Altitude sickness, the mildest form being acute mountain sickness (AMS), is the harmful
effect of high altitude, caused by rapid exposure to low
amounts of oxygen at
high elevation.
People can respond to high altitude in different ways. Symptoms may include headache
Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.
Headaches can occur as a result ...
s, vomiting, tiredness, confusion, trouble sleeping, and dizziness
Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness.
Dizziness is a common medical c ...
.[ Acute mountain sickness can progress to ]high-altitude pulmonary edema
High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above . However, cases have also been reported between in more vulnerable subjects.
...
(HAPE) with associated shortness of breath
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing disc ...
or high-altitude cerebral edema
High-altitude cerebral edema (HACE) is a medical condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves dis ...
(HACE) with associated confusion.[ ]Chronic mountain sickness
Chronic mountain sickness (CMS) is a disease in which the proportion of blood volume that is occupied by red blood cells increases (polycythaemia) and there is an abnormally low level of oxygen in the blood (hypoxemia). CMS typically develops after ...
may occur after long-term exposure to high altitude.[
Altitude sickness typically occurs only above , though some are affected at lower altitudes.][ Risk factors include a prior episode of altitude sickness, a high degree of activity, and a rapid increase in elevation.][ Diagnosis is based on symptoms and is supported in those who have more than a minor reduction in activities.] It is recommended that at high altitude any symptoms of headache, nausea, shortness of breath, or vomiting be assumed to be altitude sickness.
Prevention is by gradually increasing elevation by no more than per day.[ Being physically fit does not decrease the risk.][ Treatment is generally by descending and sufficient fluids.][ Mild cases may be helped by ibuprofen, ]acetazolamide
Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, altitude sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), urine alkalin ...
, or dexamethasone
Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...
.[ Severe cases may benefit from ]oxygen therapy
Oxygen therapy, also known as supplemental oxygen, is the use of oxygen as medical treatment. Acute indications for therapy include hypoxemia (low blood oxygen levels), carbon monoxide toxicity and cluster headache. It may also be prophylactica ...
and a portable hyperbaric bag
A portable hyperbaric bag, of which one brand is the Gamow () bag, is an inflatable pressure bag large enough to accommodate a person. The patient can be placed inside the bag, which is then sealed and inflated with a foot pump. Within minutes, th ...
may be used if descent is not possible. Treatment efforts, however, have not been well studied.
AMS occurs in about 20% of people after rapidly going to and 40% of people going to .[ While AMS and HACE occurs equally frequently in males and females, HAPE occurs more often in males.][ The earliest description of altitude sickness is attributed to a Chinese text from around 30 BCE which describes "Big Headache Mountains", possibly referring to the ]Karakoram Mountains
The Karakoram is a mountain range in Kashmir region spanning the borders of Pakistan, China, and India, with the northwest extremity of the range extending to Afghanistan and Tajikistan. Most of the Karakoram mountain range falls under t ...
around Kilik Pass
The Kilik Pass (elevation ; ; ur, کلوک پاس) to the west of Mintaka Pass is a high mountain pass in the Karakorum Mountains between Gilgit-Baltistan in Pakistan and Xinjiang in China. The two passes were, in ancient times, the two mai ...
.
Signs and symptoms
People have different susceptibilities to altitude sickness; for some otherwise healthy people, acute altitude sickness can begin to appear at around above sea level, such as at many mountain ski resorts, equivalent to a pressure of . This is the most frequent type of altitude sickness encountered. Symptoms often manifest within ten hours of ascent and generally subside within two days, though they occasionally develop into the more serious conditions. Symptoms include headache, confusion, fatigue, stomach illness, dizziness, and sleep disturbance. Exertion may aggravate the symptoms.
Those individuals with the lowest initial partial pressure of end-tidal pCO2 (the lowest concentration of carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
at the end of the respiratory cycle, a measure of a higher alveolar ventilation) and 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
Headache
Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.
