The Essentials:
Be in good health & make the most of your trip!
If it’s been a while since your last medical check-up, this is a good opportunity to have a check-up by explaining to your doctor the main characteristics of your trip (climate, altitude, difficulty, etc.); a visit to your dentist is also an excellent initiative. This advice is particularly relevant to you, as you are about to embark on a long journey at altitude.
We recommend that you consult the Ifremmont website to find your nearest mountain medicine consultation centre. For information on altitude-related problems: www.ifremmont.com
or
Here is a link to the official website in Nepal: Himalayan Rescue Association Nepal , https://www.himalayanrescue.org/health-problems
AMD (Acute Mountain Sickness):
If this trip takes place at a high altitude, some people may suffer from malaise (headaches, swelling, loss of appetite). Most of these symptoms usually disappear within a few days, but they can sometimes worsen and develop into serious illnesses such as pulmonary or cerebral oedema. There is no medication to prevent MAM. (AMS in English)
The diuretic Diamox is often effective, but you should check with your doctor that it is not contraindicated. Altitude can also revive dental problems and other chronic pain. Think about this before you leave.
During your journey, make sure you drink plenty of fluids and eliminate toxins.
Let your guide know about your state of health, even if you have minor problems.
MAM consists of a headache accompanied by one of the following symptoms, to varying degrees: nausea, fatigue, insomnia or dizziness. It can occur at altitudes of around 2,500M and above, where pathophysiological changes due to the lack of oxygen can occur. Another term, ‘altitude sickness’, is also widely used – a generic term that includes the benign acute mountain sickness and its two potentially fatal complications, the accumulation of water in the brain (high-altitude cerebral oedema, HACE) or high-altitude pulmonary oedema (HAPE, accumulation of water in the lungs). The latter two complications can follow MAM, particularly when people continue to climb despite increasing symptoms. In keeping with the Jesuit tradition of meticulous documentation, the first description of the effects of high altitude on humans was written by Father Joseph de Acosta, a 16th-century Spanish Jesuit priest. In the Nepalese vernacular, altitude sickness is called “lac lagne”; in Sanskrit, it is aptly named “damgiri” (“dam” means breathlessness and “giri”, mountain).
The people most at risk of complications are those who don’t listen to their bodies and heed the early warning signs of AMS; they can suffer from HAPE and HACE and even die from them – a process that was carefully documented in major autopsy studies carried out by Walter Bond and John Dickinson in the 1970s in the old Shanta Bhawan Hospital in Nepal.
Chronic mountain sickness is an entirely different condition, recognised by Carlos Monge Medrano in long-term high-altitude residents of South America in the 1920s. Such maladaptation is rarely seen in Sherpas or Tibetans, perhaps due to thousands of years of exposure to life at high altitude. (This discussion will be limited to acute exposure to altitude in short-term residents.
Mountaineers, serious trekkers, romantics strolling the Himalayan foothills, native porters, North American and European skiers, pilgrims to high-altitude shrines, diplomats stationed in La Paz or Lhasa, South American miners and Everest marathon runners have one thing in common: they are all exposed to the effects of high altitude and at risk of suffering a potentially fatal but eminently preventable problem: acute mountain sickness, commonly known as AMS.
ACUTE MOUNTAIN SICKNESS
If a participant in an Everest trek suffers from a mild headache and nausea at Namche Bazaar (3,440M), they can take aspirin and wait for the symptoms to subside; however, if the symptoms turn into vomiting and a severe headache, they should assume they are suffering from AMS and plan to descend. It’s amazing how many people in this situation ignore the dangers and carry on climbing with their friends, trying to blame their symptoms on poor physical condition or flu. For some, it’s the high investment of time, effort and money; for others, it may be peer pressure or a reluctance to accept defeat. What’s more, many of those involved in the thriving adventure travel sector don’t experience mountain sickness.
AMS can occur within hours or days of arriving at high altitude. The onset of symptoms is usually gradual, so it’s essential to be alert to the warning signs: does someone feel excessively tired, or is he or she the last person to drag themselves back to camp?
What causes AMS?
