Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2001-09-11
2003-12-23
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S322000, C600S323000
Reexamination Certificate
active
06668183
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of photoplethysmography and, more specifically, to an improved system and method for determining sensor attributes. The invention is particularly apt for use in pulse oximetry applications to identify compatible sensors and/or otherwise to provide for the transfer of calibration and of other information between sensors and other system components.
BACKGROUND OF THE INVENTION
In the field of photoplethysmography light signals corresponding with two or more different centered wavelengths may be employed to non-invasively determine various blood analyte concentrations. For example, blood oxygen saturation (SpO
2
) levels of a patient's arterial blood may be monitored in pulse oximeters systems by measuring the absorption of red and infrared light signals. The measured absorption data allows for the determination of the relative concentration of reduced hemoglobin and oxyhemoglobin and, therefore, SpO
2
levels, since reduced hemoglobin absorbs more light than oxyhemoglobin in the red band and oxyhemoglobin absorbs more light than reduced hemoglobin in the infrared band, and since the absorption relationships of the two analytes in the red and infrared bands are known. See e.g., U.S. Pat. Nos. 5,934,277 and 5,842,979.
Pulse oximeters systems typically comprise a disposable or reusable sensor that is releasably attached to a given patient's appendage (e.g., finger, ear lobe or the nasal septum) for a given patient monitoring procedure and include at least one red light source and one infrared light source. The light sources are focused though a patient's tissue and the unabsorbed light that passes through is measured to determine blood analyte concentrations.
As may be appreciated, in order to accurately compute blood analyte concentrations utilizing a given sensor, it is important that information regarding the sensor be known; for example, the center wavelengths of the light sources employed. A number of approaches have been developed for identifying sensor attributes to pulse oximeter monitors. By way of primary example, many sensors contain an electrical component having a characteristic(s) that may be measured by a pulse oximeter monitor when the sensor is interconnected thereto. Once the characteristic(s) is known, the monitor may determine what center wavelengths correspond with the sensor light sources, for example, by using a stored look-up table or correlation function. In turn, an appropriate calibration value can be utilized in determining blood analyte concentrations. Generally, the information in a stored look-up table or utilized to formulate a correlation function is based on data that corresponds with sensors originating from a known source. Such sources tend to approved by the monitor manufacturers and provide sensors and corresponding data that has been determined and verified through actual clinical use such that the sensors may be used with a high level of confidence. Increasingly, however, sensors are being offered for use with pulse oximeter monitors from additional sources which may, for example, utilize the same or similar identifying means as sensors from known sources while not necessarily utilizing light sources that have center wavelengths as the sensors from the known sources, thereby presenting potential difficulties in assuring accurate performance of the monitor/sensor combinations.
SUMMARY OF THE INVENTION
In light of the foregoing, a primary objective of the present invention is to provide a further improved approach for obtaining photoplethysmographic sensor information.
A related objective of the present invention is to provide for increased photoplethysmographic sensor information in a manner that does not increase sensor complexity.
Yet a further objective of the present invention is to provide for the communication of photoplethysmographic sensor information in a manner that facilitates enhanced reliability.
One or more of the above objectives and additional advantages are indeed realized by the present invention, wherein the disclosed photoplethysmographic system and method provides for the obtainment of at least one data value from a photoplethysmographic sensor in a two-mode process. In one aspect a photoplethysmographic system is provided that comprises: a signal generation means, a sensor identifying means and a processing means. More particularly, the signal generation means is able to provide at least one interrogation signal in two distinct modes of operation to the sensor identifying means. The sensor identifying means is operable to receive at least a first interrogation signal in two distinct modes of operation, wherein the interrogation signal is initially applied with a first polarity and then applied with an opposite polarity. The sensor identifying means is further operable to produce at least one output value for each mode of operation. The outputs produced by the sensor identifying means in response to the application of the two-mode interrogation signal may then be used by the processing means to determine sensor data.
By way of example, such sensor data may serve to identify a given sensor to a pulse oximetry monitor, wherein the monitor is enabled/disabled or otherwise calibrated for operation with the interconnected sensor. As will be appreciated, in conventional applications of the invention the signal generation means and processing means may be located at a pulse oximeter monitor, while the sensor identifying means may be located at a given cable interconnected thereto.
The signal generation means may further comprise a means for establishing the first and second modes of operation, wherein the interrogation signal may be applied in two distinct modes to a terminal of the sensor identifying means. For example, in the first mode, the establishing means may provide an interrogation signal to a sensor terminal with an initial polarity, while in a second mode the same interrogation signal may be applied to the same sensor terminal with an opposite polarity. The establishing means may be configured such that it automatically applies the interrogation signal in the two modes of operation when a sensor is attached to a pulse oximeter monitor. In one embodiment, the establishing means may comprise a power supply, an electrical storage means and a switching means. More particularly, the power supply may be operable to both provide an initial polarity to the sensor terminal and to provide power to charge the electrical storage means. For example, a power supply, such as a voltage divider, may supply a steady voltage to charge an electrical storage means and provide an initial interrogation signal with a steady state voltage.
With regard to the electrical storage means, an electrical potential may be stored from the power supply that may be selectively released by the switching means to change the system, for a predetermined time, from the first mode of operation to the second mode of operation. Releasing the stored electrical potential may cause the electrical operation in the system to be altered from a steady state operation to a transient condition. As will be appreciated, if the sensor identifying means is electrically connected to the signal generation means when the electrical operation is altered, the interrogation signal as applied to the sensor identifying means may also be altered, allowing for a second output reading to be taken during this altered state. For example, by selectively grounding a stored electrical potential, where the storage means is a charged capacitor, may cause an electrical imbalance in the signal generating system while the capacitor discharges. While discharging, the capacitor may pull electrical voltage from all electrically attached components, thus reversing the current flow and the polarity of the voltage as seen in the attached components. Typically, a processor will operate the switching means to selectively discharge the electrical storage means and change the system from the first mode of operation to the se
Hicks Christopher Anthony
Huiku Matti Veli Tapani
Light Scott James Charles
Norris Mark A.
Datex-Ohmeda Inc.
Marsh & Fischmann & Breyfogle LLP
McCrosky David J.
Winakur Eric F.
LandOfFree
Diode detection circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Diode detection circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diode detection circuit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3137247