WO2002062213A1

WO2002062213A1 - Oximeter sensor with temperature-sensitive film

Info

Publication number: WO2002062213A1
Application number: PCT/US2002/000187
Authority: WO
Inventors: James H. Taylor
Original assignee: Datex-Ohmeda, Inc.
Priority date: 2001-02-08
Filing date: 2002-01-03
Publication date: 2002-08-15

Abstract

An oximeter sensor (64) that disposes a temperature-sensitive film (66) over the emitter assembly (38) is disclosed. When the temperature-sensitive film (66) is exposed to temperatures that are less than a predetermined threshold temperature which preferably corresponds with a desired maximum operating temperature for the oximeter sensor (64), the temperature-sensitive film (66) remains clear and allows light from the emitter assembly (38) to pass through the temperature-sensitive film (66) to the body part. The film (66) becomes opaque upon exposure to its threshold temperature and may be accomplished through a change in color of the film (66). This change in color may be used to provide a visual indication that the threshold temperature has been met. The change in transparency of the film (66) may also be used to control the operation of the oximeter which is operatively interconnected with the oximeter sensor (64).

Description

OXIMETER SENSOR WITH TEMPERATURE-SENSITIVE FILM

CROSS-REFERENCE TO RELATED APPLICATIONS Not applicable.

STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not applicable.

FIELD OF THE INVENTION

The present invention generally relates to the field of measuring oxygen content or saturation in blood with an oximeter sensor and, more particularly, to an oximeter sensor that includes a temperature-sensitive film over an emitter assembly of the sensor.

BACKGROUND OF THE INVENTION Information on the amount of oxygen within blood or more preferably a blood flow is desirable in many instances. This is often characterized as the oxygen content or oxygen saturation of the blood. Oximeters are able to provide this type of information and are generally well known in the art. Patient data that is used by the oximeter to determine the oxygen content/saturation is monitored/measured by an oximeter sensor that operatively interfaces with the oximeter. There are at least generally two types of oximeter sensors - invasive and non-invasive. Invasive oximeter sensors are installed within the body through an appropriate aperture. Non- invasive oximeter sensors are installed on the exterior skin of an appropriate body part such as a finger or a foot.

Oximeter sensors typically employ a pair of light sources that emit light at different wavelengths, as well as one or more optical detectors. Electrical signals are provided by the oximeter to the oximeter sensor to operate the light sources in a predetermined manner (e.g., each light source is "pulsed" in accordance with a predetermined pattern or drive signal). Light from each of the light sources will either be absorbed by the blood, will pass entirely through the patient's tissue and blood for receipt by the optical detector, or will be scattered. Electrical signals from the optical detector are directed back to the oximeter. Information on how the light sources are being operated, the wavelengths of these two light sources, and the amount of light which passes through the blood to the optical detector are all used by the oximeter to calculate the oxygen content/saturation of the blood. This information will then typically be displayed for review by appropriate personnel. One common light source for oximeter sensors are light emitting diodes or

LEDs. Low drive currents are typically initially provided from the oximeter to these LEDs of the oximeter sensor. Drive currents are maintained at these lower levels so long as the signal being output from the optical detector back to the oximeter is of a sufficient magnitude. Decreases in the signal being output from the detector(s) back to the oximeter that are at least a certain magnitude will trigger an increase in the drive signal being provided by the oximeter to the LEDs of the oximeter sensor. These types of increases cause a corresponding increase in the operating temperature of the LEDs and the oximeter sensor. Although most oximeter sensors are designed to limit the maximum drive signal to that which maintains the operating temperature of the oximeter sensor at a safe limit in relation to patient exposure to this temperature through contact with the oximeter sensor, the failure of one or more components of the oximeter, the oximeter sensor, and/or the cable that interconnects the oximeter and oximeter sensor could adversely impact the operation of these types of safety features. Moreover, electrical shorts could develop which could also adversely affect the operating temperature of the oximeter sensor in relation to patient safety. It would be desirable to have an oximeter sensor with operating temperature monitoring capabilities that would not require electronics, that would not significantly add to the cost of the oximeter sensor, that would provide a visual indication that a maximum operating temperature had been reached, that would automatically terminate operation of the oximeter upon the oximeter sensor reaching its maximum operating temperature, or any combination thereof.

