Patent Application
20100240972
The present disclosure relates generally to medical monitoring devices and, more particularly, to pulse oximeters.
This section is intended to introduce the reader to various aspects of art 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.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood (SpO2), the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient.
Pulse oximeters typically utilize a non-invasive sensor that is placed on or against a patient's tissue that is well perfused with blood, such as a patient's finger, toe, forehead or earlobe. The pulse oximeter sensor emits light and photoelectrically senses the absorption and/or scattering of the light after passage through the perfused tissue. The data collected by the sensor may then be used to calculate one or more of the above physiological characteristics based upon the absorption or scattering of the light. More specifically, the emitted light is typically selected to be of one or more wavelengths that are absorbed and/or scattered in an amount related to the presence of oxygenated versus de-oxygenated hemoglobin in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of oxygen in the tissue using various algorithms.
Pulse oximeters and other medical devices are typically mounted on stands that are positioned adjacent to a patient's bed or an operating room table. When a caregiver desires to command the medical device (e.g., program, configure, and so-forth), the caregiver may manipulate controls or push buttons on the monitoring device itself. The monitoring device typically provides results or responses to commands on a Liquid Crystal Display (“LCD”) screen mounted in an externally visible position on the medical device. Patient data, alerts, and other information may be displayed on the monitor directly, or may be transmitted to a central computer monitored by caregivers.
However, in certain situations it may be desirable to have a pulse oximeter that is small, lightweight, inexpensive and battery operated. For example, conventional monitors may be too heavy and bulky to be moved from one patient to another when only periodic patient monitoring is desired. Furthermore, when medical treatment is desired in a remote location, access may not be available to a conventional power source. Therefore, smaller, battery-operated pulse oximeters may be used in such situations.
Hand-held oximeters, commonly referred to as spot check pulse oximeters, are typically found in two varieties. The first variety employs a transmittance-type sensor in which an emitter and a detector are positioned on opposite sides of a patient's finger, for example. These devices generally include a first portion and a second portion biased toward each other with a spring. A display is typically housed in the first portion to provide a patient or clinician with physiological data. The device is attached to a finger by applying a counter force to the spring to separate the two portions to allow the oximeter to be clipped onto the finger. One disadvantage of this configuration is that finger attachment requires two hands. A first hand is needed to separate the two portions, while the device is attached to a finger of the second hand.
The second variety of spot check pulse oximeters addresses this issue by employing a reflectance-type pulse oximetry sensor in which the emitter and detector are located on the same side of the oximeter. In this configuration, single-handed operation is possible because the patient merely has to place a finger on the sensor. However, one disadvantage of this configuration is that the sensor is exposed when not covered by the finger, making the sensor susceptible to contamination by dirt or other debris that may adhere to the sensor and interfere with light transmission. Furthermore, pulse oximeters of this type expose the sensor to abrasion during transport. For example, if the oximeter is placed in a pocket when not in use, the reflectance-type sensor may become scratched by other items within the pocket. Scratches on the surface of the sensor may interfere with light transmission and result in inaccurate readings. Therefore, it is desirable to have a spot check pulse oximeter that may be operated with a single hand and configured to protect the sensor when not in operation.
Certain aspects commensurate in scope with certain disclosed examples are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain embodiments and that these aspects are not intended to limit the scope of the disclosure or the claims. Indeed, the disclosure and claims may encompass a variety of aspects that may not be set forth below.
Some embodiments described herein are directed to a pulse oximeter including a first portion that includes at least one light emitter and at least one light detector and a second portion that includes a display adapted to output physiological data. The emitters and detectors may be capable of acquiring physiological data from a patient's finger, for example. The pulse oximeter also may include a drive engine, an oximetry engine, and a slider mechanism. The slider mechanism may be disposed between the first portion and the second portion and configured to facilitate translation of the second portion relative to the first portion.
