The present disclosure relates generally to medical devices, and, more particularly, to a pulse oximeter having a wait-time and/or progress indication.
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 healthcare, caregivers (e.g., doctors and other healthcare professionals) often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of monitoring devices have been developed for monitoring many such physiological characteristics. These monitoring devices often provide doctors and other healthcare personnel with information that facilitates provision of the best possible healthcare for their patients. As a result, such monitoring devices have become a perennial feature of modern medicine.
One technique for monitoring 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 oximeters may be used to measure and monitor various blood flow characteristics of a patient. For example, a pulse oximeter may be utilized to monitor 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. In fact, the “pulse” in pulse oximetry refers to the time-varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximeters typically utilize a non-invasive sensor that transmits light through a patient's tissue and that photoelectrically detects the absorption and/or scattering of the transmitted light in such tissue. A photo-plethysmographic waveform, which corresponds to the cyclic attenuation of optical energy through the patient's tissue, may be generated from the detected light. Additionally, one or more of the above physiological characteristics may be calculated based generally upon the amount of light absorbed or scattered. More specifically, the light passed through the tissue may be selected to be of one or more wavelengths that may be absorbed or scattered by the blood in an amount correlative to the amount of the blood constituent present in the blood. The amount of light absorbed and/or scattered may then be used to estimate the amount of blood constituent in the tissue using various algorithms.
Generally, the pulse oximeter begins displaying the patient's physiological characteristics after the sensor has been placed and enough time has passed for the monitor to calculate the characteristics from the data received from the sensor. In some instances, the caregiver applying the pulse oximeter sensor may expect the patient's physiological characteristics to be displayed instantly or within a very short period of time after applying the sensor. If the characteristics are not yet calculated, they will not yet be displayed, and the caregiver may erroneously believe that the sensor is misapplied. In these instances, the caregiver may reposition the sensor before the pulse oximeter has the time to calculate and display the patient's physiological characteristics. Once the sensor is repositioned, the calculations must begin again, thereby slowing down the acquisition of the patient's information. An impatient caregiver may inadvertently delay the acquisition and display of the patient's physiological characteristics by moving the sensor.
Advantages of the disclosure 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.
When a caregiver applies a medical monitor, such as a pulse oximeter, to a patient, the caregiver must generally wait for some time to pass before the monitor displays the physical characteristic being monitored. For example, when a caregiver applies a pulse oximetry sensor to a patient and turns on the monitor, some time passes before the monitor is able to display the patient's SpO2. The time delay may be due to monitor start-up processes, sensor calibration, signal detection, and so forth. In some cases, an impatient caregiver might not wait long enough for the monitor to begin displaying the physical characteristic before deciding that the sensor is misapplied and moving it. This action forces the monitor to restart the physical characteristic determination, thereby further delaying the posting of the physical parameter on the monitor. Accordingly, it may be desirable to provide the caregiver with a wait-time and/or progress indication so that the caregiver leaves the sensor in place long enough for the physical characteristic to be determined. The indication may also alert the caregiver when the sensor should be reapplied or the system should be checked.
In the illustrated embodiment the pulse oximetry system 10 also includes a multi-parameter patient monitor 26. In addition to the monitor 14, or alternatively, the multi-parameter patient monitor 26 may be capable of calculating physiological characteristics and providing a central display 28 for information from the monitor 14 and from other medical monitoring devices or systems. For example, the multi-parameter patient monitor 26 may display a patient's SpO2 and pulse rate information from the monitor 14 and blood pressure from a blood pressure monitor on the display 28. Additionally, the multi-parameter patient monitor 26 may indicate an alarm condition via the display 28 and/or a speaker 30 if the patient's physiological characteristics are found to be outside of the normal range. The monitor 14 may be communicatively coupled to the multi-parameter patient monitor 26 via a cable 32 or 34 coupled to a sensor input port or a digital communications port, respectively. In addition, the monitor 14 and/or the multi-parameter patient monitor 26 may be connected to a network to enable the sharing of information with servers or other workstations.
In one embodiment, the detector 18 may be capable of detecting the intensity of light at the RED and IR wavelengths. In operation, light enters the detector 18 after passing through the patient's tissue 40. The detector 18 may convert the intensity of the received light into an electrical signal. The light intensity may be directly related to the absorbance and/or reflectance of light in the tissue 40. That is, when more light at a certain wavelength is absorbed or reflected, less light of that wavelength is typically received from the tissue by the detector 18. After converting the received light to an electrical signal, the detector 18 may send the signal to the monitor 14, where physiological characteristics may be calculated based at least in part on the absorption of the RED and IR wavelengths in the patient's tissue 40.
