Patent Publication Number: US-2022218284-A1

Title: Disposable components for reusable physiological sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 16/425,592, filed May 29, 2019, which application is a continuation of U.S. patent application Ser. No. 15/864,389, filed Jan. 8, 2018, which application is a continuation of U.S. patent application Ser. No. 14/626,570, filed Feb. 19, 2015, which application is a continuation of U.S. patent application Ser. No. 12/782,651, filed May 18, 2010, which application claims the benefit of priority from U.S. Provisional Application No. 61/179,670, filed May 19, 2009. The entire contents of each of the above items are hereby incorporated by reference herein for all purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to disposable components of non-invasive physiological sensors. 
     BACKGROUND OF THE DISCLOSURE 
     Non-invasive physiological sensors are applied to the body for monitoring or making measurements indicative of a patient&#39;s health. One application for a non-invasive physiological sensor is pulse oximetry, which provides a noninvasive procedure for measuring the oxygen status of circulating blood. Oximetry has gained rapid acceptance in a wide variety of medical applications, including surgical wards, intensive care and neonatal units, general wards, and home care and physical training. A pulse oximetry system generally includes a physiological sensor having light emitters and a detector, such as one or more LEDs and a light sensor. The sensor is attached to a tissue site, such as a finger, toe, ear lobe, nose, hand, foot, or other site having pulsatile blood flow which can be penetrated by light from the emitters. The detector is responsive to the emitted light after attenuation by pulsatile blood flowing in the tissue site. The detector outputs a detector signal to a monitor which processes the signal to provide a numerical readout of physiological parameters such as oxygen saturation (SpO2) and pulse rate. 
     High fidelity pulse oximeters capable of reading through motion induced noise are disclosed in U.S. Pat. Nos. 6,770,028, 6,658,276, 6,157,850, 6,002,952 5,769,785, and 5,758,644, which are assigned to Masimo Corporation (“Masimo”) and are incorporated by reference herein. Advanced physiological monitoring systems may incorporate pulse oximetry in addition to advanced features for the calculation and display of other blood parameters, such as carboxyhemoglobin (HbCO), methemoglobin (HbMet) and total hemoglobin (Hbt), total Hematocrit (Hct), oxygen concentrations and glucose concentrations, as a few examples. Advanced physiological monitors and corresponding multiple wavelength optical sensors capable of measuring parameters in addition to SpO 2 , such as HbCO, HbMet and Hbt are described in at least U.S. patent application Ser. No. 11/367,013, filed Mar. 1, 2006, titled Multiple Wavelength Sensor Emitters and U.S. patent application Ser. No. 11/366,208, filed Mar. 1, 2006, titled Noninvasive Multi-Parameter Patient Monitor, assigned to Masimo Laboratories, Inc. and incorporated by reference herein. Further, noninvasive blood parameter monitors and optical sensors including Rainbow™ adhesive and reusable sensors and RAD57™ and Radical-7™ monitors capable of measuring SpO 2 , pulse rate, perfusion index (PI), signal quality (SiQ), pulse variability index (PVI), HbCO and HbMet, among other parameters, are also commercially available from Masimo. 
     SUMMARY OF THE DISCLOSURE 
     Optical sensors are widely used across clinical settings, such as operating rooms, emergency rooms, post anesthesia care units, critical care units, outpatient surgery and physiological labs, to name a few. Use in these settings exposes sensors, and in particular reusable sensors, to the potential risks of contamination and the resulting spread of nosocomial (hospital-acquired) infections. Studies have suggested that visual inspection of sensors may not detect contamination. Further, while a low-level disinfection protocol of alcohol wipes, dilute bleach scrubs or distilled water wipes can be effective when done correctly, reusable sensors may still be at risk for bacteria including MRSA (methicillin resistant  Staphylococcus aureus ). MRSA causes skin infections and can occasionally spread to almost any other organ in the body, sometimes with life-threatening potential. It is therefore a priority among medical care facilities to prevent contamination of reusable sensors by foreign and infectious materials and to prevent the spread of nosocomial infections. A sterile sensor cover advantageously provides a sterile environment without interfering with sensor functionality and capability. For example, the sterile sensor cover may be substantially impermeable to infectious agents (e.g., bacteria) and substantially optically transparent or transmissive. 
     Further, sensor elements such as the detector, emitters and associated circuitry can be expensive parts of a patient monitoring system. Often, relatively inexpensive degradable portions of the sensor become damaged due to repeated use or frequent sterilization. For example, the portions of the sensor which contact the user&#39;s skin often become soiled or damaged after each use. In such cases, users often disconnect the sensor cable from the monitor and replace the entire sensor. Moreover, in certain cases, such as for portable applications, it is useful for a sensor to be integrated into the patient monitor housing and not be attached by a cable. In such cases the sensor may not be removable from the monitor. 
     Other attempted solutions that include sensors with flexible, adhesive substrates having disposable and reusable portions. The disposable portion generally includes the adhesive portion of the sensor, which can lose its tack. Such sensors generally wrap around and adhesively attach to the tissue site. However, non-adhesive sensors having rigid housings, such as clip type sensors which clamp onto the tissue of the patient, are also commonly used in pulse oximetry and other patient monitoring applications. These sensors include degradable components that can become damaged or soiled due to frequent use, such as upper and lower pads which contact the user&#39;s skin. 
     It is therefore desirable to decouple the degradable portions from the rest of the sensor so that the degradable portions can be replaced in a cost-effective manner, and the rest of the sensor can be reused. A disposable sensor cartridge according to embodiments of the disclosure is capable of being used with a non-invasive physiological sensor and protects the sensor from damage due to repeated use or sterilization. 
     In addition, incorrect alignment of a patient&#39;s tissue site with the sensor elements can lead to inaccurate results. For example, where the tissue site is a patient&#39;s finger, the emitter and detector should generally be aligned with the nail bed of the patient. Often it is difficult to determine whether the sensor is properly aligned because, for example, the sensor housing impedes the view of the tissue site in relation to the emitter and detector. In such cases, it may take the operator a significant amount of time to realize that a sensor is misaligned. As such, there is a need for a sensor which provides for robust tissue site alignment. Embodiments of the sensor cartridge are positionable on the user before placing the treatment site in the sensor, allowing for improved alignment of the treatment site. 
