[Expert Solution]: Two days after undergoing left hemicolectomy…

Two days after undergoing left hemicolectomy for a colonic mass, a 60- year-old man develops shortness of breath. His temperature is 38.1C (100.6F), pulse is 80/min, respirations are 22/min, and blood pressure is 120/78 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 88%. Cardiopulmonary examination shows decreased breath sounds and decreased fremitus at both lung bases. Arterial blood gas analysis on room air shows: pH: 7.35 Pa02: 70m Hg PaCo2: 40mm Hg An x-ray of the chest shows collapse of the bases of both lungs. Which of the following is the most likely mechanism of this patient’s hypoxemia? Increased tidal volume Decreased hemoglobin oxygen-binding capacity Increased anatomic dead space Increased rate of oxygen consumption Decreased ratio of ventilated alveoli Decreased chest wall compliance