During your stay in Colombia, you may be required to spend a few hours or days at altitude (above 2,500 meters). This information is intended for you.
Origin of acute mountain sickness (AMS, or altitude sickness)
At altitude, atmospheric pressure drops: less oxygen is available to the body. The amount of oxygen available at 3,000 meters is two-thirds that available at sea level, and half that at 5,000 meters. At 5,000 meters, it’s half that. The body reacts to this lack of oxygen (or hypoxia) in two ways.
Immediate reaction of our body to altitude
Acceleration of ventilation and heart rate, to capture more oxygen from the air and transport it more rapidly to the organs. This reaction is energetically costly for the body, as it makes the respiratory muscles and heart work harder
Progressive reaction
The immediate reaction is replaced or supplemented by a more economical mechanism: increasing the number of oxygen carriers, i.e. red blood cells. Red blood cells take a long time to produce, and you need to spend at least a week at altitude to see their numbers increase. Ventilation rate and heart rate can then slow down, without returning to baseline values
Who is affected?
Altitude sickness (or « sorojche » in the Andes) is thought to affect around
- 15% of people above 2,500 meters
- 60% of people above 4,000 meters
- everyone at high altitude (over 5,000 metres)
Like seasickness, it can affect anyone. Age and gender are not risk factors
What are the symptoms?
The reaction to altitude is unique to each individual. Most of the time, MAM is benign, and manifests itself in a variety of disorders that can occur separately or in combination, from the very first hours of a stay at altitude
- headaches
- feeling tired and drowsy
- shortness of breath
- sleep disorders
- dizziness and balance problems
- loss of appetite and digestive disorders
- nausea
- irritability
- decreased urine output
these symptoms, which are common and normal, generally disappear on their own (or at least lessen considerably) after a few hours at altitude and with the help of painkillers (aspirin or paracetamol).
In some cases, however, serious complications can occur: pulmonary edema (coughing, spitting, blue lips, respiratory failure) or cerebral edema (severe headaches not relieved by aspirin, vomiting, visual disturbances, sometimes psychiatric disorders). This is an extreme form of MAM, and the immediate response is to
- immediately lower the sufferer to the lowest possible altitude
- consulting a specialist doctor
we know of one case of severe MAM every two years or so (usually occurring during the first few days at altitude). Our teams of guides and escorts are trained to diagnose edema when it occurs, and to react in the most appropriate way.
Before departure
Physical training prior to a stay at altitude does not protect against altitude sickness, but is obviously advisable: cycling, swimming or hiking (at altitude if possible) are good ways to prepare. Consult your GP to detect any deficiencies or ailments.
If necessary, consult a center specializing in mountain medicine (download the list of centers in France below). For a stay that includes sporting activities (trekking, mountaineering, etc.) above 3,000 meters, we’ll ask you to fill in a health questionnaire (download below): depending on the answers you provide, we’ll ask you to present a certificate, issued by a doctor, declaring you fit for sporting activities at altitude.
On site: acclimatization essential
To mitigate the effects of MAM and limit the risk of aggravation, there are two golden rules to follow.
Start slowly
One week at altitude is generally sufficient for proper acclimatization. We take particular care to ensure that our programs get off to a gentle start, with activities or excursions that are not too strenuous in the first few days, close to health centers if necessary, and with plenty of time for rest.
Climb gradually
Above 3,500 metres, we advise you not to climb more than 700 metres from one night to the next. For example, starting at 3,500 metres, you can climb to a pass at 4,500 metres (+1,000 m), provided you sleep lower down, at 4,000 metres for example, as the difference in altitude between this bivouac and the previous one is only 500 metres. All our trekking and mountaineering programs are designed to respect this progressive approach.
A few tips for your stay
In the first few days
- especially in the first 24 hours, try to conserve energy, walk slowly and ventilate well
- don’t make unnecessary or ill-considered physical efforts « to test yourself », even when you feel in top form (this can encourage the onset of MAM)
During a trek or climb
- avoid violent exertion (giant steps, jumping, running, etc.)
- don’t overextend yourself (e.g. by playing « last one in pays a visit »)
- to get a good night’s sleep, once you’ve reached the bivouac, climb 200 to 300 metres without a pack, stay there for an hour and climb back down to camp
- in case of pain (with the exception of headaches relieved by taking aspirin), stop climbing and rest
- if signs persist, descend another 300 to 400 metres, and only resume your ascent the following day if the signs have disappeared; if they don’t, don’t continue your trek or ascent
Always stay well hydrated
To avoid dehydration (favoured by the combination of altitude + sun + effort), it’s essential to drink plenty (3 to 4 liters every day). This is a good opportunity to enjoy « maté de coca » (an infusion of coca leaves, a typical drink in the Andes), an energizing beverage reputed to help alleviate the effects of altitude.
During treks or climbs, you’ll need to make sure you drink mineral water or purify the water in streams, otherwise you’ll run the risk of other problems, particularly gastric.
Always eat well
During your stay, and especially on treks and climbs
- eat a balanced diet (vegetarians may be deficient in iron, which slows down the production of red blood cells)
- eat a generous and complete breakfast
- stock up regularly: for each day in the mountains, our support teams will provide you with food for the race (cereal bars, dried fruit, sugar)
For your first meal at altitude, we advise you to eat lightly and avoid alcohol
What medication should I take?
If you are taking any medication, ask your doctor for advice. He or she will be able to tell you if there are any contraindications to taking it at altitude, precautions to take, symptoms to watch out for… In the event of a headache, take aspirin (which thins the blood) rather than paracetamol. Do not take sleeping pills, which encourage pauses in breathing during sleep, aggravating hypoxia (lack of oxygen)
The Diamox® issue
Diamox (acetazolamide) acts by increasing the ventilatory response to oxygen deprivation. We advise against taking it as a preventive measure, preferring natural acclimatization through gradual ascent to altitude. It should also be noted that
- diamox can have undesirable side effects (metabolic disturbances)
- diamox is a diuretic, which may lead to dehydration
- administered preventively, it makes it difficult to detect altitude-related problems
However, it can be useful to take some with you, and we recommend that you do so
- in the event of poor acclimatization to altitude, particularly if headaches persist despite painkillers
- when ascending too quickly
- for the treatment of peripheral edema (swelling of the face, hands and ankles, which is severe on awakening and subsides during the day) with no other signs of MAM
Don’t refuse diagnosis
If you suffer at altitude, it’s MAM until proven otherwise! Don’t tell yourself that you’ve got a headache because you’ve been walking in the sun without a hat, or that you’re throwing up because last night’s eggs weren’t fresh… The diagnosis can be vexing for a well-trained sportsman, or frustrating because it means putting an end to a trek or climb. But refusing it can lead to disaster
It’s essential to be honest with yourself and with the guides and leaders who will be supervising the trek/climb. They have extensive experience of the terrain, and will be able to give sound advice and first aid if necessary. It is up to them to decide whether or not to allow a participant to continue with a trek or climb.
Contraindications
Staying at altitude, and particularly engaging in sporting activities (trekking, mountaineering, etc.) at altitude, is strongly contraindicated for people suffering from
- vascular insufficiency
- chronic respiratory insufficiency
- epilepsy
- diseases requiring repeated injections (e.g. insulin-dependent diabetes)
- unstabilized heart disease
- certain blood disorders
it is also contraindicated for people who have undergone neurosurgery, or for those who have suffered cerebral or pulmonary edema during a previous stay at altitude. Stays at altitude are also not recommended for pregnant women and infants (under 18 months)
