SYSTEMS AND METHODS FOR HEMODYNAMIC DETECTION OF CIRCULATORY ANOMALIES

• US 20140128733A1
• Filed: 12/09/2013
• Published: 05/08/2014
• Est. Priority Date: 07/15/2008
• Status: Abandoned Application

• Current Assignee: Cardiox Corporation
• Original Assignee: Cardiox Corporation
• Inventors: Eggers, Philip E., Eggers, Andrew R., Eggers, Eric A.
• Application Number:
  US14/100,724
• Publication Number:
  US 20140128733A1
• Time in Patent Office: Days
• US Class Current: 600/432
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• 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
• CPC Class Codes: A61B 5/6815 Ear
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

Systems and methods for detecting circulatory anomalies such as, for example, right-to-left cardiac and pulmonary shunts. A fluorescing indicator is injected into the bloodstream of a subject. An optical sensor is used to transcutaneously excite the indicator into fluorescence and to transcutaneously detect the fluorescence, and a relative concentration of the indicator is determined as a function of time. An indicator dilution curve is generated from the relative concentration readings, the curve shape is analyzed for the indication of a shunt and, if a shunt is detected, a ratiometric area under the curve analysis is performed and combined with a calculated cardiac output value to provide a shunt conductance value. A Valsalva maneuver may be performed as a part of the method. System embodiments may include a controller/monitor that monitors, times, cues and/or analyzes various steps of a shunt detection test.

Claims

1. A method for detecting and quantifying a right-to-left cardiac and/or pulmonary shunt in a mammalian body, comprising:

calculating the surface area of the body;

calculating cardiac output using, among other things, the calculated surface area of the body;

determining, as a function of time, the relative concentration of a fluorescing indicator introduced to and circulating within the blood stream of the body, by analyzing indicator fluorescence readings provided by a non-invasive sensor that is located along the skin surface of the body and both transcutaneously excites the indicator into fluorescence and transcutaneously detects said fluorescence;

generating, using the determined indicator concentrations, an indicator dilution curve with a recirculation component excluded therefrom;

calculating the area under a normal portion of the dilution curve;

calculating the area under a premature peak in the dilution curve if such a peak exists;

identifying the existence of a right-to-left shunt if the area under a premature peak in the dilution curve is determined to be non-zero; and

if a shunt is identified, calculating the shunt flow rate (shunt conductance) by performing a ratiometric analysis of the area under the premature peak in the dilution curve to the area under the normal portion of the dilution curve, and multiplying the result of said analysis by the calculated cardiac output value.

2. The method of claim 1, wherein when a shunt is identified, indicating to a user the presence of a shunt along with a corresponding shunt conductance value.

3. The method of claim 1, wherein the surface area of the body (BSA) is calculated using the formula BSA=((H*W)/3131)^1/2, and where H=the height of the body and W=the weight of the body.

4. The method of claim 3, wherein cardiac output (CO) is calculated using the formula CO=SI*HR*BSA, and where SI=a known Stroke Index value, and HR=a measured heart rate of the body.

5. The method of claim 1, wherein the sensor is an optical sensor having two or more photon sources independently paired with a like number of corresponding photon detectors.

6. The method of claim 5, wherein the source/detector pairs are serially activated.

7. The method of claim 5, wherein the sensor is placed on an auricle portion of the ear of the body, with the photon sources located on one side of the ear and the corresponding photon detectors located on an opposite side of the ear.

8. The method of claim 1, further comprising causing, subsequent to the introduction of the fluorescent indicator into the blood stream, a temporary reversal of a normal pressure differential that exists between the right and left atria of a heart of the body.

9. The method of claim 1, further comprising detecting and quantifying multiple right-to-left shunts by identifying multiple premature peaks in the dilution curve, performing a ratiometric analysis of the area under each premature peak in the dilution curve to the area under the entire remainder of the dilution curve, and multiplying the result of each ratiometric analysis by the calculated cardiac output value to obtain a shunt conductance value for each detected shunt.

13. The method of claim 9, wherein the sensor includes two or more laser emitters paired with a like number of corresponding photodetectors, the laser emitters adapted to emit light energy at a first wavelength and the photodetectors adapted to detect fluorescing energy at a second wavelength.

