Dyspnea in high altitudes. Pathophysiology underlying HAPE (High Altitude Pulmonary Edema).
There are several problems while being at a high altitude, or specially going up there. AMS (Acute Mountain Sickness) is the general term of headache of someone that has arrived at an altitude of over 2500m plus one of these symptoms: anorexia, nausea, vomiting, insomnia, dizziness, apathy or fatigue. There is a mild, moderate and a severe form. The severe is divided into HAPE (High Altitude Pulmonary Edema and HACE (High Altitude Cerebral Edema). HAPE is a severe condition that can lead to death if not treated. Rapid ascent, exertion and high altitude are all negative factors that reinforces HAPE, but all forms can be prevented if you have a slow ascent and reversed if you descent immediately. We have been looking at the pathophysiology behind HAPE. The edema manifests itself with dyspnea, while resting and more when exercising, cyanosis, dry coughing and crepitation of the lungs. Late stage is bloody sputum. Lung X-ray may show diffuse dens areas. Low oxygen pressure gives hypoxia, which gives hyperventilation and alkalosis. Hypoxia will induce constriction of lung arteries. This will give a rise in lung circulation pressure and increased permeability. This will induce edema and leakage through the capillary wall. Theories about reduced hypoxic response, inflammatory reaction, leftover from foetal life and other topics is found in articles from Medline. There is also a genetic disposition involved. No conclusive theory is emerged, but probably a mixture of them is responsible.