Impact of Regional Cerebral Oximetry Monitoring on Post-operative Neurocognitive Dysfunction
Intraoperative monitoring of cerebral oxygen saturation (rSO2) using near-infrared spectroscopy (NIRS) may prevent postoperative neurocognitive dysfunction, though evidence shows mixed results with a weak recommendation (Class IIb) for its routine use.
Current Guideline Recommendations
Intraoperative monitoring of cerebral oxygen saturation (near-infrared spectroscopy) has been shown to guide anesthetic decision-making and may prevent postoperative neurocognitive dysfunction according to the 2021 ACC/AHA/SCAI guideline for coronary artery revascularization 1
The 2019 EACTS/EACTA/EBCP guidelines on cardiopulmonary bypass in adult cardiac surgery provide a Class IIb, Level B recommendation that "the use of NIRS-guided algorithms to improve clinical outcomes may be considered" 1
Earlier guidelines (2011 ACCF/AHA) stated that "the effectiveness of routine use of intraoperative or early postoperative monitoring of cerebral oxygen saturation via near-infrared spectroscopy to detect cerebral hypoperfusion in patients undergoing CABG is uncertain" 1
Mechanism and Clinical Applications
NIRS-based cerebral oximetry measures the hemoglobin saturation of blood in a specific "optical field" containing arterial, capillary, and venous blood, providing a non-invasive continuous measurement of regional cerebral oxygen saturation 2
Several studies suggest that the magnitude and duration of cerebral oxygen desaturation are associated with early postoperative neuropsychological dysfunction and prolonged hospital stays after cardiac surgery 1
Cerebral oximetry monitoring allows for the implementation of interventional algorithms aimed at improving cerebral oxygen supply/demand ratio when desaturation is detected 1, 3
Evidence for Effectiveness
A landmark study of 200 patients undergoing on-pump CABG found that while there were no differences in overall complication rates, the rates of major organ morbidity and mortality were significantly lower in patients treated using a NIRS-based algorithm 1
A randomized controlled trial with 200 CABG patients showed that the incidence of cognitive decline 7 days after surgery was significantly lower (28% vs 52%, p=0.002) in the NIRS interventional group compared to the control group 3
Patients with prolonged rSO2 desaturation, defined as area under the curve of more than 150 min% for desaturation below 20% of baseline or more than 50 min% for desaturation below 50% absolute value, had an increased risk of cognitive decline 3
However, two recent high-quality trials and a meta-analysis of 1466 patients from 10 randomized controlled studies showed no clinical benefit of NIRS-based algorithms in cardiac surgery patients at high risk of complications 1
Evidence in Non-cardiac Surgery
A pilot study in patients undergoing lumbar spine surgery in prone position found significant differences in cognitive performance between patients monitored with NIRS versus those without monitoring, suggesting potential benefits beyond cardiac surgery 4
A 2024 systematic review and meta-analysis of randomized controlled trials in noncardiac surgical patients found that optimized anesthesia management guided by intraoperative rSO2 monitoring significantly reduced the incidence of postoperative cognitive dysfunction within 7 days postoperatively 5
The same meta-analysis suggested potential reduction in cognitive dysfunction at 3 months but noted it may not reduce postoperative delirium or shorten hospital length of stay 5
Implementation Considerations
The American Society for Enhanced Recovery and Perioperative Quality Initiative consensus recommends interpreting perioperative cerebral oximetry measurements in the context of a pre-induction baseline value and the physiologic variables that affect them 2
Different commercial cerebral oximeters have technical differences that make them non-interchangeable, requiring caution when comparing values between different manufacturers 2
For optimal effectiveness, cerebral oximetry should be used with standardized interventional protocols designed to maintain rSO2 above 80% of the patient's baseline value or above 50% of the absolute value 3
Conclusion
While the evidence is mixed regarding the routine use of cerebral oximetry monitoring for preventing postoperative neurocognitive dysfunction, the most recent guidelines and studies suggest it may be beneficial, particularly in cardiac surgery and potentially in high-risk noncardiac procedures. The technology continues to evolve, and further high-quality studies are needed to strengthen the evidence base for its widespread implementation.