CARDIOPULMONARY MONITORING: Edited by Anthony S. McLeanMeasuring cardiac output at the bedsideHuang, Stephen J.Author Information Department of Intensive Care Medicine, Nepean Hospital, The University of Sydney, Sydney, New South Wales, Australia Correspondence to Stephen J. Huang, PhD, Department of Intensive Care Medicine, Nepean Hospital, The University of Sydney, NSW 2749, Australia. E-mail: firstname.lastname@example.org Current Opinion in Critical Care: June 2019 - Volume 25 - Issue 3 - p 266-272 doi: 10.1097/MCC.0000000000000599 Buy Metrics Abstract Purpose of review Bedside cardiac output (CO) measurement is an important part of routine hemodynamic monitoring in the differential diagnosis of circulatory shock and fluid management. Different choices of CO measurement devices are available. The purpose of this review is to review the importance of CO [or stroke volume (SV)] measurement and to discuss the various methods (devices) used in determination of CO. Recent findings CO measurement devices can be classified into two types: those use simple physical principles with minimal assumptions, and those predicting CO via mathematical modelling with a number of assumptions. Both have pros and cons, with the former being more accurate but with limited continuous monitoring capability whereas the latter less accurate but usually equipped with continuous monitoring functionality. With frequent updates in mathematical models, research data constantly become outdated in this area. Recent data suggest devices based on mathematical modelling have limited accuracies and poor precisions. Summary Measurement of CO or SV is important in critically ill patients. Most devices have accuracy and reliability issues. The choice of device should depend on the purpose of measurement. For diagnostic purposes, devices based on simple physical principles, especially thermodilution and transthoracic echocardiography are more reliable due to accuracy. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.