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Article of the Month – April 2019

Article: Prolonged concurrent hypotension and low Bispectral index (‘double low’) are associated with mortality, serious complications, and prolonged hospitalization after cardiac surgery

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6172972/pdf/main.pdf

DOI: 10.1093/bja/aex095

Published: Br J Anaesth. 2017 Jul; 119(1): 40–49.

Authors:  A. Maheshwari, P.J. McCormick, D.I. Sessler, D.L. Reich, J. You, E.J. Mascha, J.G. Castillo, M.A. Levin, and A.E. Duncan

Article Description:

The authors tested the hypothesis that a combination of these risk factors, a ‘double low’, is associated with death and major complications after cardiac surgery.

The authors included 8239 cardiac surgical patients who had cardiac surgery at the Cleveland Clinic main campus in Cleveland, OH, USA and Mount Sinai Hospital, New York, NY, USA during a period of five years.

For each patient, time-weighted average (TWA) MAP and BIS were calculated as the area under the curve (AUC) divided by the total time with extrapolation the measurement points.

Patients have then grouped into the following five non-overlapping ‘exposure’ categories for analysis as shown in the infographic slide.

The two primary outcomes were all-cause 30-day mortality and a composite of major in-hospital outcomes that included all-cause in-hospital mortality and postoperative neurologic, renal, and infectious morbidities.


Case-averaged “double low” was not associated with increased risk of 30-day mortality {odds ratio [OR] 1.73 [95% confidence interval (CI) 0.94–3.18] vs reference; P=0.01} or the composite of in-hospital mortality and morbidity [OR 1.47 (95% CI 0.98–2.20); P=0.01] after correction for multiple outcomes.

A prolonged concurrent “double low” was associated with 30-day mortality [OR 1.06 (95% CI 1.01–1.11) per 10-min increase; P=0.001] and the composite of in-hospital mortality and morbidity [OR 1.04 (95% CI 1.01–1.07), P=0.004].


In this retrospective analysis of data, a prolonged concurrent ‘double low’ (low bispectral index and low mean arterial pressure), but not a case-averaged double low, was associated with increased 30-day mortality and composite in-hospital mortality and morbidity.

These findings suggest that interventions to reduce the duration of simultaneous hypotension and low bispectral index might improve outcomes after cardiac surgery.

Tell us: do you think that patients having cardiac surgery benefit from the reduction of the double low condition? 

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Poll 1

In the article, prolonged concurrent hypotension and low Bispectral index (‘double low’) are associated with mortality, serious complications, and prolonged hospitalization after cardiac surgery.
In your centre, what is the target MAP during cardiac surgery?

(1) 50-60 mmHg
(2) 60-70 mmHg
(3) 70-80 mm Hg
(4) 80-100 mm Hg

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Poll 2

In your practice, how could you define the low BIS during cardiac surgery?

(1) <45
(2) <43
(3) <40
(4) <37
(5) I am not using BIS routinely

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