Randomized Controlled Trial

. 2021 Nov;127(5):704-712.

doi: 10.1016/j.bja.2021.07.021. Epub 2021 Aug 28.

Anaesthetic depth and delirium after major surgery: a randomised clinical trial

Affiliations

¹ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Anaesthesia and Acute Pain Medicine, St Vincent's Hospital, Melbourne, VIC, Australia; Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia. Electronic address: lae4004@med.cornell.edu.
² Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
³ Department of Anesthesiology, Beijing Tiantan Hospital and Capital Medical University, Beijing, China.
⁴ Department of Anaesthesia and Acute Pain Medicine, St Vincent's Hospital, Melbourne, VIC, Australia; Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia.
⁵ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
⁶ Department of Outcomes Research, Cleveland Clinic, Cleveland, OH, USA.
⁷ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Anesthesiology and Critical Care Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
⁸ Department of Medicine, University of Otago, Christchurch, New Zealand.
⁹ Department of Anaesthesiology, Auckland City Hospital, Auckland, New Zealand.
¹⁰ Department of Anaesthesia and Perioperative Medicine, Alfred Hospital and Monash University, Melbourne, VIC, Australia.
¹¹ Department of Anaesthesiology, Auckland City Hospital, Auckland, New Zealand; Department of Anaesthesiology, University of Auckland, Auckland, New Zealand.
¹² Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia; Department of Anaesthesia and Pain Medicine, Royal Melbourne Hospital, Melbourne, VIC, Australia; Monash University, Melbourne, VIC, Australia.

PMID: 34465469
PMCID: PMC8579421
DOI: 10.1016/j.bja.2021.07.021

Randomized Controlled Trial

Anaesthetic depth and delirium after major surgery: a randomised clinical trial

Lisbeth A Evered et al. Br J Anaesth. 2021 Nov.

. 2021 Nov;127(5):704-712.

doi: 10.1016/j.bja.2021.07.021. Epub 2021 Aug 28.

Authors

Affiliations

¹ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Anaesthesia and Acute Pain Medicine, St Vincent's Hospital, Melbourne, VIC, Australia; Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia. Electronic address: lae4004@med.cornell.edu.
² Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
³ Department of Anesthesiology, Beijing Tiantan Hospital and Capital Medical University, Beijing, China.
⁴ Department of Anaesthesia and Acute Pain Medicine, St Vincent's Hospital, Melbourne, VIC, Australia; Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia.
⁵ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
⁶ Department of Outcomes Research, Cleveland Clinic, Cleveland, OH, USA.
⁷ Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA; Department of Anesthesiology and Critical Care Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
⁸ Department of Medicine, University of Otago, Christchurch, New Zealand.
⁹ Department of Anaesthesiology, Auckland City Hospital, Auckland, New Zealand.
¹⁰ Department of Anaesthesia and Perioperative Medicine, Alfred Hospital and Monash University, Melbourne, VIC, Australia.
¹¹ Department of Anaesthesiology, Auckland City Hospital, Auckland, New Zealand; Department of Anaesthesiology, University of Auckland, Auckland, New Zealand.
¹² Department of Critical Care Medicine, University of Melbourne, Melbourne, VIC, Australia; Department of Anaesthesia and Pain Medicine, Royal Melbourne Hospital, Melbourne, VIC, Australia; Monash University, Melbourne, VIC, Australia.

PMID: 34465469
PMCID: PMC8579421
DOI: 10.1016/j.bja.2021.07.021

Abstract

Background: Postoperative delirium is a serious complication of surgery associated with prolonged hospitalisation, long-term cognitive decline, and mortality. This study aimed to determine whether targeting bispectral index (BIS) readings of 50 (light anaesthesia) was associated with a lower incidence of POD than targeting BIS readings of 35 (deep anaesthesia).

Methods: This multicentre randomised clinical trial of 655 at-risk patients undergoing major surgery from eight centres in three countries assessed delirium for 5 days postoperatively using the 3 min confusion assessment method (3D-CAM) or CAM-ICU, and cognitive screening using the Mini-Mental State Examination at baseline and discharge and the Abbreviated Mental Test score (AMTS) at 30 days and 1 yr. Patients were assigned to light or deep anaesthesia. The primary outcome was the presence of postoperative delirium on any of the first 5 postoperative days. Secondary outcomes included mortality at 1 yr, cognitive decline at discharge, cognitive impairment at 30 days and 1 yr, unplanned ICU admission, length of stay, and time in electroencephalographic burst suppression.

