The body compensates for this lower level of oxygen by breathing faster and increasing blood flow to the brain, by dilating blood vessels, so they can deliver more oxygen. Once the symptoms are over, the climber can ascend safely. HAPE is a life threatening disorder of the lungs, that occurs when fluid from the blood vessels that carry blood from the heart to the lungs become damaged. It allows blood to escape into the spaces in the lung, which are essential for oxygen to be exchanged from the air. The more space occupied by blood, the less oxygen will be available for the body.
Breathing then becomes difficult as the oxygen levels in the body drop.
Symptoms usually begin 24 to 72 hours after a too rapid ascent to altitudes above 10,000 ft. Signs of HAPE usually consist of shortness of breath, cough and fatigue. As the symptoms progress, coughing can become severe, with blood tinged spit and sometimes gurgling can be heard in the lungs. When oxygen levels drop, hallucinations and unconsciousness may occur. Treatment must include evacuation to lower altitudes and oxygen administration.