A Case of Air Embolism Caused by Ct-Guided Marking of A Small Peripheral Pulmonary Nodule

A 71-year-old man was referred to our department because of abnormal shadows on a chest radiograph. Computed tomography (CT) revealed an asteroid shadow with a diameter of 8 mm in the periphery of the left upper division segment (suggestive of adenocarcinoma) and an oval shadow with a diameter of 6 mm in the lingular segment (suggestive of an intrapulmonary lymph node). We determined that the former could be localized by thoracoscopy, but that the latter could not. Preoperative CT-guided marking was planned for the latter. Immediately before surgery, the Guiding-Marker System (21 G x 150 mm, Hakko Medical, Tokyo, Japan) was used in the CT room. Immediately after a marker with a nylon suture was placed with an insertion needle, the patient complained of numbness and subsequently lost consciousness. He was immediately transferred to an operating room and was attached to an electrocardiogram monitor. ST elevation was observed in nearly all leads. His blood pressure had decreased to 60/50 mmHg. Reconfirmation of the CT images revealed air in the left ventricle and the thoracic aorta, which led to a definitive diagnosis of air embolism. Application of head-down tilt, oxygen inhalation, coronary vasodilator infusion, and other treatments slightly improved his level of consciousness within 20 minutes after onset. When his blood pressure increased to 100/70 mmHg, he was transferred to a tertiary acute care hospital providing hyperbaric oxygen therapy. His general condition had already been stabilized by the time of his arrival at the tertiary acute care hospital. Because no air was detected in the body by either whole-body CT or head magnetic resonance imaging performed three hours after onset, hyperbaric oxygen therapy was not administered. After two nights and three days, the patient was returned to our department. On the 11th day after the onset of air embolism, a planned pulmonary biopsy using video-assisted thoracic surgery was performed, and he was subsequently discharged without any sequelae. When CT-guided marking is performed hereafter, provision of sufficient explanation to the patient that air embolism may occur as a rare complication, and obtaining informed consent are important. If air embolism occurs, it is essential to administer prompt and appropriate treatment, including head-down tilt, oxygen inhalation, and hyperbaric oxygen therapy, to minimize sequelae.