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The perioperative application of continuous cerebral autoregulation monitoring for cerebral protection in elderly patients.

BACKGROUND
The majority of surgical patients aged 65 years and over are accompanied with underlying conditions, making them susceptible to perioperative cerebral complications. Here, we investigated the clinical value of continuous cerebral autoregulation (CA) monitoring in protecting against cerebral dysfunction in elderly patients undergoing surgery.


METHODS
This study enrolled 40 elderly patients (aged ≥65 years) and 40 middle-aged patients (aged 45 to 64 years) selected to undergo robotic-assisted laparoscopic radical prostatectomy. Cerebral oxygenation was assessed by regional cerebral oxygen saturation (rScO2) using near-infrared spectroscopy (NIRS). CA function was estimated using the cerebral oximetry index (COX), which is the rolling correlation between rScO2 and the mean arterial pressure (MAP). With the patient in the Trendelenburg position, the rScO2, MAP, calculated COX, HR, end-tidal CO2, and sevoflurane concentrations were continuously recorded. Standardized anesthesia was administered to all patients (sevoflurane, propofol, remifentanil, and rocuronium). Postoperative delirium (POD) was screened for daily using the Confusion Assessment Method (CAM). The primary outcome was the difference in periods of CA dysfunction between the elderly and middle-aged groups. Secondary outcomes included the incidence of POD and the optimal MAP range in the 2 groups.


RESULTS
Taking positive COX values (cutoff ≥0.3) to reflect periods of CA dysfunction, we found that the cumulative duration of CA dysfunction in the Trendelenburg position was longer in elderly patients than in middle-aged patients [ratio of cumulative time of CA dysfunction: middle-aged group, 32.8% (26.3%, 43.1%) vs. elderly group, 42.2% (33.1%, 51.2%)] (P<0.01), which showed that CA function was less efficient in elderly patients. Three patients (7.5%) in the elderly group and 1 patient (2.5%) in the middle-aged group screened positive for POD on at least 1 day during their hospital stay. Additionally, using the COX-based method, we estimated the optimal MAP targets in the middle-aged and elderly groups to be (67.8±8.9, 116.4±10.5) and (71.2±12.5, 111.3±8.9) mmHg, respectively.


CONCLUSIONS
The brains of patients ≥65 years are more vulnerable to systemic insult compared with those of middle-aged patients. POD may be associated with CA dysfunction. NIRS-derived COX can be used to identify the optimal MAP range.