     In order to provide cost savings and allow for efficient use, it is also advantageous to be able to reuse sensors on different patients having tissue sites of various sizes, such as for both adults and children. The sensor cartridge of certain embodiments can be configured to allow a sensor to comfortably accommodate treatment sites of various sizes, such as for both adult and pediatric applications. 
     According to certain embodiments, a disposable sensor cartridge is provided for use with a noninvasive physiological sensor. The sensor cartridge can be capable of attaching to a tissue site and mating with a housing of the sensor. In certain embodiments, the sensor cartridge comprises a first portion comprising a first aperture configured to allow light emitted from one or more emitters of the sensor to travel through the first aperture such that the light is incident on a first region of a tissue site and travels through and is attenuated by body tissue of the tissue site. The attenuated light may exit the tissue site at a second region of the tissue site. In certain embodiments, the sensor cartridge also includes a second portion comprising a second aperture configured to allow the attenuated light to travel through the second aperture and to be received by a detector of the sensor. In some embodiments, the first and second portions coupled to define a cavity capable of receiving the tissue site. In certain embodiments, the sensor cartridge can also include an electrical component capable of electrical communication with the sensor. In some embodiments, the first portion is in contact with the first region while the cartridge is attached to the tissue site and the second portion is in contact with the second region while the cartridge is attached to the tissue site. 
     According to an aspect of the disclosure, a method of using a noninvasive physiological sensor having a housing is provided. The method can include providing a disposable sensor cartridge comprising a first portion comprising a first aperture and a second portion comprising a second aperture. In certain embodiments, the disposable sensor cartridge can also include an electrical component. The first portion and second portion may together define a cavity capable of receiving the tissue site. In certain embodiments, the method further includes attaching the sensor cartridge to the tissue site such that the tissue site is disposed within the cavity. The method according to some embodiments also includes mating the sensor cartridge with the sensor such that the sensor cartridge is disposed within a cavity of the sensor housing. In certain embodiments, mating of the sensor cartridge with the sensor is such that the electrical component is in electrical communication with a portion of the sensor. 
     In certain embodiments, a disposable sterile barrier is provided. The disposable sterile barrier may interpose a material impermeable to infectious biological substances between a tissue site and surfaces of a sensor configured to grasp the tissue site. The sensor may be configured to transmit optical radiation into the tissue site and to generate a signal responsive to the optical radiation after attenuation by pulsatile blood flow within the tissue site. In certain embodiments, the disposable sterile barrier comprises an optically transparent material that is substantially impermeable to infectious biological substances. The disposable barrier may comprise a first portion of the material formed such that the first portion can be interposed between a tissue site and a first surface of a reusable optical sensor proximate an emitter of the sensor. In certain embodiments, the disposable barrier may comprise a second portion of the material formed such that the second portion can be interposed between the tissue site and a second surface of the sensor proximate a detector of the sensor. 
     In certain embodiments, an optical sensing method of non-invasively measuring the constituents of pulsatile blood flow within a tissue site without substantial risk nosocomial infection by direct contact between a sensor and the tissue site. The optical sensing method may include providing a reusable optical sensor having an emitter disposed within a first housing and a detector disposed within a second housing, the emitter and detector in communication with a sensor cable, the first and second housings configured to be urged against opposite sides of a tissue site upon application of the sensor to the tissue site, the emitter configured to transmit optical radiation having one or more predetermined wavelengths into the tissue site and the detector configured to receive the optical radiation after attenuation by the tissue site. The sensor may be configured to generate one or more signals indicative of the attenuated radiation, the one or more signals transmitted via the sensor cable to a monitor configured to process the one or more signals to determine one or more physiological parameters of patient. The method may include applying a barrier so as to make physiological measurements without direct contact between the tissue site and the sensor. The barrier can be interposed between the tissue site and the first housing and interposed between the tissue site and the second housing upon application of the tissue site to the sensor, the barrier comprising material substantially impermeable to infectious substances and substantially transparent so as not to substantially distort the physiological measurements. 
     According to certain aspects of the disclosure, a disposable sterile barrier is provided comprising an elongate tube comprising a cavity. The elongate tube may comprise an open end and a closed end. In certain embodiments, the open end comprises an opening large enough to accommodate a reusable optical sensor. The cavity can be sized to fully enclose the reusable optical sensor and at least a portion of a sensor cable extending from the optical sensor. In some embodiments, the elongate tube comprises a material which is substantially optically transparent and substantially impermeable to infectious biological substances. In certain embodiments, the disposable sterile barrier may further include a fastener disposed proximate the open end of the elongate tube and configured to seal the open end of the elongate tube around the sensor cable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a sensor cartridge and associated sensor according to an embodiment of the disclosure; 
         FIGS. 2A-D  are side hinged-open, side hinged-closed, top and bottom perspective views, respectively, of the sensor cartridge of  FIG. 1 ; 
         FIGS. 3A-D  are side hinged-open and side hinged-closed views, top and bottom perspective views, respectively, of a sensor cartridge according to another embodiment of the disclosure; 
         FIG. 4  illustrates the mating of the sensor cartridge of  FIG. 3  with a sensor. 
         FIGS. 5A-B  illustrate side views of two sensor cartridges of differing sizes according to an embodiment of the disclosure. 
         FIGS. 6A-B  illustrate side views of two sensor cartridges of differing sizes according to another embodiment of the disclosure. 
         FIG. 7  is a side perspective view of a generally boot-shaped enclosure embodiment of a sterile sensor cover; 
         FIG. 8  is a side perspective view of a generally tube-shaped enclosure embodiment of a sterile sensor cover; 
         FIGS. 9A-F  illustrate enclosing a reusable sensor with the boot-shaped enclosure and sealing the end with an attached tie; and 
         FIGS. 10A-E  illustrate enclosing a reusable sensor with the tube-shaped enclosure and sealing the end with an adhesive strip. 
         FIGS. 11A-B  illustrate top front and bottom rear perspective views, respectively, of a sensor cartridge according to an embodiment of the disclosure. 
