Abstract:
The present disclosure generally relates to a device and method for securing a sensor to a wearer&#39;s head. According to embodiments, a headcovering, such as a stocking cap, includes an integral headband. The headband may have a generally inelastic segment capable of being placed about the wearer&#39;s head and a generally elastic portion capable of fastening the headband in a secure fashion. The headband may include an indicator that facilitates the determination of whether the headband has been fastened at an appropriate tension about the wearer&#39;s head. The headband may also include dimensional markings to facilitate the measurement of the circumference of the wearer&#39;s head.

Description:
BACKGROUND 
       [0001]    The present disclosure generally relates to medical sensors and in particular, to hat-based pulse oximeter sensors. 
         [0002]    This section is intended to introduce the reader to aspects of the at that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
         [0003]    Many types of medical sensors, such as optical sensors, are used to measure physiological characteristics of a patient. Typically, an optical sensor provides emitted light which is then scattered through a portion of a patient&#39;s tissue and detected. Various characteristics of a patient can be determined from analyzing such light, such as oxygen saturation, pulse rate, tissue bilibrubin, etc. 
         [0004]    Pulse oximetry is typically used to measure various blood flow characteristics including, but not limited to, the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and the rate of blood pulsations corresponding to each heartbeat of a patient. Measurement of these characteristics has been accomplished by use of a non-invasive sensor which scatters light through a portion of the patient&#39;s tissue where blood perfuses the tissue, and photoelectrically senses the absorption of light in such tissue. The amount of light absorbed and/or scattered is then used to calculate the amount of blood constituent being measured. 
         [0005]    The light transmitted through the tissue is selected to be of one or more wavelengths that are absorbed by the blood in an amount representative of the amount of the blood constituent present in the blood. The amount of transmitted light scattered through and/or absorbed by the tissue will vary in accordance with the changing amount of blood constituent in the tissue. For measuring blood oxygen level, such sensors have typically been provided with a light source that is adapted to generate light of at least two different wavelengths, in accordance with known techniques for measuring blood oxygen saturation. 
         [0006]    Known non-invasive sensors include devices that are secured to a portion of the body, such as a finger, an ear, or the scalp. In animals and humans, the tissue of these body portions is perfused with blood and the tissue surface is readily accessible to the sensor. More particularly, certain types of oximeter sensors are applied to a patient&#39;s forehead. For example, an oximeter sensor attached to the inside of a stocking hat provides an easy means of placing, retaining, and locating the sensor on an infant&#39;s forehead. Such hats should preferably be the correct size for the infant&#39;s head to ensure that the sensor is in contact with the tissue and applying the optimal pressure to the infant&#39;s forehead. Indeed, measurement accuracy may diminish if the hat is too tight, due to diminished blood volume and perfusion of underlying tissue, or if the hat is too loose, due to venous pulsations and/or less than optimal sensor contact. 
         [0007]    In addition to the various measurements provided by oximeter sensors, head circumference measurements are often taken by caregivers to determine an infant&#39;s developmental progress and to detect abnormal brain and skull growth. Presently, any head covering that the infant may have, whether it be a normal stocking cap or an oximetry sensor that is coupled to a stocking cap, must be removed so that such a measurement can be taken. The removal of the stocking cap not only can affect the infant&#39;s ability to maintain its temperature, but in the case of the removal of a stocking cap having an oximetry sensor, also the ability to continue taking oximetry measurements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a drawing of a stocking hat, in accordance with an embodiment of the present disclosure. 
           [0009]      FIG. 2  is a drawing of an oximeter sensor used with the stocking hat of  FIG. 1 . 
           [0010]      FIG. 3  is a cutaway view of the stocking hat of  FIG. 1  with the oximeter sensor of  FIG. 2  attached. 
