Intraoperative Glycemic Variability and Mean Glucose are Predictors for Postoperative Delirium After Cardiac Surgery: A Retrospective Cohort Study

Abstract

Purpose

Postoperative delirium (POD) is a common but serious complication after cardiac surgery and is associated with various short- and long-term outcomes. In this study, we investigated the effects of intraoperative glycemic variability (GV) and other glycemic variables on POD after cardiac surgery.

Patients and Methods

A retrospective single-center cohort analysis was conducted using data from electronic medical record from 2018 to 2020. A total of 705 patients undergoing coronary artery bypass graft surgery and/or valve surgery, and/or aortic replacement surgery were included in the analysis. Intraoperative GV was assessed with a coefficient of variation (CV), which was defined as the standard deviation of five intraoperative blood glucose measurements divided by the mean. POD assessment was performed three times a day in the ICU and twice a day in the ward until discharge by trained medical staff. POD was diagnosed if any of the Confusion Assessment Method for the Intensive Care Unit was positive in the ICU, and the Confusion Assessment Method was positive in the ward. Multivariable logistic regression was used to identify associations between intraoperative GV and POD.

Results

POD occurred in 306 (43.4%) patients. When intraoperative glycemic CV was compared as a continuous variable, the delirium group had higher intraoperative glycemic CV than the non-delirium group (22.59 [17.09, 29.68] vs 18.19 [13.00, 23.35], p < 0.001), and when intraoperative glycemic CV was classified as quartiles, the incidence of POD increased as intraoperative glycemic CV quartiles increased (first quartile 29.89%; second quartile 36.67%; third quartile 44.63%; and fourth quartile 62.64%, p < 0.001). In the multivariable logistic regression model, patients in the third quartile of intraoperative glycemic CV were 1.833 times (OR 1.833, 95% CI: 1.132–2.967, p = 0.014), and patients in the fourth quartile of intraoperative glycemic CV were 3.645 times (OR 3.645, 95% CI: 2.235–5.944, p < 0.001) more likely to develop POD than those in the first quartile of intraoperative glycemic CV.

Conclusion

Intraoperative blood glucose fluctuation, manifested by intraoperative GV, is associated with POD after cardiac surgery. Patients with a higher intraoperative GV have an increased risk of POD.

Keywords:

• postoperative delirium
• cardiac surgery
• glycemic variability
• coefficient of variation

Abbreviations

POD, postoperative delirium; ICU, intensive care unit; NYHA, New York Heart Association; CPB, cardiopulmonary bypass pump; HbA1c, hemoglobin A1c; GV, glycemic variability; IRB, Institutional Review Board; CABG, coronary artery bypass graft surgery; CAM-ICU, Confusion Assessment Method for the Intensive Care Unit; CAM, Confusion Assessment Method; CV, coefficient of variation; BIS, bispectral index; BMI, body mass index; EuroSCORE, European System for Cardiac Operative Risk Evaluation; GFR, glomerular filtration rate; CRP, c-reactive protein; TCA, total circulatory arrest; PRC, packed red blood cell; VIS, vasoactive-inotropic score; MAE, major adverse events; AUROC, area under the receiver operator characteristics.

Data Sharing Statement

The data used and/or analyzed during this study are available from the corresponding author on reasonable request.

Acknowledgments

We would like to thank Editage (www.editage.co.kr) for English language editing.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT; Ministry of Science and ICT) (No. 2021R1G1A1014702). The funder played no part in the study design; the collection, management, analysis, or interpretation of the data; the writing of the report; or the decision to submit the report for publication.