Raised IL-2 and TNF-α Concentrations are Associated with Postoperative Delirium in Patients undergoing Coronary-Artery Bypass Graft Surgery

Background:
The knowledge base regarding the pathogenesis of
postoperative delirium is limited. The primary aim of this study is to
investigate whether increased levels of IL-2 and TNF-α are associated
with delirium in patients who underwent coronary-artery bypass graft
(CABG) surgery with cardiopulmonary bypass (CPB). The secondary aim is
to establish whether any association between raised cytokine levels and
delirium is related to surgical and anesthetic procedures or mediated by
pre-existing conditions associated with raised cytokine levels, such as
major depressive disorder (MDD), cognitive impairment, or aging.

Methods:
Patients were examined and screened for MDD and cognitive
impairment one day preoperatively, using the Mini International
Neuropsychiatric Interview and The Montreal Cognitive Assessment and
Trail Making Test Part B. Blood samples were collected postoperatively
for cytokine levels. Results: Postoperative delirium screening was found
positive in 36% (41 of 113) of patients. A multivariate logistic
regression revealed that an increased concentration of pro-inflammatory
cytokines is associated with delirium, and related to advancing age,
preoperative cognitive decline of participants, and duration of CPB.
According to receiver operating characteristic analysis, the most
optimal cut-off for IL-2 and TNF-α concentrations in predicting the
development of delirium were 907.5 U/ml and 10.95 pg/ml, respectively.

Conclusions:
The present study suggests that raised postoperative
cytokine concentrations are associated with delirium after CABG surgery.
Postoperative monitoring of pro-inflammatory markers combined with
regular surveillance may be helpful in the early detection of
postoperative delirium in this patient group.