High altitude pulmonary edema (HAPE) is a life-threatening high-altitude related illness that can cripple even the healthiest mountain athletes. When ascending to high altitudes, over 2500 meters (8200 feet), arteries in the lungs begin to experience high amounts of pressure, leading to fluid accumulation in the alveoli. The fluid buildup inhibits the uptake of oxygen and release of carbon dioxide, potentially leading to the onset of hypoxia and death due to respiratory failure without immediate action. HAPE is the leading cause of altitude illness-related deaths.
Symptoms will include shortness of breath, even while resting, extreme fatigue, chest congestion, bluing of the lips and fingernails, or a cracking cough that may produce pinkish fluid. These symptoms usually will not appear until the second or third day into an expedition and require instant attention. As soon as symptoms become present in an individual they should quickly begin the descent to lower elevations. In addition to immediate descent, supplemental oxygen, if available, can be administered to help regain equilibrium in the lungs.
Luckily, HAPE is easily avoidable. The best method is to let your body gradually adjust to the altitude by making a slow approach. It is important to note that the 2500-meter mark is at the lower danger range, studies suggest that once above 3000 meters (9800 feet) the likely hood of developing HAPE symptoms are much more likely. Limiting ascents to no more than 500 meters (1600 feet) of elevation gain per day, when above 3000 meters, and taking mandatory rest days every 3 to 4 days is a common rule for high altitude travel.
Remember to listen to your body when in high altitude environments, the trip will be much more enjoyable without medical emergencies. If you are coming from low elevations plan to take an extra day or two upon arrival to begin acclimating. Monitor yourself and your companions and take immediate action if any of the symptoms of HAPE develop. You can always come back another day.