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. Non-Invasive: The Fick Equation CvCO 2 CaCO 2 VCO 2 Fick Equation:

4. Change Ventilation to get CvCO 2 Breathing Rate Final Lung CO 2 concentration Mixed venous arterial CO 2 level Time

5. Problem creating change in CO 2 Time Intubated, Ventilated ? Time Spontaneous Breathing

6. Change in CO 2 in Awake Patients Must be independent of ventilation No physical manoeuvre Comfortable

7. Constant O 2 flow

8. Exhaling…

11. Exhalation ends

12. Inhalation starts…

13. Valve opens

14. Rebreathing

16. Deeper breath

17. Problem Solved! CO 2 level Time Flow

18. Problem Solved! Breathing Rate Final Lung CO 2 concentration Mixed venous arterial

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

22. Comparison with Invasive Methods

24. Results – 1 st and 2 nd cohorts

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

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

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

28. Thanks! 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 CVICU Nursing Staff University Health Network