         FIGS. 12A-B  illustrate top front and bottom rear perspective views, respectively, of a sensor cartridge according to another embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A sensor cartridge according to embodiments of the disclosure is capable of being used with a non-invasive physiological sensor. Certain embodiments of the sensor cartridge protect the sensor from damage, such as damage due to repeated use, reduce the need for sensor sanitization, or both. Further, embodiments of the sensor cartridge are positionable on the user before insertion in the sensor and allow for improved alignment of the treatment site with the sensor. In addition, the sensor cartridge of certain embodiments of the disclosure can be configured to allow a single sensor to comfortably accommodate treatment sites of various sizes such as for both adult and pediatric applications. The terms “sensor cover” and “sensor cartridge” are used throughout to describe various embodiments of the disclosure. The terms may be used interchangeably and are not intended to be limiting. 
     The tissue site of the illustrated embodiments is a finger and the following description therefore refers specifically to the tissue site as a finger for the purposes of clarity. This is not intended to be limiting and, as described herein, the sensor cartridge  110  of certain embodiments may be used with other types of tissue sites. 
       FIG. 1  is a perspective view of a sensor cartridge  110  and associated sensor  120  according to an embodiment of the disclosure. A user can place a cartridge  110  on a finger of the patient and then insert the finger along with the attached cartridge  110  into a non-invasive physiological sensor  120 . 
     The sensor  120  can be a clip-type sensor including an upper housing  122 , a lower housing  124  and a hinge element  126 . The upper and lower housings  122 ,  124  house electrical and/or optical components (not shown) of the non-invasive physiological sensor  120 . For example, the upper and lower housings  122 ,  124  may house light emitters and a detector of a pulse oximeter sensor, such as one or more LEDs and a light sensor. The sensor  120  can be connected to a patient monitor (not shown) via a cable  128 . For example, the detector outputs a signal to the monitor over the cable  128  which then processes the signal to provide a numerical readout of physiological parameters such as oxygen saturation (SpO2) and pulse rate. 
     After placing the sensor cartridge  110  on the finger, the user can attach the sensor  120  to the patient by applying pressure to the ends  123 ,  125  of the upper and lower housings  122 ,  124 , forming a cavity  129  capable of receiving the tissue site. Once the patient inserts the tissue site along with the attached sensor cartridge  110  into the cavity  129 , the pressure on the ends  123 ,  125  can be released such that the upper and lower housings  122 ,  124  come in contact with and secure the tissue site, allowing for accurate non-invasive physiological measurement. 
     Although disclosed with reference to the sensor of  FIG. 1 , an artisan will recognize from the disclosure herein a wide variety of oximeter sensors, optical sensors, noninvasive sensors, medical sensors, or the like that may benefit from the sensor cartridges disclosed herein. The sensor may not be a hinge type sensor but may instead, for example, include an integral housing having an annular ring type opening through which the patient inserts their finger. In various embodiments, the sensor may be adapted to receive a tissue site other than a finger such as a, toe, ear lobe, nose, hand, foot, or other site having pulsatile blood flow which can be penetrated by light from the emitter. In addition, the cartridge  110  may be used with a portable monitor and associated sensor components in certain embodiments. Such monitors, including the sensor components, can be integrated into a hand-held device such as a PDA and typically do not include cables or separate monitors. Portable monitors are often used by first responders in emergency situations, in part because of their portability and ease of use. As such, disposable cartridges  110  which can protect the sensor components according to embodiments herein can be of particular benefit when used with spot-check monitors. In addition, in emergency situations medical personnel must treat a large number of patients relatively quickly and it may therefore be difficult to sanitize sensors between patients. Disposable cartridges  110  described herein benefit medical personnel in such cases because a separate pre-sterilized cartridge  110  can be used for each patient. 
     Referring still to  FIG. 1 , the cartridge  110  includes an upper portion  114 , a lower portion  116  and a hinge portion  112  which together form a cavity  118  capable of receiving a finger. The upper portion  114 , lower portion  116  and hinge portion  112  are generally curved so as to accommodate the natural shape of the finger. A hinge cut-out  113  can be disposed on either side of the cartridge  110  near the hinge portion  112 , allowing for the upper and lower portions  114 ,  116  to separate from each other by rotating about the hinge portion  112 . To apply the cartridge to the finger, the upper portion  114  and lower portion  116  may be separated such that they rotate about the hinge portion  112  and the cavity  118  becomes large enough to comfortably receive the finger. Once the finger is placed in the cavity  118 , the upper and lower portions  114 ,  116  are released, coming into contact with and releasably attaching to the finger. For example, in certain embodiments, the hinge portion  112  may provide a spring force which is transferred to the upper and lower portions  114 ,  116  when they are released such that they grab onto the finger. In some embodiments, the interior surface  119  of the cartridge  110  may include an adhesive substance such that the cartridge  110  is releasably attached to the finger or other tissue site. In other configurations, the cartridge  110  simply rests on the finger and there is not a separate attachment mechanism. 
     The upper portion  114  includes an upper aperture  115  and the lower portion  116  includes a lower aperture  117 . The apertures  115 ,  117  generally allow for proper sensor operation. For example, the apertures  115 ,  117  allow for light from one or more emitters of the sensor  120  to contact the finger and for light attenuated by the tissue site to be received by a detector of the sensor  120 . 
     Because the upper and lower sensor housings  122 ,  124  are often opaque, it can be difficult to determine whether or not a finger is properly aligned once it is placed in the sensor. The apertures  115 ,  117  can allow for proper alignment of the sensor cartridge  110  with respect to the finger prior to inserting the cartridge  110  and finger into the sensor  120 . Proper alignment of the cartridge  110  with the finger can therefore improve the accuracy of measurements by helping to ensure that the finger will be properly aligned with respect to the sensor  120  elements upon mating of the cartridge  110  and sensor  120 . In certain cases, medical personnel may not realize that an inaccurate measurement has occurred, or may not realize it until after an alarm on the sensor goes off, after removal of the sensor or after the patient has left the treatment facility. As such, proper alignment can also help reduce cost and save time. 
