Friendly Print preview
here for 1 page pdf
see also CDC Yellow Book & www.high-altitude-medicine.com/
Information mostly taken from: "International
Travel and Health" (WHO year book)
Australian Immunisation Handbook, 9th Edition - 4/2008 - Part 2 & Part 3 (large pdf
Centre for Disease Control, USA - www.cdc.gov/travel Travel Health Seminar Oct 96, June 97,Feb 98, March 99, May 2000, August 2002 &
March 2005 - Victorian Medical Postgraduate Foundation.
Manual of Travel Medicine,
Melbourne, 3rd edition 2011. Additional references & disclaimer.
AMS (Acute Mountain Sickness)
WHAT IS IT?
Most people who ascend rapidly to heights above 2500 metres (8200 ft) have a period of
unpleasant acclimatisation. During this time they may have a variety of symptoms, the most
prominent of which are headache, lassitude, insomnia, loss of appetite, nausea and
vomiting. These symptoms are collectively referred to as acute mountain sickness (AMS).
Acute mountain sickness is a preventable and potentially serious disease. Travellers to
the Himalayas, Tibet, Nepal, the Andes, Mount Kilimanjaro and Mount Kenya, or the Rocky Mountains
should be aware of AMS.
HOW AND WHEN DOES IT OCCUR?
Acute mountain sickness is infrequent below 2500 m. It occurs in travellers who rapidly
ascend to altitudes of 2500 m or more; travellers who drive, ride or fly to high altitude
sites in the Andes and the Himalayas are more at risk than those who walk in. The risk
relates more to the speed of ascent than the altitude reached. The problem is caused by
the reduction in atmospheric pressure with altitude. Less oxygen reaches the muscles and
the brain, and the heart and lungs must work harder to compensate. Individual
susceptibility to acute mountain sickness is highly variable, and males are more
susceptible than females. Youth and fitness do not prevent AMS. see also Children
WHAT ARE THE SYMPTOMS?
AMS develops over a few hours to a few days usually
during the first 1-2 days at high altitude. In rare cases AMS may be delayed by as long as
Mild form of AMS: Symptoms include headache, dizziness, fatigue, loss of appetite,
nausea, and a general feeling of being unwell that is often compared to having the flu or
The symptoms of mild AMS are an important warning and should not be ignored.
Nb. The use
of sleeping tablets and alcohol can aggravate AMS
Severe AMS: It may develop from mild AMS or it may begin with little or no warning.
There are 2 types of severe AMS-high altitude pulmonary oedema "HAPE" (fluid in the lungs) and
high altitude cerebral oedema (swelling of the brain). They may occur independently, but
usually both forms occur together. The symptoms may include severe headache, vomiting,
severe lassitude, drowsiness, giddiness, stumbling, inability to sit upright, shortness of breath at
rest, cyanosis (blue' nails and lips), cough and white or pink frothy sputum. It is
important to remember that people with AMS are a risk to themselves as well as others, are
more likely to fall or have other injuries and be belligerent, irrational and
irresponsible. (Refusing to descend to a lower altitude). A simple daily test of a
persons ability to walk a straight line will often detect early cases.
HOW CAN ACUTE MOUNTAIN SICKNESS BE PREVENTED?
The most effective preventive measure to avoid AMS is gradual acclimatisation and slow
ascent. The altitude at which the climber sleeps is the most important factor: climb high
but sleep low. Once above 3000 m particular care should be taken not to increase the
sleeping altitude by more than 300 metres per day, and to spend an extra day for each 1000
m gained. For trekking above 3500 m it is advisable that you travel with an experienced
leader or guide. Treks organised by good professionals are planned so that you acclimatise
on the approach route.
Recently the use of a high carbohydrate diet prior to acclimatisation has been
Those who fly to high altitude must be prepared to spend time acclimatising on arrival.
The body's water losses increase during an active day in the dry cold air at high
altitude, therefore, fluid intake should be increased (you may need as much as 4-7 litres
Drugs to prevent AMS often only hide the warning
symptoms. In general it is much safer to rely on good planning and gradual ascent rather
However drugs may be useful in selected individuals, such as those known to be at risk of
AMS, and those flying to altitude (eg Le Paz in Bolivia is 3600 metres), for a rescue or some other critical task.
Acetazolamide (Diamox) Diamox 250 mg tablets(1/4 up to 1 tablet)
given twice a day commencing one or 2 days before the ascent to altitude above 2500 m and
continued for at least 5 days at the higher altitude hastens the acclimatisation process
and decreases the frequency of AMS by about 30 to 50 percent. Side effects are common, but
they are mild and usually well tolerated. They include paraesthesia (tingling sensation in
fingers and toes), bowel disturbances, sleepiness and increased urine volume.
Acetazolamide should not be taken by individuals who are allergic to sulpha drugs.
Spironolactone 25 mg 4 times a day, can be used in those allergic to sulpha
medication but efficacy studies are limited.
Salmeterol inhaler: (Serevent, Oxis) 125mg inhaled 12 hourly starting the
day before ascent has recently been shown to be useful in preventing HAPE. It
should be used in conjunction with Acetazolamide.
Dexamethasone: is a
cortisone-like medication and is superior to acetazolamide in preventing AMS; the dose is
2 to 4 mg every 6 hours, begun the day of the ascent, continued for 3 days at the higher
altitude, then tapered over 5 days. Symptoms of AMS have been observed after the abrupt
discontinuation of the drug. However it is mostly reserved for treating AMS
Higher risk of UV sunlight injuries, hypothermia, thrombophebitis (dangerous blood clots
in leg veins) and retinopathy (eye damage) occur. Insurance to cover helicopter evacuation
may save you a $100,000 bill.
TREATMENT OF ACUTE MOUNTAIN SICKNESS?
The rule is to remain at the same altitude until you have recovered. This often takes
only 1 or 2 days. Most cases of mild AMS will improve with rest, aspirin or paracetamol in
normal doses, and avoidance of alcohol. If necessary, descent of a few hundred metres is
usually curative. Insomnia should not be treated with sleeping pills, since they tend to
aggravate a low oxygen level during sleep.
The most effective and important immediate measure in those with severe AMS is descent
or evacuation to a lower altitude. Frequently a descent of 500-1000 m is sufficient.
Additional measures include oxygen, Dexamethasone (8 mg initially, then 4 mg
every 6 hours for 1 to 3 days, then tapered over 5 days), nifedipine (a calcium
channel blocker, 10mg every 8 hours) for high altitude pulmonary oedema
Drug treatment should never be used to avoid descent, or enable further ascent, by a
person with AMS. A portable hyperbaric chamber such as the Gamow,
Certec bag (a large portable
airtight bag with an air pump) may be very useful in diagnosing and treating AMS. Like
medication, however, it is no substitute for evacuation of a victim. The total
packed weight of the bag and pump is approximately 5 - 7 Kg (pump included).
Initial information source:- Fairfield
Hospital Travel information pamphlet:- 1994
Examination after travel: It is advisable (if not essential) to visit your
local doctor promptly if you
suffer from a chronic disease, such as cardiovascular disease, diabetes
mellitus, chronic respiratory disease;
- experience illness in the weeks following their return home, particularly
if fever, persistent diarrhoea, vomiting, jaundice, urinary disorders, skin
disease or genital infection occurs;
- consider that you may have been exposed to a serious infectious disease while
have spent more than 3 months in a developing country.
Source: WHO - http://whqlibdoc.who.int/publications/2005/9241580364_chap1.pdf (page