Results: The incidence of postoperative delirium in the BIS 50 group was 19% and in the BIS 35 group was 28% (odds ratio 0.58 [95% confidence interval: 0.38-0.88]; P=0.010). At 1 yr, those in the BIS 50 group demonstrated significantly better cognitive function than those in the BIS 35 group (9% with AMTS ≤6 vs 20%; P<0.001).

Conclusions: Among patients undergoing major surgery, targeting light anaesthesia reduced the risk of postoperative delirium and cognitive impairment at 1 yr.

Clinical trial registration: ACTRN12612000632897.

Keywords: anaesthesia; bispectral index; cognitive dysfunction; delirium; electroencephalography; postoperative delirium.

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Figures

**Fig 1**
Enrolment, randomisation, and outcome assessment for the intention-to-treat and per-protocol groups (Consolidated Standards of Reporting Trials diagram). BIS, bispectral index.

**Fig 2**
Percentage of new delirium diagnoses for each group on each day. BIS, bispectral index.

See this image and copyright information in PMC

Comment in

Anaesthetic depth and delirium: a challenging balancing act.
Whitlock EL, Gross ER, King CR, Avidan MS. Whitlock EL, et al. Br J Anaesth. 2021 Nov;127(5):667-671. doi: 10.1016/j.bja.2021.08.003. Epub 2021 Sep 6. Br J Anaesth. 2021. PMID: 34503835
The quagmire of postoperative delirium: does dose matter?
Gaskell A, Sleigh J. Gaskell A, et al. Br J Anaesth. 2021 Nov;127(5):664-666. doi: 10.1016/j.bja.2021.08.008. Epub 2021 Sep 8. Br J Anaesth. 2021. PMID: 34507823 No abstract available.
Beware the drug titration paradox. Comment on Br J Anaesth 2021; 127: 704-12.
Schnider TW, Minto CF. Schnider TW, et al. Br J Anaesth. 2022 Jun;128(6):e335-e337. doi: 10.1016/j.bja.2022.01.004. Epub 2022 Feb 4. Br J Anaesth. 2022. PMID: 35131097 No abstract available.
How balanced is the BALANCED delirium trial? Comment on Br J Anaesth 2021; 127: 704-12.
Ajayan N, Hrishi AP. Ajayan N, et al. Br J Anaesth. 2022 Apr;128(4):e274-e275. doi: 10.1016/j.bja.2022.01.018. Epub 2022 Feb 17. Br J Anaesth. 2022. PMID: 35183347 No abstract available.
Anaesthetic depth and delirium after major surgery. Comment on Br J Anaesth 2022; 127: 704-12.
Linassi F, Maran E, Spano L, Zanatta P, Carron M. Linassi F, et al. Br J Anaesth. 2022 Aug;129(2):e33-e35. doi: 10.1016/j.bja.2022.05.001. Epub 2022 May 30. Br J Anaesth. 2022. PMID: 35654630 No abstract available.

References

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1. Evered L.A., Silbert B.S., Scott D.A., Maruff P., Ames D. Prevalence of dementia 7.5 years after coronary artery bypass graft surgery. Anesthesiology. 2016;125:62–71. - PubMed
1. Inouye S.K., Marcantonio E.R., Kosar C.M., et al. The short-term and long-term relationship between delirium and cognitive trajectory in older surgical patients. Alzheimers Dement. 2016;12:766–775. - PMC - PubMed
1. O’Regan N.A., Fitzgerald J., Timmons S., O’Connell H., Meagher D. Delirium: a key challenge for perioperative care. Int J Surg. 2013;11:136–144. - PubMed

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Anaesthetic depth and delirium after major surgery: a randomised clinical trial

Affiliations

Anaesthetic depth and delirium after major surgery: a randomised clinical trial

Authors

Affiliations

Abstract

Figures

Comment in

References

Publication types

MeSH terms

Grants and funding

LinkOut - more resources

Full Text Sources

Medical

Miscellaneous