Patent Publication Number: US-2013245408-A1

Title: Handheld pulse oximetry system

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/072,259, filed Mar. 28, 2008, and is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to medical devices and, more particularly, to powering medical devices. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, 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 invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     In the field of medicine, there is a need to monitor physiological characteristics of a patient. Accordingly, a wide variety of devices and techniques have been developed for monitoring the physiological characteristics of a patient. One such technique for monitoring certain physiological characteristics of a patient (e.g., blood flow characteristics) is commonly referred to as pulse oximetry. Devices which perform pulse oximetry are commonly referred to as pulse oximeters. Pulse oximeters may be used to measure physiological characteristics such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. 
     Specifically, these measurements may be acquired using a non-invasive sensor that transmits electromagnetic radiation, such as light, through a patient&#39;s tissue and that photoelectrically detect the absorption and scattering of the transmitted light in such tissue. Physiological characteristics may then be calculated based upon the amount of light absorbed and scattered. More specifically, the light passed through the tissue may be selected to be of one or more wavelengths that may be absorbed and scattered by the blood in an amount correlative to the amount of blood constituent present in the tissue. The measured amount of light absorbed and scattered may then be used to estimate the amount of blood constituent in the tissue using various algorithms. 
     Because of the particular physiological parameters that pulse oximeters are capable of determining, the use of pulse oximeters has become important in places besides hospitals. Traditional pulse oximeters obtain power by plugging into a wall socket. However, pulse oximeters may be used to monitor and treat patients outside of a hospital setting, such as in developing nations where constant and regular sources of electricity may be difficult to obtain. This lack of a constant and regular source of electricity renders traditional plug-in pulse oximeters at a disadvantage. While pulse oximeters powered by replaceable batteries can overcome this problem, there still exists a problem that the batteries in such pulse oximeters regularly die and need to be replaced. When this occurs in situations where replacement batteries are not readily available, these pulse oximeters become similarly disadvantaged as the traditional plug-in pulse oximeters. 
     Additionally, current pulse oximeters typically are not rugged enough to withstand use outside of a hospital setting. The pulse oximeters designed for use today are typically intended for use in a hospital where there is very little shock that the pulse oximeter must endure. Thus, current pulse oximeters have an added problem for use in developing nations in that they typically cannot handle the rough usage that may occur in areas outside of a hospital setting. 
     SUMMARY 
     Certain aspects commensurate in scope with the original claims are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain embodiment and that these aspects are not intended to limit the scope of the claims. Indeed, the disclosure and claims may encompass a variety of aspects that may not be set forth below. 
     In accordance an embodiment, there is provided a manually powered pulse oximeter that includes a manual power source. The manual power source may include a manual generator and a power storage device. The manual power source may be capable of powering the pulse oximeter without an external source of power. The manually powered pulse oximeter may also be shock resistant and capable of withstanding being shaken or dropped without damage to the internal components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the disclosure may become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  illustrates a perspective view of a pulse oximeter in accordance with an embodiment; 
         FIG. 1A  illustrates a perspective view of a sensor in accordance with the embodiment pulse oximeter illustrated in  FIG. 1 ; 
         FIG. 2  illustrates a hand held pulse oximeter in accordance with an embodiment; 
         FIG. 3  illustrates a hand held pulse oximeter having a remote sensor in accordance with an embodiment; 
         FIG. 4  illustrates a simplified block diagram of a pulse oximeter having an manual power source in accordance with an embodiment; 
         FIG. 5  illustrates an embodiment of a simplified block diagram of the manual power source in  FIG. 4 ; 
         FIG. 6  illustrates a first manual generator in accordance with an embodiment of the manual power source of  FIG. 4 ; and 
         FIG. 7  illustrates a second manual generator in accordance with an embodiment of the manual power source of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments 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. 
     Traditional pulse oximeters may use a wall socket as a power source and charger for batteries, and, thus, are ill-suited to treat patients outside of a hospital setting in such places as developing nations where constant and regular sources of electricity may be difficult to obtain. Additionally, current pulse oximeters typically are not rugged enough to withstand use outside of a hospital setting. To address these limitations, the present disclosure details the use of a manual power source used to power a pulse oximeter. Moreover, shock resistant components are described to protect the manually powered pulse oximeter from damage typically encountered during manually powering and using the pulse oximeter. 
