Detection of sensor off conditions in a pulse oximeter

• US 20020137995A1
• Filed: 01/24/2001
• Published: 09/26/2002
• Est. Priority Date: 01/24/2001
• Status: Active Grant

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Inventors: Heckel, Donald W.
• Granted Patent: US 6,510,329 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: Y10S 128/92 Computer assisted medical diagnostics

Abstract

An improved system for detecting sensor off conditions in a pulse oximeter is disclosed. In one implementation, a detector off condition is identified based a volatility of a signal quality of a filtered detector signal. The detector signal is first filtered, for example, to reduce the effects of noise or to otherwise reduce or eliminate components extraneous to the signal of interest. The filtered signal is used to perform a volatility measurement. In this regard, a correlation coefficient may be computed relative to two channels of the filtered signal and a correlation coefficient may be monitored over a moving window to calculate variance values for the correlation coefficient. The resulting variance values may be used alone or in combination with other parameter values to identify a sensor off condition.

Claims

1. A method for use in detecting and responding to a sensor off conditions in a pulse oximetry system, said pulse oximetery system including a first source for providing a first channel signal associated with a first wavelength and a second source for providing a second channel signal associated with a second wavelength, said method comprising the steps of:

obtaining first and second detector signals associated with said first and second wavelengths, respectively;

monitoring a correlation between said first and second detector signals;

determining a value related to a change in said correlation between said first and second detector signals; and

identifying a sensor off condition based on said value.

2. A method for use in detecting and responding to a sensor off conditions in a pulse oximetry system, comprising the steps of:

defining a measure of signal quality;

monitoring said measure of signal quality;

calculating a value related to variance of said measure of signal quality; and

identifying a sensor off condition based on said value.

3. A method for use in detecting and responding to a sensor off conditions in a pulse oximetry system, said pulse oximetry system including a detector for receiving light signals modulated by tissue of a patient, said method comprising the steps of:

obtaining a signal based on an output from said detector;

filtering said signal to obtain a series of filtered values;

measuring a volatility of said filtered values; and

using said measured volatility to identify a sensor off condition.

4. A method for use in detecting and responding to a sensor off conditions in a pulse oximetry system, said method comprising the steps of:

defining a measure of signal quality;

monitoring said measure of signal quality;

determining a first value related to a magnitude of said measure of said signal quality relative to a time window;

determining a second value related to a variance of said measure of said signal quality relative to said time window; and

using said first value and said second value to identify a sensor off condition.