DETECTING A VASOACTIVE AGENT IN THE BLOODSTREAM

• US 20140235971A1
• Filed: 10/05/2012
• Published: 08/21/2014
• Est. Priority Date: 10/07/2011
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Jian, Zhongping, Hatib, Feras
• Granted Patent: US 9,968,304 B2
• Time in Patent Office: Days
• US Class Current: 600/309
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• 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 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 8/488 involving Doppler signals

Abstract

A system and method are disclosed for detecting a vasoactive agent in patient'"'"'s bloodstream. In one embodiment, an input signal is received that is associated with arterial blood pressure. A change of an arterial blood pressure parameter over time is determined. A vasoactive agent is then automatically detected using the determined change. In another embodiment, a waveform associated with an arterial blood pressure signal can be received. A parameter associated with the received waveform is calculate. Then the calculated parameter can be used to determine the presence of a vasoactive agent. In yet another embodiment, detection of a vasoactive agent in any of the other embodiments can be used in a calculation of a hemodynamic parameter, such as cardiac output, stroke volume, systemic vascular resistance, stroke volume variation, cardiac index, stroke volume index, systemic vascular resistance index, vascular compliance, and vascular tone.

Claims

1. A method for detecting a vasoactive agent in a patient'"'"'s bloodstream, comprising:

receiving an input signal that is associated with arterial blood pressure;

determining a change over time associated with pulsatility of the input signal; and

automatically detecting a vasoactive agent in the bloodstream using the determined change.

2. The method of claim 1, wherein determining comprises measuring the change associated with pulsatility including calculating a first waveform parameter of the input signal at first and second times, calculating a second waveform parameter of the input signal at the first and second times, and calculating a ratio of the first waveform parameter to the second waveform parameter at the first and second times.

3. The method of claim 2, further including calculating a difference between the ratios at the first and second times to obtain the measured change and wherein automatically detecting includes determining whether the measured change exceeds a predetermined threshold.

4. The method of claim 2, wherein the first waveform parameter is one of the following:

pulse pressure, standard deviation of pressure waveform, systolic area, or diastolic area.

5. The method of claim 2, wherein the second waveform parameter is mean arterial pressure, systolic pressure, diastolic pressure, pressure at a specific time point in each beat, differentiation of pressure with respect to time, systolic area, diastolic area, or a combination thereof.

6. The method of claim 2, wherein the first waveform parameter and the second waveform parameter are exchangeable in the calculation of the ratio.

7. The method of claim 1, wherein determining comprises measuring the change associated with pulsatility by calculating a waveform parameter of the input signal at first and second times.

8. The method of claim 7, further including calculating a difference between the waveform parameters at the first and second times to obtain the measured change and wherein automatically detecting includes determining whether the measured change exceeds a predetermined threshold.

9. The method of claim 7, wherein the waveform parameter is pulse pressure, standard deviation of pressure waveform, heart rate, mean arterial pressure, systolic pressure, diastolic pressure, pressure at a specific time point in each beat, differentiation of pressure with respect to time, systolic area, diastolic area, and a combination of any of those parameters.

10. The method of claim 1, further including using that the vasoactive agent was detected in a calculation of a hemodynamic parameter.

11. The method of claim 10, wherein the hemodynamic parameter is cardiac output, stroke volume, systemic vascular resistance, stroke volume variation, cardiac index, stroke volume index, systemic vascular resistance index, vascular compliance, vascular tone.

12. The method of claim 1, wherein the received input signal is a waveform, and wherein the determining the change includes dividing the waveform into segments of a predetermined time duration, detecting each beat in a segment, and calculating a pulse pressure and mean arterial pressure for each beat.

13. The method of claim 12, further including averaging the pulse pressure and mean arterial pressure for all beats in a segment, calculating a ratio of the average pulse pressure to the average mean arterial pressure, and calculating a difference in the ratio between multiple segments.