     The upper aperture  115  allows a user to visually determine whether the nail bed of a finger is properly aligned with the aperture  115 . Proper alignment of the nail bed also ensures that the lower aperture  117  is properly aligned with the fleshy part of the underside of the finger. In addition, the user may visually determine that the underside of the finger is properly aligned by looking through the lower aperture  117 . The finger with the properly aligned cartridge  110  can then be inserted into the sensor  120  such that the light from the emitters of the sensor  120  will be incident on the nail bed through the upper aperture  115 . Further, the detector of the sensor  120  then receives attenuated light from the appropriate portion of the underside of the finger through the lower aperture  117 . In other embodiments, the emitter of the sensor  120  is housed in the lower housing  124  and the detector is housed in the upper housing  122 . 
     In certain embodiments, a film or other material (not shown) may be included in one or more of the apertures  115 ,  117 . For example, in one embodiment, translucent plastic film is placed in the apertures  115 ,  117  such that the properties of the emitted and attenuated light passing through the apertures are not affected by the material. In other embodiments, material is used which does affect the optical properties. For example, an optical film which filters out particular wavelengths of light is used in some embodiments. 
     Tactile feedback elements (not shown) may indicate proper alignment of the cartridge instead of, or in addition to, the apertures  115 ,  117 . For example, one or more of the upper and lower portions  114 ,  116  may include small protrusions which indicate to the patient whether the cartridge  110  is properly aligned. In one embodiment, for example, protrusions on either side of the finger indicate to the patient that the cartridge  110  is centered on the finger and a protrusion near the hinge portion  112  indicates that the finger is inserted appropriately deep into the cartridge  110 . Other tactile elements such as, for example, recesses, may be used in other embodiments. 
     In certain embodiments, the properties of the interior  119  of the cartridge  110  allow for proper and efficient calibration of the sensor  120 . For example, the interior  119  of the cartridge may be a highly reflective color such as white. The interior  119  may also have a glossy texture in certain embodiments, which can also aid in the calibration of the sensor. 
     As discussed, the sensor cartridge  110  is configured to mate with the sensor  120 . For example, the cartridge  110  of  FIG. 1  mates in a friction fit with the sensor  120 . To release the cartridge  110  from the sensor  120  after use, the user opens the sensor  120  clip, thereby relieving the pressure on the cartridge and tissue site from the upper and lower housings  122 ,  124 . The user can then readily pull the tissue site and cartridge  110  out of the cavity  129 . As will be appreciated by skilled artisans from the disclosure provided herein, other types of mating and release mechanisms are possible. For example, snap-fit mating configurations such as the one described below with respect to  FIG. 3  can be used. In some embodiments, a male or female track on the cartridge  110  fits into a corresponding male or female track on the sensor  120 , as appropriate. A button or lever release mechanism may be used in certain embodiments. In some embodiments, the cartridge  110  may automatically release when the sensor  120  clip is opened. 
     The sensor cartridge  110  or a portion thereof can be constructed of urethane rubber plastic in certain embodiments. In various other configurations, as will be appreciated from the disclosure herein, the cartridge  110  may be made of other appropriate materials such as Acrylonitrile Butadiene Styrene (“ABS”) or other types of rubber or plastic materials. The cartridge  110  is formed with biodegradable material in certain embodiments. 
     The general structure of the sensor cartridge  110  may differ in various configurations. For example, the cartridge may not be an integral molded piece as shown in the embodiment of  FIG. 1  and may instead include separate pieces as discussed with respect to  FIG. 3  below. 
     In an example scenario, once the user attaches the properly aligned sensor cartridge  110  to the tissue site and applies the sensor  120  as discussed above, medical personnel take a measurement of one or more physiological parameter of the patient using the sensor  120 . The patient then removes the tissue site from the sensor  120  along with the attached cartridge  110  as discussed and the patient or medical personnel may dispose of the cartridge  110 . Those of skill in the art will recognize from the disclosure herein various ways of using the cartridge  110 . For example, the cartridge  110  of certain embodiments may be mated with the sensor  120  before application to the tissue site. Moreover, the cartridge may be used more than once. For example, the cartridge  110  may be used several times by the same patient before disposal. In some embodiments, the cartridge  110  may be sterilized between uses. 
     In certain embodiments, the sensor cartridge  110  is configured to be in electrical communication with the sensor  120 . For example, the sensor cartridge  110  can also include one or more electronic components  130  and one or more coupling portions (not shown) which may be electrically coupled to the sensor  120 . For example, the coupling portions may comprise one or more electrical contacts (e.g., solder pads), electrical connectors (e.g., a socket and pin type connector), and the like. The electronic components  130  may include one or more information elements in certain embodiments. The information element may comprise one or more memory devices, such as, for example, one or more EPROMs or EEPROMs (e.g., those commercially available from Dallas Semiconductor), other memory or processing devices, combinations of the same, or the like. In some embodiments, the information element includes a conductor, a resistor, a single wire addressable memory device, or the like. In general, the information element may include a read-only device or a read and write device. The information element may advantageously comprise a resistor, an active network, or any combination of the foregoing. The information element may include data accessible by the sensor  120  and/or attached patient monitor to accomplish quality control, use monitoring, combinations of the same, or the like. For example, the information element may provide identification information to the system (e.g., the sensor  120  and/or monitor) which the system uses to determine whether the cartridge is compatible with the system. In an advantageous embodiment, the monitor reads the information element to determine one, some or all of a wide variety of data and information, including, for example, a type of patient, cartridge manufacturer information, life data indicating whether the cartridge has been used and/or should be replaced, encryption information, keys, indexes to keys or has functions, or the like monitor or algorithm upgrade instructions or data, some or all of parameter equations, information about the patient, age, sex, medications, and other information that can be useful for the accuracy or alarm settings and sensitivities, trend history, alarm history, sensor life, or the like. 
     The information element may be positioned on the hinge portion  112 . For example, in one embodiment the information element be embedded in the cartridge  112  material of the hinge portion  112  and is electrically coupled via a connector extending from the hinge portion  112  which mates with a corresponding connector on the interior of the sensor  120 . Skilled artisans will recognize from the disclosure provided herein a variety of configurations for the placement of the information element. For example, in various embodiments, the information element may be located on one or more of the inner surface of the cartridge  110 , the outer surface of the cartridge  110 , or embedded within the cartridge  110  material. Moreover, the information element may be positioned on the hinge portion  112 , the upper portion  114 , the lower portion  116 , or a combination thereof. 
