Why do breath sounds hard to auscultate and sometimes the sound is absent in the affected lung during pneumothorax?
A pneumothorax is literally free air in the pleural cavity of the thorax. Lung sounds are diminished due to increased intrathoracic pressure which pushes on the ipsilateral lung, causing atelectasis, or collapse of the alveoli. Decreased airflow causes diminished sound, resulting in difficult auscultation near the site of origin.