Correlation between cerebral oxygen saturation monitored by near-infrared spectroscopy during operation and risk of stroke after acute type A aortic dissection surgery

Abstract

Objective: Near-infrared spectroscopy (NIRS) is widely used for intraoperative cerebral oxygen saturation monitoring in patients with acute type A aortic dissection. This study aimed to investigate the correlation between NIRS-derived oxygen saturation and risk of postoperative stroke. Methods: This study included 193 patients with acute type A aortic dissection undergoing emergency surgery and elective unilateral cerebral perfusion via the right axillary artery at the Department of Cardiothoracic Surgery, Nanjing Drum Tower Hospital, Nanjing, China, from 2018 to 2020. NIRS was used for intraoperative cerebral oxygen saturation monitoring, and the basal values and the lowest values of cerebral oxygen saturation during deep hypothermic circulatory arrest (DHCA) were recorded. The patients were divided into no-stroke group (n=178, 92.2%) and stroke group (n=15, 7.8%) according to the absence or presence of postoperative stroke. The differences in preoperative, operative and postoperative clinical differences between the two groups were compared, and the relationship between the lowest cerebral oxygen saturation value and the change in cerebral oxygen saturation value ((base-lowest)/basal) and postoperative stroke were analyzed. Results: The proportion of preoperative atrial fibrillation (6.7% vs. 0.6%, P=0.026), and the proportion of preoperative hypotension (26.7% vs. 9.0%, P=0.031) were significantly higher in the stroke group than no-stroke group. There were no differences in the surgical approach between the two groups. Cardiopulmonary bypass (CPB) time ((256.1±84.8) h vs.(217.8±58.4) h, P=0.020), postoperative mechanical ventilation time ((139.3±172.8) h vs. (35.6±45.6) h, P<0.001) were significantly longer in stroke group as compared to no-stroke group. Incidence of postoperative tracheotomy (20.0% vs. 1.1%, P<0.001), acute kidney injury (73.3% vs. 30.3%, P=0.001) and continuous renal replacement therapy (46.7% vs. 11.8%, P<0.001) as well as mortality (20.0% vs. 5.1%, P=0.022) were significantly higher in the stroke group than in non-stroke group. There was no significant difference in the basal NIRS value and the lowest NIRS value during DHCA between the two groups. Patients in the stroke group had a significantly greater intraoperative change rate of right NIRS as compared to no-stroke group (15.2%±15.7% vs. 9.2%±7.0%, P=0.006). Conclusions: NIRS is valuable for monitoring cerebral oxygen saturation during acute type A aortic dissection surgery, and the rate change of NIRS during operation correlates significantly with postoperative stroke.