     The information element may advantageously store some or all of a wide variety of data and information, including, for example, information on the type or operation of the sensor cartridge, buyer or manufacturer information, software such as scripts, executable code, or the like, sensor cartridge  110  life data indicating whether the sensor cartridge  110  has expired and should be replaced, encryption information, etc. or monitor or algorithm upgrade instructions or data. In various configurations, the information element may advantageously configure or activate the monitor, monitor algorithms, monitor functionality, or the like based on some or all of the foregoing information. For example, without authorized data accessible on the information element, quality control functions may inhibit functionality of the monitor. Likewise, particular data may activate certain functions while keeping others inactive. For example, a particular cartridge  110  may be compatible for use in measuring one type of physiological parameter of a set of physiological parameters the monitor is capable of measuring. In such a circumstance, the monitor may only activate measurement of the one type of physiological parameter based on the data accessible from the information element. Further information regarding information elements and systems and methods for monitoring sensor life can be found in U.S. Publication No. 2008/0088467, which is hereby incorporated in its entirety by reference herein. 
     While disclosed with respect to the cartridge  110  of  FIGS. 1-2 , any of the cartridges described herein, such as the cartridges  300 ,  510 ,  520 ,  610 ,  620 ,  1100 ,  1200  described below of  FIGS. 3-6  and  FIGS. 11-12  may include one or more information elements. Likewise, any of the sensor covers disclosed herein, such as the sensor covers  700 ,  800  of  FIGS. 7-10  may include an information element. 
       FIGS. 2A-D  are side hinged-open, side hinged-closed, top-right perspective and top-left perspective views, respectively, of the sensor cartridge of  FIG. 1 . As discussed above, the upper portion  114  and lower portion  116  may be separated such that they rotate about the hinge portion  112  and the cavity  118  becomes large enough to comfortably receive the finger ( FIG. 2A ). Once the finger is placed in the cavity  118 , the upper and lower portions  114 ,  116  can be released, coming into contact with and releasably attaching to the finger ( FIG. 2B ). The right and left sides of the cartridge  110  of the illustrated embodiment are symmetrical. As shown by  FIGS. 2C-D , the top and bottom are also symmetrical. In other embodiments, the left and right sides and/or the top and bottom may be shaped differently, such as, for example, to accommodate asymmetric properties of the finger or other tissue site. 
       FIGS. 3A-D  are side hinged-open and side hinged-closed views, top-right perspective and top-left perspective views, respectively, of a sensor cartridge  300  according to another embodiment of the disclosure. The cartridge  300  includes an upper portion  314 , a lower portion  316  and a hinge portion  312 , which are three separate pieces. As shown, the hinge portion  312  attaches to the back  302  of the upper portion  314  and the back  304  of the lower portion  316 , forming a cavity  318  capable of receiving a finger of a patient. The hinge portion  312  may attach to the upper and lower portions  312 ,  314  with glue, may be formed integrally with the upper and lower portions  312 ,  314 , or may be connected in some other manner. As shown with respect to  FIGS. 3C-D , the cartridge  110  further includes upper and lower apertures  315 ,  317 , which may be similar in structure and function to the apertures  115 ,  117  described above with respect to  FIGS. 1-2 . 
       FIG. 4  illustrates the mating of the sensor cartridge of  FIG. 3  with a sensor  420  (shown in a cross-sectional view). The sensor  420  may be similar in structure and function to the sensor  120  of  FIG. 1 , for example, and can include an upper housing  422 , a lower housing  424  and a hinge portion  426  which form a cavity  429 . One or more securing features may be included on the cartridge  300  to secure the cartridge  300  with the one or more corresponding securing features on the sensor  420  upon mating to secure the cartridge to the sensor  420  and/or ensure the correct position of the cartridge  300  within the sensor  420 . Referring to  FIGS. 3 and 4 , for example, the attachment arm  311  is configured to secure the cartridge  300  in place when applied to the sensor  420 . Upon application to a sensor  420  the front portion  425  of the lower housing  424  of the sensor  420  may occupy the space defined by the attachment arm  311  and the underside of the lower portion  316  of the cartridge  300 . The attachment arm  311  helps to releasably secure the sensor  420 , via a friction fit, for example. One or more other features, such as the lip  313  disposed on the upper portion  314  of the cartridge  300  can be included to further secure the cartridge  300  in the sensor  420 . Upon insertion of the cartridge  300  into the sensor  420 , the front portion  423  of the upper housing  422  abuts the lip  313 . Accordingly, the lip  313  can help ensure that the cartridge  300  is positioned appropriately deep within the sensor  420 . 
     The shape of the cartridge  300  may be configured to secure the cartridge  300  and/or ensure proper positioning of the cartridge  300  upon mating with the sensor  420 . For example, as shown in  FIGS. 3-4 , the upper portion  314  and/or the lower portion  316  can be sloped such that they thicken towards the front  301  of the cartridge  300 . Upon insertion, the sloping feature can provide a friction fit with the corresponding portions of the sensor  420 . 
     As will be appreciated by skilled artisans from the disclosure provided herein, various attachment and positioning mechanisms may be used. For example, the attachment arm  311  may further include a protrusion or other feature which may fit into a corresponding feature, such as a recess (not shown), on the underside of the lower housing  424  of the sensor  420 . In other configurations, the features may be reversed. For example, the protrusion may be on the lower housing  424  and the recess may be included on the attachment arm  311  of the cartridge  300 . 
       FIGS. 5A-B  illustrate side views of two sensor cartridges  510 ,  520  of differing sizes according to embodiments of the disclosure. The sensor cartridges  510 ,  520  may be similar in structure and function to the cartridge  100  of  FIGS. 1-2  and include upper portions  514 ,  524 , lower portions  516 ,  526 , hinge portions  512 ,  522 , cavities  518 ,  528 , upper apertures  515 ,  525  and lower apertures  517 ,  527 , respectively. The cartridges  510 ,  520  are configured to configured to accommodate treatment sites of various sizes, such as for both adult and pediatric applications. For example, the length L 1  of the cartridge  510  of  FIG. 5A  is larger than the corresponding length L 4  of the cartridge  520  of  FIG. 5B . Additionally, the upper and lower apertures  515 ,  517  of the cartridge  510  of  FIG. 5A  are set back a length L 2  from the rear of the cartridge  510  which is relatively large in comparison to the length L 5  that the upper and lower apertures  525 ,  527  of cartridge  520  of  FIG. 5B  are set back from the rear of the cartridge  520 . The length L 3  of the upper and lower apertures  515 ,  517  of the cartridge  510  of  FIG. 5A  is relatively large in comparison to the length L 6  of the upper and lower apertures  525 ,  527  of the cartridge  520  of  FIG. 5B . 