Headaches can occur as a result ...
s are the primary symptom used to diagnose altitude sickness, although a headache is also a symptom of dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
. A headache occurring at an altitude above a pressure of combined with any one or more of the following symptoms, may indicate altitude sickness:
Severe symptoms
Symptoms that may indicate life-threatening altitude sickness include:
; Pulmonary edema
Pulmonary edema, also known as pulmonary congestion, is excessive edema, liquid accumulation in the parenchyma, tissue and pulmonary alveolus, air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia an ...
(fluid in the lungs)
: Symptoms similar to bronchitis
Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...
: Persistent dry cough
: Fever
: Shortness of breath even when resting
; Cerebral edema
Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compressio ...
(swelling of the brain)
: Headache that does not respond to analgesics
: Unsteady gait
: Gradual loss of consciousness
: Increased nausea and vomiting
: Retinal hemorrhage
The most serious symptoms of altitude sickness arise from edema
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...
(fluid accumulation in the tissues of the body). At very high altitude, humans can get either high-altitude pulmonary edema
High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above . However, cases have also been reported between in more vulnerable subjects.
...
(HAPE), or high-altitude cerebral edema
High-altitude cerebral edema (HACE) is a medical condition in which the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves dis ...
(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 with HACE, dexamethasone
Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...
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
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathing, breathe well enough. The American Thoracic Society defines it as "a subjective experience of brea ...
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 affected by HACE.
Cause
Altitude sickness can first occur at , with the effects becoming severe at extreme altitudes (greater than ). Only brief trips above are possible and supplemental oxygen is needed to avert sickness.
As altitude increases, the available amount of oxygen to sustain mental and physical alertness decreases with the overall air pressure, though the relative percentage of oxygen in air, at about 21%, remains practically unchanged up to . The RMS velocities of diatomic nitrogen and oxygen are very similar and thus no change occurs in the ratio of oxygen to nitrogen until stratospheric heights.
Dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
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 acclimatization occurs. However, in extreme cases, altitude sickness can be fatal.
High altitude illness can be classified according to the altitude: high (), very high () and extreme (above ).]
High altitude
At high altitude, , the onset of physiological effects of diminished inspiratory oxygen pressure (PiO2) includes decreased exercise performance and increased ventilation (lower arterial partial pressure of carbon dioxide: PCO2). While arterial oxygen transport may be only slightly impaired the arterial oxygen saturation (SaO2) generally stays above 90%. Altitude sickness is common between because of the large number of people who ascend rapidly to these altitudes.
Very high altitude
At very high altitude, , maximum SaO2 falls below 90% as the arterial PO2 falls below 60mmHg. Extreme hypoxemia
Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the body ...
may occur during exercise, during sleep, and in the presence of high altitude pulmonary edema or other acute lung conditions. Severe altitude illness occurs most commonly in this range.
Extreme altitude
Above , marked hypoxemia, hypocapnia
Hypocapnia (from the Greek words υπό meaning ''below normal'' and καπνός ''kapnós'' meaning ''smoke''), also known as hypocarbia, sometimes incorrectly called acapnia, is a state of reduced carbon dioxide in the blood. Hypocapnia usually ...
, and alkalosis
Alkalosis is the result of a process reducing hydrogen ion concentration of arterial blood plasma (alkalemia). In contrast to acidemia (serum pH 7.35 or lower), alkalemia occurs when the serum pH is higher than normal (7.45 or higher). Alkalosis ...
are characteristic of extreme altitudes. Progressive deterioration of physiologic function eventually outstrips acclimatization. As a result, no permanent human habitation occurs above . A period of acclimatization is necessary when ascending to extreme altitude; abrupt ascent without supplemental oxygen for other than brief exposures invites severe altitude sickness.
Mechanism
The physiology of altitude sickness centres around the alveolar gas equation The alveolar gas equation is the method for calculating partial pressure of alveolar oxygen (PAO2). The equation is used in assessing if the lungs are properly transferring oxygen into the blood. The alveolar air equation is not widely used in cl ...
; the atmospheric pressure is low, but there is still 20.9% oxygen. Water vapour still occupies the same pressure too—this means that there is less oxygen pressure available in the lungs and blood. Compare these two equations comparing the amount of oxygen in blood at altitude:
The hypoxia leads to an increase in minute ventilation (hence both low , and subsequently bicarbonate), Hb increases through haemoconcentration and erythrogenesis. Alkalosis shifts the haemoglobin dissociation constant to the left, 2,3-BPG increases to counter this. Cardiac output increases through an increase in heart rate.
