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Updated: Mar 6, 2026
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A comparison between four techniques to measure cardiac output
Insights
Measuring cardiac output is challenging. This study found that while individual methods are precise, estimates from different techniques poorly correlate, highlighting the need for cautious interpretation and multiple measurements.
Area of Science:
- Cardiovascular Physiology
- Hemodynamic Monitoring
- Critical Care Medicine
Background:
- Cardiac output (CO) is crucial for assessing hemodynamic status and guiding circulatory management therapies.
- Accurate CO estimation remains a significant challenge in both experimental and clinical environments.
- Reliable CO measurement is essential for effective patient management in critical care.
Purpose of the Study:
- To compare the accuracy and reliability of four distinct cardiac output measurement techniques.
- To evaluate the agreement between pressure-volume (PV) catheter, aortic flow probe, thermodilution, and PiCCO monitor.
- To assess the impact of fluid and endotoxin administration on CO measurements across different methods.
Main Methods:
- Simultaneous measurement of cardiac output using PV catheter, aortic flow probe, thermodilution, and PiCCO monitor in 7 pigs.
- Experimental induction of hemodynamic changes through fluid loading and endotoxin administration.
- Statistical analysis of precision (repeatability) and agreement between the four CO monitoring techniques.
Main Results:
- All four techniques demonstrated good precision, with relative coefficients of repeatability below 7%.
- Cardiac output estimates from any single technique showed poor correlation with estimates from the other three, despite minimal bias.
- Changes in cardiac output were detected by all methods in only 62% to 100% of cases, indicating variability in sensitivity.
Conclusions:
- This study underscores the inherent difficulties in obtaining reliable clinical cardiac output measurements.
- Significant discrepancies exist between different CO monitoring techniques, even when precise individually.
- Clinicians should exercise caution, consider using multiple CO measurement techniques, and interpret results judiciously.
Abstract:
Cardiac output is an important variable when monitoring hemodynamic status. In particular, changes in cardiac output represent the goal of several circulatory management therapies. Unfortunately, cardiac output is very difficult to estimate, either in experimental or clinical settings. The goal of this work is to compare four techniques to measure cardiac output: pressure-volume catheter, aortic flow probe, thermodilution, and the PiCCO monitor. These four techniques were simultaneously used during experiments of fluid and endotoxin administration on 7 pigs. Findings show that, first, each individual technique is precise, with a relative coefficient of repeatability lower than 7 %. Second, 1 cardiac output estimate provided by any technique relates poorly to the estimates from the other 3, even if there is only small bias between the techniques. Third, changes in cardiac output detected by one technique are only detected by the others in 62 to 100 % of cases. This study confirms the difficulty of obtaining a reliable clinical cardiac output measurement. Therefore, several measurements using different techniques should be performed, if possible, and all such should be treated with caution.
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