Which physical exam finding is expected in a patient with a pneumothorax?

In the context of a pneumothorax, the most significant physical exam finding is the absence of breath sounds on the affected side. A pneumothorax occurs when air enters the pleural space, leading to partial or complete collapse of the lung. This accumulation of air impedes normal lung expansion and can result in diminished or absent breath sounds when auscultating over the affected lung.

Evaluating the findings, when air is present in the pleural space, the lung cannot effectively transmit breath sounds to the chest wall, which explains the unilateral absence of breath sounds. This is a key diagnostic sign that can help differentiate a pneumothorax from other respiratory conditions.

Other findings, such as wheezing, rales, or increased tactile fremitus, are not typically associated with pneumothorax. Wheezing is generally more indicative of bronchospasm or airway obstruction, while rales suggest fluid in the airways—both of which are not characteristic of a pneumothorax. Increased tactile fremitus usually occurs in conditions with lung consolidation rather than air in the pleural space. Thus, the expected finding of absent breath sounds unilaterally is central to understanding the physical examination of a patient with a pneumothorax.