More on Altitude sickness

Notes by Dr. J. M. Duff

When we ascend above 2500 meters our bodies have to acclimatise to the decreasing amount of oxygen available. Most people ascending above this altitude will experience some or all of the following list of symptoms for a few days until they acclimatise.

  • headache
  • tiredness
  • disturbed sleep
  • loss of appetite/nausea
  • shortness of breath, cough
  • palpitations
  • swelling of fingers or face

In order to prevent serious AMS developing and to keep acclimatisation symptoms to a minimum, follow these directions :

  • keep to an ascent rate of 300 meters per day of less at altitudes above 4000 meters
  • avoid alcohol
  • avoid strenuous exercise while acclimatising
  • do not ascend while experiencing any of the above symptoms whenever possible
  • Diamox (acetozolamide) may be useful and/or appropriate in some cases (125mg morning and night). Diamox will not mask the symptoms of severe AMS

Note: anti-malaria pills may cause nausea, vomiting or other symptoms at high altitude. It may be necessary to stop this medication. The risks of catching malaria in Chitwan are very low. Anti-malarial medication may be started 48 hours before entering the malarial zone. If you have come from a high risk malarial area it is best to continue this medication. In case of doubt, always consult your trek leader

Treatment of mild AMS

  • rest at same altitude until symptoms subside
  • Diamox (125 mg morning and night, to be continued for remaining time at altitude)
  • Paracetamol, for headache (this is the safest pain killer at altitude)
  • avoid alcohol
  • examine the person carefully and at regular intervals, asking after and looking for evidence of worsening AMS
  • tent companions should use the "buddy system" to keep an eye on each other

Severe AMS

Mild AMS can become severe AMS if the symptoms and warning signs are ignored and the ascent is continued. All of the above symptoms described in mild AMS, may appear in severe AMS. Two indications that serious AMS is developing are:

  • resting pulse over 110 beats per minute (check morning and night)
  • a decrease in urine output after ascent (keep your urine pale and plentiful)

Other specific symptoms are described below.

HACE (High Altitude Cerebral Edema)

This is the accumulation of water in or around the brain. Symptoms may include:

  • severe headache, often worse when lying down, not relieved by mild analgesics
  • nausea or vomiting which may be severe and persistent
  • dizziness, loss of coordination, staggering, falling, inability to do the "heel-to-toe walking", inability to tie shoe laces, etc
  • blurred or double vision, seeing haloes around objects
  • loss of mental abilities (eg: memory, arithmetic)
  • confusion, hallucinations
  • change of behavior (eg: aggression, apathy)
  • drowsiness, difficult to rouse, coma

Note: any one of these symptoms is proof of HACE

HAPE (High Altitude Pulmonary Edema)

This is the accumulation of water in the lungs. Symptoms may include:

  • cough with or without frothy sputum which may be blood-stained ("rusty" colour)
  • severe breathlessness on exertion breathlessness at rest (normal respiration rate is 12/14 breaths per minute at rest at sea level, slightly faster at altitude)
  • severe fatigue
  • drowsiness, difficult to rouse, coma
  • blueness or darkness in face, lips or tongue
  • "wet" sounds in the lungs on deep inspiration: place your ear on the bare skin on the patient's back below the shoulder blades. compare with a healthy person.

Note: any one of these symptoms is proof of HAPE

Treatment of Severe AMS

  • descend immediately
  • descend as low as possible (at least 500/1500 feet)
  • if descent is not possible, the use of a pressure bag will help alleviate
  • the symptoms, at least temporarily, until the victim can descend. A pressure bag is not a substitute for going down, which is always the preferred treatment, but it will simulate a descent of approximately 2000m. (6000ft)
  • If the symptoms are severe or worsening, the victim must descend after treatment.
  • if the victim is turning blue or lapsing into a coma, give them EAR (mouth to mouth resuscitation) before placing in the bag. Do not wait for them to stop breathing before doing this
  • Some drugs, such as Nefidipine (20 mg at once, followed by 10 mg 6-hourly) for HAPE and Dexamethasone (8 mg at once, followed by 4 mg 6-hourly) for HACE, may help with symptoms of severe AMS. However these drugs will not cure the condition. The only treatment of severe AMS is to descend.