What is an Acute Mountain Sickness?

March 08 00:24 2019 Print This Article

It is defined as a disorder in which there is a effect of high altitude on humans due to the acute exposure to low partial pressure of oxygen at high altitude. It occurs above 24000 meter. It is also known as the altitude sickness. It is also referred as a hypo baropathy and soroche. It can progress to high altitude pulmonary edema or high altitude cerebral edema. The cause of this condition is not known. The percentage of the oxygen remains static up to 21 percent at the altitude up to 70 000 feet.

The air pressure drops at this altitude and the number of oxygen molecules also increases. So, the amount of oxygen available decreases and so is the mental and physical alertness. The cabin altitudes is at 8000 feet or lower in case of modern passenger aircraft. Most of the passengers on long flights may experience some symptoms of altitude sickness. A chronic mountain sickness is also known as the monges disease. It is a different condition in which there is a prolonged exposure to high altitude. A higher rate of water vapor lost from the lung at higher altitudes may lead to dehydration. It may lead to the altitude sickness.

What are the signs and symptoms of Acute mountain sickness?

The most common symptom of this disorder is the headache. It is used to diagnose the altitude sickness and a head ache is also seen in the case of dehydration. It can occur at an altitude above the 24 000 meters is combined with the other symptoms. It includes the lack of appetite, nausea or vomiting, fatigue along with the weakness and dizziness. There is insomnia and light headedness. One feels pins and needles with drowsiness and general malaise, the pulse is rapid and persistent. There is a malaise and peripheral edema. It involves the swelling of hand, feet and face.

The symptoms can be life threatening. It involves the pulmonary and cerebral edema. There is a fever, shortness of breath and persistent dry cough. There is a swelling of brain which may lead to the headache which do not respond to analgesics. The gait is unsteady and a increased vomiting with a loss of consciousness.

What are the severe cases of Acute mountain sickness?

It is mainly due to the edema in which there is accumulation of fluid in the tissues of body. At a high altitude the humans may experience a high altitude pulmonary edema which is also known as the HAPE. There is a high altitude cerebral edema which is also known as the HACE. The cause of altitude induced edema is not established. The HACE is caused due to the vaso dilation of blood vessels in the cerebellum which leads to hypoxia. It increases the blood flow and increases the capillary pressure.

The HAPE is caused due to the vaso constriction of blood vessels in the lungs which leads to increase in the cardiac output and also increases the capillary pressure. The individuals suffering from HACE may get relief from the dexa methasone so to keep descending under their own power. The HAPE occurs in 2 percent of the cases and those who adjust to the altitudes of about 3000 m. It progresses rapidly and is fatal. The symptoms include the fatigue, dyspnea and cough. It is initially dry but it can become pink with frothy sputum. In the lower altitudes the symptoms of HAPE increases.

The person who suffer from serious symptoms have a short period of time in which it can be corrected. In the peak of Mount Kilimanjaro 5 to 12 minutes of time is requires to have a useful consciousness at 20 000 ft. In the peak of Mount Everest 1 to 2 minutes of time is requires to have a useful consciousness at 29 000 ft.

What are the preventive methods of Acute mountain sickness?

The best way to deal with this disorder is ascend slowly. One must avoid the sternous exercise like skiing and hiking. It must be avoided in the first 24 hours. One must also avoid alcohol at the high altitudes as it can lead to the dehydration. The process of adjusting to the high altitude and low oxygen level is known as the altitude acclimatization. When the individual is above 3000 meter most of the climbers and high altitude trekkers have a climb high and sleep low approach.

For the people who are high altitude climbers an acclimatization regime must be given for few days at the base camp. They must climb at a higher camp slowly and then return to the base camp. A climb to the higher camp would lead to an overnight stay. It is repeated and each turn the time is extended than the later turn. It allows the body to adjust and involves the extra production of red blood cells. Once the climber gets acclimatized this process is repeated at the camps which are placed at higher elevations.

The common rule of the thumb is to not ascend more than 3000 meter per day to sleep. It means one can climb from 3000 to 4500 meter per day but must descend back to 3300 meter to sleep. It cannot be safely rushed and it explains the need of climbers to spend few days acclimatizing before they climb upwards. Simulated altitude equipment which gives rise to hypoxia is helpful in the acclimatization to altitude and reduces the total time needed on the mountain. The altitude acclimatization is necessary for some people who move from low to high altitudes with the help of air craft and ground transportation. It occurs within few hours from the sea level to 8000 ft.

