Pneumothorax can occur after a transthoracic lung biopsy. Lung biopsies involve taking tissue samples from the lungs to identify any underlying medical conditions or other abnormalities. The dysfunction can happen when air escapes into the chest cavity during the procedure and causes the biopsied lung to collapse. The risk increases if the patient already has COPD or emphysema since these diseases weaken the lungs making them more likely to rupture during a biopsy.