Dilshad Ahmed Khan, Rizwan Hashim, Muhammad Aslam.
High altitude Pulmonary Edema.
Pak Armed Forces Med J Jan ;53(2):225-33.

High altitude pulmonary edema (HAPE) is a common problem at high altitude that generally occurs above 2500 meters in un-acclimatized persons, due to hypoxemia. Variable incidence of HAPE has been reported in literature ranging from 2-15%. Recent studies have established beyond doubt,that RAPE is caused by high pulmonary artery pressures due to patchy hypoxic vasoconstriction that leads to high permeability changes in remaining patent capillaries in lung that results in protein rich oedema. The development of an inflammatory process could then occur after the initiation of the early capillary leak in alveoli. Inflammatory markers such as neutrophils, leukotriene B4, cytokines and the complement fragment C5a are frequently seen in the lungs lavage in RAPE. In addition Endothelin-1, nitric oxide, oxidative stress and genetic factors may play a role in the pathogenesis. The common clinical features include dyspnoea, cough, tachypnoea, fatigue, chest tightness, tachycardia and rales upon systemic examination of chest. Even susceptible individuals can avoid HAPE when they ascend slowly. Currently oxygen therapy, nifedipine, and nitric oxide can be used in the treatment of HAPE. This review provides latest developments in understanding pathogenesis leading to early diagnosis and better management of RAPE at high altitude that are necessary in view of the development of our troops and increasing frequency of persons going for recreation to high altitude in northern areas of Pakistan.

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