea, or vomiting, Fatigue or weakness, Dizziness or lightheadedness, Insomnia, Pins and needles, Shortness of breath upon exertion, Nosebleed, Persistent rapid pulse, Drowsiness, Excessive fluctuation, General malaise, Peripheral edema (swelling of hands, feet, and face). 

Some Serious Symptoms of AMS

Symptoms that may indicate life-threatening altitude sickness include:- Pulmonary edema (fluid in the lungs), Symptoms those are similar to bronchitis, Persistent dry cough, Fever, Shortness of breath even when resting, Cerebral edema (swelling of the brain), Headache that does not respond to analgesics, Unsteady gait, Gradual loss of consciousness, Increased nausea, Retinal hemorrhage.  The most serious symptoms of altitude sickness arise from edema (fluid accumulation in the tissues of the body). At very high altitude, humans can get either high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE). HAPE can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea at rest, and cough that is initially dry but may progress to produce pink, frothy sputum. Descent to lower altitudes alleviates the symptoms of HAPE. HACE is a life-threatening condition that can lead to coma or death. Symptoms include a headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE.

Prevention from Altitude Sickness

As getting to the higher altitude AMS is a serious problem, to avoid such issues when steeping to higher elevation certain remedies should be followed, like:

  • 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 AMS.
  • 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 AMS. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.
  • Altitude acclimatization is the process of adjusting to decreasing oxygen levels at higher elevations, in order to avoid altitude sickness.  Pre-acclimatisation significantly reduces risk because less time has to be spent at altitude to acclimatize and take the "climb-high, sleep-low" approach. 

Medical treatment

The medical treatment for the altitude sickness is done by providing with drugs or antidotes and if the problem is critical the further treatment is done. The drug acetazolamide (trade name Diamox) may help some people making a rapid ascent to sleeping altitude above 2,700 meters (9,000 ft), and it may also be effective if started early in the course of AMS. A single randomized controlled trial found that sumatriptan may help prevent altitude sickness. Despite their popularity, antioxidant treatments have not been found to be effective medications for prevention of AMS.  Prior to the onset of altitude sickness, ibuprofen is a suggested non-steroidal anti-inflammatory and painkiller that can help alleviate both a headache and nausea associated with AMS. It has not been studied for the prevention of cerebral edema (swelling of the brain) associated with extreme symptoms of AMS. Oxygen enrichment can counteract the hypoxia-related effects of altitude sickness in high-altitude conditions.   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. It’s a good idea to limit alcohol intake the first day or so at higher elevation as well.

Treatment on the trekking trails

The only reliable and the best treatment is to descend. Go down, again go down and again go down is the best way to get rid of AMS.  Attempts to treat patient at altitude are dangerous unless highly controlled and with good medical facilities. However, the following treatments have been used when the patient's location and circumstances permit:

  • Oxygen may be used for mild to moderate AMS below 3,700 m (12,000 ft) and is commonly provided by physicians at mountain resorts. Symptoms abate in 12–36 hours without the need to descend.
  • For more serious cases of AMS, or where rapid descent is impractical a Gamow bag, a portable plastic hyperbaric chamber inflated with a foot pump, can be used to reduce the effective altitude by as much as 1,500 meters (5,000 ft). A Gamow bag is generally used only as an aid to evacuate severe AMS patients, not to treat them at altitude.