A 72-year-old man with COPD develops acute shortness of breath and presents to the hospital. He appears uncomfortable: blood pressure is 120/90 mmHg, pulse 100/min, oxygen saturation 85% on room air. On examination of the chest, there is absent fremitus, absent breath sounds, and hyperresonant percussion of the right lung. The trachea is shifted to the left.For the above patient with abnormal pulmonary physical findings, select the most likely diagnosis.

Careful physical examination can be very useful in diagnosing many common pulmonary disorders. Atelectasis and large pleural effusions both can present with decreased fremitus, dullness or flatness to percussion, and absent breath sounds. In atelectasis, tracheal shift, if present, is toward the affected side, and the opposite for a large pleural effusion. Asthma's most typical manifestations are prolonged expiration and diffuse wheezing. However, impaired expansion, decreased fremitus, hyperresonance, and low diaphragms can also be found. A complete pneumothorax results in absent fremitus, hyperresonance or tympany, and absent breath sounds. Lobar pneumonia is characterized by consolidation with increased fremitus, dullness, and auscultatory findings of bronchial breathing, bronchophony, pectoriloquy, and crackles.