BRIEF SUMMARY OF THE INVENTION A first aspect of the present invention is embodied in an oximeter sensor that includes an emitter assembly and a detector assembly that may be electrically interconnected with an oximeter in any appropriate manner. Establishing an appropriate electrical interconnection between the oximeter and oximeter sensor of the first aspect allows electrical signals to be directed from the oximeter to the sensor's emitter assembly to discharge light from the emitter assembly in a desired manner, and allows electrical signals to be directed from the sensor's detector assembly back to the oximeter. Various types of information may be used by the oximeter to calculate the oxygen content/saturation in the blood that is being monitored by the oximeter sensor. Both the emitter assembly and detector assembly of the oximeter sensor of the first aspect will typically be mounted on or otherwise supported by at least some type of sensor housing. The manner of integration will be such that light from the emitter assembly will be directed to the body part on which the oximeter sensor is mounted, and further such that the light exiting the body part will impact the detector assembly. Temperature monitoring capabilities are provided by a temperature-sensitive film that is disposed within the path of the light that is emitted from the emitter assembly and intended for transmission to/through the body part on which the oximeter sensor is mounted.

Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. Any type of sensor housing, emitter assembly, detector assembly, and way of electrically interconnecting the emitter and detector assembly with an oximeter may be utilized for the oximeter sensor of the first aspect of the present invention. For instance, the sensor housing may be a laminated structured that is defined by one or more pliable thin films, a unitary body that is nonetheless pliable to allow for a bending of the same to dispose the emitter and detector assemblies on opposite sides of a body part on which the oximeter sensor is mounted, or a rigid and at least substantially non-pliable structure. The emitter assembly may include one or more light sources and the detector assembly may include one or more detectors. One representative configuration would be to use at least two light emitting diodes that emit light at different wavelengths for the emitter assembly, and to use a single photdetector or photdiode for the detector assembly.

The temperature-sensitive film of the first aspect may be interconnected with and supported by the sensor housing. One appropriate way of incorporating the temperature-sensitive film with the sensor housing is to have the temperature- sensitive film be in the form of a transparent tape. The temperature-sensitive film may then be simply adhered to an exterior surface of the sensor housing that interfaces with the body part on which the oximeter sensor is mounted. This manner of incorporating the temperature-sensitive film with the oximeter housing allows the temperature-sensitive film to be readily installed and removed, and to be a readily disposable item. Another but currently less preferred option would be to dispose the temperature-sensitive film somewhere within the interior of the sensor housing in proper alignment with the light being output by the emitter assembly for transmission to the body part on which the oximeter sensor is mounted.

How the temperature-sensitive film monitors the temperature of the oximeter sensor, and more particularly the temperature of the emitter assembly, is subject to a number of characterizations. For instance, the temperature-sensitive film may have a first degree of transparency when the temperature of the film is less than a certain predetermined threshold temperature, and a second, lesser degree of transparency when the temperature of the film reaches or exceeds this threshold temperature. This threshold temperature would be selected to somehow correspond with the desired maximum operating temperature of the oximeter sensor. Preferably the noted first degree of transparency does not adversely impact the operation of the emitter assembly in that it will allow sufficient light to be directed through the temperature- sensitive film to the body part on which the oximeter sensor is mounted for the determination of the oxygen content/saturation of blood therein or flowing therethrough in any appropriate manner. In one embodiment, the temperature- sensitive film becomes at least substantially opaque once the temperature of this film reaches the noted threshold temperature. "Reaching the threshold temperature" does not mean that the temperature of the film needs to remain at the threshold temperature, but contemplates that the temperature-sensitive film will be in the at least substantially opaque condition if the film temperature is at least as great as the noted threshold temperature. Therefore, the transparency of the temperature-sensitive film may change between two different states or degrees of transparency based upon the temperature to which the same is exposed (e.g., having one degree of transparency when exposed to temperatures less than the threshold temperature, and having another degree of transparency when exposed to temperatures greater than or equal to the threshold temperature).

