Outcomes in Cardiac Surgery Based on Preoperative, Mean Intraoperative and Stratified Cerebral Oximetry Values

Abstract

Introduction: Cardiac surgery is associated with significant morbidity and longer length-of-stay (LOS) than most other surgeries. Regional cerebral oximetry (rSO 2 ) using near-infrared spectroscopy (NIRS) on the patient's forehead monitors cerebral oxygenation during surgery and cardiopulmonary bypass (CPB). Its purpose is to detect and manage periods of cerebral hypoxia which may otherwise go undetected, thereby reducing morbidity. But outcomes have been inconsistent, and not all cardiac departments have adopted this non-invasive, simple-to-use technology. We aimed to study the efficacy of our use of rSO 2 by recording seven outcomes for each patient according to their preoperative rSO 2 , the mean intraoperative rSO 2 , and four ischemic thresholds during surgery.Method: This is a retrospective audit of cardiac surgical patients in whom a protocol was used to maintain rSO 2 above the preoperative value and studied seven major morbidity outcomes. Cerebral oximetry data were recorded for each patient and analyzed for six variables: preoperative baseline rSO 2 , mean intraoperative rSO 2, and four ischemic thresholds defined as an area under the curve (AUC) in minutes% below the baseline rSO 2 , minus 10% below the baseline, minus 20% the below baseline and minus 50% below baseline. Outcomes examined were: delirium, stroke, postoperative rise in creatinine of 50 mmol, absolute creatinine of 200 mmol, need for new renal replacement therapy (RRT), hospital LOS and inpatient mortality.Results: Complete data were available for 166 patients. Lower mean preoperative rSO 2 was associated with stroke (p=0.031), mild and severe renal dysfunction (p=0.045 and p=0.036), death-in-hospital (p=0.027) and prolonged hospital LOS (p=0.005). Lower mean intraoperative rSO 2 during surgery was associated with the outcomes of renal dysfunction, mild (p=0.027), moderate (p=0.003) or severe (p=0.002), death-inhospital (p=0.003) and prolonged hospital LOS (p=0.015). Of the four ischemic thresholds defined, only new RRT occurring at minus 20% and minus 50% below baseline was significant. Conclusion: Lower preoperative rSO 2 and mean intraoperative rSO 2 were associated with poor outcomes, notably leading to a significant increase in hospital LOS. Mild degrees of cerebral ischemia below the baseline and minus 10% of the baseline during surgery were well tolerated.

Low Intraoperative Cerebral Oxygen Saturation Is Associated with Acute Kidney Injury after Off-Pump Coronary Artery Bypass

“…The baseline rScO 2 , lowest rScO 2 and AUT 50 , but not AUT 80%base , showed significant association with AKI but lower AUROCs. Similarly, patients experiencing major organ morbidity or mortality had lower baseline and mean rScO 2 values [23], and low mean rScO 2 was seen in patients developing any degree of renal dysfunction after cardiac surgery using CPB [13]. Likewise, the prognostic importance of baseline rScO 2 in cardiac surgical patients was recommended to be used for risk stratifi-cation, while evidence was deemed insufficient to recommend the use of intraoperative rScO 2 to reduce organ-specific morbidity [24,25].…”

“…Studies have explored the association between rScO 2 and AKI in cardiac surgical patients, but the results were inconclusive [7,12,13]. These studies were mostly underpowered and addressed surgeries using cardiopulmonary bypass (CPB).…”

Factors Associated with Early Mortality in Acute Type A Aortic Dissection—A Single-Centre Experience

“…The period from the removal of the aortic clamp until systemic rewarming is complete is subsequently referred to as the "reperfusion time". Cerebral perfusion was monitored throughout the procedure using near-infrared spectroscopy (NIRS) [8,9].…”

Cerebral Perfusion and Neuromonitoring during Complex Aortic Arch Surgery: A Narrative Review

“…There are no defined normal or abnormal values for regional cerebral oxygen saturation. The most widely adopted definition for brain desaturation is a reduction of the rSO 2 area under the curve (AUC) >20% of baseline value, or rSO 2 under 50% of absolute value [61,64,65].…”