The etiology of postcardiac surgery delirium is complex. Our primary objective was to determine the effect of the postoperative environment on the prevalence of delirium by examining the in-hospital delirium rates in 2 postoperative intensive care units with differing physical infrastructure. We further sought to identify other risk factors associated with in-hospital delirium.
Methods
The rates of postoperative delirium were retrospectively examined in consecutive cardiac surgery patients during 2 separate 6-month periods. Environment 1 was characterized by a lack of physical barriers between bed spaces and was windowless, and environment 2 consisted of private rooms with physical barriers for each patient and with wall-to-wall exterior windows. Univariate and multivariate analyses to determine the risk factors associated with in-hospital delirium, including the effect of environment, were undertaken.
Results
Of the 1010 patients studied, 148 (14.7%) experienced in-hospital delirium after cardiac surgery. The prevalence of delirium was not significantly different between environments 1 and 2 (16.1% vs 13.5%; P = .25). However, in patients younger than 65 years, the proportion of intensive care unit days on which delirium occurred was greater in environment 1 than in environment 2 (5.4% vs 1.7%; P = .006). Postoperative stroke or transient ischemic attack, mechanical ventilation longer than 24 hours, age 65 years or older, concomitant coronary artery bypass grafting and valve surgery, prehospital admission benzodiazepine use, a requirement for any postoperative blood product transfusion, and postoperative renal insufficiency were identified as risk factors.
Conclusions
The intensive care unit environment did not have a significant effect on the overall prevalence of delirium. However, that does not preclude the possibility that the intensive care unit environment might interact with other factors, such as age, in a complex manner. Attempts to reduce delirium by adjusting the intensive care unit environment alone will likely not be sufficient, and instead will require a more comprehensive multimodal approach.
CTSNet classification
41.1
Abbreviations and Acronyms
CABG
coronary artery bypass grafting
CAM
Confusion Assessment Method
CAM-ICU
CAM for the intensive care unit
E1
environment 1
E2
environment 2
ICU
intensive care unit
IQR
interquartile range
RASS
Richmond Agitation-Sedation Scale
TIA
transient ischemic attack
Cited by (0)
This study was supported by an internal grant from the Department of Anesthesia and Perioperative Medicine, University of Manitoba Faculty of Medicine, Winnipeg, Manitoba, Canada.
Disclosures: Authors have nothing to disclose with regard to commercial support.