Selective Antegrade Cerebral Perfusion and Perioperative Optic Nerve Sheath Diameter in Ascending Aortic Surgery

In ascending aortic surgery the distal anastomosis may be constructed with the aortic cross-clamp maintained, or, where the extent of the aortic pathology and the geometry of the graft require it, after release of the cross-clamp during a period of systemic circulatory arrest. Both are established surgical approaches. Where the cross-clamp is released, selective antegrade cerebral perfusion (SACP) is an established cerebral protection technique and is applied for that purpose. Where release of the cross-clamp is not required, systemic circulatory arrest is avoided and SACP is not applied. Optic nerve sheath diameter (ONSD) measured by ocular ultrasonography is a non-invasive marker of raised intracranial pressure. Cardiopulmonary bypass may increase blood-brain barrier permeability through hypoperfusion, non-pulsatile flow, hemodilution and systemic inflammation, predisposing to cerebral edema. Perioperative increases in ONSD have been reported after open heart surgery and have been associated with postoperative delirium. Data on how SACP influences perioperative ONSD dynamics in ascending aortic surgery, and whether such changes relate to postoperative delirium, are limited.