Quality indicator for measurement signals, in particular, for medical measurement signals such as those used in measuring oxygen saturation

• US 6,725,074 B1
• Filed: 05/29/2002
• Issued: 04/20/2004
• Est. Priority Date: 06/10/1999
• Status: Expired due to Term

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Kästle, Siegfried
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US10/018,069
• Time in Patent Office: 692 Days
• Field of Search: 600/322-323, 600/336, 600/366, 356/39-41
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A method of determining a quantitative statement concerning the quality of a medical measurement signal in pulsoximetry includes the steps of determining factors relevant to the measurement signal and interlinking the factors by means of an uncertain logic into a quality indicator. The factors relate to combinations selected from the group consisting of signal recording, signal processing, and signal evaluation. The uncertain logic includes fuzzy logic. The quality indicator quantitatively describes a quality of a determined measurement value of the measurement signal.

Claims

1. A method of determining a quantitative statement concerning the quality of a medical measurement signal in pulsoximetry, said method comprising the steps of:

(a) determining factors relevant to the measurement signal, the factors relating to combinations selected from the group consisting of signal recording, signal processing, and signal evaluation; and

(b) interlinking the factors by means of an uncertain logic, including fuzzy logic, into a quality indicator wherein the quality indicator quantitatively describes a quality of a determined measurement value of the measurement signal.

2. The method as claimed in claim 1, wherein the step of determining factors relevant to the measurement signal comprises:

a step of determining factors relative to an obtaining of the measurement signal, wherein the factors describe at least one of a measurement location, a measurement time, and a measurement sensor arrangements;

a step of determining factors relevant to signal processing, wherein the factors describe at least one of a signal-to-noise ratio, parameters relating to a possible subsequent noise suppression, and a signal compression; and

a step of determining factors relevant to the signal evaluation, wherein the factors describe at least one of measuring algorithms used, and consideration of at least one of all basic signals and parts of all basic signals thereof.

3. The method as claimed in claim 1, further comprising:

providing a display of the quality indicator by means of a tendency display having a nature selected from at least one of “

relatively better/worse” and

“

absolutely good/bad”

, the tendency display further including a display with histogram bars of variable length.

4. The method as claimed in claim 1, wherein a visualization of the quality indicator is achieved using a display of the measurement signal describing the quality indicator that changes when the quality indicator value exceeds a given threshold value, wherein the visualization includes at least one selected from the group consisting of a switch-over from a continuous display to a flashing display with a varying flashing frequency in dependence on the quality indicator value, a change in display color including at least one of:

a) red for low quality indicator values b) green for a high quality indicator value, amber for a medium quality indicator value, and red for a low quality indicator value and c) an inversion of display colors.

5. The method as claimed in claim 1, further comprising:

controlling an alarm function in dependence on the quality indicator in response to the measurement signal deviating from at least one of a given limit value and a range.

6. The method as claimed in claim 5, wherein controlling the alarm function includes a change in an alarm delay time in dependence on a value of the quality indicator, wherein the alarm delay time is set for at least one of a maximum in the case of a low reliability of the measurement signal and a minimum in the case of a high reliability of the measurement signal.

7. The method as claimed in claim 1, further comprising a step of:

evaluating a gradient in time of the quality indicator so as to recognize at least one trend in the measurement signal.

8. The method as claimed in claim 7, wherein the trend is shown on a trend display, the trend display including an arrow pointing upwards for an improvement in signal quality, an arrow pointing downwards for a deterioration of signal quality, and an arrow remaining at a same level for indicating a substantially constant signal quality.

9. The method as claimed in claim 7, further comprising performing an error prognosis step based on the trend in the measurement signal and by giving an alarm in response to a substantially continuous drop in the quality indicator value over a given time period.

10. A computer program including a computer program product stored on a computer-readable storage medium, the computer program comprising a code for carrying out the steps as claimed in claim 1, wherein the program is carried out on a computer.

11. A device for determining a quantitative statement as to the quality of a medical measurement signal in pulsoximetry, the device comprising:

means for determining factors relevant to the measurement signal, the factors relating to a combination selected from the group consisting of signal recording, signal processing, and signal evaluation, and

means for interlinking the determined factors by means of an uncertain logic, the uncertain logic including fuzzy logic, to form to provide a quality indicator that quantitatively describes a quality of a determined measurement value of the measurement signal.

12. An apparatus for determining an oxygen content of blood by pulsoximetry, the apparatus comprising a device for determining a quantitative statement concerning the quality of a measurement signal as claimed in claim 11.