Altitude sickness
Encyclopedia
Altitude sickness—also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, or soroche—is a pathological effect of high altitude on humans
, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,400 metres (8,000 feet).
It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover". It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can climb up to 2,400 meters (8,000 ft) without difficulty.
Acute mountain sickness can progress to high altitude pulmonary edema
(HAPE) or high altitude cerebral edema
(HACE), which are potentially fatal.
Chronic mountain sickness
, also known as Monge's disease, is a different condition that only occurs after very prolonged exposure to high altitude.
of diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen. However, it is the air density itself, the number of molecules (of both oxygen and nitrogen) per given volume, which drops as altitude increases. Consequently, the available amount of oxygen to sustain mental and physical alertness decreases above 10000 feet (3,048 m). Although the cabin altitude in modern passenger aircraft is kept to 8000 feet (2,438.4 m) or lower, some passengers on long-haul flights may experience some symptoms of altitude sickness.
Dehydration
due to the higher rate of water vapor lost from the lungs at higher altitudes may contribute to the symptoms of altitude sickness.
The rate of ascent, altitude attained, amount of physical activity at high altitude, as well as individual susceptibility, are contributing factors to the onset and severity of high-altitude illness.
Altitude sickness usually occurs following a rapid ascent and can usually be prevented by ascending slowly. In most of these cases, the symptoms are temporary and usually abate as altitude acclimatisation occurs. However, in extreme cases, altitude sickness can be fatal.
The word "soroche" came from South America
and originally meant "ore
", because of an old, incorrect belief that it was caused by toxic emanations of ores in the Andes
mountains.
People have different susceptibilities to altitude sickness; for some otherwise healthy people, acute mountain sickness (AMS) can begin to appear at around 2000 meters (6,500 ft) above sea level, such as at many mountain ski resorts, equivalent to a pressure of 80 kPa. AMS is the most frequent type of altitude sickness encountered. Symptoms often manifest themselves six to ten hours after ascent and generally subside in one to two days, but they occasionally develop into the more serious conditions. Symptoms include headache, fatigue, stomach illness, dizziness, and sleep disturbance. Exertion aggravates the symptoms.
The Lake Louise assessment system of AMS is based on a self-report questionnaire as well as a quick clinical assessment.
Those individuals with the lowest initial partial pressure of end-tidal pCO2 (the lowest concentration of carbon dioxide
at the end of the respiratory cycle) as a measure of a higher alveolar ventilation, as well as individuals with a corresponding high oxygen saturation levels tend to have a lower incidence of Acute Mountain Sickness than those with high end-tidal pCO2 and low oxygen saturation levels.
s are the primary symptom used to diagnose altitude sickness, although a headache is also a symptom of dehydration
. A headache occurring at an altitude above 2,400 metres (8,000 feet = 76 kPa), combined with any one or more of the following symptoms, may indicate altitude sickness:
Pulmonary edema
(fluid in the lungs):
Cerebral edema
(swelling of the brain):
The most serious symptoms of altitude sickness arise from edema
(fluid accumulation in the tissues of the body). At very high altitude, humans can get either high altitude pulmonary edema
(HAPE), or high altitude cerebral edema
(HACE). The physiological cause of altitude-induced edema is not conclusively established. It is currently believed, however, that HACE is caused by local vasodilation of cerebral blood vessels in response to hypoxia, resulting in greater blood flow and, consequently, greater capillary pressures. On the other hand, HAPE may be due to general vasoconstriction in the pulmonary circulation (normally a response to regional ventilation-perfusion mismatches) which, with constant or increased cardiac output, also leads to increases in capillary pressures. For those suffering HACE, dexamethasone
may provide temporary relief from symptoms in order to keep descending under their own power.
HAPE can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea
at rest, and cough that is initially dry but may progress to produce pink, frothy sputum
. Descent to lower altitudes alleviates the symptoms of HAPE.