Other embodiments described herein are directed to a hand-held pulse oximeter that may include a first portion having a reflectance-type pulse oximetry sensor being capable of communicatively coupling to a patient's finger, for example. The hand-held pulse oximeter also may include a pulse oximetry circuit and a second portion that may include a display adapted to receive and display physiological data. The second portion may be capable of translation relative to the first portion between a closed position and an open position.
Further embodiments described herein are directed to a method of manufacturing a hand-held pulse oximeter that may include providing a pulse oximetry sensor and disposing the pulse oximetry sensor on a first portion of the hand-held pulse oximeter. The method also may include providing a display and disposing the display on a second portion of the hand-held pulse oximeter. The method may further include securing the first portion to the second portion such that the second portion is capable of translation relative to the first portion.
Advantages of the disclosed embodiments may become apparent upon reading the following detailed description and upon reference to the drawings in which:
One or more specific 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' 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.
The presently disclosed embodiments are directed toward a self-contained, hand-held pulse oximetry system that is small and lighweight such that it can be carried by a patient or clinician. The pulse oximetry system may include a reflectance-type pulse oximetry sensor within a first portion and a display within a second portion. The second portion may be configured to slide relative to the first portion between an open and a closed position. In the open position, the sensor may be exposed such that a patient's finger may be placed on the sensor. The pulse oximetry system may then compute blood-oxygen saturation and/or heart rate and display these parameters on the display. After use, the patient or clinician may slide the second portion into a closed position such that the second portion substantially covers the sensor. In this manner, the pulse oximetry system may be transported while protecting the sensor from scratches, dirt and/or other contaminants. For example, the sensor may remain substantially clean and unmarred even when carried in a pocket of the patient or clinician.
To prevent sensor contamination, in accordance with one embodiment, a cover may be placed over the sensor when the pulse oximeter is not in use.
Reflectance-type sensors operate by emitting light into the tissue and detecting the light that is transmitted and scattered by the tissue. Reflectance-type sensors include an emitter 18 and detector 20 that are typically placed on the same side of a sensor site. For example, a reflectance-type sensor may be placed on a patient's fingertip 21 such that the emitter 18 and detector 20 lie side-by-side. Reflectance-type sensors detect light photons that are scattered back to the detector 20. During operation, the emitter 18 directs one or more wavelengths of light onto the patient's fingertip 21, and the light received by the detector 20 is processed to determine various physiological characteristics of the patient. In each of the embodiments discussed herein, it should be understood that the locations of the emitter 18 and detector 20 may be interchanged. Regardless of the arrangement, the slider pulse oximeter 10 will perform in substantially the same manner.
The emitter 18 and the detector 20 may be of any suitable type. For example, the emitter 18 may be one or more light emitting diodes adapted to transmit one or more wavelengths of light in the red to infrared range, and the detector 20 may be one or more photodetectors selected to receive light in the range or ranges emitted from the emitter 18. Alternatively, the emitter 18 may also be a laser diode or a vertical cavity surface-emitting laser (VCSEL). Emitter 18 and detector 20 may also include optical fiber elements. An emitter 18 may include a broadband or “white light” source, in which case the detector 20 could include any variety of elements for selecting specific wavelengths, such as reflective or refractive elements or interferometers. These kinds of emitters and detectors would typically be coupled to the rigid or rigidified sensor via fiber optics. Alternatively, the slider pulse oximeter 10 may sense light detected from the tissue at a different wavelength from the light emitted into the tissue. Such sensors may be adapted to sense fluorescence, phosphorescence, Raman scattering, Rayleigh scattering and multi-photon events or photoacoustic events. Similarly, in other applications, a tissue water fraction (or other tissue constituent related metric) or a concentration of one or more biochemical components in an aqueous environment may be measured using two or more wavelengths of light. In certain embodiments, these wavelengths may be infrared wavelengths between about 1,000 nm to about 2,500 nm.
It should be understood that, as used herein, the term “light” may refer to one or more of infrared, visible or ultraviolet and may also include any wavelength within the infrared, visible or ultraviolet spectra, and that any suitable wavelength of light may be appropriate for use with the present techniques.
