Also known as oxygen desaturation, it is an insufficient or abnormally-low level of oxygenation of the arterial blood. On average, normal oxygen levels are about mm Hg. With hypoxemia, it decreases to as low as 89 mm Hg. During hypoxemia, the oxygen saturation of the blood is less than 90% (with normal values ranging from 98 to 100%), which constitutes the formal definition of hypoxemia. Below 80% is treated as severe hypoxemia. Sometimes hypoxemia can give rise to hypoxia. In preterm infants, transient episodes of hypoxemia (oxygen saturation less than 85%) are observed during mechanical ventilation, even after the acute phase of respiratory failure has occurred.
See Anoxia, Birth asphyxia, Cord prolapse, Hypoxia, Hypoxic-ischemic encephalopathy (HIE), Preterm infant