AMS is caused by a lack of oxygen. Although the proportion of oxygen in the atmosphere always remains the same (21%), the higher you climb, the lower your “driving pressure”. Motive pressure depends directly on barometric pressure and forces oxygen from the atmosphere into the capillaries of the lungs. Reduced driving pressure leads to lower oxygen saturation in the blood and tissues.
It is not known exactly what causes some people to suffer from AMS and not others, but there are clear and important preventive factors that are now well established (see below). The exact mechanism (pathophysiology) of MSA is similar to that of HACE.
HIGH ALTITUDE CEREBRAL OEDEMA (HCAO)
Our trekker in the example above would probably suffer from HACE if he continued to climb despite the headaches and vomiting; the symptoms of HACE are an extension of those of AMS.
Fatigue is followed by lethargy and then coma. There may also be confusion and disorientation. A useful test is to see if the person can walk in a straight line. If they walk like a drunk or are unsteady, we must assume that they are suffering from a potentially fatal HACE and need to get off quickly with help. This situation is serious enough to warrant immediate evacuation by helicopter.
HACE is probably caused by fluid displacement in the brain tissue. Reduced oxygen levels cause swelling within the bony skull. The resulting increase in pressure can lead to lethargy and eventually coma.
HIGH ALTITUDE PULMONARY OEDEMA (HAPO)
This condition may follow MAM, but often occurs independently. The typical scenario is that of a trekker who has no headaches or nausea, but who finds it harder to walk uphill and is out of breath after a slight effort compared with the first few days of the trek. He may have a nagging cough, and he too may have attributed these symptoms to a cold. He may be suffering from subclinical or early-onset HAPE, a well-recognised entity. With continued ascent, this may progress to breathlessness even at rest – descent is now mandatory, or the outcome may be fatal.
The lack of oxygen causes a narrowing of the pulmonary artery, leading to an exudation of blood near the small branches of the lungs (the alveoli). If the exudation continues, blood can escape into the alveoli, causing a cough with a watery phlegm tinged with blood. Such exudation, or ‘waterlogging’ of the lung tissue, further interferes with oxygenation. A popular and compact device called a pulse oximeter can measure the level of oxygen in the blood simply and quickly, using a sensor attached to the index finger. It can be very useful in confirming the presence of HAPE.
WHAT IS ACCLIMATISATION?
Acclimatisation is a state of physiological “truce” between a visitor’s body and the hostile, low-oxygen environment of high altitude. This truce allows the hiker to rise gradually. (This notion is distinct from that of ‘adaptation’ – permanent modification of the organism, perhaps over thousands of years, or even at a genetic or evolutionary level, to facilitate survival at altitude. Scientists are trying to decipher whether the Sherpas or the Tibetans underwent such an adaptation).
For acclimatisation to take place, the most important step is hyperventilation – the hiker unconsciously breathes faster and deeper than normal, even at rest, to compensate for the lack of oxygen. However, hyperventilation also leads to a loss of carbon dioxide in the blood, which makes the blood more alkaline, and in turn depresses ventilation. However, 48 to 72 hours after exposure to high altitude, the kidney comes to the rescue and begins to excrete alkali from the blood to re-establish a more balanced environment in which hyperventilation can continue without problem.
PREVENTING ALTITUDE SICKNESS
There is no doubt that mountain sickness is a 100% preventable disease. Nobody should die from it. For a quarter of a century, one of the main aims of the Himalayan Rescue Association in Nepal has been to preach the good word of prevention, from its aid stations in Pheriche (at around 5,000M in the Everest region) and Manang (at around 3,400M in the Annapurna region). There are four golden rules, plus some important general principles that should always be followed:
1. Understand and recognise the symptoms of AMS. The recent boom in adventure travel has made high-altitude trekking simpler and more accessible, with the result that more and more people who go trekking are unaware of the basic facts about mountain sickness.
2. Never climb with obvious symptoms. Incredibly, I’ve known people to hire a horse or yak to climb higher when they were too ill to walk. This is a recipe for disaster.
3. Get off if symptoms increase. It’s amazing how striking and dramatic the relief can be with even a few hundred feet of descent. People with signs of HAPE or HACE need to get off.
