Saturday, 2 June 2012

Altitude Sickness

Altitude Sickness - also known as "acute mountain sickness" (AMS) or hypobaropathy - is a patholgical illness caused by high altitudes, commonly at heights greater than 8,000 feet. Presenting as a combination of nonspecific symptoms, it is often likened to flu or a hangover.

It is very difficult to determine who will be effected by altitude sickness as there are no specific factors that correlate with a susceptibility to the illness. It is, however, uncommon and most people will find they are capable of ascending to heights exceeding 8,000 feet without suffering any signs or symptoms.


Signs and Symptoms


Different people have different susceptibilities to altitude sickness, but it is not possible to determine who may suffer from the illness before symptoms present themselves; an otherwise healthy person may start to show signs of altitude sickness at heights of as little 2,000 meters.

Often it can be between six and ten hours after ascent before symptoms manifest, and they usually subside entirely within two days. Exertion aggravates the symptoms. Occasionally altitude sickness may progress on to other more complex and dangerous conditions, including high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which can both be potentially fatal.

Primary symptoms of altitude sickness include:

  • Headaches (which may also be a sign of dehydration)
  • Lack of appetite; nausea or vomiting
  • Fatigue
  • Dizziness and lightheadedness
  • Insomnia
  • Pins and needles
  • Shortness of breath
  • Nosebleeds
  • Persistent rapid pulse
  • Drowsiness
  • General malaise
  • Peripheral edema (swelling of the face, hand and feet)
More severe potentially life-threatening symptoms of altitude sickness may present, and these include:

Pulmonary edema
  • Symptoms similar to bronchitis
  • Persistent dry cough
  • Fever
  • Shortness of breath both under exertion and when resting

Cerebral edema
  • Headache (which does not respond to analgesics)
  • Unsteady gait
  • Gradual loss of consciousness
  • Increased nausea
  • Retinal hemorrhage
If a person shows signs of either a pulmonary or cerebral edema, and immediate descent or emergency services call out will be required. HAPE can progress quickly, and is often fatal, but descent to lower altitudes can alleviate the symptoms. HACE is also life-threatening and can lead to coma or death, but again descent to lower altitudes can save those afflicted.

Treatment


In many cases of altitude sickness, as well as HAPE and HACE, the only viable treatment is to descend. Attempts to treat patients in situ at high altitudes can be dangerous unless good medical facilities are present and the environment is carefully controlled.

In certain situations, where the patients circumstances and situation allow, the following treatments have also been effective:
  • Oxygen - mild altitude sickness at altitudes lower than 12,000 feet can be treated with oxygen, and symptoms often diminish with 12-36 hours without the need for a descent. 
  • A Garrow Bag - in more severe cases of altitude sickness, where descent is not possible or not practical, a portable inflatable hyperbaric chamber (called a Garrow Bag) can be used to reduce the effects of altitude sickness. Generally speaking, these devices are only used to aid in evacuation of a patient, and not to treat them entirely.
  • Actezolamide - this drug may assist in altitude acclimatisation. It is however not a reliable treatment in anything exceeding and including mild altitude sickness.
  • Steroids - steroids, via injection, can help to relieve the symptoms of a pulmonary edema. This solution only treats the symptoms of HAPE, and does not address the underlying altitude sickness. Therefore it should only be used if evacuation is possible.


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