 Atelectasis and consolidation of lung tissue is a well recognized clinical scenario following anaesthesia, musclerelaxation and mechanical ventilation. In cardiac surgery during cardiopulmonary bypass CPB, the lungs are collapsed to a degree depending on surgical opening of the pleura, time on bypass, and gasmixture on termination of ventilation. Recruitment of the lungs on commencement of mechanical ventilation after CPB generally must be repeated before extubation. There are several different approaches to Recruitment Manoeuvers RM. Increasing pressures in the ventilator peak-pressures and PEEP, increasing tidal volumes and inspiratory hold are facilities offered by the ventilator. Different body positions by interaction of the abdomen and thorax through the diaphragm, and the action of gravity on the lungs and adjoining organs, are other principles. The contribution of spontaneous ventilatory efforts also play a major roll. 