There are a number of ways in which a change of the temperature-sensitive film from a transparent material to a less transparent or opaque material may be utilized in relation to the use/operation of the oximeter sensor of the first aspect of the present invention, an oximeter that is operatively interconnected with the oximeter sensor of the first aspect of the present invention, or both. This change in transparency may be evidenced by a change in color so as to provide a visual indication to the patient and/or attending personnel that the threshold temperature has been reached/exceeded. One option would be for the temperature-sensitive film to be clear prior to being exposed to the threshold temperature, and to turn a dark color (e.g., black) when exposed to a temperature greater than or equal to threshold temperature. In order to provide the desired visual indication with the oximeter sensor still mounted on the body part, the temperature-sensitive film would likely have to extend beyond the surface of the sensor housing that interfaces with the body part on which the oximeter sensor is mounted. In this case it would not be required to retain the temperature-sensitive film in its "less transparent" condition after any subsequent reduction of its ambient temperature to a magnitude which is less than the threshold temperature. Another option would be to limit the location of the temperature-sensitive film to the lower surface of the oximeter sensor housing that interfaces with the body part. In this case, it would be desirable for the temperature- sensitive film to retain its "less transparent" condition provided by the exposure to temperatures at least as great as the threshold temperature so as to provide the desired visual indication after the oximeter sensor is removed (i.e., such that the temperature- sensitive film would retain its "less transparent" state if the film's threshold temperature is ever exceeded).

Changes in the transparency of the temperature-sensitive film may also be monitored/detected by the oximeter. Operation of the oximeter may then be terminated upon detection of film transparency changes of at least a certain magnitude by the oximeter. One way of integrating this type of feature is for the oximeter to monitor the signal from the detector assembly of the oximeter sensor. When the temperature-sensitive film turns opaque upon exposure to a temperature which is at least as great as the noted threshold temperature, little if any light from the emitter assembly will be able to pass through the temperature-sensitive film and to/through the body part on which the oximeter sensor is mounted. There will thereby be a rather instantaneous and significant drop in the signal from the detector assembly back to the oximeter (e.g., a voltage drop of at least a certain magnitude over a certain amount of time). This type of change in the return signal from the detector assembly may be sensed by the oximeter and used as a trigger to terminate the drive signal being provided to the emitter assembly to operate its light source(s) in the desired manner. In this type of case, the temperature-sensitive film need not retain its "less transparent state" upon any subsequent reduction of the temperature of the film to below the noted threshold temperature.

Simple changes in color may be utilized to provide a visual indication of the exposure of the temperature-sensitive film to a temperature which is at least as great as the noted threshold temperature. Other options exist for providing this visual indication. For instance, it may be possible for the development of a graphical/textual display on the temperature-sensitive film upon exposure of this film to at least the threshold temperature. In addition, a plurality of temperature-sensitive films or film sections could be provided. Each of these films/film sections could undergo a change of transparency/color upon exposure to a different threshold temperature. This is one way in which a plurality of temperature-sensitive films or film sections could be employed to provide an actual temperature scale of sorts.

A second aspect of the present invention is embodied in an oximeter sensor that includes an emitter assembly and a detector assembly that may be electrically interconnected with an oximeter in any appropriate manner. Establishing an appropriate electrical interconnection between the oximeter and oximeter sensor of the second aspect allows electrical signals to be directed from the oximeter to the emitter assembly to discharge light from the emitter assembly in a desired manner, and allows electrical signals to be directed from the detector assembly back to the oximeter. Various types of information may be used by the oximeter to calculate the oxygen content/saturation in the blood that is being monitored by the oximeter sensor. Both the emitter assembly and detector assembly will typically be mounted on or supported by at least some type of sensor housing which will allow for the passage of light from the emitter assembly to the body part on which the oximeter sensor is mounted, and which will further allow for the passage of light exiting the body part to be directed to the detector assembly. The oximeter sensor of the second aspect also includes a film that undergoes a change in transparency based upon at least a certain change in the temperature to which the film is exposed. Various refinements exist of the features noted in relation to the second aspect of the present invention. Further features may also be incorporated in the second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, each of the various features discussed above in relation to the first aspect may be incorporated in the second aspect of the present invention as well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING Figure 1 is a plan view of one embodiment of a prior art oximeter sensor.