Returning to
The display 22 also may include an information window 32 that may present the patient or clinician with information about the condition of the patient or slider pulse oximeter 10. For example, the window 32 may display a graphical icon indicating an excessively low blood-oxygen saturation. In such an embodiment, the slider pulse oximeter 10 may be programmed with a threshold blood-oxygen saturation. If a patient's blood-oxygen saturation drops below this threshold value, the window 32 may display an icon indicative of that condition to warn the patient or clinician. Similarly, the window 32 may display an icon indicative of excessively high or low pulse rate, a steady decline in blood-oxygen saturation, a sudden drop in blood-oxygen saturation, or other detected conditions. Furthermore, the window 32 may display an icon indicative of a condition of the slider pulse oximeter 10. For example, the window 32 may display an icon indicating a sensor failure and/or improper contact between the finger 21 and the sensor, among other conditions. In addition, the window 32 may display a textual message representative of any of the above conditions, alone or in combination with an icon.
Other display configurations may be employed in alternative embodiments. For example, the display 22 may include additional graphical or textual information (e.g., a graph of heart rate as a function of time). Conversely, the display may include fewer elements, such as a numerical representation of heat rate and blood-oxygen saturation alone. Other embodiments may include a series of LEDs instead of a graphical display. For example, the display 22 may include an LED indicative of a low blood-oxygen saturation and another LED indicative of an excessive heart rate. Further embodiments may include an LED that illuminates upon detection of a heart beat, similar to the previously described heart icon 28. Certain embodiments may include multicolored LEDs to indicate various physiological conditions. For example, a green LED may illuminate upon detection of a heart beat, while a red LED may illuminate upon detection of a low blood-oxygen saturation.
Additionally, although not depicted, embodiments may include one or more pushbuttons coupled to the first portion 12 and/or second portion 14. The pushbuttons may allow a patient or clinician to activate and/or deactivate the slider pulse oximeter 10 and/or change the configuration of the display 22. For example, a pushbutton may enable a patient or clinician to cycle through various physiological data displayed on the display 22. Furthermore, the pushbuttons may enable a patient or clinician to input range limits for various physiological parameters. For example, the patient or clinician may enter a maximum heart rate and/or a minimum blood-oxygen saturation. If the slider pulse oximeter 10 detects a physiological parameter outside of the input range, the display 22 may inform the patient or clinician of the detected condition. Furthermore, as described below, the slider pulse oximeter 10 may emit an audible alarm if a physiological parameter exceeds the input range.
The slider pulse oximeter 10 of the present embodiment is configured to facilitate single-handed operation. For example, as seen in
One-handed operation is particularly helpful when a patient desires to measure blood-oxygen saturation and/or pulse while engaged in another activity. For example, if a patient desires to measure physiological parameters while running or otherwise exercising, the patient may draw the slider pulse oximeter 10 from a pocket, for example. The patient may then open the slider pulse oximeter 10 single-handedly, take a measurement, and then close the slider pulse oximeter 10. In this manner, the patient may take the desired measurements without significantly interfering with the activity.
Similarly, a clinician may operate the slider pulse oximeter 10 with a single hand. The clinician may open the slider pulse oximeter 10 in a similar manner to the patient. Then, the clinician may place a patient's finger on the sensor membrane 16 to measure a patient's physiological parameters. Single-handed operation of the slider pulse oximeter 10 may reduce patient monitoring time, thereby increasing clinician efficiency.