HACE is a life threatening condition that can lead to coma or death. Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE.
levels at higher elevations, in order to avoid altitude sickness. Once above approximately 3,000 metres (10,000 feet = 70 kPa), most climbers and high-altitude trekkers take the "climb-high, sleep-low" approach. For high-altitude climbers, a typical acclimatization regimen might be to stay a few days at a base camp, climb up to a higher camp (slowly), and then return to base camp. A subsequent climb to the higher camp then includes an overnight stay. This process is then repeated a few times, each time extending the time spent at higher altitudes to let the body adjust to the oxygen level there, a process that involves the production of additional red blood cells . Once the climber has acclimatised to a given altitude, the process is repeated with camps placed at progressively higher elevations. The general rule of thumb is to not ascend more than 300 metres (1,000 ft) per day to sleep. That is, one can climb from 3,000 (10,000 feet = 70 kPa) to 4,500 metres(15,000 feet = 58 kPa) in one day, but one should then descend back to 3,300 metres (11,000 feet = 67.5 kPa) to sleep. This process cannot safely be rushed, and this is why climbers need to spend days (or even weeks at times) acclimatising before attempting to climb a high peak. Simulated altitude equipment that produces hypoxic (reduced oxygen) air can be used to acclimate to high altitude, reducing the total time required on the mountain itself .
Altitude acclimatization is necessary for some people who move rapidly from lower altitudes to intermediate altitudes, e.g. by aircraft and ground transportation over a few hours, such as from sea level to 8000 feet (2,438.4 m) of many Colorado, USA mountain resorts. Stopping at an intermediate altitude overnight can reduce or eliminate an occurrence of AMS.
may help some people making a rapid ascent to sleeping altitude above 2750 metres, and it may also be effective if started early in the course of AMS. The Everest Base Camp
Medical Centre cautions against its routine use as a substitute for a reasonable ascent schedule, except where rapid ascent is forced by flying into high altitude locations or due to terrain considerations. The Centre suggests a dosage of 125–250 mg twice daily for prophylaxis, starting from 24 hours before ascending until a few days at the highest altitude or on descending; with 250 mg twice daily recommended for treatment of AMS. The Centers for Disease Control and Prevention
suggest a lower dose for prevention of 125 mg acetazolamide every 12 hours. The CDC advises that Dexamethasone
be reserved for treatment of AMS and HACE during descents, and notes that Nifedipine
may prevent HAPE.
A single randomized controlled trial
found that sumatriptan
may help prevent altitude sickness. Despite their popularity, antioxidant
treatments have not been found to be effective medications for prevention of AMS. Interest in phosphodiesterase inhibitors such as sildenafil
has been limited by the possibility that these drugs might worsen the headache of mountain sickness.
A promising possible preventative treatment for altitude sickness is myo-inositol trispyrophosphate (ITPP), which increases the amount of oxygen released by hemoglobin.
For centuries, indigenous peoples of the Americas
such as the Aymaras of the Altiplano
, have chewed coca
leaves to try to alleviate the symptoms of mild altitude sickness. In Chinese and Tibetan traditional medicine, extract of root tissue of Radix rhodiola is often taken in order to prevent the same symptoms.
related effects of altitude sickness. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms. At 3,400 meters (11,155 feet = 67 kPa), raising the oxygen concentration level by 5 percent via an oxygen concentrator
and an existing ventilation system provides an effective altitude of
3,000 metres (10,000 feet = 70 kPa), which is more tolerable for surface-dwellers.
.
Oxygen from gas bottles or liquid containers can be applied directly via a nasal cannula or mask. Oxygen concentrators based upon pressure swing adsorption
(PSA), VSA, or vacuum-pressure swing adsorption (VPSA) can be used to generate the oxygen if electricity is available. Stationary oxygen concentrators typically use PSA technology, which has performance degradations at the lower barometric pressures at high altitudes. One way to compensate for the performance degradation is to utilize a concentrator with more flow capacity. There are also portable oxygen concentrators that can be used on vehicular DC power or on internal batteries, and at least one system commercially available measures and compensates for the altitude effect on its performance up to 4,000 meters (13,000 ft). The application of high-purity oxygen from one of these methods increases the partial pressure of oxygen by raising the FiO2
(fraction of inspired oxygen).
Effects of high altitude on humans
The effects of high altitude on humans are considerable. The percentage saturation of hemoglobin with oxygen determines the content of oxygen in our blood. After the human body reaches around 2,100 m above sea level, the saturation of oxyhemoglobin begins to plummet...
, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,400 metres (8,000 feet).
It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover". It is hard to determine who will be affected by altitude sickness, as there are no specific factors that correlate with a susceptibility to altitude sickness. However, most people can climb up to 2,400 meters (8,000 ft) without difficulty.
Acute mountain sickness can progress to high altitude pulmonary edema
High Altitude Pulmonary Edema
High altitude pulmonary edema is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes typically above ....
