Congenital diaphragmatic weakness as a cause of capnothorax during laparoscopic surgery: A case report and management insights.

Capnothorax is a rare but potentially serious complication of laparoscopic surgery, typically attributed to diaphragmatic injury or retroperitoneal CO2 tracking. We report a case of intraoperative capnothorax in a 52-year-old woman undergoing laparoscopic common bile duct exploration. Two hours after pneumoperitoneum establishment (13-14 mmHg), the patient developed acute right-sided pneumothorax, presenting as a sudden increase in peak airway pressure (28 cm H2O) with stable end-tidal CO2 (36 mmHg). Intraoperative inspection and post-operative computed tomography excluded structural diaphragmatic defects, implicating transdiaphragmatic CO2 diffusion through a congenitally weakened diaphragm. Conservative management - including reduction of pneumoperitoneum pressure to 10 mmHg, application of 5 cm H2O positive end-expiratory pressure and real-time lung ultrasound - confirmed the diagnosis (stratosphere sign and lung point) and achieved resolution within 40 min without thoracic drainage or surgical interruption. This case highlights congenital diaphragmatic weakness as an under-recognised aetiology of capnothorax and supports a physiologically guided, non-invasive approach that challenges traditional protocols favouring emergent thoracostomy.