Journal of Clinical Monitoring and Computing

, Volume 32, Issue 2, pp 227–234 | Cite as

Reliability of thermodilution derived cardiac output with different operator characteristics

  • Scott C. McKenzie
  • Kimble Dunster
  • Wandy Chan
  • Martin R. Brown
  • David G. Platts
  • George Javorsky
  • Chris Anstey
  • Shaun D. Gregory
Original Research


Cardiac output (CO) is commonly measured using the thermodilution technique at the time of right heart catheterisation (RHC). However inter-operator variability, and the operator characteristics which may influence that, has not been quantified. Therefore, this study aimed to assess inter-operator variability with the thermodilution technique using a mock circulation loop (MCL) with calibrated flow sensors. Participants were blinded and asked to determine 4 levels of CO using the thermodilution technique, which was compared with the MCL calibrated flow sensors. The MCL was used to randomly generate CO between 3.0 and 7.0 L/min through changes in heart rate, contractility and vascular resistance with a RHC inserted through the MCL pulmonary artery. Participant characteristics including gender, specialty, age, height, weight, body-mass index, grip strength and RHC experience were recorded and compared to determine their relationship with CO measurement accuracy. In total, there were 15 participants, made up of consultant cardiologists (6), advanced trainees in cardiology (5) and intensive care consultants (4). The majority (9) had performed 26–100 previous RHCs, while 4 had performed more than 100 RHCs. Compared to the MCL-measured CO, participants overestimated CO using the thermodilution technique with a mean difference of +0.75 ± 0.71 L/min. The overall r2 value for actual vs measured CO was 0.85. The difference between MCL and thermodilution derived CO declined significantly with increasing RHC experience (P < 0.001), increasing body mass index (P < 0.001) and decreasing grip strength (P = 0.033). This study demonstrated that the thermodilution technique is a reasonable method to determine CO, and that operator experience was the only participant characteristic related to CO measurement accuracy. Our results suggest that adequate exposure to, and training in, the thermodilution technique is required for clinicians who perform RHC.


Cardiac output Thermodilution Pulmonary artery catheterisation Clinical measurements Measurement precision 



This study was approved by The Prince Charles Hospital Ethics Committee (approval number HREC/13/QPCH/38).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer Science+Business Media Dordrecht 2017

Authors and Affiliations

  • Scott C. McKenzie
    • 1
    • 2
  • Kimble Dunster
    • 3
  • Wandy Chan
    • 1
    • 2
  • Martin R. Brown
    • 1
    • 2
  • David G. Platts
    • 1
    • 2
    • 3
  • George Javorsky
    • 2
  • Chris Anstey
    • 1
    • 4
  • Shaun D. Gregory
    • 1
    • 3
    • 5
  1. 1.Faculty of Health Sciences, School of MedicineThe University of QueenslandBrisbaneAustralia
  2. 2.The Prince Charles HospitalChermsideAustralia
  3. 3.Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research GroupThe Prince Charles HospitalBrisbaneAustralia
  4. 4.Nambour General HospitalNambourAustralia
  5. 5.School of EngineeringGriffith UniversityBrisbaneAustralia

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