(HAPE) or high altitude cerebral edema
High altitude cerebral edema
High altitude cerebral edema is a severe form of altitude sickness. HACE is the result of swelling of brain tissue from fluid leakage and almost always begins as acute mountain sickness...
(HACE), which are potentially fatal.
Chronic mountain sickness
Chronic mountain sickness
Chronic mountain sickness is a disease that can develop during extended time living at altitude. It is also known as 'Monge’s disease' , after its first description in 1925 by Carlos Monge. While acute mountain sickness is experienced shortly after ascent to high altitude, chronic mountain...
, also known as Monge's disease, is a different condition that only occurs after very prolonged exposure to high altitude.
Causes
The percentage of oxygen in air, at 21%, remains almost unchanged up to 70000 feet (21,336 m). The RMS velocitiesRoot mean square speed
Root-mean-square speed is the measure of the speed of particles in a gas that is most convenient for problem solving within the kinetic theory of gases. It is defined as the square root of the average velocity-squared of the molecules in a gas...
of diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen. However, it is the air density itself, the number of molecules (of both oxygen and nitrogen) per given volume, which drops as altitude increases. Consequently, the available amount of oxygen to sustain mental and physical alertness decreases above 10000 feet (3,048 m). Although the cabin altitude in modern passenger aircraft is kept to 8000 feet (2,438.4 m) or lower, some passengers on long-haul flights may experience some symptoms of altitude sickness.
Dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
due to the higher rate of water vapor lost from the lungs at higher altitudes may contribute to the symptoms of altitude sickness.
The rate of ascent, altitude attained, amount of physical activity at high altitude, as well as individual susceptibility, are contributing factors to the onset and severity of high-altitude illness.
Altitude sickness usually occurs following a rapid ascent and can usually be prevented by ascending slowly. In most of these cases, the symptoms are temporary and usually abate as altitude acclimatisation occurs. However, in extreme cases, altitude sickness can be fatal.
The word "soroche" came from South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and originally meant "ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
", because of an old, incorrect belief that it was caused by toxic emanations of ores in the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
mountains.
Signs and symptoms
The Lake Louise assessment system of AMS is based on a self-report questionnaire as well as a quick clinical assessment.
Those individuals with the lowest initial partial pressure of end-tidal pCO2 (the lowest concentration of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
at the end of the respiratory cycle) as a measure of a higher alveolar ventilation, as well as individuals with a corresponding high oxygen saturation levels tend to have a lower incidence of Acute Mountain Sickness than those with high end-tidal pCO2 and low oxygen saturation levels.
Primary symptoms
HeadacheHeadache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
s are the primary symptom used to diagnose altitude sickness, although a headache is also a symptom of dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...
. A headache occurring at an altitude above 2,400 metres (8,000 feet = 76 kPa), combined with any one or more of the following symptoms, may indicate altitude sickness:
- Lack of appetite, nauseaNauseaNausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, or vomiting - FatigueFatigue (physical)Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
or weakness - DizzinessDizzinessDizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
or lightheadednessLightheadednessLight-headedness is a common and often unpleasant sensation of dizziness and/or feeling that one may be about to faint, which may be transient, recurrent, or occasionally chronic. In some cases, the individual may feel as though his or her head is weightless. The individual may also feel as... - InsomniaInsomniaInsomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
- Pins and needlesParesthesiaParesthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
- Shortness of breath upon exertion
- Nosebleed
- Persistent rapid pulse
- Drowsiness
- General malaiseMalaiseMalaise is a feeling of general discomfort or uneasiness, of being "out of sorts", often the first indication of an infection or other disease. Malaise is often defined in medicinal research as a "general feeling of being unwell"...
- Peripheral edemaPeripheral edemaPeripheral edema is the swelling of tissues, usually in the lower limbs, due to the accumulation of fluids.The condition is commonly associated with aging, but can be caused by many other conditions, including congestive heart failure, trauma, alcoholism, altitude sickness, pregnancy,...
(swelling of hands, feet, and face). - Diarrhea
Severe symptoms
Symptoms that may indicate life-threatening altitude sickness include:Pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
(fluid in the lungs):
- Symptoms similar to bronchitis
- Persistent dry cough
- Fever
- Shortness of breath even when resting
Cerebral edema
Cerebral edema
Cerebral edema or cerebral œdema is an excess accumulation of water in the intracellular or extracellular spaces of the brain.-Vasogenic:Due to a breakdown of tight endothelial junctions which make up the blood-brain barrier...
