1. Continuous Cardiac Output Monitors

2. Ready

3. Continuous Cardiac Output Monitors James H. Philip, M.E.(E.), M.D. Anesthesiologist and Director of Technology Assessment Brigham and Women's Hospital Medical Liaison, Department of Biomedical Engineering Partners HealthCare System Associate Professor of Anaesthesia Harvard Medical School I have a financial interest in Gas Man ® and Med Man Simulations, Inc. I have performed research on some of the drugs or devices described © 1984 - 2003, James H Philip, all rights reserved.

4. Cardiac Output Methods

5. Fick Indicator Dilution Ultrasound Doppler Flow Trans-thoracic Impedance

6. Fick Cardiac Output What goes in must come out Oxygen Carbon dioxide Partial CO 2 Rebreathing (later)

7. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V O2. Q Left Heart Lungs

8. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs

9. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs V ArterialO2 = V VenousO2 + V O2...

10. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs Q x c ArterialO2 = Q x c VenousO2 + V O2. V ArterialO2 = V VenousO2 + V O2...

11. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs V ArterialO2 = V VenousO2 + V O2... Q x c ArterialO2 = Q x c VenousO2 + V O2. Q x (c ArterialO2 - c VenousO2 ) = V O2.

12. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs Q = V O2. c ArterialO2 - c VenousO2 V ArterialO2 = V VenousO2 + V O2... Q x c ArterialO2 = Q x c VenousO2 + V O2. Q x (c ArterialO2 - c VenousO2 ) = V O2.

13. Original Fick Technique with Oxygen Right Heart Amount of O 2 entering the Right Heart: Q Amount of O 2 exiting the Left Heart: V ArterialO2 = c ArterialO2 x Q. V VenousO2 = c VenousO2 x Q. V O2. Q Left Heart Lungs Q = V O2. c ArterialO2 - c VenousO2 V ArterialO2 = V VenousO2 + V O2...

14. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialCO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Q = c ArterialCO2 - c VenousCO2 V CO2. -

15. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialCO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Q = c ArterialCO2 - c VenousCO2 V CO2. - x

16. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialCO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Q = c VenousCO2 - c ArterialCO2 V CO2.

17. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialCO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Q = c VenousCO2 - c ArterialCO2 V CO2. Now, a change

18. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Add partial rebreathing Q = c VenousCO2 - c ArterialCO2 V CO2..

19. Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... Add partial rebreathing Q = c VenousCO2 - c ArterialCO2 V CO2. ∆.

20. ∆ Q = c VenousCO2 - c ArterialCO2 V CO2 Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... and partial rebreathing No ∆ in 30 sec 0. V CO2.

21. Q = - c ArterialCO2 V CO2 Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... And partial rebreathing No ∆ in 30 sec - = + V CO2.. And,

22. c ArterialCO2 Q = V CO2 Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... And partial rebreathing V CO2.. So,

23. p ArterialCO2 x K Q = V CO2 Modified Fick Technique with Carbon Dioxide Right Heart Amount of CO 2 entering the Right Heart: Q Amount of CO 2 exiting the Left Heart: V ArterialO2 = c ArterialCO2 x Q. V VenousCO2 = c VenousCO2 x Q. V CO2. Q Left Heart Lungs V ArterialCO2 = V VenousCO2 + V CO2... And partial rebreathing V CO2.. or,

24. Novametrix NICO p ArterialCO2 V CO2.

25. Novametrix NICO c ArterialCO2 V CO2. Q = c ArterialCO2 V CO2.

26. Simple circuit attachment

27. Much more, later

28. Indicator Dilution Cardiac Output Indicators Colored dye Negative heat (cold) Positive heat

29. Indicator Dilution Cardiac Output Same Principle for all indicators Indicator is injected into bloodstream Flow of blood dilutes indicator Extent of dilution is proportional to flow

30. Indicator requirements Detectable No change in CO Not toxic Sterile

31. Indicator requirements Detectable - somewhere convenient Pulmonary Artery on catheter Radial Artery if none lost No change in CO - else errors Not toxic - single, multiple measurements Sterile - injected and passes heart

32. Non-Diffusable If measured in Radial Artery Must not diffuse into lung tissue Else, indicator dwells long enough to appear lost Lost indicator = “more dilution” = higher CO

33. Colored Dye Indicators Inject in vein Measure in artery Dye traverses lungs before being measured Dyes Evans Blue (TI 824) t 50 = 5 days Indocyanin Greent 50 = 10 minutes Coomasie Bluet 50 = 20 minutes Measure in Radial Artery Does not diffuse into lung tissue, so no loss

