Newly Published
Perioperative Medicine  |   April 2020
Electroencephalogram Burst-suppression during Cardiopulmonary Bypass in Elderly Patients Mediates Postoperative Delirium
Author Notes
  • From the Departments of Anesthesia, Critical Care, and Pain Medicine (J.C.P., G.S.P., S.C., E.H., B.E., J.G., R.I., J.M., K.M.C., T.H., K.T.S., J.Q., O.A.), Department of Neurology (J.J.L., M.B.W.), Department of Surgery, Division of Cardiac Surgery (D.A.D., G.T.), Henry and Allison McCance Center for Brain Health (M.B.W., O.A.), and Clinical Data Animation Center (M.B.W.), Massachusetts General Hospital, Boston, Massachusetts; Department of Anesthesiology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile (J.C.P.); and Tufts University School of Medicine, Boston, Massachusetts (G.S.P.).
  • Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).
    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • Submitted for publication April 22, 2019. Accepted for publication March 26, 2020.
    Submitted for publication April 22, 2019. Accepted for publication March 26, 2020.×
  • Correspondence: Address correspondence to Dr. Akeju: Massachusetts General Hospital, 55 Fruit Street, Grey/Jackson, Rm. 464, Boston, Massachusetts 02114. oluwaseun.akeju@mgh.harvard.edu. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Perioperative Medicine / Central and Peripheral Nervous Systems
Perioperative Medicine   |   April 2020
Electroencephalogram Burst-suppression during Cardiopulmonary Bypass in Elderly Patients Mediates Postoperative Delirium
Anesthesiology Newly Published on April 22, 2020. doi:https://doi.org/10.1097/ALN.0000000000003328
Anesthesiology Newly Published on April 22, 2020. doi:https://doi.org/10.1097/ALN.0000000000003328
Abstract

Background: Intraoperative burst-suppression is associated with postoperative delirium. Whether this association is causal remains unclear. Therefore, the authors investigated whether burst-suppression during cardiopulmonary bypass (CPB) mediates the effects of known delirium risk factors on postoperative delirium.

Methods: This was a retrospective cohort observational substudy of the Minimizing ICU [intensive care unit] Neurological Dysfunction with Dexmedetomidine-induced Sleep (MINDDS) trial. The authors analyzed data from patients more than 60 yr old undergoing cardiac surgery (n = 159). Univariate and multivariable regression analyses were performed to assess for associations and enable causal inference. Delirium risk factors were evaluated using the abbreviated Montreal Cognitive Assessment and Patient-Reported Outcomes Measurement Information System questionnaires for applied cognition, physical function, global health, sleep, and pain. The authors also analyzed electroencephalogram data (n = 141).

Results: The incidence of delirium in patients with CPB burst-suppression was 25% (15 of 60) compared with 6% (5 of 81) in patients without CPB burst-suppression. In univariate analyses, age (odds ratio, 1.08 [95% CI, 1.03 to 1.14]; P = 0.002), lowest CPB temperature (odds ratio, 0.79 [0.66 to 0.94]; P = 0.010), alpha power (odds ratio, 0.65 [0.54 to 0.80]; P < 0.001), and physical function (odds ratio, 0.95 [0.91 to 0.98]; P = 0.007) were associated with CPB burst-suppression. In separate univariate analyses, age (odds ratio, 1.09 [1.02 to 1.16]; P = 0.009), abbreviated Montreal Cognitive Assessment (odds ratio, 0.80 [0.66 to 0.97]; P = 0.024), alpha power (odds ratio, 0.75 [0.59 to 0.96]; P = 0.025), and CPB burst-suppression (odds ratio, 3.79 [1.5 to 9.6]; P = 0.005) were associated with delirium. However, only physical function (odds ratio, 0.96 [0.91 to 0.99]; P = 0.044), lowest CPB temperature (odds ratio, 0.73 [0.58 to 0.88]; P = 0.003), and electroencephalogram alpha power (odds ratio, 0.61 [0.47 to 0.76]; P < 0.001) were retained as predictors in the burst-suppression multivariable model. Burst-suppression (odds ratio, 4.1 [1.5 to 13.7]; P = 0.012) and age (odds ratio, 1.07 [0.99 to 1.15]; P = 0.090) were retained as predictors in the delirium multivariable model. Delirium was associated with decreased electroencephalogram power from 6.8 to 24.4 Hertz.

Conclusions: The inference from the present study is that CPB burst-suppression mediates the effects of physical function, lowest CPB temperature, and electroencephalogram alpha power on delirium.

Editor’s Perspective:

What We Already Know about This Topic:

  • Associations between intraoperative burst suppression and postoperative delirium have been reported.

  • The causal significance of these associations is unknown.

What This Article Tells Us That Is New:

  • In a retrospective observational substudy of 159 patients undergoing cardiac surgery, there is evidence that burst suppression during cardiopulmonary bypass mediates the effect of physical function, temperature during cardiopulmonary bypass, and intraoperative electroencephalographic alpha power on postoperative delirium. Delirium was also associated with decreased broadband power in the intraoperative electroencephalogram.