Pulse oximeter with signal sonification

• US 6,449,501 B1
• Filed: 05/26/2000
• Issued: 09/10/2002
• Est. Priority Date: 05/26/2000
• Status: Expired due to Term

• Current Assignee: Prothia
• Original Assignee: OB Scientific Incorporated
• Inventors: Reuss, James L.
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US09/579,648
• Time in Patent Office: 837 Days
• Field of Search: 600/309-311, 600/313, 600/315-316, 600/322-328, 600/336-342, 600/330, 600/338, 356/39-41
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7415 Sound rendering of measured values, e.g. by pitch or volume variation A61B5/741 takes precedence

Abstract

An improved pulse oximeter is disclosed. The pulse oximeter includes audio signal generation means, controlled by algorithms in a processing element which continuously transform the signals from the sensor into signal quality information. This information is converted into an audio signal and annunciated for the operator'"'"'s use in guiding sensor placement. This signal quality information is available even in the absence of successful computation of pulse rate and/or oxygen saturation level. It furthermore can reflect signal quality changes that may be too subtle to be reflected in the typical numerical representation of pulse rate and oxygen saturation trend. The audio representation of the signal quality can further be modulated to convey other system and/or physiological status and alerts.

Claims

1. A method of enhancing signal quality information using signal sonification while monitoring oxygen saturation in a pulse oximeter comprising the following steps:

(a) exposing a tissue site to a plurality of wavelengths of light generated by the pulse oximeter, said tissue site having one or more pulsatile characteristic(s) associated with physiological parameters;

(b) detecting light of the plurality of wavelengths transmitted by or reflected from components of the tissue site, said detected light having a detected light pulsatile component related to one or more of the pulsatile characteristic(s) of said tissue site, and converting said detected light into a plurality of electrical signals, each said electrical signal of said plurality of said electrical signalshaving an electrical signal pulsatile component related to the detected light pulsatile component;

(c) digitizing and conditioning said plurality of electrical signals in a signal data acquisition component of the pulse oximeter to remove noise while retaining said electrical signal pulsatile component of each of the digitized and conditioned said plurality of electrical signals and creating a plurality of digital signals;

(d) deriving signal quality information from said plurality of digital signals by processing said plurality of digital signals to enhance and accentuate said electrical signal pulsatile component, creating a plurality of enhanced signals; and

combining said plurality of enhanced signals to emphasize variations related to said pulsatile tissue characteristic(s) in said plurality of electrical signals from step (b);

(e) continuously transforming said signal quality information into a signal quality audio representation by applying a frequency mapping function and a volume control function;

(f) conveying said signal quality audio representation of signal quality information to an operator;

(g) analyzing said plurality of digital signals for pulse rate and oxygen saturation level;

(h) providing pulse rate and oxygen saturation information to an operator in audible and/or readable form;

(i) combining physiological and system alert information with said signal quality audio representation conveying signal quality information to form a combined audio signal;

(j) permitting operator control of the overall audio volume of said combined audio signal.

2. The method as defined in claim 1, wherein the digitizing and conditioning step includes line frequency rejection and band pass filtering.

3. The method as defined in claim 2, wherein the line frequency rejection in each electrical signal is accomplished by summing of pairs of samples taken at twice the line frequency.

4. The method as defined in claim 2, wherein the band pass filtering passes signal frequencies in the range 0.5-10 Hz.

5. The method as defined in claim 1, wherein the step of deriving signal quality includes differentiation of the digital signals.

6. The method as defined in claim 1, wherein the step of deriving signal quality includes combining the plurality of digital signals to select the one most rapidly varying, and locating pulsatile events in the data.

7. The method as defined in claim 1, wherein the step of transforming signal quality into audio includes mapping signal quality amplitude to a frequency range audible to humans.

8. The method as defined in claim 1, wherein the step of transforming signal quality into audio includes manipulating audio volume to emphasize pulsatility in the plurality of digital signals.

9. The method as defined in claim 8, wherein the manipulation of audio volume includes making audio volume proportional to signal quality data.

10. The method as defined in claim 8, wherein the manipulation of audio volume includes silencing the audio during substantially all of the diastolic phase of pulsations in the plurality of digital signals.