The encoder 42 may contain information about the sensor 12, such as what type of sensor it is (e.g., whether the sensor is intended for placement on a forehead or digit) and the wavelengths of light emitted by the emitter 16. This information may allow the monitor 14 to select appropriate algorithms and/or calibration coefficients for calculating the patient's physiological characteristics. The encoder 42 may, for instance, be a coded resistor which stores values corresponding to the type of the sensor 12 and/or the wavelengths of light emitted by the emitter 16. These coded values may be communicated to the monitor 14, which determines how to calculate the patient's physiological characteristics. In another embodiment, the encoder 42 may be a memory on which one or more of the following information may be stored for communication to the monitor 14: the type of the sensor 12; the wavelengths of light emitted by the emitter 16; and the proper calibration coefficients and/or algorithms to be used for calculating the patient's physiological characteristics. Exemplary pulse oximetry sensors capable of cooperating with pulse oximetry monitors are the OxiMax® sensors available from Nellcor Puritan Bennett LLC.
Signals from the detector 18 and the encoder 42 may be transmitted to the monitor 14. The monitor 14 generally may include processors 48 connected to an internal bus 50. Also connected to the bus may be a read-only memory (ROM) 52, a random access memory (RAM) 54, user inputs 56, the display 20, or the speaker 22. A time processing unit (TPU) 58 may provide timing control signals to a light drive circuitry 60 which controls when the emitter 16 is illuminated and the multiplexed timing for the RED LED 44 and the IR LED 46. The TPU 58 control the gating-in of signals from detector 18 through an amplifier 62 and a switching circuit 64. These signals may be sampled at the proper time, depending upon which light source is illuminated. The received signal from the detector 18 may be passed through an amplifier 66, a low pass filter 68, and an analog-to-digital converter 70. The digital data may then be stored in a queued serial module (QSM) 72 for later downloading to the RAM 54 as the QSM 72 fills up. In one embodiment, there may be multiple separate parallel paths having the amplifier 66, the filter 68, and the A/D converter 70 for multiple light wavelengths or spectra received.
The processor(s) 48 may determine the patient's physiological characteristics, such as SpO2 and pulse rate, using various algorithms and/or look-up tables based generally on the value of the received signals corresponding to the light received by the detector 18. Signals corresponding to information about the sensor 12 may be transmitted from the encoder 42 to a decoder 74. The decoder 74 may translate these signals to enable the microprocessor to determine the proper method for calculating the patient's physiological characteristics, for example, based generally on algorithms or look-up tables stored in the ROM 52. In addition, or alternatively, the encoder 42 may contain the algorithms or look-up tables for calculating the patient's physiological characteristics. In certain embodiments, the display 20 may exhibit an indication of the approximate time remaining for determination and display of the patient's physiological characteristics.
In accordance with an embodiment when the monitor 14 is turned on and the sensor 12 is applied to the patient 40, the display 20 may initially show a wait-time/progress indication 88 before the patient's physical characteristics are displayed (
In the illustrated embodiment, the wait-time/progress indication 88 is displayed in place of the physical characteristics, however in other embodiments the indication 88 may be displayed in another location (e.g., a dedicated area on the display 20). In addition, the exemplary wait-time/progress indication 88 illustrated in
In order to calculate the approximate wait-time, the monitor 14 may include software which analyzes the progress of the physical characteristic determination, as illustrated in a flow chart 100 in
Generally, the initial wait-time may be based at least in part on the durations of the generally fixed processes and minimum duration estimates of the variable processes. For example, the fixed processes may include the monitor boot-up 102, the sensor validation 104, and the sensor calibration 106. An exemplary monitor boot-up process 102 may include checking the RAM 54 (
In addition to the fixed process durations, minimum durations for the variable processes may be included in the initial wait time estimation. If a step in the process takes longer than initially anticipated, the wait-time/progress indicator 88 may be increased to compensate for the delay or paused to indicate that the process is not progressing as anticipated. Exemplary variable processes may include the sensor location detection 108 and the pulsation detection 110. Because the sensor location detection 108 depends greatly on the quality of the sensor signal, the time it takes for the monitor 14 to determine the location of the sensor 12 may vary greatly. For example, if the sensor 12 is designed for application to a finger but is erroneously applied to a forehead, the monitor 14 may take longer to determine that the sensor 12 is misapplied than it would take if the sensor 12 had been correctly applied to the finger. In instances such as this, the wait-time/progress indication 88 may pause (i.e., stop showing progress) or increase (e.g., count up or begin refilling the clear area 98 (
Because the patient's physical characteristics may be based generally on detected pulsations, the pulsations may need to be detected before the characteristics may be displayed. Accordingly, the estimated duration of the pulsation detection process 110 may also be included in the wait-time calculation. As with the sensor location detection 108, the duration of pulsation detection 110 may vary greatly depending on the signal quality from the sensor 12, correct placement of the sensor 12, and other factors. A minimum time estimate may be included in the initial wait-time calculation, and if the pulsation detection process 110 takes longer than the minimum estimated duration, the wait-time calculation may be modified (e.g., the wait-time/progress indication 88 may indicate an increased wait-time or lack of progress). In addition, if unexpected events occur which impede the determination of the patient's physical characteristics, the wait-time/progress indication 88 may again indicate an increased wait-time or lack of progress, or an error signal (e.g., a graphic, a text warning, an audible alarm, and so forth) may be provided.
While only certain features have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within their true spirit.