Skip to main content

Performance of thermodilution catheters under control and extreme circulatory conditions in a pig model

Introduction

When validating new methods of cardiac output, measurement comparisons are made using Bland-Altman and percentage errors are generated that rely on a precision error for thermodilution of ± 20% [1]; data collected 30 years ago [2]. We have re-evaluated this precision against an aortic flow probe.

Methods

Four domestic pigs, weight 30 to 32 kg, were anaesthetized. An aortic flow probe was placed via a left thoracotomy. Both Arrow (n = 6) and Edwards (n = 6) 7F pulmonary artery catheters and a Siemens SC9000 monitor were used. Sets of cardiac output readings were taken (three to six pairs). Catheters were changed frequently and cardiac output increased (for example, dopamine and adrenaline) and decreased (for example, trinitrate and beta-blocker) using drug infusions. Baseline and drug treatment data were compared.

Results

Forty-five sets (259 pairs) of averaged data (21 baseline and 24 following treatment) were collected. Baseline cardiac outputs (mean (SD)) were 1.9 (0.4) and 1.8 (0.3) l/minute for flow meter and thermodilution readings, respectively. MAP (mean (range)) was 82 (69 to 95) mmHg. Following circulatory treatment, cardiac output ranged from 0.5 to 3.4 l/minute and from 0.7 to 3.5 l/minute, respectively. MAP ranged from 44 to 118 mmHg. For baseline data, bias was 0.0 l/minute, limits of agreement ± 0.45 l/minute and percentage error ± 24.3%. Following treatment, the bias was unchanged at 0.0 l/minute, but the limits of agreement widened to ± 0.78 l/minute and percentage error widened to 42.0% (Figure 1).

Figure 1
figure1

Plots showing widening distribution.

Conclusions

The flow probe has a relatively low (1 to 2%) precision error, thus the baseline percentage error of 24.3% is in keeping the quoted precision error for thermodilution of ± 20%. However, under more extreme circulatory conditions thermodilution behaved less reliably with widened limits of agreement and precision errors (42.0%). Thermodilution is less accurate than originally thought in haemodynamically unstable patients.

References

  1. 1.

    Critchley , et al.: J Clin Monit. 1999, 15: 85-91. 10.1023/A:1009982611386

    CAS  Article  Google Scholar 

  2. 2.

    Stetz , et al.: Am Rev Respir Dis. 1982, 126: 1001-1004.

    CAS  PubMed  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to XX Yang.

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Yang, X., Critchley, L., Zhu, F. et al. Performance of thermodilution catheters under control and extreme circulatory conditions in a pig model. Crit Care 15, P46 (2011). https://doi.org/10.1186/cc9466

Download citation

Keywords

  • Catheter
  • Cardiac Output
  • Percentage Error
  • Pulmonary Artery Catheter
  • Drug Infusion