Arterial to end-tidal CO2 gradient reversal during laparoscopic pheochromocytoma resection

Abstract

Purpose: We report the development of severe intraoperative hypercarbia and a pronounced arterial to end-tidal gradient reversal during laparoscopic pheochromocytoma resection. Although complex physiologic mechanisms may be responsible for this finding, anatomic alterations such as a direct communication between a capnoperitoneum and/or capnothorax and the airways resulting from prior pathology and the type of procedure should also be considered. Clinical features: During anesthesia for laparoscopic pheochromocytoma removal we noticed an abrupt, extensive increase of the end-tidal CO2 accompanied by a change of the capnographic CO2 tracing and reversal of the normal arterial-to-end-tidal gradient. These changes consistently disappeared by intermittent deflation of the abdomen and at the end of surgery. A chest x-ray revealed a right-sided loculated pneumothorax with pleural thickening. Peritoneo-thoracic CO2 tracking and pleural scaring with pulmonary adhesions resulting in a unidirectional communication between the pleural space and airways may best explain the chest x-ray and clinical findings. Conclusion: Severe intraoperative hypercarbia and arterial to end-tidal CO2 gradient reversal represents an intraoperative challenge. The possibility of a direct communication between the pleural space and the bronchial tree should be considered when other etiologies have been excluded. Simple maneuvers such as abdominal de- and re-inflation and analysis of the end-tidal capnographic tracing might aid in the differential diagnosis and management.