Effects Of Cerebral Oxygen Desaturation During Single Lung Ventilation On Early Postoperative Cognitive Function

Objective:The objective of this prospective study is to determine effects on cerebral desaturation on early postoperative cognitive function after single lung ventilation.Methods:Seventy-six patients undergoing lung surgery with single-lung ventilation (SLV) of an expected duration of>45min were enrolled. None of the patients received any medication before surgery. Before general anesthesia, an epidural catheter was inserted at T4,5or T5,6level for perioperative analgesia. Radial arterial line placement was used for intraoperative invasive blood pressure monitoring. After intravenous anesthesia induction, a double-lumen tube was inserted under bronchoscopic assistance. Monitoring consisted of standard clinical parameters and absolute oximetry (SctO2). The Mini-Mental State Exam (MMSE) test was used to assess cognitive function before operation and at3h and24h after operation. A decline of2points in MMSE is considered as postoperative cognitive dysfunction (POCD). Data were analyzed using Spearman correlation test; risks for cognitive dysfunction were expressed as odds ratios. P<0.05was considered as statistically significant, data are presented as median (interquartile range).Results:Data of75patients were taken into analysis; one patient was excluded from the study analysis. SctO2during SLV decreased to critical values of<65%,60%, and55%in40(53%),15(20%), and5patients (7%), respectively. Twenty-two patients (29%) had a decrease of MMSE>2points3h after surgery. Eight patients (10%) had a decrease of MMSE>2points24h after surgery. Postoperative cognitive dysfunction correlated at r=0.272,0.285,0.297with patient exposure times to SctO2<65%(P=0.018),<60%(P=0.013),<55%(P=0.010), respectively. The odds ratio of developing early cognitive dysfunction ranged from2.03(95%CI:0.74-5.59) for a short (<5min) exposure to SctO2<65%to a maximum of9.56(95%CI:1.75-52.13) when SctO2-was<60%for more than30min.Conclusions:Early cognitive dysfunction after lung surgery with SIN is positively related to intraoperative deeline of SctO2, depending on its degree and time under threshold.