Measurement of Cardiac Output and Blood Volume by Non-Invasive Detection of Indicator Dilution

• US 20070203403A1
• Filed: 01/19/2007
• Published: 08/30/2007
• Est. Priority Date: 05/22/2001
• Status: Active Grant

• Current Assignee: The Alfred E. Mann Institute For Biomedical Engineering At The University Of Southern California (University of Southern California)
• Original Assignee: Alfred E MANN Institute For Biomedical Engineering At The University of Southern California, California (US) (Terreno Realty Corp.)
• Inventors: Rubinstein, Eduardo, Holschneider, Daniel, Maarek, Jean-Michel
• Granted Patent: US 8,082,016 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• CPC Class Codes: A61B 2503/40 Animals
• CPC Class Codes: A61B 5/0275 using tracers, e.g. dye dilution
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence

Abstract

A system for evaluating the cardiovascular system parameters using indicator dilution and non-invasive or minimally invasive detection and calibration methods are disclosed. Intravascular indicators are stimulated, and emissions patterns detected for computation of cardiac output, cardiac index, blood volume and other indicators of cardiovascular health.

Claims

1. A method of determining concentration of a fluorescent indicator within the cardiovascular system of a subject comprising:

a) administering to the cardiovascular system a detectable amount of an indicator that fluoresces when illuminated;

b) illuminating a portion of the cardiovascular system with an excitation light of a first wavelength and causing the administered indicator to emit an emergent fluorescence light of a second wave length;

c) detecting the intensity (x) of the excitation light that is reflected by or transmitted through a portion of the cardiovascular system;

d) detecting the intensity (y) of the emergent fluorescence light;

e) determining the ratio (y)/(x); and

f) determining the concentration (C) of the fluorescence indicator in the cardiovascular system based on the determined ratio (y)/(x), wherein the concentration of the fluorescence indicator is proportional to the ratio.

2. The method of claim 1, wherein the administered indicator is indocyanine green (ICG) having a concentration C_ICG.

3. The method of claim 2 further comprising determining a ratio C_ICG/C_Hb of indocyanine green concentration (C_ICG) to the blood hemoglobin concentration (C_Hb) based on the determined ratio (y)/(x), wherein the ratio C_ICG/C_Hb is also proportional to the ratio (y)/(x).

4. The method of claim 1, wherein the first wavelength is selected from a range of about 488 nm to about 1000 nm.

5. The method of claim 4, wherein the indicator is any one of fluorescein or rhodamine capable of emitting the second wavelength of light in a range from about 500 nm to about 900 nm.

6. A system for determining concentration of a fluorescent indicator within the cardiovascular system of a subject comprising:

a) an illumination source configured to be positioned proximately to at least one blood vessel of the cardiovascular system to provide a first wavelength of light to excite an indicator within the cardiovascular system to cause the indicator to emit a second wavelength of light;

b) at least one photodetector configured to be positioned proximate to the cardiovascular system of the subject and configured to detect information regarding the intensity (x) of the excitation light that is reflected by or transmitted through a portion of the cardiovascular system and to detect information regarding the intensity (y) of the emergent fluorescence light; and

c) a computing system configured to receive the detected intensity information from the photodetector and to determine the concentration (C) of the indicator, wherein (C) is proportional to the ratio (y)/(x).

7. The system of claim 6, wherein the photodetector is configured for placement in at least one of a transdermal detection area, a subdermal detection area, a perivascular detection area or an endovascular detection area.

8. The system of claim 6, wherein the administered indicator is indocyanine green (ICG) having a concentration C_ICG within the cardiovascular system.

9. The system of claim 8, wherein the computing system is further configured to determine a concentration ratio C_ICG/C_Hb of indocyanine green concentration (C_ICG) to the blood hemoglobin concentration (C_Hb) based on the ratio (y)/(x), wherein the ratio C_ICG/C_Hb is also proportional to the ratio (y)/(x).

10. The system of claim 7 further comprising at least one fiber optic probe operably connected to the illumination source and configured to guide the first wavelength of light from the illumination source to the detection area.

11. The system of claim 7 further comprising at least one fiber optic probe operably connected to the photodetector configured to guide the second wavelength of light from the detection area to the photodetector.

12. The system of claim 6, wherein the first wavelength is selected from a range of about 488 nm to about 1000 nm.

13. The system of claim 6, wherein the indicator is any one of fluorescein or rhodamine capable of emitting the second wavelength of light in a range from about 500 nm to about 900 nm.