     Turning to  FIG. 1 , a perspective view of a medical device is illustrated in accordance with an embodiment. The medical device may be a manually powered pulse oximeter  100  that includes a manual power source (not shown). The manually powered pulse oximeter may include a monitor  102 . The monitor  102  may be configured to display calculated parameters on a display  104 . As illustrated in  FIG. 1 , the display  104  may be integrated into the monitor  102 . However, the monitor  102  may be configured to provide data via a port to a display (not shown) that is not integrated with the monitor  102 . The display  104  may be configured to display computed physiological data including, for example, an oxygen saturation percentage, a pulse rate, and/or a plethysmographic waveform  106 . As is known in the art, the oxygen saturation percentage may be a functional arterial hemoglobin oxygen saturation measurement in units of percentage SpO 2 , while the pulse rate may indicate a patient&#39;s pulse rate in beats per minute. The monitor  102  may also display information related to alarms, monitor settings, and/or signal quality via indicator lights  108 . 
     To facilitate user input, the monitor  102  may include a plurality of control inputs  110 . The control inputs  110  may include fixed function keys, programmable function keys, and soft keys. Specifically, the control inputs  110  may correspond to soft key icons in the display  104 . Pressing control inputs  110  associated with, or adjacent to, an icon in the display may select a corresponding option. 
     The monitor  102  may also include a sensor port  112 . The sensor port  112  may allow for connection to an external sensor.  FIG. 1A  illustrates a sensor  114  that may be used with the monitor  102 . The sensor  114  may be communicatively coupled to the monitor  102  via a cable  116  which connects to the sensor port  112 . The sensor  114  may be of a disposable or a non-disposable type. Furthermore, the sensor  114  may obtain readings from a patient, which can be used by the monitor to calculate certain physiological characteristics such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. The sensor  114  and the monitor  102  may combine to form the pulse oximeter  100 . 
     The monitor  102  may also include a casing  118 . The casing  118  may be made of shock resistant material such as hard plastic or hard rubber. The casing  118  may also include an internal and/or external layer of shock absorbing material such as foam or other types of insulating material. The combination of the shock resistant and shock absorbent materials used for the casing  118  ruggedizes the manually powered pulse oximeter  100 , so that the manually powered pulse oximeter  100  may be shaken vigorously or dropped without damage. 
     The manually powered pulse oximeter  100  may of a standard size. However, it may be beneficial to incorporate aspects of the ruggedized manually powered pulse oximeter  100  into a more portable or hand-held medical device, such as the manually powered pulse oximeter  200  illustrated in  FIG. 2 . The casing  202  of the portable manually powered pulse oximeter  200  may be designed to generally fit within the palm of a user&#39;s hand, making it easy to carry and convenient to use. For example, the pulse oximeter  10  may be ½ in.×1 in.×2 in. and weigh approximately 0.1 lbs. As such, a user, such as a caregiver or a patient, may carry it around in a pocket or a small bag for easy use outside of a hospital or traditional health care environment. The casing  202  may be made of shock resistant material such as hard plastic or hard rubber, and may also include an internal and/or external layer of shock absorbing material such as foam or other types of insulating material. These materials aid in ruggedizing the portable manually powered pulse oximeter  200 , so that the portable manually powered pulse oximeter  200  may be shaken vigorously or dropped without damage. 
     In an embodiment, the portable manually powered pulse oximeter  200  may include a sensor  204 , a keypad  206 , and a display  208 . The sensor  204  may be configured to allow the user to place a finger on the sensor pad or, alternatively, to place the sensor on a forehead. The keypad  206  may be capable of allowing a user to interface with the portable manually powered pulse oximeter  200 . For example, the keypad  206  may be configured to allow a user to select a particular mode of operation. In an embodiment (not shown), the keypad  206  may not be provided. The display  208  may be oriented relative to the sensor  204  to facilitate a user reading the display  208 . The display  208  may also allow a user to read the various measured parameters of the pulse oximeter, such as oxygen saturation level and/or pulse rate. 
