[Indications for the use of differential ventilation and selective positive end-expiratory pressure]

In some cases of unilateral or bilateral severe lung disease, there is serious hypoxia despite a high level of oxygen in the inspiratory gas mixture. Disturbances in the ventilation/perfusion ratio (V/Q) is a major contributing factor to the hypoxia seen in acute lung disease. The use of positive end expiratory pressure (PEEP) has in some cases been shown to make this V/Q mismatch even worse, and the use of high levels of PEEP is known to increase the risk of barotrauma and to reduce cardiac output. In this article, a method is described which makes it possible to ventilate each lung separately in proportion to its expected perfusion (differential lung ventilation), with or without the use of PEEP to one or both lungs (selective PEEP). Because of a more uniform V/Q the oxygenation in unilateral as well as in bilateral lung disease is improved. The risk of barotrauma as well as the impact on cardiac output is reduced. The patient has to be intubated with a double lumen endotracheal catheter. The gas is delivered by two ventilators synchronized by a master-slave cable. This method can also be used in the operating room, when surgical procedures have to take place in the lateral position, in order to counteract V/Q mismatch and hypoxia.