Diode detection circuit

• US 20030050545A1
• Filed: 09/11/2001
• Published: 03/13/2003
• Est. Priority Date: 09/11/2001
• Status: Active Grant

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Inventors: Light, Scott James Charles, Hicks, Christopher Anthony, Norris, Mark A., Huiku, Matti Veli Tapani
• Granted Patent: US 6,668,183 B2
• Time in Patent Office: Days
• US Class Current: 600/322
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A photoplethysmographic system and method is provided to identify compatible sensors to monitors and/or for determining sensor attributes. The improved system includes a signal generation means for providing an interrogation signal, an identifying means coupled between a first and second sensor terminal operable to produce multiple outputs upon application of the interrogation signal in two modes of operation, and a processor to interpret the outputs. When the interrogation signal is applied to a sensor terminal in a first mode, a first output is obtained. Upon applying the same interrogation signal to the sensor terminal in a second mode, a second output is obtained. The first and second outputs may then be utilized by the processor comprising, for example, a photoplethysmographic monitor to yield enhanced sensor information. The disclosed method may be carried out utilizing the inventive photoplethysmographic system.

Claims

1. A photoplethysmographic system for use in determining at least one data value corresponding with a photoplethysmographic sensor comprising:

signal generation means for generating at least one interrogation signal in each of a first mode of operation and a second mode of operation;

sensor identifying means for receiving at least one interrogation signal, wherein an initial polarity of said interrogation signal is established at a first sensor terminal in said first mode of operation and an opposite polarity of said interrogation signal is established at the first terminal in said second mode of operation, and wherein said identifying means produces a first output in said first mode of operation and a second output in said second mode of operation; and

processor means for employing said first and second outputs to determine at least a first data value corresponding with said sensor.

2. A photoplethysmographic system as recited in claim 1, wherein said signal generation means comprises means for establishing said first and second modes of operation.

3. A photoplethysmographic system as recited in claim 2, wherein said means for establishing comprises:

a power supply for providing said initial polarity at said first terminal;

an electrical storage means for storing an electrical potential from said power supply; and

a switching means for selectively discharging said electrical storage means to produce said opposite polarity at said first terminal.

4. A photoplethysmographic system as recited in claim 3, wherein said power supply comprises a steady state power source.

5. A photoplethysmographic system as recited in claim 4, wherein said steady state power source comprises a voltage divider for providing a constant voltage.

6. A photoplethysmographic system as recited in claim 3, wherein said electrical potential has an equal voltage and opposite polarity of said power supply.

7. A photoplethysmographic system as recited in claim 6, wherein said electrical storage means comprises a capacitor.

8. A photoplethysmographic system as recited in claim 3, wherein said switching means is selectively activable to change said system from said first mode of operation to said second mode of operation for a predetermined time.

9. A photoplethysmographic system as recited in claim 8, further comprising a processing means for selectively activating said switching means to change said system to said opposite polarity for said predetermined time.

10. A photoplethysmographic system as recited in claim 2, wherein said signal generating means is located at least partially in a cable connecting said photoplethysmographic sensor to said processing means.

11. A photoplethysmographic system as recited in claim 2, wherein said signal generating means is located at least partially in said photoplethysmographic sensor.

12. A photoplethysmographic system as recited in claim 2, wherein said signal generating is located at least partially in a photoplethysmographic monitor.

13. A photoplethysmographic system as recited in claim 1, wherein said identifying means comprises a plurality of electrical components electrically interconnected between said first and second sensor terminals.

14. A photoplethysmographic system as recited in claim 13, wherein at least one of said plurality of electrical components is an active component.

15. A photoplethysmographic system as recited in claim 1, wherein said first output comprises at least a first response of said interrogation signal as applied to said first terminal in said first mode of operation.

16. A photoplethysmographic system as recited in claim 15, wherein said first mode of operation comprises a steady state mode of operation.

17. A photoplethysmographic system as recited in claim 15, wherein said first mode of operation comprises a transient mode of operation.

18. A photoplethysmographic system as recited in claim 1, wherein said second output comprises at least a first response of said interrogation signal as applied to said first terminal in said second mode of operation.

19. A photoplethysmographic system as recited in claim 18, wherein said second mode of operation takes place over a predetermined time and said second output comprises a plurality of said responses over said predetermined time.

20. A photoplethysmographic system as recited in claim 18, wherein said second output comprises a time profile of said interrogation signal over said predetermined time.

21. A photoplethysmographic system as recited in claim 18, wherein said second mode of operation comprises a transient mode of operation.

22. A photoplethysmographic system as recited in claim 1, wherein said processing means is operable to compare said first and second outputs to stored data values to determine data particular to said sensor.

23. A photoplethysmographic system as recited in claim 1, wherein said processing means comprises a photoplethysmographic monitor.

24. A method to determine at least one data value from a photoplethysmographic sensor comprising the steps of:

applying an interrogation signal to a photoplethysmographic sensor with an identifying means between at least a first and second terminal, wherein a first output is obtained in a first mode of operation;

reversing the polarity of said interrogation signal, wherein a second output is obtained in a second mode of operation; and

employing said first and second outputs to determine at least one data value corresponding with said photoplethysmographic sensor.

25. The method of claim 24, wherein said step of applying an interrogation signal comprises applying a steady state electrical signal to said identifying means.

26. The method of claim 24, wherein obtaining said first output comprises measuring a steady state response of said interrogation signal as applied to said identifying means.

27. The method of claim 24, wherein said step of reversing further comprises:

supplying an interrogation signal with an initial polarity to said first terminal;

charging an energy storage means with said interrogation signal to store an electrical potential; and

utilizing said electrical potential to selectively reverse said interrogation signal polarity as applied to said first terminal for a predetermined time wherein at least one said second output is obtained during said predetermined time.

28. The method of claim 27, wherein obtaining said second output comprises measuring a transient response of said interrogation signal as applied to said identifying means during said predetermined time.

29. The method of claim 28, wherein measuring said transient response comprises taking a plurality of measurements during said predetermined time.

30. A method as recited in claim 24, said employing step comprising:

comparing at least one of first and second outputs with at least a first predetermined data range.

31. A method as recited in claim 24, wherein when at least one of said first and second output values are outside of a first and second predetermined data range, respectively, said method further comprises at least one of the following steps:

providing an output signal to a user to indicate that the photoplethysmographic sensor is outside the predetermined ranges; and

,

disabling the photoplethysmographic monitor for use with the interconnected photoplethysmographic sensor.

32. A method as recited in claim 31, further comprising:

displaying a visual message to a user at said photoplethysmographic monitor indicating one of;

at least one of said first and second values is outside a predetermined range; and

said photoplethysmographic monitor is disabled.

33. A method as recited in claim 24, wherein when said first output value is within a first predetermined data range and said second output value is within said second predetermined data range, said method further comprises:

utilizing said photoplethysmographic sensor to obtain an identification signal indicative of light absorption by the tissue-under-test; and

,

employing said detector signal to obtain a concentration value for at least one blood analyte.

34. A method as recited in claim 24, said employing step including:

utilizing at least one of said first output and second output to select one of a plurality of a calibration values for use with said sensor.