The body's response to high altitude includes the following:
* ↑ Erythropoietin → ↑ hematocrit and haemoglobin
* ↑ 2,3-BPG (allows ↑ release of and a right shift on the Hb- disassociation curve)
* ↑ kidney excretion of bicarbonate (use of acetazolamide can augment for treatment)
* Chronic hypoxic pulmonary vasoconstriction (can cause right ventricular hypertrophy)
People with high-altitude sickness generally have reduced hyperventilator response, impaired gas exchange, fluid retention or increased sympathetic drive. There is thought to be an increase in cerebral venous volume because of an increase in cerebral blood flow and hypocapnic cerebral vasoconstriction causing oedema.
Diagnosis
Altitude sickness is typically self-diagnosed since symptoms are consistent: nausea, vomiting, headache, and can generally be deduced from a rapid change in altitude or oxygen levels. However, some symptoms may be confused with dehydration
In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...
. Some severe cases may require professional diagnosis which can be assisted with multiple different methods such as using an MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
or CT scan to check for abnormal buildup of fluids in the lung or brain.
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 may reduce the symptoms of AMS. Alcohol and sleeping pills are respiratory depressants, and thus slow down the acclimatization process and should be avoided. Alcohol also tends to cause dehydration and exacerbates AMS. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.
]
Pre-acclimatization
Pre-acclimatization is when the body develops tolerance to low oxygen concentrations before ascending to an altitude. It significantly reduces risk because less time has to be spent at altitude to acclimatize in the traditional way. Additionally, because less time has to be spent on the mountain, less food and supplies have to be taken up. Several commercial systems exist that use altitude tent
An altitude tent is a sealed tent used to simulate a higher altitude with reduced oxygen. Living or training at altitude causes the body to adapt to the lower oxygen content by producing more oxygen-carrying red blood cells and hemoglobin, thu ...
s, so called because they mimic altitude by reducing the percentage of oxygen in the air while keeping air pressure constant to the surroundings. Examples of pre-acclimation measures include remote ischaemic preconditioning, using hypobaric
A hypobaric chamber, or altitude chamber, is a chamber used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body, especially hypoxia (low oxygen) and hypobaria (low ambien ...
air breathing in order to simulate altitude, and positive end-expiratory pressure.
Altitude acclimatization
Altitude acclimatization is the process of adjusting to decreasing oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
levels at higher elevations, in order to avoid altitude sickness. Once above approximately a pressure of 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
Mountaineering or alpinism, is a set of outdoor activities that involves ascending tall mountains. Mountaineering-related activities include traditional outdoor climbing, skiing, and traversing via ferratas. Indoor climbing, sport climbing, an ...
, 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
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...
. Once the climber has acclimatized to a given altitude, the process is repeated with camps placed at progressively higher elevations. The rule of thumb is to ascend no more than per day to sleep. That is, one can climb from () to () in one day, but one should then descend back to () to sleep. This process cannot safely be rushed, and this is why climbers need to spend days (or even weeks at times) acclimatizing before attempting to climb a high peak. Simulated altitude equipment such as altitude tent
An altitude tent is a sealed tent used to simulate a higher altitude with reduced oxygen. Living or training at altitude causes the body to adapt to the lower oxygen content by producing more oxygen-carrying red blood cells and hemoglobin, thu ...
s provide hypoxic (reduced oxygen) air, and are designed to allow partial pre-acclimation 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 higher altitudes.
Medications
The drug acetazolamide
Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, altitude sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), urine alkalin ...
(trade name Diamox) may help some people making a rapid ascent to sleeping altitude above , and it may also be effective if started early in the course of AMS. Acetazolamide can be taken before symptoms appear as a preventive measure at a dose of 125 mg twice daily. The Everest Base Camp
There are two base camps on Mount Everest, on opposite sides of the mountains: South Base Camp is in Nepal at an altitude of (), while North Base Camp is in Tibet, China at ().