4. Group members must look out for each other (perhaps like the buddy system in scuba diving). This rule is broken with unfailing regularity every trekking season in the Himalayas, because people are simply too eager to finish their trek, even if one of their group is ill. A trekker suffering from AMS, HAPE or HACE will want nothing more than to be left alone, undisturbed, at the same altitude – a potentially fatal option. There is no alternative but to bring the person down to a lower altitude, accompanied by a friend who speaks the same language.
Follow a cautious pace of ascent
Climbing too high, too fast, is the main cause of susceptibility to MAM. Above around 2,700M, the altitude at which you sleep should not be more than 450/500M higher than the previous night. It is the sleeping altitude, and not the altitude reached during the day, that is important. Altitude sickness often manifests itself at night, as during sleep the level of oxygen in the blood can fall even further. Many mountaineers have climbed to 4,400m or more in the Alps or in North America, but few have slept at this altitude. In the Himalayas, you don’t have to be an experienced mountaineer or use crampons to be able to ‘hang out’ at 4,500M or more for days on end: the easy access to these altitudes also makes it easier to be exposed to MSA.
During the climb, every second or third day should be a rest day for acclimatisation. “Climb high and sleep low” is the saying, but it is important not to make excessive efforts to achieve this.
Trekkers should not be in a hurry in the mountains. The itinerary should be planned in such a way as to allow enough “margin days” in case you need more time to acclimatise. Trying to do a two-week trek at high altitude in one week is always fraught with problems.
Avoid over-exertion in the first few days
Excessive physical effort at high altitude makes you more vulnerable to MAM. It is important to take it easy at high altitude, especially in the first few days. People who are in very good physical shape, such as marathon runners or those who carry very heavy rucksacks, seem to be more vulnerable to MAM than others, probably because they overexert themselves. I once looked after a trekker who felt he couldn’t stop his morning jogging sessions despite an exhausting day’s trek ahead, even at an altitude of 4,000 m! The feeling of “man against nature” is perhaps stronger in this fitter group.
Avoiding alcohol
Jim, a rock star, decided to “refuel” with four bottles of beer when he arrived at 3500 metres in the Everest region. He felt ill and had to be evacuated by helicopter two days later. He had been advised not to drink alcohol during the trek, especially during the ascent. Alcohol can dehydrate the trekker but, more importantly, it depresses breathing or ventilation. Sleeping pills can have a similar effect.
Maintain adequate hydration
Adequate quantities of liquid (around 3 litres a day) are necessary in the mountains: dehydration mimics altitude sickness and can even predispose to it. On the other hand, avoid drinking too much water, as this can lead to electrolyte imbalances.
Maintain a high-carbohydrate diet
A diet rich in carbohydrates facilitates ventilation and the efficient use of oxygen. The good news is that in many high-altitude locations, there aren’t many alternatives: rice, potatoes and other strach-laden foods are generally the staples, and there aren’t many other choices.
Drug prevention (prophylaxis)
Diamox (actazolamide) may be necessary for people taking part in high-altitude rescue missions or flying to high-altitude cities such as La Paz or Lhasa. People with a sulphate allergy should not take diamox, the main preventive medication, and further details are given below: Click HERE TrekMAg-. A second drug, dexamethasone (see below), should also be taken, especially if the destination is remote: it can be life-saving in the event of HACE.
And also this interesting article to ponder: Can anxiety trigger acute mountain sickness? –Click HERE–
TREATMENT
Descent
As far as possible, you should try to descend. There is no magic altitude at which to descend, but the ill patient may suddenly feel something rising and feel hungry. This is the altitude to which the body is adjusted. Patients with HAPE should descend slowly and with assistance: excessive effort even during descent can increase blood flow to the lungs and exacerbate the problem.
Oxygen
The lack of oxygen at altitude is the main reason why people suffer from altitude sickness, so breathing extra oxygen will obviously make a difference. But oxygen is a difficult commodity to find in the mountains – oxygen cylinders are not easily portable. When oxygen is available in AMS environments, you have to use it.
Medicines
Acetazolamide (diamox): This is the most proven drug for the prevention and treatment of mountain sickness. Unlike dexamethasone, this drug does not mask the symptoms but actually treats the problem. It appears to work by increasing the amount of alkali (bicarbonate) excreted in the urine, making the blood more acidic. Acidification of the blood leads to ventilation, which is the cornerstone of acclimatisation.
