A comparison of three minimally invasive cardiac output devices with thermodilution in elective cardiac surgery

Area of Science:

• Cardiovascular Physiology
• Medical Device Technology
• Anesthesiology and Critical Care Medicine

Background:

• Hemodynamic monitoring is crucial in cardiac surgery for optimizing patient outcomes.
• Minimally invasive cardiac output monitoring devices are widely used, but their accuracy compared to traditional methods requires rigorous evaluation.
• Thermodilution is a reference standard for cardiac output measurement, though it has limitations.

Purpose of the Study:

• To compare the accuracy and precision of three minimally invasive cardiac output monitors (Oesophageal Doppler Monitor, Vigileo-Flotrac, LiDCOrapid) against thermodilution in cardiac surgical patients.
• To assess the agreement and variability of cardiac output measurements obtained from these devices during hemodynamic interventions.
• To evaluate the clinical utility of these monitors for tracking dynamic changes in cardiac output.

Main Methods:

• Prospective observational study involving cardiac surgical patients undergoing hemodynamic interventions.
• Concurrent measurement of cardiac output using thermodilution and three minimally invasive devices: Oesophageal Doppler Monitor, Vigileo-Flotrac, and LiDCOrapid.
• Statistical analysis including kappa statistic for agreement and Bland-Altman analysis for precision and bias.

Main Results:

• Significant discrepancies were observed in cardiac output changes among the devices following fluid bolus and vasopressor administration.
• Agreement between the tested devices and thermodilution was poor, with kappa statistics indicating only fair agreement at best.
• Bland-Altman analysis revealed wide limits of agreement and substantial percentage errors for all three devices, highlighting significant variability.

Conclusions:

• The Oesophageal Doppler Monitor, Vigileo-Flotrac, and LiDCOrapid demonstrate considerable differences in their measurement of cardiac output responses compared to thermodilution.
• These minimally invasive monitors do not consistently provide the same information as thermodilution and exhibit significant variability.
• Clinicians should exercise caution and avoid using these devices interchangeably for tracking cardiac output changes in cardiac surgical patients due to their limitations.