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High altitude causes decreased blood flow to the placenta, even in acclimatized women, which interferes with fetal growth. [28] Consequently, children born at high-altitudes are found to be born shorter on average than children born at sea level. [29]
At very high altitude, 3,500 to 5,500 metres (11,500 to 18,000 ft), maximum SaO 2 falls below 90% as the arterial PO 2 falls below 60mmHg. Extreme hypoxemia may occur during exercise, during sleep, and in the presence of high altitude pulmonary edema or other acute lung conditions. Severe altitude illness occurs most commonly in this range.
Re-entry HAPE is also an entity that has been described in persons who normally live at high altitude but who develop pulmonary edema after returning from a stay at low altitude. [3] If HAPE is not treated, there is a 50% risk of mortality. [4] Symptoms include crackling sounds when breathing, dyspnea (at rest), and cyanosis. [4]
In those with underlying heart or lung disease, effective control of congestive and respiratory symptoms can help prevent pulmonary edema. [37] Dexamethasone is in widespread use for the prevention of high altitude pulmonary edema. Sildenafil is used as a preventive treatment for altitude-induced pulmonary edema and pulmonary hypertension.
CMS was first described in 1925 by Carlos Monge Medrano, a Peruvian doctor who specialised in diseases of high altitude. [3] While acute mountain sickness is experienced shortly after ascent to high altitude, chronic mountain sickness may develop only after many years of living at high altitude. In medicine, high altitude is defined as over ...
Hyperpnea is distinguished from tachypnea, which is a respiratory rate greater than normal, resulting in rapid and shallow breaths, but not necessarily increasing volume in breathing. [1] Hyperpnea is also distinguished from hyperventilation , which is over-ventilation (an increase in minute ventilation ), which involves an increase in volume ...
This response can be attributed to genetic factors, but the development of the resistance to acute hypoxia is highly affected by when the individual is exposed to high altitude; [20] while genetic factors play an indefinite role in a person's HVR, because long term migrants do not show reduction in their reactions of high altitude even after ...
High-altitude adaptation in humans is an instance of evolutionary modification in certain human populations, including those of Tibet in Asia, the Andes of the Americas, and Ethiopia in Africa, who have acquired the ability to survive at altitudes above 2,500 meters (8,200 ft). [1]