Figure 2 is an exploded, perspective view of an oximeter sensor which uses the same sensor housing as the oximeter sensor of Figure 1, but which includes a temperature-sensitive film.

Figure 3 is a perspective view of the oximeter sensor of Figure 2, with the temperature-sensitive film being disposed over the emitter assembly and with the film being in a transparent condition.

Figure 4 is a perspective view of the oximeter sensor of Figure 2, with the temperature-sensitive film being disposed over the emitter assembly and with the film being in an opaque condition. Figure 5 is a schematic representation of an oximeter assembly which uses the oximeter sensor of Figures 2-4.

Figure 6 is a perspective view of an oximeter sensor that includes an alternative temperature-sensitive film to that illustrated in Figures 2-4.

DETAILED DESCRIPTION OF THE INVENTION

One prior art configuration is illustrated in Figure 1 in the form of an oximeter sensor 10. The oximeter sensor 10 generally includes a sensor housing 30 that is disposed within a carrier 14. Components of the carrier 14 include a body 18 and an attachment strap 26 that is attached to the body 18. Compressible materials are preferably used to form the carrier body 18. A cavity 22 is formed in the carrier body 17 to receive the sensor housing 30. Preferably, the cavity 22 at least generally approximates the perimeter configuration of the sensor housing 30 and is sufficiently recessed relative to a patient interface surface 20 of the carrier body 18 so as to dispose this patient interface surface 20 in at least generally coplanar relation with a patient interface surface 34 of the sensor housing 30. Attachment of the oximeter sensor 10 to a relevant body part is provided by the attachment strap 26 and is such that the patient interface surface 20 of the carrier body interfaces with or at least projects toward the patient's body part, as does the patient interface surface 34 of the sensor housing 30. Both an emitter assembly 38 and a detector assembly 50 of the oximeter sensor 10 are disposed on and supported by the sensor housing 30. Multiple emitters 42a, 42b define the emitter assembly 38 and emit light at different wavelengths. A transparent emitter cover 46 is disposed over the emitter assembly 38 on the patient interface surface 34 side of the sensor housing 30, and is appropriately secured to the sensor housing 30. The detector assembly 50 is disposed in spaced relation to the emitter assembly 38 and includes a single detector 54. A transparent detector cover 58 is disposed over the detector assembly 50 on the patient interface surface 34 side of the sensor housing 30, and is appropriately secured to the sensor housing 30. An electrical lead 62 (e.g., a cable with a plurality of electrically conductive wires disposed therein) extends within the sensor housing 30 and provides for an electrical connection between an oximeter (not shown) and each of the emitter assembly 38 and detector assembly 50 of the oximeter sensor 10. The oximeter sensor 10 of Figure 1 is described in more detail in U.S. Patent No. 5,919,133, which issued July 6, 1999, and the entire disclosure of which is incorporated by reference herein.

Figures 2-4 depict an oximeter sensor 64 with temperature sensing/monitoring capabilities. Components of the oximeter sensor 64 of Figures 2-4 having corresponding components in the oximeter sensor 10 of Figure 1 are identified by the same reference numeral. The oximeter sensor 64 would also utilize the carrier 14 that is depicted in Figure 1 and that was discussed in relation to the sensor 10. The primary distinction between the oximeter sensor 64 of Figure 2-4 and the oximeter sensor 10 of- Figure 1 is the addition of a temperature-sensitive film 66 for the oximeter sensor 64.

