Dr Arvind Kohli
The stresses of high altitude trek include extreme cold, low humidity, increased ultraviolet radiation and decreased air pressure all of which can cause serious health problems for the person undergoing the trek, and may develop diseases like acute mountain illness, high altitude pulmonary edema and high altitude cerebral oedema.
What causes high-altitude illness ?
The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen. In addition, for reasons not entirely understood, high altitude and lower air pressure causes fluid to leak from the capillaries which can cause fluid build-up in both the lungs and the brain. Continuing to higher altitudes without proper acclimatization can lead to potentially serious, even life-threatening illnesses.
Acute Mountain Sickness (AMS)
AMS is common at high altidues. At elevations over 10,000 feet (3,048 meters), 75% of people will have mild symptoms. Many people will experience mild AMS during the acclimatization process. Symptoms usually start 12-24 hours after arrival at altitude and begin to decrease in severity about the third day. The symptoms of Mild AMS are headache, dizziness, faitugue, shortness of breath, loss of appetitite, nausea, disturbed sleep, and a general feeling of malaise.
Basic Treatment of AMS
The only cure is either acclimatization or descent. Symptoms of Mild AMS can be treated with pain mdeications for headache and drug called Acetazolamide (Diamox) which allows you to breathe faster so that you metabolize more oxygen, thereby minimizing the symptoms caused by poor oxygenation. This is especially helpful at night when respiratory drive is decreased. Since it takes a while for Diamox to have an effect, it is advisable to start taking it 24 hours before you go to altitude and continue for at least five days at higher altitude. Possible side effects include tingling of the lips and finger tips, blurring of vision, and alteration of taste. Diamox has also been known to cause severe allergic reactions to people with no previous history of diamox or sulfa allergies.
Moderate AMS
Moderate AMS includes severe headahce that is not relieved by medication, nausea and vomitting, increasing weakness and fatigue, shortness of breath and decreased coordiantion (ataxia). Descending even a few hundred feet (70-100 meters) may help and definite improvement will be seen in descents of 1,000 – 2,000 feet (305-610 meters). Twnty four hours at the lower altitude wll result in significant improvements. The person should remain at lower altitude until symptoms have subsided (upto 3 days).
Severe AMS
Severe AMS presents as an increase in the severity of the aforementioned symptoms, including shortness of breath at rest, inability to walk, decreasing mental status, and fluid buildup in the lungs. Severe AMS requires immediate descent to lower altitudes (2,000-4,000 feet).
High Altiitude Pulmonary Edema (HAPE)
HAPE results from fluid buildup in the lungs. The fluid in the lungs prevents effective oxygen exchange. As the condition becomes more severe it can lead to cyanosis, impaired cerebral function and death. Symptoms include shortness of breath even at rest, “tighteness in the chest’’, marked fatigue, a feeling of impending suffocation at night, weakness andna persistent productive cough brinigng up whit,e watery, or frothy fluid.Confusion, and irrational behaviour are signs that insufficient oxygen is reaching the brain. In case of HAPE, immediate descent is a necessary life-saving measure (2,000-4,000 feet (610-1,220 meters). Anyone suffering from HAPE must be evacuated to a medical facility for proper follow-up treatment.
High Altitude Cerebral Edema (HACE)
HACE is the result of swelling of brain tissue from fluid leakage. Symptoms can include headache, loss of coordiantion (ataxia), weakness, and decreasing levels of consciousness including, disorientation, loss of memory, hallucinations, psychotic behaviour, and coma. It generally occurs after a week or more at high altitude. Severe instances can lead to death if not treated quickly. Immediate descent is a necessary life-saving measure. Anyone suffering from HACE must be evacuated to a medical facility for proper follow-up treatment.
Prevention
Take your time traveling to higher altitudes. When you travel to a high altitude, your body will begin adjusting right away to the lower amount of oxygen in the air, but it takes several days for your body to adjust completely. If you’re healthy, you can probably safely go from sea level to an altitude of 8,000 feet in a few days. But when you reach an altitude above 8,000 feet, don’t go up faster than 1,000 feet per day. The closer you live to sea level, the more time your body will need to get used to a high altitude.
Role of Hyperbaric Chambers
Hyperbaric chambers are now available, and are very helpful in treating severe forms of altitude illness. They all are all similar to the extent that they are air-impermeable bags that complete enclose the patient, and are inflated to a significant pressure above ambient atmospheric. This effects a physiological ‘’discent’’. This can be demonstrated with an altimeter inside the bag, and marked improvements in oxygen saturation are measurable with a pulse oximter. The extent of the descent depends on the altitude at which the bag is used; as an example, at 4250m (14,000 ft), the inside of the bag is equivalent to 2100 m (7,000 ft).
People with heart or lung disease
If you have a chronic disease, ask your doctor if it’s safe for you to travel to a high altitude. Most people who have a chronic illness, such as heart or lung disease, can safely spend time at a high altiude, if their disease is under good control. People who have coronary artery disease, mild emphysema or high blood pressure aren’t at greater risk of high-ltidue illness than people who don’t have these diseases. People who have sickle cellanemia shouldn’t go to a high altidue. A high altitude is also dangerous for people who have severe lung disease, such as chronic obstructive pulmonary disease (COPD) or severe emphysema, and for people who have severe heart disease.
Children Pregnant women
It’s usually safe for children to go to high altitudes, but they’re more likely to get high-altitude illness because their bodies have a hard time adjusting to the low oxygen level. A child may not be able to recognize the symptoms of high-altitude illness, so parents and other adults must carefully watch for any signs of high-altitude illness in children. Some experts reommend that pregnant women not travel to an altidue above 8,000 feet. If you’re pregnant ask your doctor for advice before you travel to a high altitude.
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