14. The method of claim 1, further including calculating the pulsatility using one or more of the following techniques on the received input signal:

integral analysis, correlation, Fourier analysis, maximum-minimum, derivative, or standard deviation.

15. The method of claim 1, wherein the input signal is proportional to, or derived from one or more of the following measurements:

arterial pressure, flow rate, vascular resistance, pulse oximetry, Doppler ultrasound, or bioimpedance signal.

16. The method of claim 1, further including measuring the arterial blood pressure invasively or non-invasively to produce the input signal.

17. The method of claim 1, wherein the vasoactive agent is selected from the following:

vasoconstrictor, vasodilator, or inotrope.

18. The method of claim 1, wherein determining includes receiving data associated with measuring a change over time of the pulsatility of the input signal.

19. The method of claim 1, wherein the input signal is a waveform, a digitized signal, or an analog signal.

20. A method of detecting a vasoactive agent, comprising:

receiving a waveform associated with an arterial blood pressure signal;

using the received waveform, calculating at least one parameter associated with pulsatility of the arterial blood pressure signal; and

detecting a presence of a vasoactive agent using the calculated parameter.

21. The method of claim 20, further including measuring an average of the waveform over a period of time and wherein detecting the presence of the vasoactive agent includes detecting a change of greater than a threshold amount of the parameter.

22. The method of claim 20, further including dividing the waveform into segments of a predetermined period of time, detecting heart beats within each segment, and calculating the at least one parameter for each beat.

23. The method of claim 20, wherein the at least one parameter includes one of the following:

pulse pressure, standard deviation of pressure waveform, systolic area, diastolic area, mean arterial pressure, systolic pressure, diastolic pressure, pressure at a specific time point in each heartbeat, differentiation of pressure with respect to time, or a combination thereof.

24. The method of claim 20, further including calculating a hemodynamic parameter using the presence of the vasoactive agent.

25. The method of claim 20, wherein the at least one parameter is a first parameter that includes one of the following:

pulse pressure, standard deviation of pressure waveform, systolic area, or diastolic area and further including measuring a second parameter, which includes one of the following;

mean arterial pressure, systolic pressure, diastolic pressure, pressure at a specific time point in each beat, differentiation of pressure with respect to time, systolic area, diastolic area, or a combination thereof.

26. The method of claim 25, further including calculating a ratio comprising the first parameter and the second parameter.

27. The method of claim 25, wherein calculating includes using one or more of the following techniques:

integral analysis, correlation, Fourier analysis, maximum-minimum, derivative, or standard deviation.

28. The method of claim 25, further including determining the first parameter at first and second times and the second parameter at first and second times, and calculating a change over time associated with the first and second parameters.

29. The method of claim 25, further including determining a heart rate and differentiating between different vasoactive agents using at least one of the first and second parameters in conjunction with the heart rate.

30. A system for detecting a vasoactive agent, comprising:

a sensor that generates a signal corresponding to arterial blood pressure; and

a processor for using the signal to calculate a parameter corresponding to pulsatility and analyzing whether a change in the parameter over time exceeds a predetermined threshold and, if so, calculating a hemodynamic parameter taking into account a presence of a vasoactive agent.

31. The system of claim 30, wherein the parameter is a ratio comprising one of the following:

pulse pressure, standard deviation of pressure waveform, systolic area, or diastolic area and one of the following;

mean arterial pressure, systolic pressure, diastolic pressure, pressure at a specific time point in each beat, differentiation of pressure with respect to time, systolic area, diastolic area, or a combination thereof.

32. A method for detecting a vasoactive agent in a bloodstream, comprising:

receiving data associated with a blood-pressure parameter at a first point in time;

receiving data associated with the blood-pressure parameter at a second point in time;

comparing the data at the first and second points in time; and

based on the comparison, detecting a presence of a vasoactive agent in the bloodstream.

33. The method of claim 32, further including determining a type of vasoactive agent using the received blood-pressure parameter.