By Dr Eddy Bajrovic*, pictured tackling Mt Kilimanjaro (5895m) which he climbed in 2011.
The recent death of a 64-year-old Australian man in Nepal’s Gokyo Valley from suspected acute altitude sickness has again put the condition in the spotlight for travellers.
Gokyo has been dubbed the ‘Valley of Death’ because it can be climbed quickly – too quickly to allow trekkers to acclimatise adequately to the thinner air.
While it could be tempting to suggest that that age or fitness may have been factors in the man’s sudden death, young, fit travellers are not immune to the potentially fatal effects of altitude sickness. In 2011, a 28-year-old British woman died of altitude sickness while trekking in Gokyo only weeks after completing a marathon back home.
Altitude sickness is becoming more common as travellers visit remote, high-altitude destinations to test their fitness and stamina, to escape the madding crowds, or simply to get a bird’s-eye perspective on the country.
Blame busy lifestyles, packed schedules
Altitude sickness is preventable and we better understand the causes today. So, why does it continue to happen?
There are several reasons:
- With all the demands of today’s busy lifestyle, too few travellers prepare themselves properly for the rigours of high-altitude travel. They don’t see their GP or a travel medicine practitioner for information and advice on how to minimise altitude illness, and recognise and manage the symptoms if they occur.
- Rapid flights and connections make it easy to reach high elevation destinations quicker than ever.
- Many trekkers don’t allow enough time to acclimatise as they make their ascent – perhaps due to the pressure of trying to cram as much as possible into always-too-short holiday schedules (or because some trekking companies use shorter schedules to cut costs).
Mountain climbers are generally well versed in the dangers of altitude sickness. It’s adventure travellers who often fail to appreciate its dangers and need to know how to prevent, self-diagnose, and self-treat the condition – all of which are best discussed with a doctor experienced in travel medicine.
If you are heading to a lofty location, here are some things you should know:
What constitutes high altitude?
A high-altitude destination is classed as being between 1500m-3500m above sea level, very high altitude is 3500m-5500m, and extreme altitude is any location above 5500m.
What causes altitude sickness?
Each step up to a higher altitude means a slight reduction in atmospheric pressure and less oxygen in the air. With less oxygen reaching muscles and brain, the heart and lungs are forced to work harder to compensate. The resulting symptoms are called altitude sickness (AS) and they can range from mild acute mountain sickness (AMS) to severe high-altitude cerebral oedema (HACE) and/or high-altitude pulmonary oedema (HAPE).
What is acclimatisation?
Acclimatisation is the physical adjustment each person’s body makes to the ever-decreasing oxygen levels at higher altitudes. Some acclimatise more quickly and efficiently than others.
Who is most likely to experience altitude sickness?
Altitude sickness affects everyone to some degree: Men, women and children are all at risk of AS and being physically fit offers no guarantee against experiencing it. Some people may even be genetically pre-disposed to it, while others tolerate it better based on their own unique physiology.
What we are sure of is that those with a history of AS are likely to experience it again, and individuals with an underlying heart or respiratory condition, or anaemia (a low red blood cell count) are more likely to experience severe symptoms at higher altitudes.
How common is altitude sickness?
AS is uncommon under 2500m – only around 1-in-10 travellers will experience it. At 3000m, the incidence rises to 4-in-10, and then jumps to 7-in-10 among those who ascend rapidly to 4500m – especially if they fail to acclimatise for a day or two at a midway point during their ascent. AMS is a distinct possibility in some of the world’s most visited destinations: around 25-50% of trekkers arriving at Everest base camp will experience symptoms, and 25-35% of direct arrivals into La Paz, Bolivia (3658m).
What are the signs or symptoms?
Every traveller visiting a destination which is 2500m above sea level can expect to experience some or all of the following symptoms: a lingering headache, dizziness, fatigue and weakness, loss of appetite, nausea, vomiting, flu-like sensation, insomnia, and irritability. Symptoms usually appear in the first 8-24 hours and can last from 24-48 hours as acclimatisation takes effect. The warning signs in fellow trekkers include: missing meals, irritability or antisocial behaviour, stumbling, or simply having difficulty performing everyday activities.
What are HAPE and HACE?
With little or no warning, the symptoms of altitude sickness can become severe – indeed, potentially fatal – very quickly. There are 2 acute forms – HAPE (high-altitude pulmonary oedema) and HACE (high-altitude cerebral oedema). These can occur together but more often occur independently of one another.