     The cartridge  510  is configured accommodate a larger finger than the cartridge  520 . For example, the cartridge  510  may be used in adult applications and the cartridge  520  may be used in pediatric applications. A pediatric patient, for example, may have a nail bed that is set back a relatively short distance from the tip of the finger in comparison to an adult patient. As such, the shorter set back length L 5  may be appropriate for a pediatric patient while the length L 2  may be appropriate for an adult patient. A pediatric patient may also have a relatively smaller nail bed than an adult patient such that the smaller length L 6  appropriately accommodates a pediatric patient while the length L 3  may more appropriately accommodate an adult patient. Finally, pediatric patients typically have shorter fingers than adult patients such that the shorter overall cartridge length L 4  may be appropriate for a pediatric patient while the longer length L 1  may be more appropriate for adult patients. 
     As shown, the external profile of the cartridges  520 ,  521 , characterized in part by the maximum height of the cartridges  520 ,  521  H 1  may be the same. As such, the cartridges  520 ,  521  may mate with a single sized sensor, thereby reducing cost and complexity. One of skill in the art will recognize from the disclosure herein other configurations. Some of the lengths which are shown as different in the embodiments  510 ,  520  of  FIGS. 5A-B  may be the same in alternative configurations. For example, in various embodiments, one or more of the pairs of lengths L 1  and L 4 , L 2  and L 5 , L 3  and L 6  may be the same. 
       FIGS. 6A-B  illustrate side views of two sensor cartridges  610 ,  620  of differing sizes according to embodiments of the disclosure. The sensor cartridges  610 ,  620  may be similar in structure and function to the cartridge  300  of  FIG. 3  and include upper portions  614 ,  624 , lower portions  616 ,  626 , hinge portions  612 ,  622 , cavities  618 ,  628 , attachment arms  611 ,  621  and lips  613 ,  623  respectively. The cartridges  610 ,  620  are configured to configured to accommodate treatment sites of various sizes, such as for both adult and pediatric applications. For example, the upper and lower portions  614 ,  616  of the cartridge  610  are thinner than the corresponding portions  624 ,  626  of the cartridge  620  and define a relatively large cavity  618 , characterized in part by the length H 2 . On the other hand, the upper and lower portions  624 ,  626  of the cartridge  620  are relatively thick and define a relatively small cavity  628 , characterized in part by the length H 3 . As such, the cartridge  610  is configured accommodate a larger finger than the cartridge  620 . For example, the cartridge  610  may be used in adult applications and the cartridge  620  may be used in pediatric applications. 
     As shown, the external profile of the cartridges  620 ,  621 , characterized in part by the maximum height of the cartridges  620 ,  621  H 1  may be the same. As such, the cartridges  620 ,  621  may mate with a single sized sensor, thereby reducing cost and complexity. One of skill in the art will recognize from the disclosure herein other configurations. In some embodiments, the hinge portions  612 ,  614  are also shaped to accommodate tissue sites of various sizes. In some configurations, the upper portion, the lower portion and/or the hinge portion of the sensor cartridge are constructed of a resilient material (e.g., a spongy material) which conforms to the shape of the finger such that a sensor cartridge of a single size can accommodate tissue sites of multiple sizes. In some embodiments in which the opening of the cartridge is generally circular, the circumference of the opening through which the patient inserts their finger into the cavity  518  is larger than the opening of the cartridge  528 . 
       FIGS. 7-8  illustrate two embodiments of a sterile cover  700 ,  800  each advantageously configured to enclose a reusable sensor  120  ( FIG. 1 ). In this manner, a patient&#39;s tissue site, such as a finger, can be inserted into the sensor and a physiological measurement made without contamination of the sensor or the patient. The sensor and the patient are thus advantageously protected from exposure to infectious agents such as MRSA. 
     As shown in  FIG. 7 , a boot-shaped cover  700  defines an enclosure having a generally tubular leg  720  and a smaller, generally tubular foot  730  both extending from a cross-member  710 . In some embodiments, the cross-member  710  is sealed or substantially sealed. The leg  720  has an open end  722  of sufficient diameter to receive a reusable sensor  120 , as described with respect to  FIGS. 9A-B , below. The foot  730  has a closed end  732  of sufficient diameter to receive the lower housing  124  of a reusable sensor  120 , as described with respect to  FIGS. 9C-D , below. A tie  740  wraps around the open end  722  so as to close that end around the sensor cable  128 . In one embodiment, the tie  740  is a self-adhesive tie, for example. In an embodiment, the tie  740  wraps around the open end  722  so as to seal the end around the sensor cable  128 . A gap  750  between the leg  720  and foot  730  of the cover  700  defines a space configured to accommodate a finger-tip within the sensor  120 . 
     As shown in  FIG. 8 , a tube-shaped cover  800  defines an enclosure having a generally cylindrical body  810  with an open end  812  and a closed end  814 . The open end  812  is of sufficient diameter to receive first the lower housing  124  followed by the upper housing  122  of a reusable sensor  120 , as described with respect to  FIGS. 10A-D , below. A self-adhesive strip  820  disposed internal to the body  810  proximate the open end  812  closes the open end  812  around the sensor cable  128 . In one embodiment, for example, the open end  812  forms a seal around the sensor cable  128 . In an embodiment, the covers  700 ,  800  include of an optically transparent or substantially transparent material so as to negligibly attenuate or otherwise negligibly distort those wavelengths in the red and infrared spectrum utilized in pulse oximeters or otherwise for the measurement of blood constituents. For example, the covers  700 ,  800  may be substantially optically transmissive. 
     As used herein, the term “tube” is used to describe a generally elongate member comprising a cavity and may include an open end and a closed end, for example. As used herein, a tube may have a variety of shapes and characteristics. For example, the tube  800  of various may comprise a cylindrical, rectangular, ovular, triangular, or some other cross-sectional shape, or may be generally deformable. 