The base camps are rudimentary campsites at the base of Mount Eve ...
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 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
The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
(CDC) suggest the same dose for prevention of 125 mg acetazolamide every 12 hours. Acetazolamide, a mild diuretic, works by stimulating the kidneys to secrete more bicarbonate in the urine, thereby acidifying the blood. This change in pH stimulates the respiratory center to increase the depth and frequency of respiration, thus speeding the natural acclimatization process. An undesirable side-effect of acetazolamide is a reduction in aerobic endurance performance. Other minor side effects include a tingle-sensation in hands and feet. Although a sulfonamide
In organic chemistry, the sulfonamide functional group (also spelled sulphonamide) is an organosulfur group with the structure . It consists of a sulfonyl group () connected to an amine group (). Relatively speaking this group is unreactive. ...
; acetazolamide is a non-antibiotic and has not been shown to cause life-threatening allergic cross-reactivity in those with a self-reported sulfonamide allergy. Dosage of 1000 mg/day will produce a 25% decrease in performance, on top of the reduction due to high-altitude exposure. The CDC advises that Dexamethasone
Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena cav ...
be reserved for treatment of severe AMS and HACE during descents, and notes that Nifedipine
Nifedipine (3,5-dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate), sold under the brand name Adalat and Procardia, among others, is a calcium channel blocker medication used to manage angina, high blood pressure, Ra ...
may prevent HAPE.
There is insufficient evidence to determine the safety of sumatriptan
Sumatriptan, sold commonly under brand names Imitrex and Treximet among others, is a medication used to treat migraine headaches and cluster headaches. It is taken orally, intranasally, or by subcutaneous injection. Therapeutic effects gen ...
and if it may help prevent altitude sickness. Despite their popularity, antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
treatments have not been found to be effective medications for prevention of AMS. Interest in phosphodiesterase inhibitors such as sildenafil
Sildenafil, sold under the brand name Viagra, among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. It is unclear if it is effective for treating sexual dysfunction in women. It is taken by ...
has been limited by the possibility that these drugs might worsen the headache of mountain sickness. A promising possible preventive for altitude sickness is myo-inositol trispyrophosphate
Myo-inositol trispyrophosphate (ITPP) is an inositol phosphate, a pyrophosphate, a drug candidate, and a putative performance-enhancing substance, which exerts its biological effects by increasing tissue oxygenation.
Chemistry
ITPP is a pyrophosp ...
(ITPP), which increases the amount of oxygen released by hemoglobin.
Prior to the onset of altitude sickness, ibuprofen is a suggested non-steroidal anti-inflammatory and painkiller that can help alleviate both the headache and nausea associated with AMS. It has not been studied for the prevention of cerebral edema
Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compressio ...
(swelling of the brain) associated with extreme symptoms of AMS.
Over-the-counter herbal supplements and traditional medicines
Herbal supplements and traditional medicines are sometimes suggested to prevent high altitude sickness including ginkgo biloba
''Ginkgo biloba'', commonly known as ginkgo or gingko ( ), also known as the maidenhair tree, is a species of tree native to China. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossils ...
, ''R crenulata'', minerals such as iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
, antacid
An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alumi ...
s, and hormonal
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required fo ...
-based supplements such as medroxyprogesterone
Medroxyprogesterone (MP), is a progestin which is not used medically. A derivative, medroxyprogesterone acetate (MPA), is used as a medication in humans, and is far more widely known in comparison. ''Medroxyprogesterone'' is sometimes used as a ...
and erythropoietin
Erythropoietin (; EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bo ...
. Medical evidence to support the effectiveness and safety of these approaches is often contradictory or lacking. Indigenous peoples of the Americas
The Indigenous peoples of the Americas are the inhabitants of the Americas before the arrival of the European settlers in the 15th century, and the ethnic groups who now identify themselves with those peoples.
Many Indigenous peoples of the A ...
, such as the Aymaras of the Altiplano
The Altiplano (Spanish for "high plain"), Collao (Quechua and Aymara: Qullaw, meaning "place of the Qulla") or Andean Plateau, in west-central South America, is the most extensive high plateau on Earth outside Tibet. The plateau is located at the ...