(swelling of the brain):
- Headache that does not respond to analgesics
- Unsteady gait
- Gradual loss of consciousness
- Increased nausea
- Retinal hemorrhage
The most serious symptoms of altitude sickness arise from edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
(fluid accumulation in the tissues of the body). At very high altitude, humans can get either high altitude pulmonary edema
High Altitude Pulmonary Edema
High altitude pulmonary edema is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes typically above ....
(HAPE), or high altitude cerebral edema
High altitude cerebral edema
High altitude cerebral edema is a severe form of altitude sickness. HACE is the result of swelling of brain tissue from fluid leakage and almost always begins as acute mountain sickness...
(HACE). The physiological cause of altitude-induced edema is not conclusively established. It is currently believed, however, that HACE is caused by local vasodilation of cerebral blood vessels in response to hypoxia, resulting in greater blood flow and, consequently, greater capillary pressures. On the other hand, HAPE may be due to general vasoconstriction in the pulmonary circulation (normally a response to regional ventilation-perfusion mismatches) which, with constant or increased cardiac output, also leads to increases in capillary pressures. For those suffering HACE, dexamethasone
Dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
may provide temporary relief from symptoms in order to keep descending under their own power.
HAPE can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
at rest, and cough that is initially dry but may progress to produce pink, frothy sputum
Sputum
Sputum is mucus that is coughed up from the lower airways. It is usually used for microbiological investigations of respiratory infections....
. Descent to lower altitudes alleviates the symptoms of HAPE.
HACE is a life threatening condition that can lead to coma or death. Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE.
Prevention
Ascending slowly is the best way to avoid altitude sickness. Avoiding strenuous activity such as skiing, hiking, etc. in the first 24 hours at high altitude reduces the symptoms of AMS. As alcohol tends to cause dehydration, which exacerbates AMS, avoiding alcohol consumption in the first 24-hours at a higher altitude is optimal.Altitude acclimatization
Altitude acclimatization is the process of adjusting to decreasing oxygenOxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
levels at higher elevations, in order to avoid altitude sickness. Once above approximately 3,000 metres (10,000 feet = 70 kPa), most climbers and high-altitude trekkers take the "climb-high, sleep-low" approach. For high-altitude climbers, a typical acclimatization regimen might be to stay a few days at a base camp, climb up to a higher camp (slowly), and then return to base camp. A subsequent climb to the higher camp then includes an overnight stay. This process is then repeated a few times, each time extending the time spent at higher altitudes to let the body adjust to the oxygen level there, a process that involves the production of additional red blood cells . Once the climber has acclimatised to a given altitude, the process is repeated with camps placed at progressively higher elevations. The general rule of thumb is to not ascend more than 300 metres (1,000 ft) per day to sleep. That is, one can climb from 3,000 (10,000 feet = 70 kPa) to 4,500 metres(15,000 feet = 58 kPa) in one day, but one should then descend back to 3,300 metres (11,000 feet = 67.5 kPa) to sleep. This process cannot safely be rushed, and this is why climbers need to spend days (or even weeks at times) acclimatising before attempting to climb a high peak. Simulated altitude equipment that produces hypoxic (reduced oxygen) air can be used to acclimate to high altitude, reducing the total time required on the mountain itself .
Altitude acclimatization is necessary for some people who move rapidly from lower altitudes to intermediate altitudes, e.g. by aircraft and ground transportation over a few hours, such as from sea level to 8000 feet (2,438.4 m) of many Colorado, USA mountain resorts. Stopping at an intermediate altitude overnight can reduce or eliminate an occurrence of AMS.
Medical treatment
The drug acetazolamideAcetazolamide
Acetazolamide, sold under the trade name Diamox, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, Idiopathic intracranial hypertension , altitude sickness, cystinuria, and dural ectasia...
may help some people making a rapid ascent to sleeping altitude above 2750 metres, and it may also be effective if started early in the course of AMS. The Everest Base Camp
Everest Base Camp
There are two base camps on opposite sides of Mount Everest. South Base Camp is in Nepal at an altitude of , and North Base Camp is in Tibet at ). These camps are rudimentary campsites on Mount Everest that are used by mountain climbers during their ascent and descent...
