ACUTE MOUNTAIN SICKNESS/ALTITUDE SICKNESS

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What is Altitude Sickness?
Symptoms associated with altitude sickness result from the body's inability to adjust to lower levels of oxygen in the blood. At sea  level, the concentration of oxygen is about 21% and the barometric  pressure averages 760 mmHg. As altitude increases, oxygen concentration  remains the same but the number of oxygen molecules per breath is  reduced due to lower barometric pressure. At 3,658 meters (12,000 feet),  barometric pressure decreases to 483 mmHg, resulting in roughly 40%  fewer oxygen molecules per breath. In order to increase oxygen levels in  the blood, your body responds by breathing faster. Although oxygen  levels increase, sea level concentrations cannot be reached. The body  must adjust to having less oxygen. This adjustment is called  acclimatization. At elevations above 5,500 meters, acclimatization is  not possible and the body begins to deteriorate.

Acclimatization
The main cause of altitude sickness is going too high too fast. Given  enough time, your body will adapt to the decrease in oxygen at a  specific altitude. This process is known as acclimatization and  generally takes one to three days at any given altitude. Upon climbing  to a higher elevation, the body must readjust to the new altitude again  over a period of one to three days.

In order to cope with decreased oxygen levels, the body reacts in the following ways:

•Respiration frequency and depth increases

•Pressure in pulmonary arteries is increased, "forcing" blood into  portions of the lung which are normally not used during sea level  breathing.

•Additional red blood cells are produced to carry oxygen

•Enzymes are produced to facilitate the transfer of oxygen from hemoglobin to body tissues. 

It is imperative that hikers be aware of symptoms of Acute Mountain  Sickness during Kilimanjaro and Meru trips and that they communicate  with the guide regularly regarding their condition. It is very important  to rest and not ascend further if experiencing severe symptoms of AMS.

Cheyne-Stokes Respiration
Above 3,000 meters (9,842 feet), most people experience a periodic  breathing during sleep known as Cheyne-Stokes Respirations. The pattern  begins with a few shallow breaths and increases to deep sighing  respirations then falls off rapidly for a few seconds before shallow  breathing begins again. During the period when breathing stops the  person often becomes restless and may wake with a sudden feeling of  suffocation. This can disturb sleeping patterns, exhausting the climber.  This type of breathing is not considered abnormal at high altitudes.  Diamox is helpful in relieving this periodic breathing.

Acute Mountain Sickness (AMS)
Acute Mountain Sickness is common at high altitudes and 75% of people  experience some symptoms over 3,000 meters (9,842 feet). The severity of  AMS depends on several factors including rate of ascent, elevation, and  individual susceptibility. Symptoms usually begin between 12 and 24  hours after reaching altitude and decrease in severity by the third day.

Mild AMS symptoms include: headache, nausea and dizziness, loss of appetite, fatigue, shortness of breath, and inability to sleep.
As long as the symptoms are mild, hikers can continue to climb at a  moderate rate. All symptoms of AMS should be communicated to the head  guide and progress reports should be given daily.

Moderate AMS symptoms include: severe headache, nausea and vomiting, increased weakness and fatigue, shortness of breath, and decreased coordination.

Although the hiker may be able to continue walking on their own while  experiencing moderate symptoms of AMS, normal activity becomes more and  more difficult as the hiker gains altitude. At this stage, only medicine  and descent can reverse the symptoms of AMS. Even a minor descent of only 300 meters will result in a significant improvement. All symptoms of moderate AMS should be communicated to the guide at  which point the guide will make a decision whether or not to evacuate.  Depending on symptoms, the climber may be told to walk a straight line.  If he or she is not able to walk a straight line on their own, immediate  descent is required.

Severe AMS symptoms include: increased shortness of breath, loss of ability to walk, decreasing mental awareness, and fluid buildup in lungs.
Severe AMS can only be treated by immediate descent to lower altitudes.

Other Severe Altitude-Related Illnesses
Two other severe forms of altitude sickness may result from failure to  descend to lower altitudes. These include High Altitude Pulmonary Edema  (HAPE) and High Altitude Cerebral Edema (HACE). Although these happen  less frequently, they usually result from fast ascents among people who  are not properly acclimatized. The lack of oxygen in the body causes a  leakage of fluid through the capillary walls into either the lungs or  brain.

