CARbon Dioxide Flooding to Reduce Postoperative Neurological Injury Following Surgery for Acute Type A Aortic Dissection

Aortic dissection is a life-threatening condition and a consequence of a tear of the innermost of the three aortic layers- the intima. When a tear occurs, blood surges through the tear and causes the flow of blood between the aortic layers, causing a "false lumen". This causes a weakening of the aortic wall and hinders the blood from reaching its target organs and life saving emergent surgery is performed as routine. Approximately 20% of patients undergoing acute type a aortic dissection (ATAAD) surgery suffer from postoperative neurological injuries and It has been demonstrated that neurological injuries account for 10-15% of in-hospital deaths. In association with other cardiac procedures where the left side of the heart is opened and air may be trapped within the arterial circulation, carbon dioxide flooding is used to displace open air from the surgical wound. In comparison to air, carbon dioxide is significantly more soluble in blood and may therefore decrease the risk of air embolism. In cardiac surgery, carbon dioxide flooding has been demonstrated to reduce levels of biomarkers of cerebral injury, but carbon dioxide is not routinely employed in ATAAD surgery and has not been studied in association with these procedures. The hypothesis is that carbon dioxide flooding reduces cerebral air embolism and the aim of this project is to evaluate whether carbon dioxide flooding may reduce neurological injuries following ATAAD surgery. This is a prospective, randomized, controlled, patient- and reviewer blinded interventional study. Patients will be randomized to undergo surgery with carbon-dioxide flooding at 5L/min to the open chest cavity or conventional surgery without carbon dioxide flooding. Remaining aspects of the procedure will be identical. The patient, external statistician and the reviewer analyzing the primary endpoints will be blinded for the randomization arms. The study will assess the following endpoints: Primary outcomes: Presence, number and