       FIG. 3  illustrates an embodiment of a portable or hand-held medical device. The medical device may be a portable manually powered pulse oximeter  300  similar to the portable manually powered pulse oximeter  200  described above. The portable manually powered pulse oximeter  300  may include a casing  202 , a sensor  204 , a keypad  206 , and a display  208 , which function as described above. However, the sensor  204  is not included in the physical structure of portable manually powered pulse oximeter  300 , but instead is coupled to casing  202  via a cable  302 . This configuration allows for the sensor  202  and the cable  302  to be removable from the portable manually powered pulse oximeter  300 . In this manner, the sensor  202  and cable  302  may be interchangeable with other components, and alternatively, may be disposable. Alternatively, another embodiment similar to this configuration allows for removal of the cable  302  altogether. In this embodiment, the sensor  204  may transmit information wirelessly to the portable manually powered pulse oximeter  300 . 
     Although the size and location of the sensors  114  and  202  differ with respect to the three pulse oximeters  100 ,  200 , and  300  described above, the internal circuitry may be similar amongst the three.  FIG. 4  illustrates a simplified block diagram of an embodiment of the manually powered pulse oximeter  100 , however, the block diagram may equally apply to the portable manually powered pulse oximeters  200  and  300 . The manually powered pulse oximeter  100  may include a sensor  114  having an emitter  402  configured to transmit electromagnetic radiation, i.e., light, into the tissue of a patient  404 . The emitter  402  may include a plurality of LEDs operating at discrete wavelengths, such as in the red and infrared portions of the electromagnetic radiation spectrum for example. Alternatively, the emitter  402  may be a broad spectrum emitter. 
     The sensor  114  may also include a detector  406 . The detector  406  may be a photoelectric detector which may detect the scattered and/or reflected light from the patient  404 . Based on the detected light, the detector  406  may generate an electrical signal, e.g. current, at a level corresponding to the detected light. The sensor  114  may direct the electrical signal to the monitor  102 , where the electrical signal may be used for processing and calculation of physiological parameters of the patient  404 . 
     In this embodiment, the monitor  102  may be a pulse oximeter, such as those available from Nellcor Puritan Bennett L.L.C. Further, the monitor  102  may include an amplifier  414  and a filter  416  for amplifying and filtering the electrical signals from the sensor  114  before digitizing the electrical signals in the analog-to-digital converter  418 . Once digitized, the signals may be used to calculate the physiological parameters of the patient  404 . The monitor  102  may also include one or more processors  408  configured to calculate physiological parameters based on the digitized signals from the analog-to-digital converter  418  and further using algorithms programmed into the monitor  102 . The processors  408  may be connected to other component parts of the monitor  102 , such as one or more read only memories (ROM)  410 , one or more random access memories (RAM)  412 , the display  104 , and the control inputs  110 . The ROM  410  and the RAM  412  may be used in conjunction, or independently, to store the algorithms used by the processors in computing physiological parameters. The ROM  410  and the RAM  412  may also be used in conjunction, or independently, to store the values detected by the detector  406  for use in the calculation of the aforementioned algorithms. The control inputs  110 , as described above, may allow a user to interface with the monitor  102 . 
     Further, the monitor  102  may include a light drive unit  420 . Light drive unit  420  may be used to control timing of the emitter  402 . An encoder  422  and decoder  424  may be used to calibrate the monitor  102  to the actual wavelengths being used by the emitter  402 . The encoder  422  may be a resistor, for example, whose value corresponds to the actual wavelengths and to coefficients used in algorithms for computing the physiological parameters. Alternatively, the encoder  422  may be a memory device, such as an EPROM, that stores wavelength information and/or the corresponding coefficients. For example, the encoder  442  may be a memory device such as those found in OxiMax® sensors available from Nellcor Puritan Bennett L.L.C. The encoder  442  may be communicatively coupled to the monitor  102  in order to communicate wavelength information to the decoder  424 . The decoder  424  may receive and decode the wavelength information from the encoder  422 . Once decoded, the information may be transmitted to the processors  408  for utilization in calculation of the physiological parameters of the patient  404 . 
     The monitor  102  may also include a manual power source  426 . The manual power source  426  may be used to transmit power to the components located in the monitor  102  and/or the sensor  114 . The manual power source  426  may harness kinetic energy derived from a user and convert the kinetic energy into usable power, for example electricity, that the components in monitor  102  and sensor  114  use to function. 