11. The method as defined in claim 1, wherein the step of transforming signal quality into audio includes manipulating the audio volume as determined by a controlling physiological or system parameter.

12. The method as defined in claim 11, in which the controlling parameter is derived from the intensity with which the light emitting devices of the sensor are driven.

13. The method as defined in claim 11, in which the maximum audio volume during a pulsation is proportional to the controlling parameter.

14. The method as defined in claim 1, wherein the step of transforming signal quality into an audio signal includes manipulating the frequency range as determined by a controlling physiological or system parameter.

15. The method as defined in claim 14, in which the controlling parameter is the oxygen saturation trend.

16. The method as defined in claim 14, in which the highest audio frequency of the signal quality audio representation in a particular pulsation is a value proportional to the controlling parameter.

17. The method as defined in claim 1, further comprising the step of combining the audio representation of signal quality with the audio representation of physiological and system alert information.

18. The method as defined in claim 1, where the tissue site is located on an adult or neonatal subject.

19. The method as defined in claim 1, where the tissue site is located on a fetus in utero.

20. A pulse oximeter system with enhanced signal quality information using signal sonification comprising:

a sensor device;

a monitor device comprising at least a data acquisition component, a computing component, a memory storage component, an audio signal generation component, a visual presentation component;

wherein the system is used by (a) exposing a tissue site to a plurality of wavelengths of light generated by the sensor device of the pulse oximeter, the tissue site having one or more pulsatile characteristic(s) associated with physiological parameters;

(b) detecting light of the plurality of wavelengths transmitted by or reflected from components of the tissue site using the sensor device of the pulse oximeter, the detected light having a detected light pulsatile component related to the one or more pulsatile characteristic(s) of the tissue site and converting the detected light into a plurality of electrical signals in the data acquisition component, each of the electrical signals of the plurality of electrical signals having an electrical signal pulsatile component related to the detected light pulsatile component;

(c) digitizing and conditioning the plurality of electrical signals in a signal data acquisition component of the computing component of the pulse oximeter to remove noise while retaining the electrical signal pulsatile component of each of the digitized and conditioned plurality of the electrical signals and creating a plurality of digital signals;

(d) deriving signal quality information from the plurality of the digital signals in the computing component, by processing the plurality of digital signals to enhance and accentuate the electrical signal pulsatile component, creating a plurality of enhanced signals, and combining the plurality of enhanced signals to emphasize variations related to the pulsatile tissue characteristic(s) in the plurality of electrical signals from step (b);

(e) continuously transforming the signal quality information into a signal quality audio representation, by applying a frequency mapping function and a volume control function;

(f) conveying the signal quality audio representation of signal quality information to an operator using the audio signal generation component;

(g) analyzing the plurality of digital signals for pulse rate and oxygen saturation level;

(h) providing pulse rate and oxygen saturation information to an operator in audible form using the audio signal generation component and/or readable form using the visual presentation component;

(i) combining physiological and system alert information with the signal quality audio representation conveying signal quality information to form a combined audio signal;

(j) permitting operator control of the overall audio volume of the combined audio signal using the audio signal generation component.

21. The pulse oximeter as defined in claim 20, wherein the sensor device comprises a plurality of light emitting devices and at least one associated detector, the light emitting devices and the at least one associated detector being used for measuring oxygen saturation.

22. The pulse oximeter as defined in claim 20, wherein the computing component is used to derive signal quality information from the sensor device.

23. The pulse oximeter as defined in claim 20, wherein the audio signal generation component is used to convey the signal quality information to an operator.

24. The pulse oximeter as defined in claim 20, wherein the audio signal generation component includes a headset.

25. The pulse oximeter as defined in claim 20, wherein the audio signal generation component includes a speaker.

26. The pulse oximeter as defined in claim 20, wherein the audio signal generation component includes a connection for an external sound system.

27. The pulse oximeter as defined in claim 20, wherein the audio signal generation component includes a connection for a remote annunciator.

28. The pulse oximeter as defined in claim 20, wherein the sensor device is designed for use in monitoring adults or neonates.

29. The pulse oximeter as defined in claim 20, wherein the sensor device is designed for use in fetal monitoring.