Medical Centre cautions against its routine use as a substitute for a reasonable ascent schedule, except where rapid ascent is forced by flying into high altitude locations or due to terrain considerations. The Centre suggests a dosage of 125–250 mg twice daily for prophylaxis, starting from 24 hours before ascending until a few days at the highest altitude or on descending; with 250 mg twice daily recommended for treatment of AMS. The Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
suggest a lower dose for prevention of 125 mg acetazolamide every 12 hours. The CDC advises that Dexamethasone
Dexamethasone
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs. It acts as an anti-inflammatory and immunosuppressant...
be reserved for treatment of AMS and HACE during descents, and notes that Nifedipine
Nifedipine
Nifedipine is a dihydropyridine calcium channel blocker...
may prevent HAPE.
A single randomized controlled trial
Randomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
found that sumatriptan
Sumatriptan
Sumatriptan is a triptan sulfa drug containing a sulfonamide group. It is used for the treatment of migraine headaches. Sumatriptan is produced and marketed by various drug manufacturers with many different trade names such as Sumatriptan, Imitrex, Imigran, Imigran recovery.-Approval and...
may help prevent altitude sickness. Despite their popularity, antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
treatments have not been found to be effective medications for prevention of AMS. Interest in phosphodiesterase inhibitors such as sildenafil
Sildenafil
Sildenafil citrate, sold as Viagra, Revatio and under various other trade names, is a drug used to treat erectile dysfunction and pulmonary arterial hypertension . It was originally developed by British scientists and then brought to market by the US-based pharmaceutical company Pfizer...
has been limited by the possibility that these drugs might worsen the headache of mountain sickness.
A promising possible preventative treatment for altitude sickness is myo-inositol trispyrophosphate (ITPP), which increases the amount of oxygen released by hemoglobin.
For centuries, indigenous peoples of the Americas
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
such as the Aymaras of the Altiplano
Altiplano
The Altiplano , in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet...
, have chewed coca
Coca
Coca, Erythroxylum coca, is a plant in the family Erythroxylaceae, native to western South America. The plant plays a significant role in many traditional Andean cultures...
leaves to try to alleviate the symptoms of mild altitude sickness. In Chinese and Tibetan traditional medicine, extract of root tissue of Radix rhodiola is often taken in order to prevent the same symptoms.
Oxygen enrichment
In high-altitude conditions, oxygen enrichment can counteract the hypoxiaHypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
related effects of altitude sickness. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms. At 3,400 meters (11,155 feet = 67 kPa), raising the oxygen concentration level by 5 percent via an oxygen concentrator
Oxygen concentrator
An oxygen concentrator is a device providing oxygen therapy to a patient at minimally to substantially higher concentrations than available in ambient air. They are used as a safer, less expensive, and more convenient alternative to tanks of compressed oxygen. Common models retail at around US$800...
and an existing ventilation system provides an effective altitude of
3,000 metres (10,000 feet = 70 kPa), which is more tolerable for surface-dwellers.
Other methods
Drinking plenty of water will also help in acclimatisation to replace the fluids lost through heavier breathing in the thin, dry air found at altitude, although consuming excessive quantities ("over-hydration") has no benefits and may cause dangerous hyponatremiaHyponatremia
Hyponatremia is an electrolyte disturbance in which the sodium concentration in the serum is lower than normal. In the vast majority of cases, hyponatremia occurs as a result of excess body water diluting the serum sodium and is not due to sodium deficiency. Sodium is the dominant extracellular...
.
Oxygen from gas bottles or liquid containers can be applied directly via a nasal cannula or mask. Oxygen concentrators based upon pressure swing adsorption
Pressure swing adsorption
Pressure swing adsorption is a technology used to separate some gas species from a mixture of gases under pressure according to the species' molecular characteristics and affinity for an adsorbent material. It operates at near-ambient temperatures and so differs from cryogenic distillation...
(PSA), VSA, or vacuum-pressure swing adsorption (VPSA) can be used to generate the oxygen if electricity is available. Stationary oxygen concentrators typically use PSA technology, which has performance degradations at the lower barometric pressures at high altitudes. One way to compensate for the performance degradation is to utilize a concentrator with more flow capacity. There are also portable oxygen concentrators that can be used on vehicular DC power or on internal batteries, and at least one system commercially available measures and compensates for the altitude effect on its performance up to 4,000 meters (13,000 ft). The application of high-purity oxygen from one of these methods increases the partial pressure of oxygen by raising the FiO2
FiO2
FiO2, in the field of medicine, is the fraction of inspired oxygen in a gas mixture.The FiO2 is expressed as a number from 0 to 1 .The FiO2 of normal room air is 0.21 ....
