• Karim Kouz, Alina Bergholz, Lea M Timmermann, Lennart Brockmann, Moritz Flick, Phillip Hoppe, Luisa Briesenick, Leonie Schulte-Uentrop, Linda Krause, Kamal Maheshwari, Daniel I Sessler, and Bernd Saugel.
• From the Department of Anesthesiology, Center of Anesthesiology and Intensive Care Medicine.
• Anesth. Analg. 2022 Feb 1; 134 (2): 322-329.

BackgroundCardiac output is an important hemodynamic variable and determines oxygen delivery. In contrast to blood pressure, cardiac output is rarely measured even in high-risk surgical patients, suggesting that clinicians consider blood pressure to be a reasonable indicator of systemic blood flow. However, the relationship depends on constant vascular tone and volume, both of which routinely vary during anesthesia and surgery. We therefore tested the hypothesis that there is no clinically meaningful correlation between mean arterial pressure and cardiac index in major abdominal surgery patients.MethodsIn this prospective observational study, we assessed the relationship between mean arterial pressure and cardiac index in 100 patients having major abdominal surgery under general anesthesia.ResultsThe pooled within-patient correlation coefficient calculated using meta-analysis methods was r = 0.34 (95% confidence interval, 0.28-0.40). Linear regression using a linear mixed effects model of cardiac index on mean arterial pressure revealed that cardiac index increases by 0.014 L·min-1·m-2 for each 1 mm Hg increase in mean arterial pressure. The 95% Wald confidence interval of this slope was 0.011 to 0.018 L·min-1·m-2·mm Hg-1 and thus within predefined equivalence margins of -0.03 and 0.03 L·min-1·m-2·mm Hg-1, thereby demonstrating lack of clinically meaningful association between mean arterial pressure and cardiac index.ConclusionsThere is no clinically meaningful correlation between mean arterial pressure and cardiac index in patients having major abdominal surgery. Intraoperative blood pressure is thus a poor surrogate for cardiac index.Copyright © 2021 International Anesthesia Research Society.

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