PATTERN OF CUFF INFLATION AND DEFLATION FOR NON-INVASIVE BLOOD PRESSURE MEASUREMENT

• US 20120215118A1
• Filed: 02/18/2011
• Published: 08/23/2012
• Est. Priority Date: 02/18/2011
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Chen, Bo, Li, Youzhi, Lisogurski, Daniel
• Granted Patent: US 8,721,557 B2
• Time in Patent Office: Days
• US Class Current: 600/490
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors

Abstract

Embodiments of the present disclosure relate to a system and method for determining a physiologic parameter of a patient. Specifically, embodiments provided herein include methods and systems for non-invasive determination of blood pressure. Information from a photoplethysmography sensor may be used to determine a systolic pressure, which in turn may be used to control a deflation pattern of a blood pressure cuff.

Claims

1. A method of monitoring blood pressure in a subject comprising:

using a monitor to;

receive a signal from a photoplethysmography sensor positioned proximate to an inflatable blood pressure cuff;

receive a signal from a pressure transducer associated with the inflatable blood pressure cuff; and

determine a systolic blood pressure of the subject based on a pressure in the inflatable blood pressure cuff at a first appearance of a plethysmographic waveform in the signal from the photoplethysmography sensor during linear deflation of the inflatable blood pressure cuff from an oversystolic pressure.

2. The method of claim 1, comprising using the monitor to provide instructions to implement stepwise deflation of the inflatable blood pressure cuff at pressures lower than the systolic pressure.

3. The method of claim 1, comprising using the monitor to determine a mean arterial pressure based on a peak pressure amplitude during the stepwise deflation.

4. The method of claim 3, comprising using the monitor to provide instructions to stop the stepwise deflation after the mean arterial pressure is determined.

5. The method of claim 1, comprising using the monitor to determine a diastolic pressure of the subject based on the systolic pressure and the mean arterial pressure.

6. The method of claim 1, wherein each step of the stepwise deflation comprises at least two pressure oscillations.

7. The method of claim 1, wherein a step of the stepwise deflation is about 8 mm Hg or less than a previous step.

8. The method of claim 1, wherein the first appearance of the plethysmographic waveform is determined using a pulse qualification.

9. The method of claim 8, wherein the pulse qualification comprises an assessment of one or more of degree of arrhythmia, pulse amplitude variations, individual pulse quality, or pulse periods.

10. A monitor, comprising:

an input circuit configured to receive a photoplethysmographic signal and a pressure transducer signal from a pressure transducer associated with an inflatable blood pressure cuff;

a memory storing an algorithm configured to calculate systolic pressure based at least in part on the photoplethysmographic signal and the pressure transducer signal; and

a processor configured to execute the algorithm and provide instructions to control an intracuff pressure in the inflatable blood pressure cuff;

wherein a switch between linear deflation and stepwise deflation of the inflatable blood pressure cuff is based on a determination of systolic pressure, wherein the determination of systolic pressure is based on a correlation between the photoplethysmographic signal and the intracuff pressure.

11. The monitor of claim 10, wherein the systolic pressure is determined based on the intracuff pressure at which a plethysmographic waveform signal is first detected during deflation of the inflatable blood pressure cuff from an oversystolic pressure.

12. The monitor of claim 11, comprising correlating a sudden increase in an amplitude of arterial pressure oscillation during deflation to the systolic pressure.

13. The monitor of claim 10, wherein the algorithm comprises a pulse identification step.

14. The monitor of claim 13, wherein the pulse identification step comprises amplitude matching.

15. The monitor of claim 13, wherein the pulse identification step comprises pulse shape matching.

16. The monitor of claim 13, wherein the pulse identification step comprises pulse period assessment.

17. The monitor of claim 10, a display configured to provide an indication related to the systolic pressure.

18. A system for determining non-invasive blood pressure, comprising:

a sensor configured to be applied to a subject to acquire photoplethysmographic data and generate a signal relating to the photoplethysmographic data;

an inflatable blood pressure cuff configured to be applied to a subject proximate to the sensor; and

a monitor configured to;

provide instructions to a control system for the inflatable blood pressure cuff to deflate the inflatable blood pressure cuff in a substantially linear manner at pressures greater than the systolic pressure and to deflate the cuff in a stepwise manner at pressures less than the systolic pressure; and

determine a pressure in the inflatable blood pressure cuff at which a plethysmographic waveform cannot be sensed by the sensor, wherein the pressure correlates to the subject'"'"'s systolic pressure.

19. The system of claim 18, wherein the instructions to deflate the inflatable blood pressure cuff in a substantially linear manner comprise instructions to deflate at a rate of 3 mm Hg per second or less.

20. The system of claim 18, wherein the instructions to deflate the inflatable blood pressure cuff in a substantially stepwise manner comprise instructions to hold a particular intracuff pressure until at least two correlated arterial pressure oscillations have been detected by a pressure transducer associated with the inflatable blood pressure cuff.

21. A method of monitoring blood pressure in a subject comprising:

using a monitor to;

receive a signal from a photoplethysmography sensor positioned proximate to an inflatable blood pressure cuff;

receive a signal from a pressure transducer associated with the inflatable blood pressure cuff; and

determine a systolic blood pressure of the subject based on a pressure in the inflatable blood pressure cuff at a first disappearance of a plethysmographic waveform in the signal from the photoplethysmography sensor during linear inflation of the inflatable blood pressure cuff to an oversystolic pressure.