Is the cardiac output obtained from a Swan-Ganz catheter always zero?

J Clin Monit Comput. 2008 Dec;22(6):431-3. doi: 10.1007/s10877-008-9149-5. Epub 2008 Nov 14.


Objective: By means of a Swan-Ganz catheter cardiac output is calculated using the Stewart-Hamilton thermodilution equation. Assuming the body as a thermally isolated inert system, this equation theoretically always results in zero cardiac output.

Methods: Using the first and second law of thermodynamics together with a few lines simple analysis this statement is proven.

Conclusion: It is at least a necessary condition for the application of the Stewart-Hamilton equation, that core body temperature is kept constant in a thermo- regulatory steady state.

Publication types

  • Evaluation Study

MeSH terms

  • Blood Pressure Determination / methods*
  • Cardiac Output / physiology*
  • Catheterization, Swan-Ganz / methods*
  • Computer Simulation
  • Diagnosis, Computer-Assisted / methods*
  • Heart Function Tests / methods*
  • Humans
  • Models, Cardiovascular*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Thermodilution / methods*