To protect the sensor when the slider pulse oximeter 10 is not in use, the second portion 14 may slide in the direction 15 to cover the sensor membrane 16, as shown in
The display 22, shown in
To conserve power, the slider pulse oximeter 10 may deactivate the electronic components associated with measurement of patient physiological data while the slider pulse oximeter 10 is in the closed position. For example, the slider pulse oximeter 10 may disable the emitter 18 and detector 20. In alternative embodiments, the slider pulse oximeter 10 may also deactivate the display 22 while the slider pulse oximeter 10 is in the closed position to further reduce power consumption. In further embodiments, other techniques for activating and deactivating the slider pulse oximeter 10 may be included. For example, the slider pulse oximeter 10 may include a power button or switch, or, alternatively, the slider pulse oximeter 10 may include a pressure sensitive button embedded within the sensor membrane 16 that activates the slider pulse oximeter 10 upon contact with a patient's finger 21. In addition, the slider pulse oximeter 10 may be configured to deactivate the electronic components upon detecting an absence of the finger 21 for a predetermined time. For example, if the slider pulse oximeter 10 is in the open position, but no finger 21 has contacted the emitter 18 and detector 20 for two minutes, for example, the slider pulse oximeter 10 may be deactivated.
To facilitate transport, the slider pulse oximeter 10 may include a lanyard 38 disposed to the first portion 12. For example, the lanyard 38 may be worn around the clinician's neck to provide easy access to the slider pulse oximeter 10 as the clinician examines each patient. Similarly, the lanyard 38 may be worn around the patient's neck to provide easy access to the slider pulse oximeter 10 whenever the patient desires to monitor blood-oxygen saturation and/or heart rate. As shown in
Turning now to
The signal generated by the detector 20 may then be amplified by an amplifier 40, filtered by a filter 42, and provided to one or more processor(s) 44. The processor(s) 44 may include an analog-to-digital converter 50 that converts the analog signal provided by the detector 20 into a digital signal. The analog-to-digital converter 50 may provide the digital signal to a core 52 to be processed for computing physiological parameters related to the patient. For example, the core 52 may compute a percent oxygen saturation of hemoglobin and/or a pulse rate, among other useful physiological parameters, as will be appreciated by one of ordinary skill in the art. By utilizing an analog-to-digital converter 50 within the processor(s) 44, the size and cost of the oximeter may be reduced, compared to traditional pulse oximeters that use a separate analog-to-digital converter. In presently contemplated embodiments, the processor(s) 44 may include a Mixed-Signal Microcontroller such as model number C8051F353 available from Silicon Laboratories.
In addition to computing physiological parameters, the processor(s) 44 may control the timing and intensity of the emitted electromagnetic radiation of the emitters 18A and 18B via a light drive circuit 54. In embodiments, the light drive circuit 54 may be driven by a digital-to-analog converter 56, included in the processor(s) 44. By utilizing a digital to analog converter 56 within the microprocessor 44, the size and cost of the oximeter may be reduced, compared to traditional pulse oximeters that use a separate digital-to-analog converter. In accordance with an embodiment, the light drive circuit 54 may have a low part count such as the light drive circuit discussed in detail in U.S. patent application Ser. No. 12/343,799, entitled “LED Drive Circuit and Method for Using Same” which was filed Dec. 24, 2008, and is incorporated herein by reference in its entirety for all purposes. The reduced part count of the drive circuit 54 may further reduce the size, complexity, and cost of the slider pulse oximeter 10.
Furthermore, the processor(s) 44 may also include a RAM 58 and/or a flash memory 60 coupled to the core processor 52. The RAM 58 may be used to store intermediate values that are generated in the process of calculating patient parameters. The flash memory 60 may store certain software routines used in the operation of the slider pulse oximeter 10, such as measurement algorithms, LED drive algorithms, and patient parameter calculation algorithms, for example. In certain embodiments, the slider pulse oximeter 10 may include simplified pulse oximetry algorithms such that the computer code associated with those algorithms may be contained in the memory components of the processor(s) 44,
In some embodiments, the slider pulse oximeter 10 may also include other memory components that are not included in the processor(s) 44. For example, the slider pulse oximeter 10 may include a read-only memory (ROM), which may be used to store such things as operating software for the slider pulse oximeter 10 and algorithms for computing physiological parameters. In other embodiments, however, all of the processing memory and measurement software is included in the processor(s) 44.