The stop at the intermediate altitude overnight can eliminate or decrease the episode of AMS. There are certain drugs like acetazolamide which help the people to move rapidly to the sleeping altitudes above 2750 meters and can be effective if it is started early. The Everest base camp medical do not allow its routine use as a substitute for ascent schedule. It can be used where rapid ascent is forced by flying into the high altitudes or into the terrain. It also suggests a dosage of 200 mg twice daily for the prophylaxis. It starts from 24 hours and ascend until a few days at the highest altitude or it occurs on descending.

The centers for disease control and prevention have suggested a dose of 125 mg of acetazolamide every 12 hours. It also advices that the dexamethasone must be reserved for the treatment of AMS and HACEduring descents and one must note that nifedipine can prevent HAPE. A single randomized controlled trial found that the sumatriptan may prevent the altitude sickness. It is popular but the antioxidant treatments have not been much effective. There are certain phosphor di esterase inhibitors like the sildenafil which is limited by the possibility that these drugs may worsen the headache of mountain sickness.

For many centuries the indigenous culture of Altiplano like the Aymaras chewed the coca leaves to try to increase the symptoms of mild altitude sickness. At the high altitude conditions the enrichment of oxygen is counteracted by the effects of altitude sickness which is also known as the hypoxia. A small amount of supplemental oxygen decreases the equivalent altitude in the climate controlled rooms. At 34oo m raising the oxygen concentration by 5 percent by an oxygen concentrator and an exisisting ventilation system provides the effective altitude of 3000 m which is more tolerable for the surface dwellers.

There are other methods also in which drinking a lot of water helps in the acclimatization. It replaces the lost fluid due to the heavier breathing in the thin dry air found at the altitudes by consuming excessive quantities which has no benefits and may lead to hyponatremia. The oxygen from the gas bottles or liquid containers is applied directly via a nasal cannula or mask. The oxygen concentrators are based upon the pressure swing absorption which is also known as the PSA. There is a vacuum pressure swing absorption which is also known as the VPSA. It can generate oxygen if the electricity is available.

The stationary oxygen concentrators use PSA technology which performs not up to the mark at lower barometric pressures and at high altitudes. One can overcome it by the concentrator with a more flow capacity. There are portable oxygen concentrators that can be used on direct current or with the help of internal batteries. One system which is commercially available overcomes the high altitude effects up to 4000 meter. The use of high purity oxygen by any of the above methods increases the partial pressure of oxygen by increasing the fraction of inspired oxygen which is referred as a FIO2.

What is the treatment of Acute mountain sickness?

The only reliable treatment in this disorder is to descend. The attempts to treat this disorder in situ at latitude are dangerous and highly controlled. It must be with good medical facilities. But the following treatments must be used when the condition of the patient and circumstances allow. The oxygen can be used in case of mild to moderate AMS below 12000 ft. It is commonly provided by the physician at mountain resorts. The symptoms disappear within 12 to 36 hours without any further need of descent.

In the severe cases of AMS where the rapid descent is not possible one can go for the Gamow bag which is portable and hyper baric chamber which is inflated with the foot pump and can be used quite effectively at high altitudes. The Gamow bag is used to evacuate the patients but not to treat them. There are certain drugs like acetazolamide which help the people to move rapidly to the sleeping altitudes above 2750 meters and can be effective if it is started early.

The Everest base camp medical do not allow its routine use as a substitute for ascent schedule. It can be used where rapid ascent is forced by flying into the high altitudes or into the terrain. It also suggests a dosage of 200 mg twice daily for the prophylaxis. It starts from 24 hours and ascend until a few days at the highest altitude or it occurs on descending. The centers for disease control and prevention have suggested a dose of 125 mg of acetazolamide every 12 hours. A few people claim that the mild altitude sickness can be controlled by the 10 to 12 breaths which are large and rapid after every 5 minutes is known as the hyper ventilation.

This claim is not properly supported and needs a further improvement. If the hyper ventilation is done too much it may lead to the loss of carbon bi oxide resulting in hypo capnia. The common people in Ecuador, Peru and Bolivia use coca plant to treat this condition. The other treatments can be inject able steroids which reduce the pulmonary edema and increase the time to descend. It treats the symptoms but it does not treat the under lying condition.

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