NIRS-assisted cerebral autoregulation in elderly patients during thoracic surgery: a prospective observational study

Postoperative cerebral complications may be related to abnormal intraoperative cerebral blood flow, and blood pressure fluctuations are common during thoracoscopic surgery and affect the cerebral blood supply, especially in elderly patients. Here, we investigated the clinical value of continuous cerebral autoregulation (CA) monitoring in protecting against cerebral dysfunction in elderly patients undergoing thoracoscopic surgery. This study included 84 patients who underwent video-assisted thoracoscopic lobectomy under general anaesthesia and were divided by age into an elderly group (aged ≥ 65 years, 40 patients) and a middle-aged group (aged 40–64 years, 44 patients) based on age-related physiological differences that may influence cerebral autoregulation and postoperative outcomes. General patient information, intraoperative regional cerebral saturation oxygenation (rScO2), mean arterial pressure (MAP), and the surgery duration were recorded. The Pearson correlation coefficient between rScO2 and MAP was calculated to obtain the cerebral oximetry index (COx), which was used to assess CA function and determine the upper limit of cerebral autoregulation (ULA) and the lower limit of cerebral autoregulation (LLA), i.e., the optimal MAP range. Postoperative delirium (POD) was assessed using the 3-Minute Diagnostic Confusion Assessment Method (3D-CAM). All patients underwent total intravenous anaesthesia. The primary observation was the difference in the cumulative time of impaired CA function between the elderly and middle-aged groups. The secondary observations included the incidence rates of POD and the optimal MAP range in both groups. Elderly patients had a significantly longer cumulative impaired CA time than middle-aged patients (cumulative impaired CA time ratio (%): middle-aged group, 9.72 ± 6.44 vs. elderly group, 20.41 ± 9.27; P<0.001). Two patients (5%) in the elderly group and 1 patient (2.27%) in the middle-aged group screened positive for POD on at least 1 day. Furthermore, based on the COx calculation, the optimal MAP range was determined to be (67.13 ± 5.46,96.40 ± 7.01) mmHg for the elderly group and (63.77 ± 5.74,101.66 ± 8.23) mmHg for the middle-aged group. Compared with middle-aged patients, elderly patients have double the duration of intraoperative cerebral blood flow autoregulation impairment, and their optimal mean arterial pressure (MAP) range is narrower, with the maintenance interval being 10 mmHg smaller than that of middle-aged patients (67–96 mmHg in elderly patients vs. 63–102 mmHg in middle-aged patients). The study was registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn/; registration no. ChiCTR2400080120; registration date: January 22, 2024).