Furthermore, in some embodiments, the slider pulse oximeter 10 may also include a long-term memory device used for long-term storage of measured data, such as measured physiological data or calculated patient parameters. In other embodiments, however, the long-term memory device may be omitted to reduce the cost and/or part count of the slider pulse oximeter 10. By omitting the long-term memory device, smaller, less expensive memory components may be utilized, thereby reducing the part count and the size and complexity of the slider pulse oximeter 10, compared to traditional pulse oximetry systems.
Further embodiments may include a memory card reader (not shown) configured to electrically couple with a removable memory card (not shown). The memory card may include patient identification information. This information may be uploaded to the processor(s) 44 automatically upon insertion of the memory card. In addition, the memory card may be configured to store measured data, such as measured physiological data or calculated patient parameters. In certain embodiments, the measured data may be associated with the patient identification information stored on the memory card. The stored data may be transferred to a computer, for example, by removing the memory card from the slider pulse oximeter 10 and inserting it into a reader electrically coupled to the computer.
As mentioned previously, also included in the slider pulse oximeter 10 is a display that may be coupled to the processor(s) 44 to allow for display of the computed physiological parameters. For example, the display may include an LCD display 22, which is operably coupled to the processor(s) 44 and programmed to operate as described above in relation to
Embodiments may also include a wireless device 62 configured to transmit computed patient parameters such as, for example, pulse rate, blood-oxygen saturation, or the raw data. The wireless device 62 may include any suitable wireless technology. For example, the slider pulse oximeter 10 may transmit data via a wireless communication protocol such as WiFi, Bluetooth or ZigBee.
The slider pulse oximeter 10 may utilize a slider mechanism 63 to facilitate translation of the second portion 14 relative to the first portion 12. A spring-biased slider mechanism 63 is shown in the cutaway top view of
As discussed in detail below, the slider mechanism 63 of the present embodiment includes a pair of tracks 64, a pair of pins 66, a spring 68, and a pair of grooves 70. The tracks 64 are disposed within the second portion 14 and configured to facilitate translation of the second portion 14 with respect to the first portion 12. Pins 66 are disposed within the tracks 64 of the second portion 14 and the grooves 70 of the first portion 12. The pins 66 serve to secure the second portion 14 to the first portion 12, while enabling translation. Specifically, as the second portion 14 translates with respect to the first portion 12, the tracks 64 translate relative to the pins 66. Due to the chevron shape of the tracks 64, the pins 66 are driven to translate along a lateral axis 71 as the tracks 64 move along the pins 66. The grooves 70 are elongated to enable the pins 66 to translate along the lateral axis 71. Spring 68 serves to bias the pins 66 laterally inward such that the second portion 14 is biased toward the closed position when the second portion 14 is closer to the closed position. Similarly, the spring 68 serves to bias the second portion 14 toward the open position when the second portion 14 is closer to the open position.
As illustrated, the second portion 14 includes a circuit board 72. The circuit board 72 may be particularly shaped to fit between the tracks 64 to prevent interference with the slider mechanism 63. As appreciated, the circuit board 72 may be enclosed within the first portion 12 in alternative embodiments. The circuit board 72 may include the processor 44, as well as other circuit components 74, such as the circuit components discussed above with regard to
The second portion 14 may also include a battery door (not shown), facilitating access to the batteries 76. For example, a section of the second portion 14 may swing or slide open to expose a battery compartment, allowing batteries 76 to be changed. Alternatively, the battery door may be disposed to the first portion 12 in embodiments in which the first portion 12 houses the batteries 76. Further embodiments having non-removable batteries 76 may omit the battery door. For example, embodiments employing rechargeable batteries 76 may include a power connector coupled to the second portion 14 or the first portion 12 to facilitate recharging the batteries 76.
The illustrated embodiment also includes a wireless device 62 on the circuit board 72. As discussed above, the wireless device 62 may allow the slider pulse oximeter 10 to transmit data wirelessly to a remote monitor. As such, the wireless device 62 may include wireless transmitter circuitry and a radio frequency antenna, such as, for example a microstrip or patch antenna.
