Reliability of thermodilution derived cardiac output with different operator characteristics

McKenzie, Scott C., Dunster, Kimble, Chan, Wandy, Brown, Martin R., Platts, David G. , Javorsky, George, Anstey, Chris and Gregory, Shaun D.  (2017) Reliability of thermodilution derived cardiac output with different operator characteristics. Journal of Clinical Monitoring and Computing, 32 2: 1-8. doi:10.1007/s10877-017-0010-6


Author McKenzie, Scott C.
Dunster, Kimble
Chan, Wandy
Brown, Martin R.
Platts, David G. 
Javorsky, George
Anstey, Chris
Gregory, Shaun D. 
Title Reliability of thermodilution derived cardiac output with different operator characteristics
Journal name Journal of Clinical Monitoring and Computing   Check publisher's open access policy
ISSN 1573-2614
1387-1307
Publication date 2017-03-09
Year available 2018
Sub-type Article (original research)
DOI 10.1007/s10877-017-0010-6
Open Access Status Not yet assessed
Volume 32
Issue 2
Start page 1
End page 8
Total pages 8
Place of publication Dordrecht, Netherlands
Publisher Springer Netherlands
Language eng
Subject 2718 Health Informatics
2706 Critical Care and Intensive Care Medicine
2703 Anesthesiology and Pain Medicine
Abstract 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 r 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.
Formatted abstract
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.
Keyword Cardiac output
Clinical measurements
Measurement precision
Pulmonary artery catheterisation
Thermodilution
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
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