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

Abstract

Background: Postoperative cognitive dysfunction (POCD) occurs commonly after cardiac surgery. Near-infrared spectroscopy (NIRS) has been used to monitor regional cerebral oxygen saturation (rScO 2) in order to minimise the occurrence of POCD by applying dedicated interventions when rScO 2 decreases. However, the association between rScO 2 intraoperatively and POCD has not been clarified. Methods: This is a secondary analysis of a randomised trial with physician-blinded NIRS monitoring and cognitive testing at discharge from hospital and at 3 months after surgery. The association between intraoperative rScO 2 values and POCD at discharge from hospital and at 3 months after surgery was investigated. The prespecified candidate predictive variable of interest was cumulative time during surgery with rScO 2 !10% below its preoperative value. Results: One hundred and fifty-three patients had complete NIRS data and neurocognitive assessments at discharge, and 44 of these patients (29%) had POCD. At 3 months, 148 patients had complete data, and 12 (8%) of these patients had POCD. The median time with rScO 2 >10% below preoperative values did not differ for patients with and without POCD at discharge (difference¼0.0 min; Hodges-Lehmann 95% confidence interval, À3.11e1.47, P¼0.88). Other rScO 2 time thresholds that were assessed were also not significantly different between those with and without POCD at discharge. This applied both to absolute rScO 2 values and relative changes from preoperative values. Similar results were found in relation to POCD at 3 months. Conclusions: No significant association was found between intraoperative rScO 2 values and POCD. These findings bring into question the rationale for attempting to avoid decreases in rScO 2 if the goal is to prevent POCD. Clinical trial registration: NCT 02185885.

Serum‐neuroproteins, near‐infrared spectroscopy, and cognitive outcome after beach‐chair shoulder surgery: Observational cohort study analyses

“…Patients with manifest neurologic incumbencies who were exposed to low rSO 2 during cardiopulmonary bypass (CPB) 11,22 could potentially have elevated biomarkers, but the CPB wash‐out effect could obliterate such results. Similarly, POCD incidence was not different in CPB patients grouped according to rSO2 profile (high‐ vs. low saturation), presumably because all patients had equal microcirculatory shortcomings undifferentiated by NIRS 27 . Our data reveal, perhaps merely an indication, that a previously unreported significant association between tau elevation and POCD z‐scores, exists.…”

Regional Cerebral Oxygen Saturation Monitoring during Spinal Surgery in Order to Identify Patients at Risk for Cerebral Desaturation

“…However, NIRS is believed to be best used as a trend monitor, without following strict thresholds [19]. It seems to be better for recognizing patients at risk than guiding interventions [20].…”

The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

“…In the latter studies, in the intervention group, cerebral StO 2 was monitored during the surgical operation by NIRS, and supplemental oxygen dosage was adjusted according to StO 2 level, while in the control group, the treatment was not directed by NIRS readings. In several studies, the intervention group demonstrated a decreased incidence of adverse events compared with the control group [ 145 , 146 , 147 ], while in similar studies [ 148 , 149 , 150 ], the NIRS-guided intervention was not associated with improved patient outcomes. Yu et al [ 151 ], in a systematic review, inferred low quality of evidence for the beneficial effect of cerebral NIRS monitoring on postoperative adverse events, such as stroke, delirium or death, due to a low number of events and wide confidence intervals.…”