Acclimatisation & Altitude Issues

Altitude Related Issues

All our trips are meticulously planned and the altitude gain profiles are studied very carefully by our trip leaders who have years of experience of leading trips to the high mountains. On all the trips going to high altitudes we take rest days at critical altitudes to give people plenty of time to acclimatise to the changing altitudes. These rest days have proven to be highly beneficial for people who are a little slow in acclimatising. For members who are feeling fully fit these rest days give opportunities to do some side-walks and explore some hidden areas. On climbing trips and demanding treks we normally keep a buffer day or two for bad weather which at times come in very handy to give people more time to acclimatise.

Our trip leaders are widely experienced in these matters and keep a close eye on everyone’s condition at high altitudes. They will be able to give you good advice to help minimise any temporary discomfort that you might experience. If you have suffered serious problems at altitude before, you should seek the advice of your doctor or a specialist. We are always ready to give advice on this subject.

Travellers are visiting high altitude regions in ever increasing numbers and the dangers of altitude illness are being conveniently ignored. The risks are potentially fatal but eminently preventable.

Acclimatising to high altitude

As you gain altitude the air becomes thinner, the barometric pressure falls, and less oxygen is available. Imagine travelling in a pressurized airplane at 29,000 feet (8,800 metres). If the cabin were to suddenly lose pressure, so that the air inside was at the same pressure as the air outside, unless you were breathing supplemental oxygen you would lose consciousness in about four minutes. However, Everest at the same altitude has been climbed many times without supplemental oxygen. What’s the difference between the two scenarios? A gradual process in the body called acclimatization, during which the body gradually adapts to the lower oxygen in the air. Individuals who have acclimatized properly are able to climb unassisted to altitudes as high as Everest and survive for brief spells.

The result of acclimatization, which occurs over a period of time ranging from days to weeks, is that the body adapts to the increasingly thinner air and delivers the necessary amounts of oxygen to the cells.

According to the experience gained by everyone at White Magic, low altitude is defined as 7,000 feet (2,130m), intermediate altitude extends to 12,000 feet (3,660m), while extreme altitude is above 18,000 feet (5,490m). The term ‘high altitude’ encompasses the ranges of intermediate and extreme altitude.

Breathing adaptation
The most important difference you’ll notice as you gain altitude is the need to breathe more often when active and as well as while resting.
Pulse increase
Just as your respiration increases with increase in altitude, your resting pulse rises during the first few days at high altitude. As you acclimatize, your pulse would drop back to the normal, indicating that your body is responding well to altitude. Drugs for angina or high blood pressure may limit this response, in which case taking your pulse won’t be a useful way to judge what is happening.
Urinary response
The body experiences diuresis at altitude, that is, you urinate more often and lose fluids. If it doesn’t happen, be more wary of altitude illness; this doesn’t mean that you will get altitude illness, but you are slightly more susceptible.
Changes during sleep
Most people at altitude find it difficult to fall asleep. In the tent, you may hear your mates breathing increase and become loud, decrease after a minute or two and become very quiet, almost imperceptible, or even cease, and then start up again. This pattern is called periodic breathing. Periodic breathing often causes anxiety, and some may wish to call off the trip. It is normal, however, and diminishes with acclimatisation.
Optimum period for acclimatisation
Acclimatizing to avoid altitude illness takes less time than acclimatising to maximize performance at high altitude. There is no magic wand for the best approach; it varies from person to person and trip to trip. To avoid altitude illness the most popular approach is to increase the sleeping altitude by 1,000 feet (300 metres) each night above 10,000 feet (3,050 metres). While ascending, take a break every two to three days by sleeping at the same altitude as the previous day. You can also average the process and ascend 750 feet (230 metres) a day.

Follow the rule of ‘climb high, sleep low’, meaning climb as high as you can during the day, but descend and sleep at the same elevation or a little higher than the night before. If you are not feeling well, don’t raise your sleeping altitude at all.

What Is Altitude Illness?

The point at which you feel the altitude, varies with the speed of ascent and with your individual condition on a particular journey. Some people will feel the altitude at 6,000 feet (1,830m), most will feel it by 10,000 feet (3,050m) and all will feel it by 15,000 feet (4,570m).

Acute Mountain Sickness (AMS)
Acute Mountain Sickness (AMS) is an assemblage of symptoms that represents your body not being acclimatized to its current altitude. The exact mechanisms of AMS are not completely understood, but the symptoms are thought to be due to mild swelling of brain tissue in response to the hypoxic stress. If this swelling worsens, significant brain dysfunction occurs (See next section, on HACE). This brain tissue distress causes a number of symptoms; universally present is a headache, along with a variety of other symptoms.

