Decreases of regional cerebral oxygen saturation reading during hip arthroplasty associated with postoperative delirium in older adults

Background Postoperative delirium (POD) is a sign of deterioration in the homeostasis and physical status of the patient. However, there have been no reports regarding the relationship between the decrease of regional cerebral oxygen saturation (rSctO2) reading during surgery and the POD in hip replacement in the elder. This study aims to investigate this correlation and the incidence of POD.Methods We performed a retrospective study of 4834 patients who underwent hip arthroplasties between 2015 and 2019 at our hospital. Data were collected as part of routine patient care. The patients’ cognitive performance was evaluated by using the Manual of Mental Disorders (DSM-IV-TR 4th edition) criteria. Patients found to be delirious after surgery served as the delirium group, other patients who did not develop delirium after surgery regarded as the no-delirium group. The various factors including the decline of rSctO2 reading intraoperatively were assessed using Multivariable logistic regression models. Odds ratio (OR) and 95% confidence intervals (CI) are reported.Results POD was found in 27 patients (n=351); the incidence of POD was 7.7%; all of them were in their 70’s or 80’s. Lab data and rSctO2 reading before surgery were no significantly difference between the delirium group and the no-delirium group. Patients who displayed the decline of rSctO2 reading intraoperatively were at higher risk for POD (compared with no-delirium patients: OR2.169 CI 1.663-2.829 p=0.000) and gender (compared with no-delirium patients: OR 0.163 CI 0.029-0.909 p=0.039) was at a higher risk. Twenty-four patients recovered from POD gradually. One patient had persistent and severe cognitive dysfunction after surgery, two patients died of complications either acute pulmonary embolism 4 days after surgery or acute stroke 21 days after surgery respectively.Conclusions The incidence of POD was 7.7%. This study shows that the decline of rSctO2 reading during hip replacement surgery in the elder is associated with increased probability for the POD.