Delayed Detection of Iatrogenic Pneumothorax Under Positive-Pressure Ventilation: A Case Report.

Subclavian venous access may result in pleural injury. During positive-pressure ventilation (PPV), increased intrathoracic pressure compresses peripheral lung tissue, promoting closure of terminal airways. As a result, air leakage from injured lung regions may remain confined and not communicate with the pleural space, rendering intraprocedural and early post-procedure imaging falsely negative. We report a 67-year-old woman in whom pneumothorax became radiographically apparent only after extubation. The transition to spontaneous (negative-pressure) breathing reduced surrounding pressure, allowing reopening of peripheral airways and facilitating the movement of air into the pleural space. This case provides a mechanistic explanation for delayed radiographic detection of pneumothorax under PPV and supports the use of planned post-extubation imaging when pleural injury is suspected.