       FIGS. 9A-F  illustrate the use of a sterile cover  700  embodiment to enclose a reusable sensor  120 , thereby advantageously protecting the sensor from contamination and the patient from exposure to infectious agents. A reusable sensor  120  in its normally closed position is initially inserted into the open end  722  of the cover  700  ( FIG. 9A ). The sensor  120  is then pushed through the length of the leg  720  until, for example, the sensor abuts the wall of the cross-member  710  ( FIG. 9B ). The sensor grips  123 ,  125  are pressed from outside the cover  700  so as to move the sensor  120  to its open position ( FIG. 9C ). While maintaining pressure on the grips  123 ,  125 , the sensor lower housing  124  slides into the foot  730  until it abuts the closed end  732  ( FIG. 9D ). Pressure is released from the grips  123 ,  125  so that the sensor  120  returns to its closed position over the gap  750  ( FIG. 9E ). The tie  740  is wrapped around the leg  720  so as to close-off the end  722  tightly around the sensor cable  128  ( FIG. 9F ). The covered sensor  120  is now ready for single-patient use by squeezing the grips  123 ,  125  to open the sensor and by inserting a patient finger into the cover gap  750 , which is now disposed inside the sensor  120 , between the emitters and detector. 
       FIGS. 10A-E  illustrate the use of another sterile cover  800  embodiment to enclose a reusable sensor  120 , likewise substantially protecting the sensor and patient from contamination and/or infectious agents. Sensor grips  123 ,  125  are pressed to place the sensor  120  in an open position ( FIG. 10A ). The cover  800  may be initially in an “accordion” state or otherwise folded, rolled or compressed, or otherwise collapsible to a reduced overall length. The cover opening  812  is slipped over the lower housing  124  ( FIG. 10A ). Maintaining the sensor  120  in the open position, the cover  800  is unfolded or otherwise extended in length as the opening  812  is pulled over the grips  123 ,  125  and onto the upper housing  122  ( FIG. 10B ). The cover opening  812  is pulled further along the upper housing  122  and onto the sensor cable  128  ( FIGS. 10C-D ). The sensor grips  123 ,  125  are released so that the sensor  120  returns to its normally closed position ( FIG. 10E ). The self-adhesive strip  820  just inside the opening  812  is then exposed, such as by peeling back and removing a liner, and the opening  812  is securely closed around the cable  128  ( FIG. 10E ). The covered sensor  120  is now ready for single-patient use by squeezing the grips  123 ,  125  to open the sensor and by inserting  850  a patient finger into the sensor between the folded over wall  810  portions of the cover  800  ( FIG. 10E ). This places the patient&#39;s fingertip inside the sensor  120 , between the emitters and detector. 
     Skilled artisans will recognize a variety of alternatives sensor covers  700 ,  800  from the disclosure provided herein. For example, in other embodiments, the covers  700 ,  800  may include one or more apertures such as one or more of the apertures described herein. The covers  700 ,  800  may comprise a rigid or semi-rigid material. Moreover, the covers  700 ,  800  may be used in addition to a cartridge such as one or more of the cartridges described herein with respect to  FIGS. 1-6 and 11-12 . In one alternative embodiment, the cover  700 ,  800  may extend beyond the sensor  120  along some length of the cable  128 . For example, the cover  700 ,  800  may extend substantially along the entire cable to the monitor in one embodiment. In another embodiment, the cover  700 ,  800  may extend partially along the cable  128 . 
       FIGS. 11A-B  illustrate top front and bottom rear perspective views, respectively, of a sensor cartridge  1100  according to an embodiment of the disclosure. In certain circumstances, light incident on the finger from the emitter may not be entirely absorbed by the finger. In addition, a certain portion of attenuated light will exit the other side of the finger. Such portions of light may reflect within the space between the cartridge and the finger or between the cartridge and the sensor. These portions of light can interfere with each other, with the emitted light and/or with the attenuated light. These portions of reflected light and associated interfering light can be incident on the detector. This phenomena, sometimes referred to herein as “light bounce,” can potentially cause inaccurate measurements, depending on certain factors such as the amount of light bounce and the relative sensitivity of the measured signal. 
     The sensor cartridge  1100  is configured for application to a tissue site such as a finger, for example. The finger or other tissue site may be placed in the opening  1102 . In addition, the cartridge  1100  is configured for insertion into a reusable sensor such as the sensor  120 . The sensor cartridge  1100  further includes an upper aperture  1104  and a lower aperture  1106 . The apertures  1104 ,  1106  generally allow for proper sensor operation. For example, the apertures  1104 ,  1106  allow for light from one or more emitters of the sensor  120  to contact the finger and for light attenuated by the tissue site to be received by a detector of the sensor  120 . The apertures  1104 ,  1106  may function in a manner similar to and provide similar advantages as the apertures  115 ,  117  of the cartridge  110  of  FIGS. 1-2 . The cartridge may comprise Acrylonitrile Butadiene Styrene (“ABS”), other types of rubber or plastic materials, or some other material compatible with the embodiments described herein. 
     As shown, the sensor cartridge  1100  generally envelopes the finger when it is applied to the cartridge  1100 . Moreover, the cartridge  1100  may comprise a color absorptive of the light emitted from the emitter of the sensor  120 . For example, the cartridge  1100  may comprise a dark material as shown, such as a substantially black or opaque material. As described above, a certain portion of incident on the finger from the emitter of the sensor  120  may not be absorbed by the finger, but may instead be reflected off of the finger. In addition, a certain portion of attenuated light will exit the other side of the finger. Because the cartridge  1100  generally envelopes the finger and is absorptive of the emitted light, light which is not absorbed by the finger or otherwise may advantageously escape into the region between the cartridge and the finger will be substantially absorbed by the cartridge  1100  due to its absorptive properties, reducing the effect of light bounce. 