, have for centuries chewed coca
Coca is any of the four cultivated plants in the family Erythroxylaceae, native to western South America. Coca is known worldwide for its psychoactive alkaloid, cocaine.
The plant is grown as a cash crop in the Argentine Northwest, Bolivia, Al ...
leaves to try to alleviate the symptoms of mild altitude sickness. This therapy has not yet been proven effective in a clinical study. In Chinese and Tibetan traditional medicine, an extract of the root tissue of '' Radix rhodiola'' is often taken in order to prevent the symptoms of high altitude sickness, however, no clear medical studies have confirmed the effectiveness or safety of this extract.
Oxygen enrichment
In high-altitude conditions, oxygen enrichment can counteract the hypoxia related effects of altitude sickness. A small amount of supplemental oxygen reduces the equivalent altitude in climate-controlled rooms. At (), raising the oxygen concentration level by 5% via an oxygen concentrator
An oxygen concentrator is a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched product gas stream. They are used industrially and as medical devices for oxy ...
and an existing ventilation system provides an effective altitude of (), which is more tolerable for those unaccustomed to high altitudes.
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 (PSA) is a technique used to separate some gas species from a mixture of gases (typically air) under pressure according to the species' molecular characteristics and affinity for an adsorbent material. It operates at nea ...
(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 use 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 . 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).
Other methods
Increased water intake may also help in acclimatization 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 hyponatremia
Hyponatremia or hyponatraemia is a low concentration of sodium in the blood. It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. Symptoms can be abs ...
.
Treatment
The only reliable treatment, and in many cases the only option available, is to descend. Attempts to treat or stabilize the patient ''in situ'' (at altitude) are 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 and is commonly provided by physicians at mountain resorts. Symptoms abate in 12 to 36 hours without the need to descend.
* For more serious cases of AMS, or where rapid descent is impractical, a Gamow bag
A portable hyperbaric bag, of which one brand is the Gamow () bag, is an inflatable pressure bag large enough to accommodate a person. The patient can be placed inside the bag, which is then sealed and inflated with a foot pump. Within minutes, th ...
, a portable plastic hyperbaric chamber
A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of ...
inflated with a foot pump, can be used to reduce the effective altitude by as much as . A Gamow bag is generally used only as an aid to evacuate severe AMS patients, not to treat them at altitude.
* Acetazolamide
Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, altitude sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), urine alkalin ...
250 mg twice daily dosing assists in AMS treatment by quickening altitude acclimatization. A study by the Denali Medical Research Project concluded: "In established cases of acute mountain sickness, treatment with acetazolamide relieves symptoms, improves arterial oxygenation, and prevents further impairment of pulmonary gas exchange."
* The folk remedy for altitude sickness in Ecuador
Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
, Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = Seal (emblem), National seal
, national_motto = "Fi ...
and Bolivia
, image_flag = Bandera de Bolivia (Estado).svg
, flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center
, flag_alt2 = 7 × 7 square p ...
is a tea made from the coca plant. See mate de coca
Coca tea, also called mate de coca, is an herbal tea (infusion) made using the raw or dried leaves of the coca plant, which is native to South America. It is made either by submerging the coca leaf or dipping a tea bag in hot water. The tea is mo ...
.
* Steroids
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...
can be used to treat the symptoms of pulmonary or cerebral edema, but do not treat the underlying AMS.
* Two studies in 2012 showed that ibuprofen 600 milligrams three times daily was effective at decreasing the severity and incidence of AMS; it was not clear if HAPE or HACE was affected.
* Paracetamol (acetaminophen) has also shown to be as good as ibuprofen for altitude sickness when tested on climbers ascending Everest.
See also
*
*
*
*
* Secondary
*
References
External links
Travel at High Altitude: a free booklet about how to keep healthy at altitude. Available in many languages.
{{DEFAULTSORT:Altitude Sickness
Effects of external causes
Mountaineering and health
Skiing
Wikipedia medicine articles ready to translate
Hazards of outdoor recreation