Association between postoperative delirium and postoperative cerebral oxygen desaturation in older patients after cardiac surgery

Abstract

Background: Near-infrared spectroscopy non-invasively measures regional cerebral oxygen saturation. Intraoperative cerebral desaturations have been associated with worse neurological outcomes. We investigated whether perioperative cerebral desaturations are associated with postoperative delirium in older patients after cardiac surgery. Methods: Patients aged 70 yr and older scheduled for on-pump cardiac surgery were included between 2015 and 2017 in a single-centre, prospective, observational study. Baseline cerebral oxygen saturation was measured 1 day before surgery. Throughout surgery and after ICU admission, cerebral oxygen saturation was monitored continuously up to 72 h after operation. The presence of delirium was assessed using the confusion assessment method for the ICU. Association with delirium was evaluated with unadjusted analyses and multivariable logistic regression. Results: Ninety-six of 103 patients were included, and 29 (30%) became delirious. Intraoperative cerebral oxygen saturation was not significantly associated with postoperative delirium. The lowest postoperative cerebral oxygen saturation was lower in patients who became delirious (P¼0.001). The absolute and relative postoperative cerebral oxygen saturation decreases were more marked in patients with delirium (13 [6]% and 19 [9]%, respectively) compared with patients without delirium (9 [4]% and 14 [5]%; P¼0.002 and P¼0.001, respectively). These differences in cerebral oxygen saturation were no longer present after excluding cerebral oxygen saturation values after patients became delirious. Older age, previous stroke, higher EuroSCORE II, lower preoperative Mini-Mental Status Examination, and more substantial absolute postoperative cerebral oxygen saturation decreases were independently associated with postoperative delirium incidence. Conclusions: Postoperative delirium in older patients undergoing cardiac surgery is associated with absolute decreases in postoperative cerebral oxygen saturation. These differences appear most detectable after the onset of delirium. Clinical trial registration: NCT02532530.

Effects of electroencephalography and regional cerebral oxygen saturation monitoring on perioperative neurocognitive disorders: a systematic review and meta-analysis

“…It has been revealed by several studies that the risk of PND is increased by either that excessively deep anesthesia or lower level of regional cerebral oxygen saturation during the operation [11][12][13]. These findings provided evidence to support the necessities of maintaining proper depth of anesthesia and enhancing cerebral perfusion, therefore increasing the level of cerebral oxygen saturation.…”

The Use of Near-Infrared Spectroscopy and/or Transcranial Doppler as Non-Invasive Markers of Cerebral Perfusion in Adult Sepsis Patients With Delirium: A Systematic Review

“…Thus, it is still unclear if altered cerebral perfusion is similar across delirium subtypes and if these neurophysiologic alterations resolve concurrently with delirium cessation. Furthermore, as excessive burst suppression has been previously associated with delirium, 61,62 as well as increased mortality in the ICU, 63 electroencephalography may be another viable non-invasive neuromonitoring device to provide additional neurological information as an adjunct to NIRS and/or TCD monitoring. Additionally, numerous studies did not report an a priori power analysis and had small sample sizes (n < 20), which may limit the validity of study findings.…”

Why is delirium more frequent in the elderly?

“…Harman [ 135 ] suggested that this process, which induces muscle volume to shrink from mid-life onwards, was the basic mechanism of aging but it is now regarded as just part of the involution of various interactive cell pathways [ 136 ]. However, it has been suggested that delirium is related to oxidative neuronal stress because oxygen saturation and catalase levels are consistently lowered in delirious post-operative patients [ 137 , 138 ]. Neurons are particularly vulnerable to mitochondrial impairment and anaerobic metabolism, and the consistently increased lactate levels in elderly brains due to mitochondrial involvement may be a marker of aging in general [ 139 ].…”