Capnothorax: Diagnosis

Advanced, Clinical Subspecialties

Capnothorax is a type of pneumothorax where carbon dioxide occupies space in the pleural cavity preventing full inflation of the lung. Capnothorax is suspected in the setting of abdominal laparoscopic surgery when CO2 is used for insufflation and the procedure involves manipulation of the diaphragm as in esophageal surgery. In most cases of pneumothorax, etCO2 gradually decreases as the relative shunt created by the air in the pleural space prevents alveoli expansion and gas exchange. In a capnothorax, however, etCO2 gradually increases as carbon dioxide in the pleural space is absorbed and exchanged.  Other diagnostic clues include absent or decreased breath sounds on the side of the pneumothorax, increasing etCO2 despite compensatory increases in minute ventilation, gradually increasing mean airway pressure, decreasing oxygen saturation, and chest Xray showing pneumothorax. When capnothorax is suspected, pneumoperitoneum should be released and 100% FiO2 administered until oxygen saturation recovers. Chest Xray can confirm the diagnosis and thoracentesis should be pursued in cases of large pneumothorax or pneumothorax unresponsive to conservative management.

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Answered correctly

2019

Year asked

Author
Elliot Winters, MD