Pulse rate and heart rate coincidence detection for pulse oximetry

• US 6,178,343 B1
• Filed: 05/20/1999
• Issued: 01/23/2001
• Est. Priority Date: 06/05/1998
• Status: Expired due to Term

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett Packard Company (HP Inc.)
• Inventors: Bindszus, Andreas, Boos, Andreas
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US09/315,698
• Time in Patent Office: 614 Days
• Field of Search: 600/323, 600/324, 600/333, 600/336, 600/479, 600/483
• US Class Current: 600/323
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/14551 for measuring blood gases

Abstract

A coincidence recognition unit receives a first signal indicative of a pulse rate derived from pulse oximetry and a second signal indicative of a heart rate. A coincidence detection unit generates a third signal indicative of the coincidence between the first signal and the second signal. The pulse rate of a patient (detected by pulse oximetry) can thus be compared with the heart rate of the patient (e.g. from EKG or ultrasound). An indicator is preferably generated when the pulse rate and the heart rate do not match e.g. within a pre-given limit. A warning signal might further be generated indicating that the oxygen saturation value as measured by the pulse oximetry is not sufficiently accurate and/or invalid. A pulse oximetry unit according to the invention comprises a pulse oximeter for generating the first signal, a heart rate determination unit for generating the second signal, and the coincidence recognition unit receiving the first and second signals. The coincidence recognition unit provides the third signal indicative of the coincidence between the first and the second signal to the pulse oximeter for validating the accuracy of measured oxygen saturation values of any kind of patient such as adults, pediatrics, or neonates.

Claims

1. A signal matching recognition unit receiving a first signal indicative of a pulse rate derived from pulse oximetry and a second signal, indicative of a heart rate, that is derived from a technique other than pulse oximetry, the signal matching recognition unit comprising:

a signal matching detection unit for generating a third signal

indicative of a signal match between the first signal and the second signal.

2. The signal matching recognition unit of claim 1, further comprising:

a signal matching evaluation unit receiving the third signal for generating therefrom a fourth signal when the third signal exceeds a predefined relation to a given limit.

3. The signal matching recognition unit of claim 1, wherein the signal matching detection unit comprises means for determining a signal match between the first signal and the second signal.

4. The signal matching recognition unit of claim 1, wherein the signal matching detection unit comprises:

a summing circuit, receiving the first signal and the second signal, for generating a difference signal indicative of the difference between the first signal (PR) and the second signal (HR),

a first comparator for comparing the difference signal with a predetermined limit and for providing an output corresponding the difference signal,

an integrator circuit for summing up the output received from the first comparator, and

a second comparator for comparing a signal provided by the integrator circuit with one or more threshold values and for providing the third signal.

5. The signal matching recognition unit of claim 4, wherein the signal matching detection unit further comprises an absolute value generator, receiving the difference signal, for generating the absolute value of the difference signal, whereby the first comparator receives and compares the absolute value of the difference signal with a predetermined limit and provides an output corresponding the received absolute value of the difference signal.

6. A pulse oximetry unit comprising:

a pulse oximeter generating a first signal indicative of a pulse rate,

a heart rate determination unit generating a second signal, indicative of a heart rate, that is derived from a technique other than pulse oximetry, and

a signal matching recognition unit wherein said signal matching recognition unit receives the first signal from the pulse oximeter and the second signal from the heart rate determination unit and provides a third signal indicative of the signal matching between the first signal and the second signal to the pulse oximeter for validating the accuracy of measured oxygen saturation values.

7. The pulse oximetry unit of claim 6, wherein the signal matching recognition unit provides a warning signal to the pulse oximeter, indicating that the oxygen saturation value is not sufficiently accurate and/or invalid, when the signal matching recognition unit recognizes a mismatch between the pulse rate and the heart rate.

8. A method for validating the accuracy of oxygen saturation values measured by a pulse oximeter, comprising the steps of:

(a) receiving a first signal indicative of a pulse rate derived from pulse oximetry and a second signal, indicative of a heart rate, that is derived from a technique other than pulse oximetry, and

(b) generating a third signal indicative of the signal matching between the first signal and the second signal.

9. The method of claim 8, further comprising the step of:

(c) generating a fourth signal from the third signal when the third signal exceeds a predefined relation to a given limit.

10. The method of claim 8, further comprising the step of:

(d) providing a warning signal to the pulse oximeter, indicating that the oxygen saturation value as measured by the pulse oximeter is not sufficiently accurate and/or invalid, when a mismatch between the pulse rate and the heart rate is recognized.