Pneumothorax

Positive pressure is dangerous - Mechanical ventilation can rapidly enlarge an existing pneumothorax and precipitate tension physiology; a significant untreated pneumothorax should be drained before positive-pressure ventilation.

Avoid nitrous oxide - N2O diffuses into and expands closed air spaces, enlarging a pneumothorax fast — avoid it.

Recognize tension - Sudden hypoxemia, rising airway pressures, hypotension, distended neck veins, absent breath sounds, and tracheal deviation — decompress immediately (needle, then chest tube).

At-risk patients - Trauma, central line placement, barotrauma, bullous lung disease, and recent thoracic procedures raise suspicion; watch after any of these.

Chest tube management - Confirm the drain is working, watch for recurrence, and never clamp a bubbling tube in a ventilated patient.

A pneumothorax is air in the pleural space that collapses the lung and impairs ventilation. A tension pneumothorax — air accumulating under pressure — shifts the mediastinum, obstructs venous return, and causes cardiovascular collapse: a true emergency.

Under anesthesia the danger is amplified, because positive-pressure ventilation and nitrous oxide can rapidly enlarge a pneumothorax and convert a simple one into a tension pneumothorax. A high index of suspicion is essential.