The risk of air embolism is lowest in the supine position, but there is enough blood in the surgical field. In addition, it increases the pressure of superficial structures on deep structures. The lateral position also reduces air embolism and has the advantage of good air access. The disadvantage is that the upper cerebellum interferes with the surgical access due to gravity. The seated position allows drainage of cerebrospinal fluid and blood due to gravity and has good visualization of the superior cerebellar earthworms. However, it makes the surgeon uncomfortable because the procedure requires the surgeon to operate with a straightened arm. Also there is a high incidence of venous air embolism. Therefore preoperative transesophageal echocardiography needs to be checked and bubbles studied and evaluated for the patient’s foramen ovale. Intraoperatively, the patient is checked for venous air embolism by ultrasound Doppler and a central venous catheter is placed to allow air extraction if necessary.