           [0011]      FIG. 4  is a patient monitoring system coupled to a multi-parameter patient monitor and the oximeter sensor of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0013]    The presently disclosed embodiments are directed towards adjusting a stocking hat containing a reflectance-type oximeter sensor to fit different head sizes and using the hat to measure the circumference of a user&#39;s head. With regard to the location of the sensor on the patient&#39;s forehead, the sensor may be located on the lower forehead region, above the eyebrow, with the sensor optics (emitter and detector) located above and predominantly lateral to or centered over the iris. The oximeter sensor can be attached to the inside of a stocking hat for use on an infant, for example. Coupling the sensor with a stocking hat allows easy placement of the sensor on the infant&#39;s forehead while applying a predictable pressure on the sensor. As discussed below, the stocking hat&#39;s ability to adapt to different head sizes further ensures that the sensor applies optimal pressure to the infant&#39;s forehead. Further, dimensional markings on the stocking hat allow the infant&#39;s head circumference to be measured without disrupting the placement of the sensor. Thus, a stocking hat with an attached oximeter sensor can be used on patients to measure heart rate, oxygen saturation, head circumference, and other parameters. 
         [0014]      FIG. 1  is a drawing of a stocking hat in accordance with an embodiment. In this example, the stocking hat  10  has an adjustable headband  12 . As illustrated, the headband  12  may be integral to the stocking hat  10 , such that it is inserted into a pocket formed around the periphery of the stocking hat  10 . The headband  12  may include a low-stretch, i.e., generally inelastic, segment  14  sized to fit around an infant&#39;s head, and a generally elastic band  16  that may be coupled to the low-stretch segment  14 . The generally elastic band  16  may be elastic along substantially its entire length, or it may include an elastic portion and an inelastic portion. In this embodiment, the elastic band  16  has a loose end  18  and an attached end  20 , where the elastic band  16  is attached at its attached end  20  with the low-stretch segment  14 . The elastic band  16  is threaded through a guide band  22  of the low-stretch segment  14 , which functions to prevent slippage of the elastic band  16 . The elastic band  16  also may include tension arrows  26  that align with a tension indicator zone  28  on the low-stretch segment  14  when the elastic band  16  is in a stretched state. In this embodiment, the opposite face of the loose end  18  of the elastic band  16  has hook and loop fasteners  30  which may couple to the low-stretch segment  14  and/or the stocking hat  10  to affix to the headband  12  around the infant&#39;s head and maintain the headband  12  at the desired tension. Hence, when the low-stretch segment  14  has been placed about an infant&#39;s head and secured in the proper range with the tension arrows  26  aligned in the tension indicator zone  28 , the stocking hat  10  should be adequately secured to the infant&#39;s head in a manner that will facilitate proper sensor readings from the sensor described below. 
         [0015]    Also, the bottom of the low-stretch segment  14  may have dimensional markings  32  which allow the infant&#39;s head circumference to be measured without removing the stocking hat  10 . For example, the dimensional markings  32  may be segmented in inches at 1/16 th  intervals, or in centimeters at millimeter intervals. Since the dimensional markings  32  are on the low-stretch segment  14 , the measurement thus provided should remain accurate even after the headband  12  has been secured to the infant&#39;s head. 
         [0016]      FIG. 2  is a drawing of an oximeter sensor. A sensor  34 , as discussed herein, may be configured for reflective type sensing. Furthermore, the sensor  34  may include various structural and functional features designed to facilitate its use. Examples of such sensor and its use and construction may be found in U.S. Pat. No. 7,047,056, which issued on May 16, 2006, as well as U.S. application Ser. No. 11/494,357 titled “Hat-Based Oximeter Sensor,” and filed on Jul. 26, 2006, which are both herein incorporated by reference in their entirety for all purposes. In the illustrated embodiment, the sensor  34  includes a flexible circuit  36 , on which an emitter  38  and a detector  40  may be mounted. The flexible circuit  36  may be used to transmit signals to the emitter  38  and from the detector  40  via a cable  42 . The emitter  38  may be one or more light emitting diodes adapted to transmit one or more wavelengths of light, such as a red to infrared range, and the detector  40  may be a photodetector, such as a silicon photodiode package, selected to receive light in the range emitted from the emitter  38 . In an embodiment, the sensor  34  is coupled to the cable  42  that may be used to transmit electrical and/or optical signals to and from the emitter  38  and the detector  40 . The cable  42  may be permanently or removably coupled to the sensor  34 . The removable coupling of the cable  42  may be utilized in situations where the sensor  34  is disposable, e.g., where a sensor is disposed of after being used on a patient. 