HAPE is the most common cause of high altitude fatalities, often occurring on the second night after ascent to high altitude. Around 3% of travellers ascending above 3000m will develop HAPE. Early symptoms include decreased physical performance, a dry cough, fatigue, rapid heart rate (tachycardia) and rapid breathing (tachypnoea), which may progress to a cough with frothy white, blood-stained sputum, shortness of breath (dyspnoea) and blue nails and lips (cyanosis).
HACE is very uncommon below 3000m, but more likely to occur following rapid ascent to high altitudes. HACE is really a progression of acute mountain sickness. Most cases usually occur several days after the symptoms of AMS first appear. However, it can occur in as little as 12 hours, while death can follow in less than 24 hours. A telling early sign of HACE is loss of muscle coordination, along with such diverse symptoms as impaired judgement, indecisiveness, irrational behaviour, confusion, a severe headache, nausea, vomiting, drowsiness, and giddiness. Coma and death may follow.
Preventing AS - the do’s and don’ts
Gradual acclimatisation: Not getting sick at altitude is all about gradual acclimatisation and slow ascent. Don’t over-exert and ensure adequate hydration. Once above 2500m, it is advisable to sleep no higher than 300 - 500m above the previous night’s elevation, and spend two nights at the same altitude for each 1000m gained.
Climb high, sleep low: It’s one of the golden rules of high-altitude trekking. It is better to walk than to fly to any altitude above 3000m, but if you do fly, take time to acclimatise. Have 1 or 2 ‘rest days’ at the initial altitude. It is okay to climb to much higher altitudes during the day as long as you then descend to sleep at the same altitude as the night before – or no more than 300-500m higher than the previous night.
Food, fluids are important: FLUIDS – Increase (non-alcoholic) fluid intake to between 4-7 litres a day to counter fluid lost during daily activities. FOOD – A high-carb (but not high-fat) diet increases the respiratory quotient and improves oxygenation of the blood at very high altitude, reducing the symptoms of AMS by as much as 30%.
Take Diamox: Diamox (Acetazolamide) is the only drug currently known to prevent AMS. The usual dosage is 125mg (1/2 tab) twice a day. It may cause some minor side effects, such as tingling in fingers and toes, and some users complain about its metallic taste. In my experience, most people – even those with a history of sulpha allergy – can tolerate it. If you have a history of allergy, I’d recommend a test dose overseen by your doctor.
To summarise, the guidelines for preventing altitude sickness are:
- Climb slowly.
- Climb high, sleep low. (Spend one night at 1500m-2000m before sleeping above 2500m. Above 2500m, sleep no more than 300-500m above the starting altitude).
- Allow two nights to acclimatise for every 1000m gain in camp altitude above 3000m.
- Don’t over-do it – get plenty of rest.
- Increase your fluid intake (aim to drink between to 4-7 litres of water a day).
- Switch to a high-carb diet.
- Avoid alcohol, sedatives and tranquillisers. Don’t smoke (it increases the risk of acute symptoms).
- Use Diamox if you have past history of altitude sickness, or if you are planning a rapid ascent to a location above 3000m.
Treating altitude sickness - rest and recover...or retreat
If you experience the symptoms of AMS it is advisable to remain at the same altitude until you’ve recovered, which may take 1-2 days. Most symptoms will ease with rest, small meals, non-alcoholic fluids, and taking ibuprofen.
Descending even a few hundred metres will further reduce any lingering symptoms. If insomnia occurs, don’t resort to sleeping pills they could aggravate already low oxygen levels during sleep.
Descend to a lower altitude if you experience any of the following:
- A severe headache which persists despite taking ibuprofen.
- Unusual behaviour, unsteadiness, or an inability to sit upright.
- Ongoing vomiting and drowsiness.
- Shortness of breath at rest.
- Blue nails and lips.
- Cough and white, frothy sputum.
- Mild symptoms that do not improve in 2-3 days.
More about high-altitude travel...
For more on how to prevent or treat altitude sickness, visit the Travelvax Australia website or call our obligation-free travel health advisory service on 1300 360 164.
The US Centers for Disease Control and Prevention's Yellow Book has a good chapter on altitude sickness.
There is also plenty of useful information at www.altitude.org
* Dr Bajrovic is the Medical Director of Travelvax Australia.
