Snapshot A 42-year-old obese women develops fever, dyspnea, and elevation of the right diaphram 24 hours after an elective cholecystectomy. Introduction Refers to the collapse of the lung in an area distal to an area of obstruction Most common cause of fever in first 24 postoperative hours caused by dry secretions from anasthesia fever is the result of a nidus of infection Evaluation Elevated diaphram on CXR Loss of lung mass leads to elevation of the diaphram on the same side Treatment Conservative deep inspiration while standing is the best way to prevent incentive spirometry