Unilateral pulmonary oedema/atelectasis in the lateral decubitus position

An obese male patient developed hypoxia, hyercarbia and radiological signs of pulmonary oedema/atelectasis in the dependent lung after surgery in the lateral decubitus position. This appears to have been due to ventilation-perfusion mismatch, although other factors were considered. The patient recovered following 36 hours of intermittent positive pressure ventilation of the lungs.