Effect Of Cerebral Oxygen Saturation Guided Metaraminol Pump On Postoperative Delirium In Elderly Patients Undergoing Hip Arthroplasty

Objective:To explore the effect of cerebral oxygen saturation guided metaraminol pump on postoperative delirium in elderly patients undergoing hip arthroplasty.Methods:A total of 100 elderly patients who underwent hip replacement in our hospital from April 2022 to December 2022 were selected,aged 65-85 years old,ASA grade II-III,BMI:18.5-28kg/m²,and randomly divided into two groups（n=50）:metaraminol group（group M）and control group（group C）.Patients in both groups were operated under general anesthesia.Invasive radial artery catheterization was performed under local anesthesia before operation,and mean arterial pressure（MAP）was continuously monitored during the operation.Regional cerebral oxygen saturation（r SO₂）was continuously monitored by cerebral oxygen saturation monitor.The forehead and cerebral oxygen saturation probe were disinfected with alcohol cotton tablets.The cerebral oxygen saturation probe was tightly fixed on the 1.5cm on both eyebrows of the patient.Shading measures were taken on the probe and the surface of the tested site.In group M,the dose of metaraminol was regulated under the guidance of r SO₂,and the pump speed of metaraminol was 0.2-2.0μg·kg^-1·min^-1,with a change rate of r SO₂≤5%;in group C,routine anesthetic management was performed,r SO₂ was monitored during operation,but the monitoring screen will be covered,and the change of r SO₂ was not used as a regulation index during operation;20%of the change of MAP≤basal value should be maintained in both groups.The general conditions of the patients in the two groups were recorded,including sex,age,BMI,ASA grade,education level,history of hypertension,history of diabetes and preoperative mini-mental state scale（MMSE） score.MAP,r SO₂ and heart rate（HR）were recorded at each time point,including 5min after inhaling oxygen（T₀）,5min after anesthesia induction（T₁）,5min after changing posture（T₂）,5min after operation（T₃）,30min after operation（T₄）,60min after operation（T₅）and after operation（T₆）.The duration of operation,duration of anesthesia,blood loss,infusion volume,urine volume,the use of isoproterenol during operation,postoperative adverse reactions and total hospital stay were recorded,and the levels of partial pressure of oxygen,partial pressure of carbon dioxide,hemoglobin and blood glucose in arterial blood gas analysis before and after operation were recorded.The levels of neuron specific enolase（NSE）and central nervous system specific protein（S100β）in peripheral venous blood were recorded before and 24 hours after operation,and the MMSE scores,confusion assessment method-Chinese reversion（CAM-CR）and visual analogue scale（VAS）scores were recorded 24 hours,48 hours and 72 hours after operation,and the incidence of postoperative delirium（POD）was recorded in the two groups.Results:1.Compared with group C,MAP and r SO₂ in group M were significantly higher at T₁-T₆（P<0 05）.2.Compared with group C,MMSE score was higher and CAM-CR score was lower in group M at 24 and 48 hours after operation（P<0.05）.3.The levels of NSE and S100βin peripheral venous blood at 24 hours after operation in both groups were significantly higher than those before operation,and the levels of NSE and S100βin group M were significantly lower than those in group C at24 hours after operation（P<0.05）.4.Compared with group C,the incidence of POD in group M was significantly lower at 3 days after operation（P<0.05）.Conclusion:Continuous infusion of metaraminol under the guidance of cerebral oxygen saturation can increase the intraoperative levels of MAP and r SO₂ in elderly patients undergoing hip arthroplasty under general anesthesia,reduce the CAM-CR score at 24 and 48 hours after operation,and reduce the levels of NSE and S100βat 24hours after operation,thus reducing the incidence of postoperative delirium and has a certain brain protective effect.