Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Is enough oxygen too much? | Schumacker Critical Care 2010 14 191 http content 14 4 191 CRITICAL CARE COMMENTARY L__ Is enough oxygen too much Paul T Schumacker See related viewpoint by Martin etal. http content 14 4 315 Abstract Human cells require O2 for their energy supply and critical illness can threaten the efficient delivery of O2 in accordance with tissue metabolic needs. In the accompanying article Martin and colleagues point out that hypoxia is a normal and well-tolerated stress during embryonic development. A better understanding of how fetal cells survive these conditions and how adult cells adapt to high altitude exposure may provide insight into how these mechanisms might be engaged in the treatment of hypoxemic patients. They suggest that permissive hypoxia represents a therapeutic possibility. But before we turn down the inspired O2 levels we should consider the broader effects of hypoxia on tissue repair in critical illness. Intensivists direct much effort toward maintaining tissue oxygenation in critically ill patients. While the consequences of oxygen deprivation are well known we also know that excessive oxygenation creates new problems because hyperoxia exacerbates lung injury. So like many things in life too much is not the solution to not enough . Assessments of tissue oxygenation have taught us that normoxia differs among organs and that tissue oxygenation can decrease when the environment or activity levels change. For example lung alveolar cells normally reside under 14 O2 while oxygenation in intestinal epithelium can be less than 2 . Severe exercise decreases myocardial oxygenation from 4 to less than 1 O2 while high altitude induces systemic hypoxemia. During embryonic development systemic oxygenation in the fetus is severely hypoxic by comparison to the adult. Correspondence p-schumacker@ Division of Neonatology Department of Pediatrics Northwestern University Feinberg School of Medicine 310 E. Superior St Morton .
