Differences in regional cerebral oximetry during cardiac surgery for patients with or without postoperative cerebral ischaemic lesions evaluated by magnetic resonance imaging

Abstract

Background: Near infrared spectroscopy (NIRS) is widely used to monitor regional cerebral tissue oxygenation (rScO 2 ). We compared rScO 2 values during cardiac surgery in patients with or without new cerebral ischaemic lesions on diffusion weighted magnetic resonance imaging (DWI). We hypothesised patients with new cerebral lesions would have impaired tissue oxygenation reflected in their rScO 2 values. Methods: NIRS and DWI data were collected in 152 elective cardiac surgery patients. Absolute rScO 2 values, duration of desaturation below thresholds (baseline, 10%, and 20%), and accumulated cerebral desaturation load were compared between patients with or without new cerebral lesions on DWI. Primary outcome was time below 10% from rScO 2 baseline. Results: The time below 10% from rScO 2 baseline was significantly longer for patients with new cerebral lesions than for patients without [median (inter-quartile range): 11.0 (0.4; 37.5) min vs 1.8 inter-quartile range: (0.05; 20.9) min, P¼0.02]. Furthermore, they had a higher accumulated desaturation load below baseline (P¼0.02) and 10% below baseline (P¼0.02). Finally, their absolute minimum rScO 2 value was significantly lower (P¼0.01). However, the frequency of patients with desaturation below 10% and 20% was comparable between patients with and without new cerebral lesions. Receiveroperating characteristic curve analysis did not identify a clear-cut critical threshold among the investigated rScO 2 variables. Conclusions: Use of NIRS identified significant group differences in rScO 2 values between patients with or without new ischaemic lesions. However, a critical threshold could not be identified because of a high variation in NIRS values across both groups.

The association between postoperative cognitive dysfunction and cerebral oximetry during cardiac surgery: a secondary analysis of a randomised trial

“…In a previous paper, we observed that patients with new lesions on DWI had lower rScO 2 values compared with patients without lesions, both in terms of time below rScO 2 baseline and time below 10% desaturation from the preoperative value, CDL preoperative, CDL10, and minimum rScO 2 . 9 These findings indicate that the NIRS monitoring somehow reflects cerebral damage, whereas there were no differences in severity and duration of desaturation when looking for POCD. Fifty-two patients had POCD either at discharge or at 3 months and new cerebral lesions on DWI, reflecting a markedly higher frequency of DWI lesions in patients with POCD.…”

“…The trial found that low rScO 2 was associated with new cerebral lesions evaluated by diffusion weighted MRI (DWI), but no obvious BP safety threshold could be idenfied. 9 In the current study, we aimed to explore associations between blinded NIRS measurements and neuropsychological test data collected in the PPCI trial. We hypothesised that patients with POCD would have longer cumulative time with rScO 2 >10% below its baseline values.…”

Cerebrovascular Disease and Perioperative Neurologic Vulnerability: A Prospective Cohort Study

“…With this participant, the pre-defined oximetry strategy may not have been sensitive enough to detect the injury. In fact, recent evidence demonstrates that the magnitude of time spent below a 10% relative decrease correlates with MRI findings of ischemia after cardiac surgery (34). Additionally, the nature of the injury might not have been detected by the near-infrared spectroscopy methodology.…”

“…For example, real-time correlation analysis with cerebral oximetry and mean arterial blood pressure may allow for individual autoregulation monitoring intraoperatively (37). Surgical patients with pre-existing cerebrovascular disease may benefit from such dynamic cerebrovascular monitoring strategies, given that absolute oximetry thresholds are difficult to establish (34). Cognitive function scores were also lower in the cerebrovascular disease group across the entire perioperative period.…”

Commentary: Is seeing believing?

“…Interpretation of values and trends is challenging due to wide variations in baseline values. 2,3 These limitations may explain the findings of a systematic review by Zheng and colleagues, 4 in which they state that ''data are insufficient to conclude that interventions to improve rScO 2 desaturation prevent stroke or POCD [postoperative cognitive dysfunction].'' Adjuncts to help interpret rSO 2 include transcranial Doppler flow ultrasonography, bispectral index monitoring, and electroencephalographic monitoring.…”