Method and apparatus for detection of venous pulsation

• US 8,123,695 B2
• Filed: 09/27/2006
• Issued: 02/28/2012
• Est. Priority Date: 09/27/2006
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Baker, Clark R. Jr.
• Primary Examiner(s): Le, Miranda
• Assistant Examiner(s): Messersmith, Eric
• Application Number:
  US11/528,295
• Publication Number:
  US 20080077022A1
• Time in Patent Office: 1,980 Days
• Field of Search: 600323-324, 600500-504, 702189-194
• US Class Current: 600/500
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Methods and systems for detecting venous pulsation are provided. In one embodiment, a metric of the pulse shape of one or more plethysmographic signals is derived and the presence of venous pulsation is detected based on the metric of pulse shape. Examples, of metrics of pulse shape include a skew metric and a ratio of a minima-to-maxima time over a pulse period interval. In an exemplary embodiment, the presence of venous pulsation is detected based on a metric of the pulse shape of one or more plethysmographic signals and on a phase comparison of the plethysmographic signals.

Claims

1. A method for detecting venous pulsation with a patient monitor having a microprocessor, comprising:

deriving a skew metric for one or more plethysmographic signals with the microprocessor;

wherein the skew metric comprises a measure of the skewness of the derivative of the one or more plethysmographic signals;

filtering the skew metric based on a first set of filters with the microprocessor to generate a filtered skew metric;

adjusting the filtered skew metric with the microprocessor based on a pulse rate to generate an adjusted skew metric;

detecting the presence of venous pulsation with the microprocessor by comparing the adjusted skew metric to a predetermined threshold.

2. The method of claim 1, wherein the skew metric is processed to compensate for the typical rate-dependent changes in the skewness of arterial waveforms.

3. The method of claim 1, further comprising providing a notification of the presence of venous pulsation when detected.

4. One or more non-transitory machine readable media, comprising code executable by a microprocessor to perform the acts of:

deriving a skew metric for one or more plethysmographic signals wherein the skew metric comprises a measure of the skewness of the derivative of the one of more plethysmographic signals;

filtering the skew metric based on a first set of filters to generate a filtered skew metric;

adjusting the filtered skew metric based on a pulse rate to generate an adjusted skew metric; and

detecting the presence of venous pulsation by comparing the adjusted skew metric to a predetermined threshold.

5. The non-transitory, machine readable media of claim 4, further comprising code executable by the microprocessor to perform the act of processing the skew metric to compensate for the typical rate-dependent changes in the skewness of arterial waveforms.

6. The non-transitory, machine readable media of claim 4, further comprising code executable by the microprocessor to perform the acts of providing a notification of the presence of venous pulsation when detected.

7. A patient monitoring system comprising:

a patient monitor configured to;

derive a skew metric for one or more plethysmographic signals wherein the skew metric comprises a measure of the skewness of the derivative of the one or more plethysmographic signals;

filter the skew metric based on a first set of filters to generate a filtered skew metric;

adjust the filtered skew metric based on a pulse rate to generate an adjusted skew metric; and

detect the presence of venous pulsation by comparing the adjusted skew metric to a predetermined threshold.

8. The system of claim 7, wherein the patient monitor is configured to process the skew metric to compensate for the typical rate-dependent changes in the skewness of arterial waveforms.

9. The system of claim 7, wherein the patient monitor is configured to provide a notification of the presence of venous pulsation when detected.