14. The method of claim 13, wherein the emitter/detector pairs are serially activated.

10. A method for detecting and quantifying a right-to-left cardiac and/or pulmonary shunt in a human subject, comprising:

causing the subject to perform a Valsalva maneuver at some predetermined pressure level for some predetermined length of time;

at a point prior to termination of the Valsalva maneuver, injecting a bolus of a fluorescing indicator into the bloodstream of the subject at a peripheral venous location, and subsequently injecting a bolus of an isotonic flushing material behind the indicator from the same location;

providing a non-invasive, optical sensor adapted to excite the indicator into fluorescence upon exposure to photon energy emitted therefrom, the sensor further adapted to detect said fluorescence;

locating the optical sensor along the skin surface of the subject in an area of underlying vasculature, and using the sensor to transcutaneously excite the indicator and to transcutaneously detect the resulting fluorescence of the indicator as the indicator passes through the vasculature;

calculating the body surface area of the subject;

calculating the cardiac output of the subject using, among other things, the calculated body surface area;

repeatedly determining the relative concentration of the indicator as a function of time using indicator fluorescence readings received from the sensor;

generating an indicator dilution curve using the determined indicator concentrations, while excluding a recirculation component from the indicator dilution curve;

calculating the area under a normal portion of the dilution curve;

calculating the area under a premature peak in the dilution curve, if such a peak exists;

identifying the existence of a right-to-left shunt if the area under a premature peak in the dilution curve is determined to be non-zero;

if a shunt is identified, calculating the shunt flow rate (shunt conductance) by performing a ratiometric analysis of the area under the premature peak in the dilution curve to the area under the normal portion of the dilution curve, and multiplying the result of said analysis by the calculated cardiac output value; and

indicating any identified shunt, along with a corresponding shunt conductance value.

11. The method of claim 10, wherein the body surface area (BSA) of the subject is calculated using the formula BSA=((H*W)/3131)^1/2, and where H=the height of the subject and W=the weight of the subject.

12. The method of claim 11, wherein cardiac output (CO) is calculated using the formula CO=SI*HR*BSA, and where SI=a known Stroke Index value, and HR=a measured heart rate of the subject.

15. The method of claim 10, wherein the sensor is placed on an auricle portion of the ear of the subject, with the laser emitters thereof located on one side of the ear and the corresponding photodetectors thereof located on an opposite side of the ear.

16. The method of claim 10, further comprising providing a controller/monitor that includes a microprocessor and associated programming and is in communication with the optical sensor, and using the controller/monitor to calculate the body surface area, to calculate the cardiac output, to determine the concentration of the indicator, to generate the dilution curve, to calculate the area under the normal portion of the dilution curve, to calculate the area under any premature peak in the dilution curve, and to calculate the shunt conductance value if a shunt is found to exist.

17. The method of claim 16, further comprising using the controller/monitor to monitor and time the Valsalva maneuver, and to cue an operator at least to inject the bolus of indicator.

18. The method of claim 16, further comprising placing a flow sensor in the path of the injected indicator and flushing material, and using the flow sensor to detect the injection thereof, the flow sensor reporting injection detection to the controller/monitor such that the controller/monitor may determine whether the injections were initiated within a predetermined time period after the start of and before the end of the Valsalva maneuver.

19. The method of claim 10, further comprising detecting and quantifying multiple right-to-left shunts by identifying multiple premature peaks in the dilution curve, performing a ratiometric analysis of the area under each premature peak in the dilution curve to the area under the entire remainder of the dilution curve, and multiplying the result of each ratiometric analysis by the calculated cardiac output value to obtain a shunt conductance value for each detected shunt.

20. A system for detecting and quantifying a right-to-left cardiac and/or pulmonary shunt in a human subject, comprising:

a controller/monitor that includes a microprocessor and associated programming that are together operative to provide a function(s) selected from the group consisting of one or more of monitoring, cueing, timing and analyzing various steps of a shunt detection test;

a pressure sensor located within the controller/monitor;

a Valsalva maneuver device comprising a mouthpiece and tubing assembly, the mouthpiece located at one end of the tubing, an opposite end of the tubing in fluid communication with the pressure sensor;

a first syringe for injecting a bolus of a fluorescing indicator into the bloodstream of the subject at a peripheral venous location, and a second syringe for subsequently injecting a bolus of an isotonic flushing material behind the indicator from the same location;

a flow sensor in communication with the controller/monitor for detecting and reporting injection of the indicator and the flushing material; and

a non-invasive, optical sensor in communication with the controller/monitor, the sensor having at least two serially activatable and paired laser emitters and photodetectors, the sensor adapted to transcutaneously excite the indicator and to transcutaneously detect the resulting fluorescence of the indicator from the skin surface of the subject as the indicator passes through underlying vasculature thereof.