         [0017]    With regard to the location of the sensor  34  on a patients forehead, the sensor  34  may be situated on the lower forehead region, above the eyebrow, with the sensor optical devices located above and predominantly lateral to or centered over the iris. In the depicted embodiment of  FIG. 3 , the sensor  34  may be attached to the inside of the headband  12  and/or of the stocking hat  10 . The low-stretch segment  14  or the stocking hat  10  also may have an indicia  24  (see  FIG. 1 ) corresponding to the location of the underlying sensor  34 . This facilitates proper placement of the stocking hat  10 , and thus the sensor  34 , on the infant&#39;s head. Hence, coupling the sensor  34  with a stocking hat  10  allows easy placement of the sensor  34  on the infant&#39;s forehead while applying a predictable pressure on the sensor  34 . 
         [0018]    In another embodiment, the top opening of the stocking hat  10  may provide an outlet for an intravenous tube  44  inserted into the patient. For infants in particular, it is not uncommon for tubes to be inserted in or near their heads. Since an infant&#39;s movement could potentially disturb an intravenous tube so placed, it may be advantageous to route the tube  44  through the top opening of the stocking hat  10  to minimize the possibility of such a disruption. 
         [0019]    It should be appreciated that a stocking hat  10  with an attached oximeter sensor  34  is designed for use with a patient monitoring system. For example, referring now to  FIG. 4 , the stocking hat  10  as depicted in  FIG. 3  may be used in conjunction with a patient monitor  46 . In an embodiment, a cable  42  connects the sensor  34  to the patient monitor  46 . The sensor  34  and/or cable  42  may include or incorporate one or more integrated circuit or electrical devices, such as a memory processor chip, that may facilitate or enhance communication between the sensor  34  and the patient monitor  46 . Similarly, the cable  42  may be an adaptor cable, with or without an integrated circuit or electrical device, for facilitating communication between the sensor  34  and various types of monitors, including different versions of the patient monitor  46  or other physiological monitors. In other embodiments, the sensor  34  and the patient monitor  46  may communicate via wireless means, such as using radio frequency, infrared or optical signals. In such embodiments, a transmission device may be connected to sensor  34  to facilitate wireless transmission between sensor  34  and patient monitor  46 . The cable  42  (or a corresponding wireless connection) may typically be used to transmit control or timing signals from the patient monitor  46  to the sensor  34  and/or to transmit acquired data from the sensor  34  to the patient monitor  46 . In other embodiments, the cable  42  may be an optical fiber that enables optical signals to be transmitted between the patient monitor  46  and the sensor  34 . 
         [0020]    In one embodiment, the patient monitor  46  may be a suitable pulse oximeter, such as those available from Nellcor Puritan Bennett L.L.C. In other embodiments, the patient monitor  46  may be a monitor suitable for measuring tissue water fractions, or other body fluid related metrics, using spectrophotometric or other techniques. Furthermore, the patient monitor  46  may be a multipurpose monitor suitable for performing pulse oximetry and measurement of tissue water fraction, or other combinations of physiological and/or biochemical monitoring processes, using data acquired via the sensor  34  and/or other sensors. Moreover, to upgrade conventional monitoring functions provided by the system, the patient monitor  46  may be coupled to a multi-parameter patient monitor  48  via a monitor cable  50  connected to a sensor input port and/or a cable connected to a digital communication port. 
         [0021]    In summary, the ability of the stocking hat  10  to adapt to different head sizes helps to ensure that the sensor  34  applies optimal pressure to the infant&#39;s forehead. Further, dimensional markings  32  on the stocking hat  10  allow the infant&#39;s head circumference to be measured without removing the stocking hat  10  or disrupting the placement of the sensor  34 . Indeed, a stocking hat  10  with an attached oximeter sensor  34  as depicted in  FIG. 3  can be used on patients in order to measure heart rate, oxygen saturation, head circumference, and/or other parameters. 
         [0022]    While the disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms provided. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the following appended claims. Indeed) the present disclosed methods may not only be applied to transmission type sensors for use in pulse oximetry, but also to other sensor designs.