[Multiple cerebral infarction by air embolism associated with remarkable low BIS value during lung segmentectomy with video assisted thoracic surgery (VATS) technique: a case report].

A 64-year-old woman (151 cm, 43 kg) with well controlled hypertension was diagnosed as having right lung cancer at S8 segment. She underwent right S8 segmentectomy by video assisted thoracic surgery (VATS) under general anesthesia combined with epidural anesthesia. Her vital signs were stable and BIS value was around 45 before the surgeon injected the air using a syringe with a 22 G needle to confirm the lesion resected. After the injection of air, her systolic blood pressure rapidly increased from 120 to 170 mmHg and the BIS value suddenly decreased to 5. Blood propofol concentration was reduced from 3 microg x ml(-1) to 2 microg x ml(-1) in the target-controlled infusion technique, and thereby the BIS value increased slowly. She did not wake up nor maintain sufficient spontaneous breathing even 2 hours after the discontinuation of opioids, and was transferred to ICU with tracheal intubation. In ICU, she showed clonic convulsions. Urgent CT and MRI confirmed cerebral air embolism. Her vital signs were too unstable to choose hyperbaric oxygen therapy as her first treatment. Her consciousness was recovered and her trachea was extubated on 11th postoperative day. She was discharged with left hemiparalysis from hospital.