[The correlation between tissue oxygen saturation and postoperative cognitive dysfunction in elderly patients with...

Objective: To investigate the correlation between tissue oxygen saturation during one lung ventilation and postoperative neuro cognitive dysfunction (PND) in elderly patients in thoracic surgery. Methods: One hundred and twenty-eight elderly patients who underwent selective lobectomy from August 2017 to September 2018 in the Forth Hospital of Hebei Medical University were enrolled. The patients were divided into PND group (n=34) and non-PND group (n=94) according to whether PND occurred 3 days after surgery. Tissue oxygenation was monitored at bilateral forebrain, brachioradialis muscle and quadriceps. Cognitive function was assessed by the Montreal Cognitive Assessment (MoCA) at baseline and the third day after the operation. Postoperative cognitive dysfunction was diagnosed if postoperative MoCA decreased at least 2 scores compared with preoperative baseline value. Outcomes included the incidence of PND, the incidence of tissue oxygen desaturation during one lung ventilation, postoperative complications within 30 days and length of postoperative in-hospital stay. Logistic regression was used to screen independent risk factors of PND. Results: The incidence of postoperative cognitive dysfunction was 26.6% (34/128). The two groups had no significant difference in the incidence of non-neurogenic complications (new occurred arrhythmia, pulmonary infection, pulmonary embolism, acute renal insufficiency, sepsis, deep vein thrombosis, all P>0.05). However, the length of postoperative in-hospital stay of PND group was 7.0 (6.0, 8.5) d, which was longer than that of non-PND group [6.0 (5.0, 8.0) d]. There was significant difference (U=2.394, P=0.017) . There was no correlation between the two groups within the minimum of SmtO(2) in upper limbs (OR=0.988, 95%CI: 0.954-1.024, P=0.519) and the range of desaturation (OR=1.010, 95%CI: 0.979-1.042, P=0.514) , as well as the minimum of SmtO(2) in legs (OR=0.996, 95%CI: 0.961-1.032, P=0.832) and the range of desaturation (OR=0.997, 95%CI: 0.971-1.025, P=0.851) . Multivariate logistic regression analysis showed that the high ASA grade (OR=2.617, 95%CI: 1.112-6.157, P=0.029) and the minimum of cerebral oxygen saturation during one lung ventilation (OR=0.931, 95%CI: 0.880-0.986, P=0.014) were independent risk factors of PND. There was no statistical correlation between muscle oxygen saturation and PND. Conclusion: Cerebral desaturation during one lung ventilation increased the risk of PND in elderly patients, while the muscle desaturation has no statistical correlation with PND.