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Measuring Cardiac Output: A New Respiratory Method David Preiss

Measuring Cardiac Output: A New Respiratory Method David Preiss Institute for Biomaterials and Biomedical Engineering University of Toronto Department of Anesthesia University Health Network November 29, 2004. Introduction – Cardiac Output. Swan-Ganz Catheter. Fick Equation:.

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Measuring Cardiac Output: A New Respiratory Method David Preiss

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  1. Measuring Cardiac Output: A New Respiratory Method David Preiss Institute for Biomaterials and Biomedical Engineering University of Toronto Department of Anesthesia University Health Network November 29, 2004

  2. Introduction – Cardiac Output Swan-Ganz Catheter

  3. Fick Equation: Non-Invasive: The Fick Equation VCO2 CvCO2 CaCO2

  4. CO2 level Mixed venous arterial Time Change Ventilation to get CvCO2 Final Lung CO2 concentration Breathing Rate

  5. ? Problem creating change in CO2 Intubated, Ventilated Spontaneous Breathing Time Time

  6. Change in CO2 in Awake Patients • Must be independent of ventilation • No physical manoeuvre • Comfortable

  7. Constant O2 flow

  8. Exhaling…

  9. Exhaling…

  10. Exhalation ends

  11. Inhalation starts…

  12. Valve opens

  13. Rebreathing

  14. Rebreathing

  15. Deeper breath

  16. Problem Solved! Flow Flow CO2 level Time

  17. Mixed venous arterial Problem Solved! Final Lung CO2 concentration Breathing Rate

  18. Evaluating the Method • Compare with direct measurements • 3 pilot studies: • Jan, 2003 (32 patients) • June, 2003 (36 patients) • Feb, 2004 (37 patients) • Patients were conscious and extubated

  19. Comparison with Invasive Methods

  20. Comparison with Invasive Methods

  21. Results – 1st and 2nd cohorts

  22. Results – 3rd cohort SD = 0.80 L/min

  23. Limitations • Periodic breathing • Good seal around mouth required • Requires supply of compressed air • Pain for some patients – deeper breaths

  24. Future Work • Larger range of cardiac outputs • Exercise • Patients in poorer health • Alveolar deadspace • Shunt

  25. Joseph Fisher MD Arthur Slutsky MD Jim Duffin PhD Al Olszowka MD Takafumi Azami MD Cliff Ansel MBA Ludwik Fedorko MD PhD George Djaiani MD Jo Caroll RN Marat Slessarev Steve Iscoe PhD Ron Somogyi MSc Hiroshi Sasano MD Thanks! CVICU Nursing Staff University Health Network

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