Furthermore, embodiments may also include a speaker 77 and supporting circuitry configured to drive the speaker 77. The speaker 77 may emit sound to communicate physiological data to a patient or clinician. For example, the speaker 77 may be configured to emit a beeping sound corresponding to the heartbeat of a patient, or the speaker 77 may be configured to sound an audible alarm when the patient's blood-oxygen saturation level and/or pulse falls outside of a certain acceptable range. Furthermore, as previously discussed, the speaker 77 may emit an audible reminder to a clinician to being rounds.
If the emitter 18 and detector 20 and the circuit board 72 are on different portions of the slider pulse oximeter 10, the slider pulse oximeter 10 may be configured to maintain a connection between the emitter 18 and detector 20 and the circuit board 72 throughout the range of motion of the second portion 14. As illustrated in
As previously discussed, the pins 66 are configured to secure the first portion 12 to the second portion 14. As shown in
Similarly, as shown in
As illustrated in
Conversely, the slider mechanism 63 is also configured to hold the second portion 14 in the closed position during transportation and storage. As illustrated in
The grooves 70 are configured to accommodate lateral translation of pins 66 as pins 66 are driven to move in the lateral direction 71 by tracks 64. As best seen in
As a patient or clinician continues to move the second portion 14 in direction 15 past the transition point tracks 64 continue to translate in direction 15 relative to pins 66. As previously discussed, the spring 68 biases the pins 66 laterally inward. Therefore, due to the laterally inward orientation of tracks 64 past the transition point, interaction between the pins 66 and the tracks 64 induces the second portion 14 to automatically translate toward the closed position. Specifically, pins 66 apply a inward force to tracks 64 along lateral axis 71. Due to the laterally inward orientation of the tracks 64, this lateral force is converted to a force in direction 15. Consequently, if the patient or clinician releases the second portion 14 while the pins 66 are within the laterally inward section of tracks 64, the second portion 14 may automatically translate toward the closed position. Furthermore, this configuration holds the second portion 14 in the closed position during transportation and storage of the slider pulse oximeter 10.
Other slider mechanisms may be employed in alternative embodiments. For example, the slider mechanism may be configured to bias the second portion 14 toward the closed position when the second portion 14 is substantially in the closed position, and bias the second portion 14 toward the open position when the second portion 14 is substantially in the open position. In this configuration, to transition the slider pulse oximeter 10 from the closed position to the open position, the patient or clinician applies a force to the second portion 14 to overcome the bias toward the closed position After the second portion 14 translates away from the substantially closed position, the patient or clinician may translate the second portion 14 without bias toward the open position. Upon reaching the substantially open position, the second portion 14 is biased toward the open position. In this arrangement, the slider mechanism holds the second portion 14 in the open position during use, and the closed position during storage and transportation.
In a further embodiment, the slider mechanism is configured to bias the second portion 14 toward the open position, secure the second portion 14 in the closed position when the second portion 14 is substantially in the closed position, and release the second portion 14 from the closed position upon activation of a release mechanism. In other words, during transportation or storage, the second portion 14 is locked into the closed position by the release mechanism. Prior to use, the patient or clinician activates the release mechanism, thereby causing a spring to direct the second portion 14 from a closed position to an open position. The spring also serves to hold the second portion 14 in the open position during use. After use, the patient or clinician may direct the second portion 14 toward the closed position by applying a force to the second portion 14 to counteract the spring bias. Upon reaching the closed position, the release mechanism may automatically lock the second portion 14 into the closed position for transportation or storage.
Other embodiments may include a pedometer that is used to collect general information about user mobility for patients on a rehab program. Other embodiments may include memory on which music or other data may be stored. Rhythmic music may be played bio-feedback to adjust the user's pulse, etc.
Other embodiments may include reflectance sensor that includes a pressure-sensor in the pad where the finger contacts the device. The sensor may be used for open- or closed-loop feedback for ensuring the finger has the required amount of contact pressure. For example, it could sense if the patient was pressing too hard and restricting blood flow.