High Altitude Pulmonary Edema (HAPE)
HAPE results from fluid buildup in the lungs and can prevent effective  oxygen exchange. Impaired cerebral function, cyanosis, and death may  result in severe cases of HAPE. Symptoms of HAPE include: shortness of  breath even at rest; fatigue and weakness; feeling of impending  suffocation or drowning; grunting or gurgling sounds when breathing;  persistent cough which brings up white, watery, or frothy fluid;  confusion and irrational behavior. In cases of HAPE, immediate descent  is necessary. Patients should be evacuated to a medical facility for  follow-up treatment.

High Altitude Cerebral Edema (HACE)
HACE is the result of swelling of brain tissue from fluid leakage.  Symptoms include the following: headache; loss of coordination (ataxia);  weakness; decreasing levels of consciousness including, disorientation,  loss of memory, hallucinations, blindness, and coma. HACE generally  occurs after a week or more at high altitude. Severe instances can lead  to death if not treated quickly and immediate descent is a necessary  life-saving measure. Follow-up care must be sought at a medical facility  following HACE.

Preventing Altitude Sickness
There are two ways to prevent altitude-related illness: proper  acclimatization and preventative medicines. These recommendations are  written specifically for climbing Mounts Meru and Kilimanjaro in  Tanzania and may not be applicable to other high mountains. But always  Summit Odyssey advises our climbers to have a ‘polepole ’pace and  drinking plenty of water as the best preventative method to slow down altitude sickness.

•Tell guide your AMS symptoms and keep him as well as the other group members informed of your progress.

•Climb high and sleep low. It is recommended that you acclimate during  the day by climbing to high elevations and then descending to sleep.

•If you begin to show symptoms of moderate altitude illness, don't go higher until symptoms decrease.

•If symptoms become severe, descend.

•Stay properly hydrated. Acclimatization is often accompanied by fluid  loss, so you need to drink lots of fluids to remain properly hydrated  (at least 4-6 liters per day). Urine should be clear.

•Don't over-exert yourself at altitude. Light activity during the day is  better than sleeping because respiration decreases during sleep,  exacerbating the symptoms.

•Avoid tobacco and alcohol and other depressant drugs including,  barbiturates, tranquilizers, and sleeping pills. Depressants further  decrease the rate of respiration during sleep resulting in a worsening  of the symptoms.

•Eat a high calorie diet of which 70% is carbohydrates.

PREVENTANTITVE MEDICATIONS
Diamox (Acetazolamide): Diamox is a drug that allows  you to breathe faster so that you metabolize more oxygen. Although  gradual ascent is recommended as opposed to Diamox, the drug does help  to avert symptoms of Altitude Mountain Sickness. Because 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. The recommended dose is between 125 mg and 250 mg  twice daily starting one to two days before the trek and continuing for  three days once the highest altitude is reached. Possible side effects  include tingling of the lips and finger tips, excessive urination,  blurring of vision, and alteration of taste. Contact your physician for a  prescription. Since Diamox is a sulfonamide drug, people who are  allergic to sulfa drugs should not take Diamox. Diamox has also been  known to cause severe allergic reactions to people with no previous  history of Diamox or sulfa allergies. (There are other medications that  may be taken to prevent altitude sickness. You must ask your doctor if  they are right for you.)

OTHER MEDICATIONS
Ibuprofen relieves altitude induced headache.

Nifedipine rapidly decreases pulmonary artery pressure  and also seems able to decrease the narrowing in the pulmonary artery  caused by low oxygen levels, thereby improving oxygen transfer. It can  therefore be used to treat HAPO, though unfortunately its effectiveness  is not anywhere as dramatic as that of dexamethasone in HACO. The dosage is  20mg of long acting nifedipine, six to eight hourly.

Furosemide may clear the lungs of water in HAPO and  reverse the suppression of urine brought on by altitude. However,  Furosemide can also lead to collapse from low volume shock if the victim  is already dehydrated. Treatment dosage is 120mg daily.