34. Diffusable indicator is OK, if Measure before diffusion location For heat, this is before lungs Sense in PA (pulmonary artery) Catheter tip is there (PA) This is “Thermodilution”

35. Two thermodilution methods Both use Catheter Catheter tip is in PA (pulmonary artery) Cold bolus Cyclic warmed catheter Indicator buildup is a good thing, adding to patient warmth, slightly

36. Cold Bolus Thermodilution Conventional method 10 cc of iced or room temperature saline Inject fast (bolus, impulse) Measure temperature downstream Integral of coldness recovers all injected CO x Coldness = Injected Cold Coldness = 10 mL x 37C = 1500 Ws for 2 s = 750 W

37. Pulmonary-artery balloon-floatation catheter

38. RA RV PA

39. The balloon makes it “float”

40. Balloon-tipped catheter floats through heart

42. Inject and measure inject here measure here

43. Typical Thermodilution Curve T Blood(Baseline) - T Blood (t) [ o C] Time 5ml bolus of 0 o C 5% Dextrose in Water Cardiac Output = 6.22 l/min From: Geddes L: Cardiac Output Measurement. In: Bronzino (Ed.):The Biomedical Engineering Handbook. CRC Press, Boca Raton FL; 1995: 1212-1222 Cold Inject

44. T Blood(Baseline) - T Blood (t) Time Peak Value 30% of Peak Value Estimated Area Reduce the effect of thermal noise Estimate the curve when it is almost back to baseline

45. Simple, huh? Infection, septicemia Subsequent heart-valve disease Possibly misguides clinical care Possibly worsens outcome after MI

46. One-up this one Continuous Thermodilution Cardiac Output Heater on the catheter Adds heat Quasi-intermittantly Waveform of heat Computes CO and RV mixing volume

47. Baxter Continuous Thermal- Dilution Philip JH, Long MC, Quinn MD, Newbower RS. Continuous thermal measurement of cardiac output. IEEE Trans Biomed Eng. l984;3l:393-400.

48. Heater Catheter

49. Heater Thermistor Balloon

50. Thermal noise is a problem Maximum heater power is 4 W 50 m˚C temperature rise at thermistor is typical Required to prevent cell injury at heater surface Surface Temp maximum = 44˚C Must restrict power to about 4W Requires analysis time of 50 s

51. Thermal noise is a problem

52. Abbott CCO is similar Similar catheter Different math Square wave of heat Time-delay related rather than true dilution

53. Cardiac Output Methods Ultrasound Doppler Flow-Meter sound bouncing off a moving target (e.g., blood cell) experiences a frequency shift proportional to the target velocity

54. The Doppler Effect Observer Stationary: Sound like a car

55. The Doppler Effect Observer Approaching: Sound shifts to higher frequencies

56. The Doppler Effect Observer Leaving: Sound shifts to lower frequencies

57. The Doppler Effect Observer Bounce sound off car:

58. The Doppler Effect Observer Bounce sound off car: Bounced sound shifts to higher frequencies or higher pitch

59. The Doppler Effect Observer Bounce sound off car: Bounced sound shifts to higher frequencies or higher pitch We call this the “Doppler Frequency Shift”

60. Doppler Flow Blood Vessel of Interest (e.g., Aorta) Ultrasound Transducer Doppler measures velocity not flow: Need to know cross-sectional area A Need to assume velocity profile v (r) Velocity vs time curve obtained by Doppler Adapted from: Saidmann, Smith (Eds.): Monitoring in Anesthesia, 3rd Ed., Butterworth-Heinemann, Boston, 1993

61. Esophageal Doppler Cardiac Output Monitor LV Failure After inotropes Figures: Deltex, Inc., Dallas, TX Non-Invasive Needs Cross-Sectional-Area 1) guesses from patient weight, height, age 2) measures diameter, assumes cylinder Measures descending aorta after carotids and coronaries

62. Deltex Probe in patient

63. Shows waves

64. Shows parameters

65. Cardiac Output Methods Bioimpedance Trans-thoracic impedance Impedance changes when blood is ejected from the ventricle Measure at high (safe) frequency Hope that other factors don’t confuse Bomed, other names through the years Never worked in ill patients

66. CardioDynamics

67. Research Only Circumferential Vessel Methods Electromagnetic Doppler

68. Electromagnetic Flowmeter Blood Vessel of Interest (e.g., PA, Aorta) EM Flowmeter Probe clamped onto vessel Transducer Requires direct access to vessel destructively invasive research only

69. TEE Trans Esophageal Echocardiograph Next

70. End