The article discusses the prediction, prevention and treatment of hypoxemia during one-lung ventilation (OLV). It notes that hypoxemia may occur upon switching from two-lung to OLV, which is required in some thoracic procedures, due to increased shunt fraction, impairing oxygenation. It says that occurrences of hypoxemia may be predicted through knowledge of lung functions. It stresses that ventilation strategy avoiding alveolar collapse at the same time minimally impairing perfusion of the dependent lung may be used to prevent hypoxemia. As for the treatment, correcting the position of the double-lumen tube is administered which clears the main bronchi of the ventilated lung.