The temperature-sensitive film 66 in the oximeter sensor 64 of Figures 2-4 is disposed over the emitter cover 46 for the emitter assembly 38. Light that is emitted from the emitter assembly 38 during operation of the oximeter sensor 64 is thereby directed toward the temperature-sensitive film 66 and in the direction of the body part on which the oximeter sensor 64 is mounted. Operation of the emitter assembly 38 for light-generating purposes also generates heat that is transferred to the temperature- sensitive film 66. Temperature sensing/monitoring capabilities are provided by the film 66 through a relationship between the transparency of the film 66 and the temperature to which the film 66 is exposed. Generally, the temperature-sensitive film 66 is clear/transparent so long as the temperature of the film 66 is below a certain threshold temperature that is based upon the properties of the film 66. This threshold temperature for the temperature-sensitive film 66 is selected to correspond with a desired maximum operating temperature for the oximeter sensor 64. Sufficient light from the emitter assembly 38 is able to pass through the temperature-sensitive film 66 for oximetry purposes so long as the threshold temperature is not reached/exceeded. In one embodiment, this threshold temperature is about 42°C. Exposure of the temperature-sensitive film 66 to the threshold temperature or temperatures in excess of this threshold causes a change in transparency in the temperature-sensitive film 66. Therefore, in one temperature range (any temperature below the threshold temperature) the film 66 is at a first transparency, and in another non-overlapping temperature range (any temperature which is greater than or equal to the threshold temperature) the film 66 is at a second transparency which differs from the first transparency.

Providing two states of transparency for the temperature-sensitive film 66 that is determined by its ambient temperature may be used in a number of manners by the oximeter sensor 64. One is to provide a visual indication to the patient and/or attending personnel that the threshold temperature has or has not been reached/exceeded. Another is to integrate the temperature-sensitive film 66 with the operational controls of an oximeter that controls the operation of the oximeter sensor 64. Figure 4 illustrates a condition of the temperature-sensitive film 66 after its threshold temperature has been reached/exceeded, and which may be utilized to provide the above-noted visual notification. The temperature-sensitive film 66 in Figure 4 has turned black after being exposed to a temperature that is at least as great as its threshold temperature, which accomplishes/evidences a change in the transparency of the temperature-sensitive film 66. Generally, the temperature- sensitive film 66 in Figure 4 is at least substantially opaque such that little or no light from the emitter assembly 38 is able to pass therethrough to the body part on which the oximeter sensor 64 is mounted. This provides an obvious visual indication to the patient and/or attending personnel that the threshold temperature of the sensor 64 has been reached/exceeded after the oximeter sensor 64 is removed so as to expose the patient interface surface 20 of the carrier body 18 and the patient interface surface 34 of the sensor housing 34. The oximeter sensor 64 may then be discarded or examined/repaired. Visual indications that the threshold temperature of the oximeter sensor 64 has been reached/exceeded while the oximeter sensor 64 is still mounted on the patient may be accomplished by extending the temperature-sensitive film 66 beyond the patient interface surface 34 of the sensor housing 30 and the patient interface surface 20 of the carrier body 18 so that the same is visible while the oximeter sensor 64 is still mounted on the patient. Figure 5 illustrates one embodiment of an oximeter assembly 70. There are two basic components of the oximeter assembly 70, namely an oximeter 74 and the above-noted oximeter sensor 64 that are operatively interconnected. The oximeter 74 generally includes a processor 78 for controlling various aspects of the operation of the oximeter assembly 70 and for calculating the oxygen content/saturation of the blood or blood flow that is being monitored by the oximeter sensor 64. Another component of the oximeter 74 is an emitter drive signal assembly 82 that is operatively interconnected with the processor 78 and which generates and provides an appropriate drive signal to the emitter assembly 38 of the oximeter sensor 64 in a manner that is determined/controlled by the processor 78. Electrical signals from the detector assembly 50 of the oximeter sensor 64 are returned to a detector return signal assembly 86 of the oximeter 74, which is also operatively interconnected with the processor 78. Information used/provided by both the emitter drive signal assembly 82 and the detector return signal assembly 86 are used by the processor 78 to calculate the oxygen content/saturation of the blood or blood flow being monitored by the oximeter sensor 64. A return signal monitoring assembly 90 of the oximeter 74 also monitors the return signal being provided back to the oximeter 74 from the oximeter sensor 64, and operatively interfaces with the processor 78 as well. Any configuration may be utilized by the oximeter 74 that will provide the basic oximetry functions and allow the return signal from the detector assembly 50 to be monitored for certain changes that are discussed below.