     Examples of the components utilized in the manual power source  426  to harness and convert the kinetic energy provided by a user are illustrated in  FIG. 5 , which illustrates a simplified block diagram of a manual power source  426 . The manual power source  426  may include a manual generator  502 . The manual generator  502  converts kinetic energy into usable power. The manual generator  502  may be used to generate an alternating current through inductance. For example, kinetic energy input by the user may be translated into alternating current through the inductive characteristics and arrangement of the components of the manual generator  502 . This generated current may then be transmitted to the converter  504 . The converter  504  rectifies the alternating current transmitted from the manual generator  502  into direct current. The converter  504  may be a full wave rectifier made up of, for example, diodes. The rectification of the electricity by the converter  504  may also include smoothing the output of the converter  504 . A filter, such as a reservoir capacitor, may be used to smooth the output of the converter  504 . The smoothed direct current may then be transmitted a power storage device  506 . The power storage device  506  stores the generated and converted power for use by the components of monitor  102  and sensor  114 . In one embodiment, power storage device  506  may include one or more rechargeable batteries. In another embodiment, the power storage device  506  may include one or more capacitors. 
     The manual generator  502  may include a variety of kinetic energy generation systems. One such system is illustrated in  FIG. 6 . The manual generator  502  includes a case  602 , a magnet  604 , one or more buffers  606 , a coil  608 , and one or more leads  610 . The case  602  may be composed of plastic or any other non-conducting material. The case  602  may enclose the magnet  604  and the buffers  606 . The case  602  may also be sized to allow lateral movement of magnet  604 . In one embodiment, the case  602  is cylindrical in shape. 
     The magnet  604  may be sized to fit within the case  602  and move laterally within the case  602 . The magnet  604  may be a permanent magnet. The magnet  604  may be capable of sliding from one end of the case  602  to the other in response to an input of kinetic energy. In one embodiment, the kinetic energy may include a user shaking the manual generator  502 . The movement of the magnet  604  through the case  602  causes the magnet to pass through the coil  608 . The coil  608  may be made up of a conductive substance and may be wrapped around the case  602 . In one embodiment, the coil  608  may be made from coiled aluminum. In another embodiment, the coil may be made from coiled copper wire. The copper wire may be covered by thin insulation. 
     As the magnet  604  passes through the coil  608 , electricity is generated via electromagnetic induction. This electricity may then be transmitted via the leads  610  to the converter  504 . The converter  504  may include a rectifier circuit, as described above. Additionally, the converter  504  may include a transformer (not pictured) or a phase converter (not pictured). The leads  610  may be made from a conductive material such as metal wire. Additionally, the leads  610  may include a single wire, two wires, or three wires, allowing the leads  610  to conduct one, two, or three phase power. 
     The magnet  604  also may contact buffers  606  as it passes through the case  602 . The buffers  606  may be made of elastic material such as rubber. In another embodiment, the buffers  606  may be springs. The buffers  606  at to help conserve the kinetic energy being focused into the sliding magnet  604  by redirecting the magnet  604  back through the case  602  when the buffer  606  is contacted by the magnet  604 . In this manner, the buffers  606  aid in the conversion of kinetic energy into usable electricity. 
     Another embodiment for the manual generator  502  is illustrated in  FIG. 7 . The manual generator  502  may include a handle  702 . The handle  702  may be rotatable about an axis. The handle  702  may also be foldable (not shown) into the casing  118  for ease of storage when not in use. The handle  702  may be connected to a gear train  704 . As a user cranks the handle in a circular direction, the gear train  704  acts to transfer the rotational torque from the handle  702  to a magnet  706 . In one embodiment, the gear train  704  is set to create increased rotations of the magnet  706  relative to the handle  702 . The magnet  706  may rotate inside of a coil  708 . The rotational motion of the magnet  706  inside the coil  708  induces an electrical current in the coil  708  which may be transmitted via conductive leads  710  to the converter  504 . Converter  504  may include a rectifier circuit, a transformer, or a phase converter. Moreover, the leads  710 , which may be made from a conductive material, may include a single wire, two wires, or three wires, allowing the leads  710  to conduct one, two, or three phase power. Through the use of these leads  710 , the manual generator  502  may convert inputted kinetic energy, here the cranking of a handle, into electricity useable by the pulse oximeter  100 . The manual power source may also work similarly to watches which do not need to b wound, or powered with a battery. 
     Various 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 claims are not intended to be limited to the particular forms disclosed. Rather, the claims are to cover all modifications, equivalents, and alternatives falling within their spirit and scope.