LAUSR

The human system of oxygen transport and metabolism is complex, and appropriate means to follow its single steps intraoperatively do not exist. Intraoperative tissue hypoxia is one of the leading dangers for patients receiving one-lung ventilation (OLV). Pulmonary, cerebral, or cardiac injuries may be the result. To summarize the current knowledge about the tolerable human limits of hypoxia, inside and outside the thoracic surgery room, is the purpose of this review. High altitude mountaineers and apnea divers teach us that the healthy human body is able to acclimatize to and cope with severe hypoxemia to prevent fatal tissue hypoxia. The patients receiving OLV for thoracic surgery, however, are lacking adequate time for hypoxic acclimatization. Chronical medical conditions and effects of anesthesia prevent them further from exploiting their full hypoxia defense capacity. Controlled outcome studies on hypoxemia during OLV do not exist. Patients are no mountaineers. Thus, prevention of tissue hypoxia by avoiding relevant hypoxemia must be still the major goal during OLV. However, if permissive hypoxemia as a protection against perioperative oxygen stress could be tolerable in highly selected patients is the objective of current research.