Operation of the oximeter sensor 64 may also be controlled based upon the temperature-sensitive film 66 assuming the condition presented in Figure 4. The temperature-sensitive film 66 in Figure 4 again changed from a sufficiently transparent condition to an insufficiently transparent condition (in relation to providing light for oximetry purposes) after being exposed to at least its threshold temperature. That is, the temperature-sensitive film 66 changed from a clear condition (Figure 3) to an at least substantially opaque condition (Figure 4) upon reaching/exceeding its threshold temperature such that little or no light from the emitter assembly 38 is thereafter able to pass through the temperature-sensitive film 66. Light from the emitter assembly 38 is intended for transmission to/through the body part on which the oximeter sensor 64 is mounted. Some of this light is absorbed by body tissue and/or blood, or is scattered. At least some of the light, however, passes entirely through the body part and to the detector assembly 50 for return to the oximeter 74. Both the drive signal which is provided by the emitter drive signal assembly 82 of the oximeter 74 to the emitter assembly 38 of the oximeter sensor 64, as well as the return signal provided by the detector assembly 50 of the oximeter sensor 64 to the oximeter 74, are used by the processor 78 of the oximeter 74 to calculate the oxygen content/saturation within the blood (along with using other relevant information). The opaque condition of the temperature-sensitive film 66 will cause an almost instantaneous effect on the return signal from the detector assembly 50 to the oximeter 74 (e.g., a voltage drop of at least a certain amount over a certain amount of time). This type of condition may be readily recognized by the return signal monitoring assembly 90 of the oximeter 74. The return signal monitoring assembly 90 would then send an appropriate signal to the processor 78, which in turn would send an appropriate signal to the emitter drive signal assembly 82 to terminate the drive signal being provided to the emitter assembly 38 of the oximeter sensor 64.

A variation of the oximeter sensor 64 of Figures 2-4 is illustrated in Figure 6 in the form of an oximeter sensor 64'. Instead of having the entire temperature- sensitive film 66 change from a transparent condition to an opaque condition upon reaching/exceeding the threshold temperature, only portions of the temperature- sensitive film 66' in the oximeter sensor 64' of Figure 5 change transparency/color upon reaching/exceeding the threshold temperature. Those portions of the temperature-sensitive film 66' that change transparency/color may do so in a graphical and/or textual sense that visually indicates to the patient and/or attending personnel that the threshold temperature has been reached/exceeded.

Any type of film that provides the functions noted above in relation to the temperature-sensitive film 66 may be utilized by an oximeter sensor and/or oximeter assembly to monitor the temperature of the oximeter sensor. Representative films of this type that may be used in the application described herein are commercially available from Thermographic Measurement Inc. and are sold under the trademark Thermax®.

The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.

Claims

What is claimed is:

1. An oximeter sensor, comprising: a sensor housing; an emitter assembly that is interconnected with said sensor housing; a temperature sensitive film that is interconnected with said sensor housing and that is disposed over an output from said emitter assembly; and a detector assembly that is interconnected with said sensor housing in spaced relation to said emitter assembly.

2. An oximeter sensor, as claimed in Claim 1, wherein: said sensor housing comprises upper and lower surfaces, an emitter assembly aperture that extends between said lower surface of said sensor housing and said emitter assembly, and a detector assembly aperture that extends between said lower surface of said sensor housing and said detector assembly.

3. An oximeter sensor, as claimed in Claim 1, wherein: said sensor housing is selected from the group consisting of a laminated structure, a plurality of thin films that are sealed together, a unitary, pliable body, a rigid structure, and any combination thereof.