The diagnosis of AMS is made when a headache, with any one or more of the following symptoms, is present after an ascent above 2,500 meters (8,000 feet):
- Loss of appetite, nausea, or vomiting
- Fatigue or weakness
- Dizziness or light-headedness
- Difficulty sleeping

All of these symptoms may vary from mild to severe. However, because the symptoms of mild AMS can be somewhat vague, a useful rule-of-thumb is: if you feel unwell at altitude, it is altitude sickness unless there is another obvious explanation (such as diarrhoea). Anyone who goes to altitude can get AMS. It is primarily related to individual physiology and the rate of ascent; there is no significant effect of age, gender, physical fitness, or previous altitude experience. Some people acclimatize quickly, and can ascend rapidly, others acclimatize slowly and have trouble staying well even on a slow ascent. There are factors that we don't understand; the same person may get AMS on one trip and not another despite an identical ascent itinerary. Unfortunately, no way has been found to predict who is likely to get sick at altitude.

It is remarkable how many people mistakenly believe that a headache at altitude is "normal"; it is not. Denial is also common - be willing to admit that you have altitude illness, that's the first step to staying out of trouble.

High Altitude Cerebral Edema (HACE)
AMS is a broad spectrum of illness, from mild to life-threatening. At the "severely ill"-end of this spectrum is HACE; this is when the brain swells and ceases to function properly. HACE can progress rapidly, and can be fatal in a matter of a few hours to one or two days. Patients with this illness are often confused, and may not recognize that they are ill.

The hallmark of HACE is the inability to think. There may be confusion, alterations in behaviour, or lethargy. There is also a characteristic loss of coordination that is called ataxia. This is a staggering walk that is similar to the way a person walks when very intoxicated on alcohol. Have the sick person do a straight line walk. Draw a straight line on the ground, and have them walk along the line, placing one foot immediately in front of the other. Try this yourself. You should be able to do it without difficulty. If they struggle to stay on the line, can't stay on it, fall down, or can't even stand up without assistance, they fail the test and should be presumed to have HACE.

Immediate descent is the best treatment for HACE. Descent should be to the last elevation at which they woke up feeling well. Bearing in mind that the majority of HACE cases occur in people who ascend with symptoms of AMS, this is likely to be the elevation at which the person slept two nights previously. If you are uncertain, a 500-1,000 meter descent is a good starting point.

High Altitude Pulmonary Edema (HAPE)
Another form of severe altitude illness is HAPE, or fluid in the lungs. Though it often occurs with AMS, it is not related and the classic signs of AMS may be absent. Signs and symptoms of HAPE include any of the following:
- Extreme fatigue
- Breathlessness at rest
- Fast, shallow breathing
- Cough, possibly productive of frothy or pink sputum
- Gurgling or rattling breaths
- Chest tightness, fullness, or congestion
- Blue or gray lips or fingernails
- Drowsiness

In some people, the hypoxia of high altitude causes constriction of some of the blood vessels in the lungs, pumping all the blood through a limited number of vessels that are not constricted. This dramatically elevates the blood pressure in these vessels and results in a high-pressure leak of fluid from the blood vessels into the lungs.

Immediate descent is the treatment of choice for HAPE; unless oxygen is available, delay may be fatal. Descend to the last elevation where the victim felt well. Descent may be complicated by extreme fatigue and possibly also by confusion (due to inability to get enough oxygen to the brain).

It is common for people with severe HAPE to also develop HACE, presumably due to the extremely low levels of oxygen in their blood. However, HAPE is often confused with a number of other respiratory conditions:

High Altitude Cough and Bronchitis are characterized by a persistent cough with or without sputum production. There is no shortness of breath at rest, no severe fatigue. Normal oxygen saturations (for the altitude) will be measured if a pulse oximeter is available.

Pneumonia can be difficult to distinguish from HAPE. Fever is common with HAPE and does not prove the patient has pneumonia. Coughing up green or yellow sputum may occur with HAPE, and both can cause low blood levels of oxygen. The diagnostic test (and treatment) is descent - HAPE will improve rapidly. If the patient does not improve with descent, then consider antibiotics. HAPE is much more common at altitude than pneumonia, and more dangerous; many climbers have developed HAPE when they were mistakenly treated for pneumonia.

Other Symptoms And Conditions At High Altitude
High Altitude Edema
High altitude edema or swelling of the hands, face and ankles is common among those trekking to 14,000 feet (4,270m). Twice as common in women as in men, it is also more frequent in those with AMS. Not serious by itself, it should alert the victim and others to look at other more perilous forms of altitude illness.

High Altitude Retinopathy
High altitude retinopathy refers to changes in the retina of the eyes, in which there is bleeding and other pathology. Common in people going above 15,000 feet (4,570m), and almost universal above 26,250 feet (8,000m), the condition clears with descent. Slow ascent is often protective.

High Altitude Syncope
Syncope, a medical term denoting a brief loss of consciousness, is often commonly referred to as fainting. Some people after arriving at altitude may stand up after eating or drinking some alcohol and faint. They normally recover swiftly without further problems and don’t faint again. This fainting maybe due to blood pooling in leg veins coupled with a slow pulse that decreases blood flow to the brain. Make the victim comfortable and raise his legs above the heart.

Other conditions may cause high altitude syncope and require medical attention. If a person faints long after arrival at altitude, the condition warrants investigation.

