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The other major effect of altitude is due to lower ambient temperature. The oxygen saturation of hemoglobin determines the content of oxygen in blood. After the human body reaches around 2,100 metres (6,900 ft) above sea level, the saturation of oxyhemoglobin begins to decrease rapidly. [2]
By contrast, the women of long-resident, high-altitude populations are known to give birth to heavier-weight infants than women of the lowland. This is particularly true among Tibetan babies, whose average birth weight is 294–650g (~470) g heavier than the surrounding Chinese population, and their blood-oxygen level is considerably higher. [24]
As HVR is a response to decreased oxygen availability, [1] it shares the same environmental triggers as hypoxia. Such precursors include travelling to high altitude locations [6] and living in an environment with high levels of carbon monoxide. [7] Combined with climate, HVR can affect fitness and hydration. [2]
Atmospheric nitrogen has a partial pressure of approximately 0.78 bar at sea level. Air in the alveoli of the lungs is diluted by saturated water vapour (H 2 O) and carbon dioxide (CO 2), a metabolic product given off by the blood, and contains less oxygen (O 2) than atmospheric air as some of it is taken up by the blood for metabolic use. The ...
Total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen, which is defined as hypobaric hypoxia. Oxygen remains at 20.9% of the total gas mixture, differing from hypoxic hypoxia, where the percentage of oxygen in the air (or blood) is
Chronic mountain sickness (CMS) is a disease in which the proportion of blood volume that is occupied by red blood cells increases (polycythaemia) and there is an abnormally low level of oxygen in the blood . CMS typically develops after extended time living at high altitude (over 2,500 metres (8,200 ft)).
Altitude acclimatization is the process of adjusting to decreasing oxygen levels at higher elevations, in order to avoid altitude sickness. [17] Once above approximately 3,000 metres (10,000 ft) – a pressure of 70 kilopascals (0.69 atm) – most climbers and high-altitude trekkers take the "climb-high, sleep-low" approach.
[3] [9] [15] Giving oxygen at flow rates high enough to maintain an SpO 2 at or above 90% is a fair substitute for descent. [3] [9] [15] In the hospital setting, oxygen is generally given by nasal cannula or face mask for several hours until the person is able to maintain oxygen saturations above 90% while breathing the surrounding air. [3]