4. An oximeter sensor, as claimed in Claim 1, wherein: said emitter assembly comprises at least two light sources.

5. An oximeter sensor, as claimed in Claim 1, wherein: said emitter assembly comprises first and second light sources that emit light at first and second wavelengths, wherein said first and second wavelengths are different.

6. An oximeter sensor, as claimed in Claim 1, wherein: said detector assembly comprises at least one photodetector.

7. An oximeter sensor, as claimed in Claim 1, further comprising: an electrical conductor assembly that is electrically interconnected with each of said emitter assembly and said detector assembly and which is at least electrically interconnectable with an oximeter.

8. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film is attached to a surface of said sensor housing which interfaces with a patient when said sensor is mounted on the patient.

9. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film is transparent prior to being exposed to a temperature of less than a first temperature.

10. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film has a first degree of transparency when exposed to temperatures less than a first temperature and a second degree of transparency when exposed to temperatures at least as great as said first temperature, wherein said second degree of transparency is less than said first degree of transparency.

11. An oximeter sensor, as claimed Claim 10, wherein: said second degree of transparency corresponds with said temperature- sensitive film being at least substantially opaque.

12. An oximeter sensor, as claimed in Claim 10, wherein: said temperature-sensitive film remains at said second degree of transparency if ever exposed to temperatures at least as great as said first temperature.

13. An oximeter sensor, as claimed in Claim 10, wherein: said temperature-sensitive film will revert from said second degree of transparency to said first degree of transparency when a temperature to which said temperature-sensitive film is exposed falls below said first temperature.

14. An oximeter sensor, as claimed in Claim 10, wherein: said temperature-sensitive film comprises means for a least substantially inhibiting light from said emitter assembly from passing through said temperature- sensitive film when said temperature-sensitive film is at said second degree of transparency.

15. An oximeter sensor, as claimed in Claim 10, wherein: said first temperature is about 42 degrees Celsius.

16. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film comprises means for providing a visual indication if said temperature-sensitive film has been exposed to a temperature which is at least as great as a first temperature.

17. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film is transparent so long as said temperature- sensitive film is exposed to temperatures less than a first temperature, and turns into a dark color if exposed to temperatures at least as great as said first temperature.

18. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film comprises means for rendering said oximeter sensor inoperable if said temperature-sensitive film is exposed to a temperature at least as great as a first temperature.

19. An oximeter sensor, as claimed in Claim 1, wherein: said temperature-sensitive film changes color upon exposure to any temperature at least as great as a first temperature.

20. An oximeter sensor, as claimed in Claim 1, wherein: at least a portion of said temperature sensitive film is visible when said oximeter sensor is mounted on a patient.

21. An oximeter sensor, comprising: a sensor housing; an emitter assembly that is interconnected with said sensor housing; a first film that is disposed over an output from said emitter assembly; a detector assembly that is interconnected with said sensor housing in spaced relation to said emitter assembly; and means for changing a transparency of said first film based upon a temperature of said first film.

22. An oximeter sensor, as claimed in Claim 21, wherein: said first film is transparent prior to being exposed to a temperature of less than a first temperature.

23. An oximeter sensor, as claimed in Claim 21, wherein: said first film has a first degree of transparency when exposed to temperatures less than a first temperature and a second degree of transparency when exposed to temperatures at least as great as said first temperature, wherein said second degree of transparency is less than said first degree of transparency.

24. An oximeter sensor, as claimed Claim 23, wherein: said second degree of transparency corresponds with said first film being at least substantially opaque.

25. An oximeter sensor, as claimed in Claim 23, wherein: said first film remains at said second degree of transparency if ever exposed to temperatures at least as great as said first temperature.

26. An oximeter sensor, as claimed in Claim 23, wherein: said first film will revert from said second degree of transparency to said first degree of transparency when a temperature to which said first film is exposed falls below said first temperature.

27. An oximeter sensor, as claimed in Claim 23, wherein: said first film comprises means for a least substantially inhibiting light from said emitter assembly from passing through said first film when said first film is at said second degree of transparency.