Treatment of Altitude Illness

The mainstay of AMS treatment is rest, fluids, and mild analgesics. The natural progression for AMS is to get better, and often simply resting at the altitude at which you became ill is adequate treatment. Improvement usually occurs in one or two days, but may take as long as three or four days. Descent is also an option, and recovery will be quite rapid.

A frequent question is how to tell if a headache is due to altitude. Altitude headaches are usually nasty, persistent, and frequently accompanied by other symptoms. However, there are other causes of headaches, and you can try a simple diagnostic/therapeutic test. Dehydration is a common cause of headache at altitude. Drink one litre of fluid, and take any mild analgesic. If the headache resolves quickly and totally (and you have no other symptoms of AMS) it is very unlikely to have been due to AMS.

Rest
Rest for mild to moderate symptoms of AMS may be the only treatment necessary and one that is commonly overlooked.
Descent
Whenever practical, the patient should be made to descend. Although, there is no ideal descent, but any altitude at which the patient starts feeling better and the symptoms resolve, should be considered as the altitude to which the body has adapted. Patients with HAPE need to descend slowly and with assistance: excessive exertion even during descent may increase the blood flow to the lungs and exacerbate the problem.
Oxygen
Lack of oxygen at altitude is the chief cause of altitude sickness, so breathing supplemental oxygen is obviously going to make a difference. Whenever oxygen is available and AMS is suspected, it should be used.

AMS symptoms resolve very quickly (minutes) on moderate-flow oxygen (2-4 litres per minute, by nasal cannula). There may be rebound symptoms if the duration of therapy is inadequate - several hours of treatment may be needed. In most high altitude environments, oxygen is a precious commodity, and as such is usually reserved for more serious cases of HACE and HAPE.

Hyperbaric Bag
This is a simple, effective device, made of airtight nylon; it is about 7 feet long and looks like a long duffel bag. With the patient inside, the bag is inflated with a foot pump until it becomes like a large sausage-shaped balloon. There is a one-way valve to avoid CO2 build up inside, and it has transparent panels to assist communication with its occupant (patient).

For both HACE and HAPE (but especially, in our experience, for HACE) the changes are usually dramatic within an hour. However, there may be a "rebound" two or three hours after therapy and the patient may need to get in the bag again. This bag only helps to buy time and descent is still mandatory as soon as possible

Drugs / Diamox
Acetazolamide (Diamox) is a medication that helps speed up acclimatization. However, acetazolamide isn't a magic pill and cure of AMS is not immediate. It makes a process that might normally take about 24-48 hours speed up to about 12-24 hours.
Acetazolamide is a sulphonamide medication, and persons allergic to sulpha medicines should not take it. Common side effects include numbness, tingling, or vibrating sensations in hands, feet, and lips. Also, taste alterations, and ringing in the ears. These go away when the medicine is stopped. Since acetazolamide works by forcing a bicarbonate diuresis, you will urinate more on this medication. Uncommon side effects include nausea and headache. A few trekkers have had extreme visual blurring after taking only one or two doses of acetazolamide; fortunately they recovered their normal vision swiftly once the medicine was discontinued.

We recommend a dosage of 250 mg every 12 hours. The medicine can be discontinued once symptoms resolve. Children may take 2.5 mg/kg body weight every 12 hours.

Myths About Diamox
• MYTH: Acetazolamide hides symptoms
Acetazolamide accelerates acclimatization. As acclimatization occurs, symptoms resolve, directly reflecting improving health. Acetazolamide does not cover up anything - if you are still sick, you will still have symptoms. If you feel well, you are well.

• MYTH: Acetazolamide will prevent AMS from worsening during ascent
Acetazolamide does not protect against worsening AMS with continued ascent. Plenty of people have developed HAPE and HACE who believed this myth.

• MYTH: Acetazolamide will prevent AMS during rapid ascent
This is actually not a myth, but rather a misused partial truth. Acetazolamide does reduce the risk of AMS, that's why we recommend it for people on forced ascents. This protection is not absolute, however, and it is unwise to believe that a rapid ascent on acetazolamide is without serious risk.

• MYTH: If Acetazolamide is stopped, symptoms will worsen
There is no rebound effect. If acetazolamide is stopped, acclimatization slows down to your own intrinsic rate.

Preventing Altitude Illness

The key to avoiding AMS is a gradual ascent that gives your body time to acclimatize. People acclimatize at different rates, so it is difficult to generalizations.

Things To Avoid
Respiratory depression (the slowing down of breathing) can be caused by various medications, and may be a problem at altitude. The following medications can do this, and should never be used by people who have symptoms of altitude illness (these may be safe in persons who are not ill, although this remains controversial):
- Alcohol
- Sleeping pills (acetazolamide is the sleeping tablet of choice at altitude)
- Narcotic pain medications in more than modest doses
Prophylaxis
Under certain circumstances, prophylaxis with medication may be advisable:
- For persons on forced rapid ascents (such as flying into Lhasa, Tibet, or La Paz, Bolivia), for climbers who cannot avoid a big altitude gain due to terrain considerations, or for rescue personnel on a rapid ascent
- For persons who have repeatedly had AMS in the past.