     Alternative configurations of the cartridge  1100  are possible as will be recognized by skilled artisans from the disclosure herein. For example, the cartridge  1100  body may comprise a substantially thin rubber material in some embodiments. The cartridge  1100  may include an adhesive proximate the perimeter of the opening  1102 , such as the self-adhesive strip  820  of the cartridge  800  of  FIG. 8 , which may help create a seal between the finger and the cartridge  1100 . In other configurations, the perimeter of the opening may include an elastic band capable of creating an elastic seal between the finger and the cartridge  1100 . In certain embodiments, the cartridge  1100  or a portion thereof may include a different color such as a relatively light color, or may be translucent or partially translucent. In one configuration, the interior of the cartridge  1100  comprises a substantially dark color and the outer surface comprises another color, such as a light color. In yet another embodiment, the interior of the cartridge  110  comprises a substantially light color and the outer surface comprises a substantially dark color. 
       FIGS. 12A-B  illustrate top front and bottom rear perspective views, respectively, of a sensor cartridge according to another embodiment of the disclosure. The cartridge  1200  of  FIG. 12  may be generally similar in structure and function to the cartridge  1100  of  FIG. 11 . For example, the cartridge  1200  includes an opening  1202 , a cavity  1208 , an upper aperture  1204  and a lower aperture  1206 . In addition, the cartridge  1200  comprises a color absorptive of the emitted light and advantageously reduces the effect of light bounce. 
     The cartridge  1200  may not fit in a uniformly snug manner with the upper and lower sensor housings  122 ,  124 . For example, as the upper and lower sensor housings  122 ,  124  exert force directly on the outer surface of the cartridge  1200  and thus indirectly on the tissue site within the cartridge  1200 , the sensor cartridge  1200  may flex and partially deform in response to this force. This flexing may create gaps between portions of the inner surfaces of the upper and lower sensor housings  122 ,  124  and the outer surface of the cartridge  1200 . The cartridge  1200  includes connecting portions  1210 ,  1212  which are configured to bridge potential gaps between the outer surface of the cartridge  1200  and the inner surfaces of the upper and lower sensor housings  122 ,  124 . Particularly, the connecting portions  1210 ,  1212  are configured to bridge these gaps substantially in the region of the perimeter of the apertures  1204 ,  1206 , respectively. The connecting portions  1210 ,  1212  thereby create a seal between the perimeter of the apertures  1204 ,  1206  and the inner surfaces of the upper and lower sensor housings  122 ,  124 , respectively. Channel regions are thus created whereby light from the emitter can travel from the emitter to the aperture  1204  and whereby attenuated light can travel from the tissue site to the detector. Thus, the connecting portion  1210  prevents light directed towards the upper aperture  1204  from the emitter from escaping into the region between the between the inner surface of the upper sensor housing  122  and the outer surface of the cartridge  1200 . Likewise, the connecting portion  1212  prevents attenuated light exiting the tissue site towards the detector of the sensor  120  from prevented from escaping into the region between the inner surface of the lower sensor housing  124  and the cartridge  1200 . Because light escaping into these regions may contribute to light bounce, as described above, the connecting portions  1210 ,  1212  advantageously provide further reduction of light bounce. Moreover, the connecting portions  1210 ,  1212  generally cause a greater percentage of light from the emitter to be directly incident on the tissue site and a cause greater percentage of attenuated light exiting from the tissue site to be directly incident on the detector. The connecting portions  1210 ,  1212  thus can provide for increased measurement accuracy, improved calibration and efficiency of sensor operation, among other advantages. 
     The connecting portions  1210 ,  1212  of the illustrated embodiment include four panels each extending from one side of the perimeter of the upper and lower apertures  1204 ,  1206  to form raised rectangular borders around the apertures  1204 ,  1206 . The connecting portions  1210 ,  1212  are configured to contact the interior surfaces of the upper and lower sensor housings  122 ,  124  around the emitter and the detector, respectively. The connecting portions  1210 ,  1212  include a flexible material such as a rubber or plastic which conforms to the interior surfaces of the upper and lower sensor housings  122 ,  124 , respectively. As such, the connecting portion  1210  helps to create a seal between the emitter of the sensor  120  and the cartridge as described above, thereby reducing light bounce and providing for increased measurement accuracy. Likewise, the connecting portion  1212  helps to create a seal between the detector of the sensor  120  and the cartridge  1200  as described above, thereby further reducing light bounce and improving measurement accuracy. 
     As will be appreciated by those of skill in the art from the disclosure provided herein, alternative configurations of the cartridge  1200  are possible. For example, in certain embodiments, one or more of the connecting portions  1210 ,  1212  may comprise a rigid material. The connecting portions  1210 ,  1212  may mate with corresponding features of the interior surfaces of the upper and lower sensor housings  122 ,  124 , respectively. For example, the connecting portions  1210 ,  1212  may form raised features such as in the illustrated embodiment which fit into corresponding female portions, such as recesses in the interior surfaces of the sensor housings  122 ,  124 . In various embodiments, snap-fit, friction-fit, and other mating mechanisms may be employed. Certain features may be reversed in some embodiments. For example, one or more of the interior surfaces of the sensor housings  122 ,  124  may include male portions and the connecting portions  1210 ,  1212  may include female portions. In certain embodiments, connecting portions such as the connecting portions  1210 ,  1212  may be used on other cartridges described herein, such as, for example, the cartridge  110  of  FIGS. 1-2 , or the cartridge  300  of  FIG. 3 . 
     Various sensor cartridges and covers have been disclosed in detail in connection with various embodiments. These embodiments are disclosed by way of examples only and are not to limit the scope of the claims that follow. One of ordinary skill in the art will appreciate the many variations, modifications and combinations. For example, in one embodiment, the cartridge  110  of  FIG. 2  includes a securing feature such as the securing feature  311  of the cartridge  300  of  FIG. 3 . In some embodiments, the cartridges  110 ,  300  of  FIGS. 2 and 3  are configured to substantially envelope the tissue site in a manner similar to the cartridges  1100 ,  1200  of  FIGS. 11 and 12 . In various embodiments, any of the cartridges described throughout the disclosure, such as the cartridges  300 ,  510 ,  610 ,  1100 ,  1200  described with respect to  FIGS. 3, 5, 6, 11 and 12 , may include a film covering the respective apertures. For example, the film may include a film such as the one described above with respect to the apertures  115 ,  117  of the cartridge  110  of  FIGS. 1-2 . In addition, in various embodiments the sensor cartridges and covers are used with a sensor that may measure any type of physiological parameter. In various embodiments, the sensor cartridges and covers may be for any type of medical device.