Tension pneumoperitoneum combined with CO2 gas embolism during peroral endoscopic myotomy: a case report and review of literature

Background Peroral endoscopic myotomy (POEM) is a safe, effective, and minimally invasive treatment for achalasia. While continuous carbon dioxide (CO 2 ) insufflation during POEM may lead to various insufflation-related adverse events, the occurrence of gas embolism remains an exceedingly rare complication. This report describes a case of tension pneumoperitoneum complicated by carbon dioxide gas embolism during POEM. Case A 51-year-old man was diagnosed with achalasia and underwent POEM. Intraoperatively, the end-tidal carbon dioxide (PetCO 2 ) continuously increased to 70 mmHg, accompanied by clinical manifestations of tension pneumoperitoneum. The peak inspiratory pressure (PIP) rose abruptly from 16 to 40 cmH 2 O, alongside significant subcutaneous emphysema and abdominal distension. Vital signs gradually stabilized following percutaneous abdominal needle decompression (PND). However, when the patient’s position was changed from left lateral decubitus to supine, PetCO 2 suddenly dropped from 68 to 53 mmHg, and peripheral oxygen saturation (SpO 2 ) declined to 90%, accompanied by frequent ventricular premature beats. A characteristic “mill-wheel” murmur was audible over the precordium, leading to a high suspicion of CO 2 gas embolism. Immediate interventions, including oxygen administration, positional adjustment, and supportive care, resulted in rapid clinical improvement. The patient was subsequently transferred to the intensive care unit (ICU) for further management and was successfully discharged on postoperative day 6 without additional complications. Conclusion During POEM, elevated intra-abdominal pressure resulting from tension pneumoperitoneum represents a significant risk factor for gas embolism. The simultaneous occurrence of multiple complications under general anesthesia further increases diagnostic complexity, as clinical signs may be masked or overlapping. Therefore, close intraoperative monitoring, early recognition of pathognomonic indicators, and prompt intervention are essential to ensure patient safety.