dy. Some of these changes happen immediately in response to reduced levels of oxygen while others are a slower adaptation. Some of the most significant changes are: Chemoreceptor mechanism increases the depth of alveolar ventilation. This allows for an increase in ventilation of about 60% (Guyton, 1969). This is an immediate response to oxygen debt. Over a period of several weeks the capacity to increase alveolar ventilation may increase 600-700%. Pressure in pulmonary arteries is increased, forcing blood into portions of the lung which are normally not used during sea level breathing. The body produces more red blood cells in the bone marrow to carry oxygen. This process may take several weeks. Persons who live at high altitude often have red blood cell counts 50% greater than normal. The body produces more of the enzyme 2,3-biphosphoglycerate that facilitates the release of oxygen from hemoglobin to the body tissues (Tortora, 1993). The acclimatization process is slowed by dehydration, over-exertion, alcohol and other depressant drug consumption. Longer term changes may include an increase in the size of the alveoli, and decrease in the thickness of the alveoli membranes. Both of these changes allow for more gas transfer. TREATMENT FOR AMS The symptoms of mild AMS can be treated with pain medications for headache. Some physicians recommend the medication Diamox (Acetazolamide). Both Diamox and headache medication appear to reduce the severity of symptoms, but do not cure the underlying problem of oxygen debt. Diamox, however, may allow the individual to metabolize more oxygen by breathing faster. 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 going to altitude. The recommendation of the Himalayan Rescue Association Medical Clinic is 125 mg. twice a day. The standard dose has been 25...