(fraction of inspired oxygen).
Treatment
The only reliable treatment and in many cases the only option available is to descend. Attempts to treat or stabilise the patient in situ at altitude is dangerous unless highly controlled and with good medical facilities. However, the following treatments have been used when the patient's location and circumstances permit:- Oxygen may be used for mild to moderate AMS below 12000 feet (3,657.6 m) and is commonly provided by physicians at mountain resorts. Symptoms abate in 12–36 hours without the need to descend.
- For more serious cases of AMS, or where rapid descent is impractical, a Gamow bagGamow bagA Gamow bag is an inflatable pressure bag large enough to accommodate a person inside. By inflating the bag with a foot pump, the effective altitude can be decreased by 1000 to as much as 3000 meters . It is primarily used for treating severe cases of altitude sickness.The gamow bag was named after...
, a portable plastic hyperbaric chamber inflated with a foot pump, can be used to reduce the effective altitude by as much as 1,500 meters (5,000 ft). A Gamow bag is generally used only as an aid to evacuate severe AMS patients, not to treat them at altitude. - AcetazolamideAcetazolamideAcetazolamide, sold under the trade name Diamox, is a carbonic anhydrase inhibitor that is used to treat glaucoma, epileptic seizures, Idiopathic intracranial hypertension , altitude sickness, cystinuria, and dural ectasia...
may assist in altitude aclimatisation but is not a reliable treatment for established cases of even mild altitude sickness. - Some claim that mild altitude sickness can be controlled by consciously taking 10-12 large, rapid breaths every 5 minutes, (hyperventilationHyperventilationHyperventilation or overbreathing is the state of breathing faster or deeper than normal, causing excessive expulsion of circulating carbon dioxide. It can result from a psychological state such as a panic attack, from a physiological condition such as metabolic acidosis, can be brought about by...
) but this claim lacks both empirical evidence and a plausible medical reason as to why this should be effective. If overdone, this can remove too much carbon dioxide causing hypocapniaHypocapniaHypocapnia or hypocapnea also known as hypocarbia, sometimes incorrectly called acapnia, is a state of reduced carbon dioxide in the blood. Hypocapnia usually results from deep or rapid breathing, known as hyperventilation....
. - The folk remedy for altitude sickness in EcuadorEcuadorEcuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, PeruPeruPeru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
and BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
is a tea made from the coca plant. See mate de cocaCoca teaCoca tea, also called mate de coca, is a tisane made using the leaves of the coca plant; typically the raw leaves of the plant. It is made either by submerging the coca leaf or dipping a tea bag in hot water...
. - Other treatments include injectable steroids to reduce pulmonary edema, this may buy time to descend but treats a symptom, it does not treat the underlying AMS.
See also
- Altitude trainingAltitude trainingAltitude training is the practice by some endurance athletes of training for several weeks at high altitude, preferably over above sea level, though more commonly at intermediate altitudes due to the shortage of suitable high-altitude locations...
- Cabin pressurizationCabin pressurizationCabin pressurization is the pumping of compressed air into an aircraft cabin to maintain a safe and comfortable environment for crew and passengers when flying at altitude.-Need for cabin pressurization:...
- High altitude cerebral edemaHigh altitude cerebral edemaHigh altitude cerebral edema is a severe form of altitude sickness. HACE is the result of swelling of brain tissue from fluid leakage and almost always begins as acute mountain sickness...
- High altitude pulmonary edemaHigh Altitude Pulmonary EdemaHigh altitude pulmonary edema is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes typically above ....
- Mountain climbing
- Secondary polycythemiaPolycythemiaPolycythemia is a disease state in which the proportion of blood volume that is occupied by red blood cells increases...
External links
- Altitude.org: what every climber should know about altitude sickness.
- An online calculator to show the effects of high altitude on oxygen delivery
- Travel at High Altitude: a free booklet about how to keep healthy at altitude. Available in many languages.
- Merck Manual entry on altitude sickness
- Base Camp MD: Guide To High Altitude Medicine
- Altitude Illness Clinical Guide for Physicians
- General information about Altitude sickness by the Prince Leopold Institute of Tropical Medicine
- Find the altitude for any place to see if altitude sickness is a factor