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Received Apr 28, 2017; Revised Jul 21, 2017; Accepted Aug 20, 2017
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1. Introduction
Measurement of cardiac output (CO) and cardiac index (CI) is commonly used in patients undergoing cardiac surgery. The continuous pulmonary artery thermodilution technique is well known as a method for advanced monitoring of cardiovascular function and is regularly used as a clinical reference technique in method comparison studies. However, a couple of studies during the past years showed that a true golden standard for measuring cardiac output does not exist.
Due to its invasive nature, the use of the PAC is associated with severe risk and there is still discussion on whether the positive effects of PAC outweigh the adverse effects [1–5].
Today, there are less invasive or even noninvasive monitoring devices available. The ideal technique should be reliable, noninvasive, continuous, cost-effective, and user independent and should have a fast response time enabling rapid detection of hemodynamic changes [6]. Considering the growing age of the surgical population with severe comorbidity, it is likely that monitoring of CO will be important, also in non-cardiac-surgery patients. Moreover, assessment of CO and stroke volume (SV) is a prerequisite to establish early goal-directed therapy during the perioperative period.
One of the most recent noninvasive techniques for assessment of CO is based on a modified thoracic bioimpedance algorithm. Briefly, thoracic bioimpedance is based on the theory that the thorax is a blood filled...