21. The system of claim 20, wherein the pressure sensor is a manometer or pressure transducer.

22. The system of claim 20, wherein the controller/monitor is adapted to display visual feedback in response to subject exhalation into the mouthpiece of the Valsalva maneuver device, the visual feedback used to guide the subject through a Valsalva maneuver.

23. The system of claim 22, wherein the visual feedback is in the form of at least a dynamic pressure graph.

24. The system of claim 20, wherein the controller/monitor is adapted to terminate a Valsalva maneuver if the exhalation pressure exerted by the subject falls below a predetermined pressure for some predetermined period of time.

25. The system of claim 20, wherein the controller/monitor is adapted to time a Valsalva maneuver performed by the subject and, based on the timing of the Valsalva maneuver, to display a cue at the appropriate time to inject the fluorescing indicator.

26. The system of claim 20, wherein the optical sensor is adapted to fit over and be retained on an auricle portion of a subject'"'"'s ear, with the laser emitters of the sensor on one side of the ear and the corresponding photodetectors on an opposite side of the ear.

27. A system for detecting and quantifying a right-to-left cardiac and/or pulmonary shunt in a human subject, comprising:

a controller/monitor that includes a microprocessor and associated programming that are together operative to provide a function(s) selected from the group consisting of one or more of monitoring, cueing, timing and analyzing various steps of a shunt detection test;

a pressure sensor located within the controller/monitor;

a Valsalva maneuver device comprising a mouthpiece and tubing assembly, the mouthpiece located at one end of the tubing and the other end of the tubing in fluid communication with the pressure sensor;

a first syringe for injecting a bolus of a fluorescing indicator into the bloodstream of the subject at a peripheral venous location, and a second syringe for subsequently injecting a bolus of an isotonic flushing material behind the indicator from the same location; and

a non-invasive, optical sensor adapted to be located along the skin of the subject, and to transcutaneously excite the indicator and to transcutaneously detect the resulting fluorescence of the indicator as the indicator passes through underlying vasculature of the subject;

wherein the programming in the controller/monitor is adapted to, in some order;

(a) calculate the body surface area of the subject,

(b) calculate the cardiac output of the subject,

(c) repeatedly determine the relative concentration of the indicator as a function of time using indicator fluorescence readings received from the optical sensor,

(d) generate an indicator dilution curve using the determined indicator concentrations, while excluding a recirculation component from the indicator dilution curve,

(e) calculate the area under a normal portion of the dilution curve,

(f) calculate the area under a premature peak in the dilution curve, if such a peak exists,

(g) identify the existence of a right-to-left shunt if the area under a premature peak in the dilution curve is determined to be non-zero,

(h) calculate the shunt flow rate (shunt conductance), if a shunt is identified, by performing a ratiometric analysis of the area under the premature peak in the dilution curve to the area under the normal portion of the dilution curve, and multiplying the result of said analysis by the calculated cardiac output value, and

(i) indicate the presence of a detected right-to-left shunt, along with a corresponding shunt conductance value.

28. The system of claim 27, wherein the pressure sensor is a manometer or pressure transducer.

29. The system of claim 27, wherein the controller/monitor is adapted to display visual feedback in response to subject exhalation into the mouthpiece of the Valsalva maneuver device, the visual feedback used to guide the subject through a Valsalva maneuver.

30. The system of claim 29, wherein the visual feedback is in the form of at least a dynamic pressure graph.

31. The system of claim 27, wherein the controller/monitor is adapted to terminate a Valsalva maneuver if the exhalation pressure exerted by the subject falls below a predetermined pressure for some predetermined period of time.

32. The system of claim 27, wherein the controller/monitor is adapted to time a Valsalva maneuver performed by the subject and, based on the timing of the Valsalva maneuver, to display a cue at the appropriate time to inject the fluorescing indicator.

33. The system of claim 27, wherein the optical sensor is adapted to fit over and be retained on an auricle portion of a subject'"'"'s ear, with the emitters of the sensor on one side of the ear and the corresponding detectors on an opposite side of the ear.