As a preventive measure, 125 mg twice a day, starting the evening before and continuing for three days once the highest altitude has been reached, is effective. A recent article in the British Medical Journal suggests taking a higher dosage – 750 mg a day. In our experience in the Indian subcontinent, 250 mg a day has proved satisfactory, whereas an excessive dosage simply increases the side effects.
The side effects of diamox are: an uncomfortable tingling of the fingers, toes and face (called “jhum jhum” in Nepali); a flat taste in fizzy drinks; excessive urination; and rarely, blurred vision. On most treks in Nepal, a gradual ascent is possible and prophylaxis tends to be discouraged. Certainly, if trekkers develop headaches and nausea or the other symptoms of AMS, then treatment with diamox is indicated. The treatment dose is 250 mg twice a day for about three days.
Dexamethasone: This steroid medication can be a lifesaver for people with HACE. It works by reducing swelling and pressure in the bony skull. The dose is 4 mg three times a day, and obvious improvement usually occurs within six hours. Like the hyperbaric bag (see below), this medication helps to ‘buy time’, especially at night, when descending can be problematic. The descent should be made the following day. It is not advisable to ascend on dexamethasone: unlike diamox, this drug merely masks the symptoms.
Dexamethasone can be very effective: many people who are lethargic or even in a coma improve considerably after taking tablets or receiving an injection, and may even be able to descend with help. Many pilgrims taking part in the annual festival at Gosainkunda Lake in Nepal suffer from HACE after a rapid ascent and respond remarkably well to dexamethasone. Climbers also sometimes take dexamethasone to prevent or treat AMS. It should be used with caution, however, as it can cause stomach irritation, euphoria or depression.
It may be advisable to take this medicine with you when trekking at high altitude, to be used in an emergency in the event of SHA. For people allergic to sulphonamides (and therefore unable to take diamox), dexamethasone can also be used as a preventive measure: 4 mg twice a day for around three days may be sufficient.
Nifedipine: This drug is generally used to treat high blood pressure, but also appears to be able to reduce the narrowing of the pulmonary artery caused by low oxygen levels, thereby improving oxygen transfer. It can therefore be used to treat HAPE, although unfortunately its efficacy is not as spectacular as that of dexamethasone in HACE. The dose is 20 mg of long-acting nifedipine, six times an hour.
This drug can cause a sudden drop in blood pressure, so patients should be warned to rise slowly from a sitting or lying position. It has also been used at the same dosage to prevent EHPAD in people with a history of this condition.
The hyperbaric bag
This is a simple and effective device, made of airtight nylon; it is about 2.5 metres long and looks like a long sports bag. With the patient inside, the bag is inflated with a foot pump until it becomes like a large sausage-shaped balloon. It has a one-way valve to prevent the build-up of carbon dioxide inside, and transparent panels to facilitate communication with its occupant.
The pressure inside the bag is 2 p.s.i., so the effect is about the same as lowering the patient a few thousand feet. For HACE and HAPE (but especially, in our experience, for HACE), the changes are generally spectacular within an hour. However, there may be a ‘rebound’ two or three hours after treatment and the patient may need to get back into the bag. Like dexamethasone, this bag is only used to ‘buy time’. Descent remains mandatory as soon as possible.
OTHER PROBLEMS AT ALTITUDE
Periodic breathing
Abnormal breathing during sleep is common at high altitude: short periods of accelerated breathing alternate with brief periods when breathing slows down and seems to stop – the medical term for this phenomenon is ‘Cheyne Stokes’ breathing. This is only a problem if the people affected wake up repeatedly, out of breath, anxious and unable to sleep. An effective remedy is Diamox 125 mg before dinner, which counteracts the drop in oxygen during sleep that triggers the problem. Sleeping pills should be avoided.
Upper respiratory tract infections and symptoms
Many people develop a persistent, troublesome cough and cold symptoms in the cold, dry air of high altitude. An antihistamine taken in the evening, such as Benadryl 25 mg, can help suppress the cough. Antibiotics are sometimes useful, but keeping your head and face covered and breathing through a silk or woollen scarf to humidify the air can also help. Numerous studies have shown that upper respiratory tract infections can predispose to SMA.
