This viewpoint designates detrimental effects of routine administration of high-dose supplemental oxygen in a variety of medical emergencies. Not only is supplemental oxygen often part of routine practice, many guidelines support its use in several medical emergencies. For example, the US task force on decompensated CHF recommends oxygen therapy to maintain a normal oxygen saturation (at least 95% in non-COPD patients, class I recommendation, level of evidence C) [50,51]. Similarly, in patients with acute myocardial infarction, oxygen therapy is recommended not only for patients with arterial hypoxia (oxygen saturation of less than 90%) but also for those with subjective respiratory distress or high-risk features for hypoxemia [51]. The British Thoracic Society guideline for emergency oxygen use in adult patients recommends immediate administration of high-concentration oxygen in all critically ill, hypoxic non-COPD patients to achieve a target peripheral oxygen saturation of 94% to 98% [52]. These guidelines do, however, underscore that there is little or no evidence to support the recommendations.
Despite its relatively small weight (2% of total body weight), the human brain accounts for approximately 20% of the body's oxygen consumption, rendering it vulnerable to hypoxemia. Even modest hypoxemia is associated with enduring cognitive sequelae [53]. When PaO2 falls to below 60 mm Hg, hypoxic vasodilatation occurs as a part of cerebral autoregulation [54]. Hyperoxia, on the other hand, is associated with vasoconstriction and therefore hampers cerebral perfusion [32,33]. Even mild levels of hyperoxia are associated with a decrease in perfusion of grey matter [55]. Both hyperoxia and hypoxia may be detrimental for cerebral oxygenation. A recent retrospective study in patients with traumatic brain injury showed hyperoxia and hypoxia to be equally detrimental to both mortality and functional outcomes [56].
This viewpoint designates detrimental effects of routine administration of high-dose supplemental oxygen in a variety of medical emergencies. Not only is supplemental oxygen often part of routine practice, many guidelines support its use in several medical emergencies. For example, the US task force on decompensated CHF recommends oxygen therapy to maintain a normal oxygen saturation (at least 95% in non-COPD patients, class I recommendation, level of evidence C) [50,51]. Similarly, in patients with acute myocardial infarction, oxygen therapy is recommended not only for patients with arterial hypoxia (oxygen saturation of less than 90%) but also for those with subjective respiratory distress or high-risk features for hypoxemia [51]. The British Thoracic Society guideline for emergency oxygen use in adult patients recommends immediate administration of high-concentration oxygen in all critically ill, hypoxic non-COPD patients to achieve a target peripheral oxygen saturation of 94% to 98% [52]. These guidelines do, however, underscore that there is little or no evidence to support the recommendations.Despite its relatively small weight (2% of total body weight), the human brain accounts for approximately 20% of the body's oxygen consumption, rendering it vulnerable to hypoxemia. Even modest hypoxemia is associated with enduring cognitive sequelae [53]. When PaO2 falls to below 60 mm Hg, hypoxic vasodilatation occurs as a part of cerebral autoregulation [54]. Hyperoxia, on the other hand, is associated with vasoconstriction and therefore hampers cerebral perfusion [32,33]. Even mild levels of hyperoxia are associated with a decrease in perfusion of grey matter [55]. Both hyperoxia and hypoxia may be detrimental for cerebral oxygenation. A recent retrospective study in patients with traumatic brain injury showed hyperoxia and hypoxia to be equally detrimental to both mortality and functional outcomes [56].
การแปล กรุณารอสักครู่..