In European countries, day-7 mortality rate could reach 1-5. %. Emergency conditions, American Society Assessment (ASA) and major surgery were associated with a higher risk of immediate mortality. Moreover, hemodynamic instability is well known to lead to postoperative complications and a higher risk of mortality.~Since, nearly 30 years, optimization of hemodynamic conditions, especially via an optimization of the fluid administration has been shown to improve immediate and long-term patient outcome. This strategy is currently widely accepted and recommended in medium and high-risk surgery. Therefore, optimizing cardiac output and one of its surrogate is proposed over intraoperative surgery. For assessing the cardiac output or the indexed stroke volume, esophageal Doppler and pulse contour technique have been proposed and have shown that they could improve patient outcome.~However, the reliability of esophageal Doppler, pulse contour and non-invasive techniques assessing cardiac output and its ability to detect a change in the initial value of CO have been challenged. Initially, the reliability of a technique for measuring CO has been described by using a correlation coefficient and by building Bland & Altman diagram. However, searching a correlation between two different techniques measuring the same parameter will lead to a correlation. In the same, Bland & Altman technique shows the mean difference between measurements of the same parameters; However, demonstrating a good reliability should be shown by a narrow limit of agreement with no definition of the narrowness. Indeed, a value of cardiac index (CI) = 3 l/min/m2 with a mean difference of 0 +/- 1.1 /min/m2 by Bland & Altman technique mean that the CI value could be within 1 and 5 l/min/m2 that could lead to different treatment such as fluid challenge, vasopressor or inotrope infusion.~An interesting method for comparing two techniques measuring the same parameter could be to challenge one technique versus the other one in decision-making. Applying this method to techniques measuring CO, we could search for the interest of a new technique for diagnosing an increase in CO after a fluid challenge for optimizing cardiac preload and hemodynamic status. Esophageal Doppler is classically recommended for optimizing hemodynamic patient in high-risk surgery.~A new device using pulse contour technology has been available since a few years. Therefore, the present study aims at assessing the ability of this device for diagnosing an increase in CO > 15% during patient hemodynamic optimization by fluid challenge.
The present study aims at assessing the ability of a new pulse contour device for diagnosing a >15% stroke volume (SV) increase during patient hemodynamic optimization by fluid challenge in high risk abdominal surgery.