Peripheral oedema
There may be swelling around the eyes, fingers and ankles at high altitude, but this does not necessarily indicate AMS per se, unless it is accompanied by AMS symptoms. These non-AMS symptoms generally require no treatment.
High altitude syncope (fainting): This is a well-known but harmless problem in which fainting occurs suddenly, usually shortly after arrival. Simple measures, such as keeping the person lying down and elevating the legs, are useful.
Travellers with pre-existing health problems, children and contraceptive pills.
Hypertension: Blood pressure initially rises at high altitude due to the initial stress of oxygen deprivation, which triggers neurohumoral changes. However, people suffering from high blood pressure can go to high altitude as long as it is well controlled and they continue to take their medication.
Coronary heart disease: People with a history of heart attack (myocardial infarction) and even those who have undergone coronary bypass surgery or angioplasty, but who do not have angina pectoris, can hike at high altitude provided they are in good physical condition and can hike rigorously at low altitude. High altitude does not seem to add any extra burden to the heart.
Epilepsy: Although seizures can be provoked by altitude, there is no convincing evidence that it is dangerous for well-controlled epileptics to travel at high altitude, although they should always take their anti-seizure medication conscientiously.
Migraine: Sufferers may have more attacks in the mountains, which can sometimes be difficult to distinguish from SMA. If in doubt, it’s best to go back down.
Lung diseases: It is also worth noting the limited observation that bronchial asthma does not seem to be exacerbated at high altitude due to the cold and exercise. However, it is prudent for asthma sufferers to take inhalers and other medication with them. Obviously, people with chronic obstructive pulmonary disease may be more short of breath and it is not advisable to travel to high altitudes.
Neck surgery and radiotherapy: People with a treated cancer, such as lymphoma, or a tumour in the neck who have undergone major surgery or radiotherapy may be particularly prone to tonsillitis syndrome due to damage to the carotid bodies – tiny organs in the carotid arteries that sense oxygen and facilitate ventilation.
Diabetes: Diabetics on insulin need a reliable glucometer to monitor their blood sugar levels regularly, but altitude does not appear to entail any additional risks.
Corneal surgery: people who have undergone non-laser surgery (radial keratotomy) to correct myopia may experience problems at high altitude due to swelling of the cornea caused by the low oxygen levels. These people must also wear corrective lenses if they travel at high altitude.
Pregnancy: Pregnant women should not sleep above 12,000 feet, as this can endanger the foetus. Another problem is that high-altitude locations are usually remote, making emergencies more difficult to manage.
Children: Children do not suffer from the effects of altitude any more than adults. However, it is important for a child to be able to communicate any symptoms to a responsible adult, so that a rapid descent can be organised. It can therefore be dangerous to take children who are not yet old enough to go to high altitude.
Contraception: Oral contraceptive pills can predispose to abnormal blood coagulation (thrombosis) at high altitude. Hypoxia (low oxygen content), excess red blood cells (polycythemia) in the blood and possible dehydration in this environment may already be other factors predisposing to thrombosis. It is therefore preferable to use other forms of contraception at high altitude.
Other risks of illness
Many high-altitude destinations are in developing countries. It is therefore important to be up to date with vaccinations against diseases such as typhoid and hepatitis, to be familiar with traveller’s diarrhoea and its treatment, and to understand the other precautions described in this book. Malaria is not a risk at altitude – transmission does not occur above 2000 metres.
Conditions that mimic altitude sickness
Thanks to improved medical facilities in countries such as Nepal, it is much easier to distinguish altitude sickness from conditions that can produce similar symptoms, such as brain haemorrhages (subarachnoid haemorrhage), strokes, dehydration and problems related to blood viscosity, such as venous thrombosis.
Carriers in the Himalayas
It is important to be aware that porters can be just as vulnerable to the effects of altitude as tourists; for your own safety, it is also vital to confirm with the trekking agency that your porter has been provided with appropriate clothing, boots and equipment before the trek begins. Association pour le Respect & la Dignité des Porteurs de l’Himalaya -More details HERE-
in general, local actions :https://www.himalayanrescue.org
