Abstract:
Embodiments of the present disclosure include a digit gauge used to ensure the size of a patient&#39;s digit is appropriate for the medical sensor applied thereto.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority benefit under 35 U.S.C. §119(e) from U.S. Provisional Application No. 61/162,669, filed Mar. 23, 2009, entitled “Digit Gauge for Noninvasive Optical Sensor,” which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present disclosure relates to medical sensors and specifically to noninvasive optical sensors that include light sources and light detectors configured to output signals responsive to an attenuation of light by body tissue such that the output signals are indicative of one or more physiological parameters of the tissue. 
         [0004]    2. Description of the Related Art 
         [0005]    Pulse oximetry has become a standard of care in many patient monitoring environments. In general, an oximeter system is capable of determining often a variety of measurement values for various blood parameters including oxygenated hemoglobin, carboxyhemoglobin, methemoglobin, total hemoglobin, fractional saturation, and the like. Additionally, today&#39;s commercially available oximeters from, for example, Masimo Corporation of Irvine Calif., may advantageously measure other physiological parameters including pulse rate, indications of perfusion, sleep apnea, indications of drug use, possible heart diagnoses, ventilation, hydration and the like. 
         [0006]    Oximeter systems generally include one or more noninvasive optical sensors applied to a digit of a patient. The sensors also communicate, often through a cable, with an instrument configured to manage sensor activation and receive sensor output signals. The instrument processes the output signals to determine output values for some or all of the foregoing patient measurements. The noninvasive sensors may be reusable, disposable, or hybrids having reusable and disposable portions. The sensors are usually designed for a particular cross-sectional sized digit, and are often available in sizes including adult, slender digit, pediatric, neonatal and the like. 
       SUMMARY OF INVENTION 
       [0007]    Often, the instrument communicating with a particular sensor includes in its processing some assumptions about the sensor, or at least the tissue associated with the sensor. For example, in some instruments, the processing includes application of a calibration curve to determine output values for a given measurement. The calibration curve generally includes one or more often complicated relationships between processed signals responsive to output voltages of the sensor and clinical data of monitored patients. These relationships are often dependent upon whether the tissue being measured belongs to an adult digit, a pediatric digit, a neonatal digit or the like. 
         [0008]    However, in the case of at least reusable optical sensors, care givers may not be sure which type of sensor is appropriate for the cross-sectional size of the particular digit of their patient. The inappropriate choice of sensor may be in part due to readily proximate supplies, misunderstandings by staff, the inherent disorder of an emergency situation, misguided cost cutting measures, or the like. 
         [0009]    Based on at least the foregoing, there is a need for a straightforward, relatively quick match between a size of a measurement site and an optical sensor. Accordingly, embodiments of the present disclosure include a digit gauge configured for straightforward relatively quick use. In additional embodiments, the digit gauge is fixedly associated with a particular sensor to provide for consistent size matching between digits and sensors without a risk of loss of the sizing device. 
         [0010]    For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the disclosure have been described herein. Of course, it is to be understood that not necessarily all such aspects, advantages or features will be embodied in any particular embodiment of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The following drawings and the associated descriptions are provided to illustrate embodiments of the present disclosure and do not limit the scope of the claims. 
           [0012]      FIG. 1  shows a perspective simplified illustration of an exemplary embodiment of a digit gauge where a digit size matches an associated sensor. 
           [0013]      FIG. 2  shows a perspective simplified illustration of an exemplary embodiment of the digit gauge of  FIG. 1 , where a digit size does not match an associated sensor. 
           [0014]      FIG. 3  shows a perspective view of a patient monitoring system including a monitoring instrument, an optical sensor, a connecting cable, and an exemplary digit gauge fixedly associated with the connecting cable and optical sensor. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Embodiments of the present disclosure include a digit gauge associated with an optical sensor of a patient monitoring system. In an embodiment, the monitoring instrument is configured to accept different sensors where some sensors are specifically designed for different cross-sectional sizes of patient tissue. For example, sensor often are available in adult, slender adult, pediatric, neonatal and the like. In some cases, the instrument may provide less accurate measurements when an attached sensor is placed on a mismatched patient&#39;s digit. Accordingly, embodiments of the digit gauge advantageously provide a quick, straightforward measurement to determine whether the sensor matches the patient&#39;s digit size. In an embodiment, an opening is sized to accept a patient&#39;s digit to indicate whether the digit matches the associated sensor. For example, in an embodiment, the digit gauge includes a tab with a substantially circular or circular opening. In various embodiments, how the digit fits through the opening dictates whether the sensor is appropriately sized. In some embodiments, the tab is affixed to a portion of the sensor and/or cable to conveniently provide consistent measurements for a particular sensor and to avoid misplacement of the tab. 
         [0016]    To facilitate a complete understanding of the invention, the remainder of the detailed description describes the invention with reference to the drawings, wherein like reference numbers are referenced with like numerals throughout. 
         [0017]      FIGS. 1-2  illustrate the digit gauge including a plastic tab having a measurement portion and a sensor association portion. In an embodiment, the measurement portion includes a circular or substantially circular or oval opening capable of accepting a digit of a potential patient to be monitored. The gauge is slid over, preferably the ring finger of the non-dominate hand. When the gauge stops sliding on the finger because the finger becomes too large to further slide through the opening, the caregiver inspects the gauge to see whether a cuticle of the finger is visible through the gauge. When it is not ( FIG. 1 ), the finger size is appropriately matched to the associated sensor. When the finger cuticle can be seen ( FIG. 2 ), in that the gauge slid beyond the cuticle, the caregiver should select another digit for testing with the gauge or use a different sized sensor. 
         [0018]    The digit gauge of  FIGS. 1-2  also includes the sensor association portion. As shown, the association portion includes an opening accepting the sensor cable. In such embodiments, the gauge is conveniently and advantageously nonremovably associated with a particular sensor to avoid misplacement or misassociation. 
         [0019]    In an embodiment, the digit gauge may be tab-shaped and comprise a semi-hardened plastic material. The digit gauge may include rounded edges to avoid discomfort during measuring. 
         [0020]    An artisan will recognize from the disclosure herein a wide variety of possible gauge configurations capable of quickly and efficiently matching finger size to sensor. For example, the gauge may include multiple different sized openings, where each opening designates via color, text, or the like the appropriate sensor for that particular opening. The gauge may advantageously comprise a ring structure, a sleeve, or the like and shaped to fit a toe, thumb, fingers, or the like. Moreover, the gauge may function differently from the foregoing disclosure. For example, the opening may be sized such that when the finger fits through the opening, a smaller sensor should be used, when the finger does not fit, the sensor is appropriately matched, a larger sensor should be used, or the like. 
         [0021]    Additionally, more complex gauges may be used that indicate electronically whether the finger is sized appropriately for the sensor. For example, the sensor may include LEDs that indicate an appropriate size, the instrument may supply feedback messages related to size, or the like. Such message or LED indications may be simply red for mismatched, yellow for borderline, and green for matched cross sectional finger size and sensor. 
         [0022]    Although the finger gauge is disclosed with reference to its preferred embodiment, the disclosure is not intended to be limited thereby. Rather, a skilled artisan will recognize from the disclosure herein a wide number of alternatives accomplishing the same or similar functions. Additionally, other combinations, omissions, substitutions and modifications will be apparent to the skilled artisan in view of the disclosure herein. Accordingly, the present disclosure is not intended to be limited by the reaction of the preferred embodiments, but is to be defined by reference to the appended claims.