Pulse oximetry pulse indicator

• US 6,606,511 B1
• Filed: 01/06/2000
• Issued: 08/12/2003
• Est. Priority Date: 01/07/1999
• Status: Expired due to Term

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Novak, Jerome J., Breed, Divya S., Ali, Ammar Al
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US09/478,230
• Time in Patent Office: 1,314 Days
• Field of Search: 600/309-310, 600/322-324, 600/330, 600/336, 600/508, 600/515-519
• US Class Current: 600/324
• 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 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths

Abstract

An intelligent, rule-based processor provides a pulse indicator designating the occurrence of each pulse in a pulse oximeter-derived photo-plethysmograph waveform. When there is relatively no distortion corrupting the plethysmograph signal, the processor analyzes the shape of the pulses in the waveform to determine where in the waveform to generate the pulse indication. When distortion is present, looser waveform criteria are used to determine if pulses are present. If pulses are present, the pulse indication is based upon an averaged pulse rate. If no pulses are present, no indication occurs. The pulse indicator provides a trigger and amplitude output. The trigger output is used to initiate an audible tone “beep” or a visual pulse indication on a display, such as a vertical spike on a horizontal trace or a corresponding indication on a bar display. The amplitude output is used to indicate data integrity and corresponding confidence in the computed values of saturation and pulse rate. The amplitude output can vary a characteristic of the pulse indicator, such as beep volume or frequency or the height of the visual display spike.

Claims

1. A processing apparatus having as an input a plethysmograph waveform, said waveform comprising a plurality of pulses, said apparatus generating a trigger synchronous with the occurrence of said pulses, said apparatus comprising:

a waveform analyzer in communication with said waveform and responsive to the shape of said pulses, wherein the waveform analyzer derives a measure of distortion in said waveform that is indicative of a quality of said waveform; and

a decision element conditionally responsive to said measure of distortion derived by said waveform analyzer to provide said trigger.

2. The processing apparatus of claim 1 further comprising a pulse rate input, wherein said decision element is conditionally responsive to said pulse rate input to provide said trigger.

3. The processing apparatus of claim 2 wherein said decision element is responsive to said measure of distortion when said measure of distortion indicates that said waveform is substantially undistorted and is responsive to said pulse rate when said waveform is substantially distorted.

4. The processing apparatus of claim 1 wherein said trigger is used to generate an audible indicator of pulse occurrence.

5. The processing apparatus of claim 1 wherein said trigger is used to generate a visual indicator of pulse occurrence.

6. The processing apparatus of claim 5 wherein said visual indicator also incorporates an indication of data integrity.

7. A method of indicating a pulse in a plethysmograph waveform comprising the steps of:

deriving a measure of distortion in said waveform;

wherein said measure of distortion is indicative of a quality of said waveform;

establishing a trigger criterion dependent on said measure;

determining whether said trigger criterion is satisfied to provide a trigger; and

generating a pulse indication upon occurrence of said trigger.

8. The method of claim 7 wherein said deriving step comprises the steps of:

computing a first value related to integrity of said waveform;

computing a second value related to the recognizable pulses in said waveform; and

combining said first value and said second value to derive said measure.

9. The method of claim 7 wherein said trigger criterion is based on a waveform shape.

10. The method of claim 7 wherein said trigger criterion is based on a pulse rate.

11. An apparatus for indicating the occurrence of pulses in a plethysmograph waveform comprising:

a waveform analyzer means for recognizing a physiological pulse in said waveform;

a detector means for determining a measure of distortion in said waveform, wherein said measure of distortion is indicative of a quality of said waveform;

a decision means for triggering a pulse indicator based on at least one of said physiological pulse and a pulse rate depending on said measure.