Certified Respiratory Therapist Exam 2025 – 400 Free Practice Questions to Pass the Exam

Absence of breath sounds on examination can be attributed to the presence of a pneumothorax, which occurs when air enters the pleural space, leading to a collapse of the lung on the affected side. This collapse reduces the lung's ability to expand and produce normal breath sounds during auscultation. In a pneumothorax, the air in the pleural cavity impairs the transmission of sound from the lungs to the chest wall, resulting in diminished or absent breath sounds.

While atelectasis, pneumonia, and allergic reactions can present with other respiratory signs and symptoms, they generally do not lead to a complete absence of breath sounds in the same way that a pneumothorax does. Atelectasis might cause decreased breath sounds but is often still detectable. Pneumonia typically produces abnormal breath sounds, such as crackles or wheezing, due to fluid and inflammatory processes in the lungs. Allergic reactions can result in wheezing or stridor but usually do not cause the total absence of breath sounds unless severe bronchospasm occurs, which is less common in those who are simply allergic. Thus, the clear distinction of absence of breath sounds is most closely linked to a pneumothorax.