What is it?

AMS is a group of symptoms seen in people who have recently arrived at a high altitude or have just gained altitude.  As altitude increases, the air becomes thinner and the body may have difficulty coping with this. AMS may affect persons at 3,000 meters (10,000 feet) or higher.  Age, physical fitness or general health have no bearing on susceptibility to AMS.

Symptoms

There are three degrees of AMS - (Listed in order of severity),

• Early Mountain Sickness
• High Altitude Pulmonary Edema (Water logged lungs)
• High Altitude Cerebral Edema (Swollen brain)

1. Early Mountain Sickness

Symptoms:  headache, nausea, vomiting, difficulty breathing, weakness, anorexia (lack of appetite), sleep disturbance, insomnia

Headache that persists despite rest, ASA or acetaminophen or is still present after a night's rest is a clear warning sign of altitude sickness and other symptoms will follow if not treated.

Early Mountain sickness acts as a warning and can progress rapidly to pulmonary or cerebral edema.

Symptoms:  weakness, tiredness, increased breathing and heart rate, dry cough initially - becomes productive with watery or bloody sputum, noisy or bubbly breathing, blue fingernails and lips

Symptoms:  extreme tiredness, vomiting, severe headache, difficulty walking (drunken like, uneven steps), abnormal speech and behaviour, drowsiness, unconsciousness

AMS may be prevented by following some easy practical suggestions.

1. Gradual ascent: The faster the ascent, the more likely the symptoms are to occur.

• If possible, do not fly or drive to high altitude.  Start below 3,000 meters (10,000 feet) and walk up.
• If climbing, limit net gain to 300 meters per day.  You may climb higher during the day but should descent to sleep.
• Take an "ACCLIMATIZATION" day.  This means, SLEEP, at the same altitude for two consecutive nights every 1,000 meters climbed.

• Drink enough fluids to maintain copious amounts of urine that is clear in colour (approximately 2-4 litres of fluid per day).
• Avoid salt tablets.  Mildly salty drinks may be consumed.

• If flying or driving to a high altitude, rest for 24 hours after arrival.
• If climbing:
• Packs should be lighter than at lower altitudes
• Breathe more deeply.  Rapid shallow breathing (hyperventilation) is normal at high altitudes.
• Layer clothing.  Adding or removing layers of clothing increases comfort and avoids fluid loss through excessive sweating.
• Rest or slow down if panting, excessively breathless or if pulse is greater than 135-145 beats/minute.
• The Rest step should be used going up steep hills.

• Consume large amounts of carbohydrates for energy.
• Protein and fat consumption should be no more than in the normal less active diet.

• Lozenges (anesthetic and antiseptic) relieve dryness of the mucous membranes caused by the cold, dry air of high altitude.
• ASA or Acetaminophen can be taken for headaches.
• Certain medications have been used in the prevention and treatment of AMS.  These medications, through effective, can have serious side effects and should be discussed with your physician (eg. Diamox or Aceotozolamide).
• The use of tranquilizer and sleeping pills for insomnia at high altitudes is dangerous and should be avoided.

1. Treatment for Early Mountain Sickness

• DO NOT CONTINUE TO CLIMB!  It is best to stop and spend an extra day or night at the same altitude.  If there is no improvement after your rest day or night then descend.
• Descend at least 300 - 600 meters.  A rest of 2 - 3 days is recommended.  If symptoms resolve, it is okay to climb again slowly.  If symptoms re-occur stop ascent.  Some people cannot acclimatize past a certain elevation.

• IMMEDIATE AND RAPID DESCENT IS ESSENTIAL AS DEATH MAY OCCUR!
• It may be necessary to descent 1,000 meters or more.  In the case of cerebral edema ABORT THE CLIMB.  Emergency evacuation may be indicated.  It may be necessary to transport the victim at night.

Persons with cardiac and/or pulmonary problems should consult their physician before traveling to high altitudes.