WO2013095481A1

WO2013095481A1 - Dynamic light filtering device and method for enhanced patient parameter monitoring

Info

Publication number: WO2013095481A1
Application number: PCT/US2011/066711
Authority: WO
Inventors: Kokovidis GEORGIOS
Original assignee: Draeger Medical System, Inc.
Priority date: 2011-12-22
Filing date: 2011-12-22
Publication date: 2013-06-27

Abstract

An apparatus and method for measuring at least one patient parameter is provided. A connector connects the apparatus to the patient. The connector includes a light emitting device and a sensor that senses light emitted by the light emitting device for use in calculating the at least one patient parameters. A dynamic light filtering device filters light emitted from the light emitting device to be sensed by the sensor. A controller is coupled to the dynamic light filtering device and selectively controls the dynamic light filtering device to dynamically steer a particular type of light emitted by the light emitting device in a direction towards the sensor and other types of light away from the sensor, the sensor sensing of the particular type of light used in determining the at least one patient parameters.

Description

Dynamic Light Filtering Device and Method for Enhanced

Patient Parameter Monitoring

Field of the Invention

This invention concerns a system and method for patient monitoring devices and, more specifically, in dynamically selecting a type of data for use in determining and monitoring at least one patient parameter.

Background of the Invention

In the course of providing healthcare to patients, it is necessary to monitor vital statistics and other patient parameters. A plurality of different patient monitoring devices are able to selectively detect an amount of light emitted from a light emitter that pass through a patient's body in order to derive data used in determining a patient parameter. An exemplary patient parameter that may be determined in this manner is a blood oxygen saturation level of a patient. Blood oxygen saturation level may be determined using a technique known as transmission spectrophotometry, which is more widely known as pulse oximetry (Sp02). Conventionally, pulse oximetry measures an amount of light passing through a finger of a patient using a sensor positioned on the finger. A drawback associated with this configuration is the existence of ambient or other undesirable light (noise) that reduces the accuracy and effectiveness of the detector resulting in a less precise patient parameter measurement.

A digital light processing (DLP) chip may selectively control a Digital Micromirror Device (DMD) for use in spatially modulating light. A DMD includes a plurality of micromirrors that are arranged in an array and controlled via a microelectromechanical system. The DLP chip is able to selectively control the microelectromechanical system to position the mirrors in a desired manner to achieve a particular objective. Exemplary DLP and DMD devices are sold by TEXAS INSTRUMENTS as chipsets known as 0.17 HVGA chipset and/or 0.55 XGA chipset.

It is desirable to spatially modulate light close to a photodetector used to sense the light applied. This will filter light and improve the signal being detected to determine the monitored patient parameter. A system according to invention principles addresses deficiencies of known systems. Summary of the Invention

In one embodiment, an apparatus for measuring at least one patient parameter is provided. A connector connects the apparatus to the patient. The connector includes a light emitting device and a sensor that senses light emitted by the light emitting device for use in calculating the at least one patient parameters. A dynamic light filtering device filters light emitted from the light emitting device to be sensed by the sensor. A controller is coupled to the dynamic light filtering device and selectively controls the dynamic light filtering device to dynamically steer a particular type of light emitted by the light emitting device in a direction towards the sensor and other types of light away from the sensor, the sensor sensing of the particular type of light used in determining the at least one patient parameters.

In another embodiment a method for monitoring at least one patient parameter is provided. The method includes the activities of configuring a dynamic light filtering device to steer at least one type of light towards a sensor and emitting light from a light source through a patient. The emitted light is dynamically filtered towards the sensor. The sensor senses the dynamically filtered light and determines data representing the at least one patient parameter based on the dynamically filtered light data.

Brief Description of the Drawings

Figure 1 is an exemplary block diagram of the patient monitoring apparatus including the dynamic light filter according to invention principles;

Figure 2 depicts an exemplary block diagram of a component of the dynamic light filter according to invention principles;

Figure 3 is a block diagram of a control signal generated by the patient monitoring apparatus for controlling the dynamic light filter according to invention principles;

Figure 4 is an illustrative block diagram detailing the operation of the dynamic light filter according to invention principles; and

Figure 5 is a flow diagram detailing an exemplary operation of the patient monitoring apparatus including the dynamic light filter according to invention principles. Detailed Description

A patient monitoring device including a dynamic light filtering apparatus employs a digital micromirror device (DMD) under the control of a digital light processor (DLP) that automatically and dynamically filters predetermined types of light from a light sample. The DMD includes an array of mirrored pixels that are selectively controllable to reflect and steer certain types of light in a particular direction. The dynamic light filtering apparatus is advantageously positioned in series between an object that allows for a light sample to pass at least partially therethrough and a photodetector able to detect at least one type of light from the light sample. The dynamic light filtering apparatus may be controlled by a microcontroller or other processor of the patient monitoring device to identify at least one type of light being measured by a detector (herein after "measured light") and at least one type of light not being measured by the detector (hereinafter "non- measured light"). The patient monitoring device determines the type of measured light based on the type of patient parameter to be monitored thereby. The controller of the patient monitoring device controls the plurality of mirrors comprising the DMD to at least one of reflect and absorb wavelengths of light corresponding to the measured light and non-measured light. By reflecting wavelengths of measured light, the dynamic light filter apparatus advantageously concentrates the reflected wavelengths to provide an enhanced light signal having higher amplitudes for detection by the detector. This allows the detector to use the enhanced set of light data to calculate or otherwise determine the at least one patient parameter being monitored.

In an exemplary embodiment, the apparatus including the dynamic light filtering apparatus includes a DMD which is a core of the DLP processing chip. The DLP with the DMD may be a reflective microelectromechanical device that enables selective control of each of the plurality of mirrors (e.g. pixels) that form the DMD. In this embodiment, the patient monitoring apparatus may be a pulse oximetry monitoring apparatus that selectively determines and monitors data representing the Sp02 level of a patient. Conventional pulse oximetry devices include a device that is selectively positioned on patient' s body part having blood vessels therein (e.g. finger). The apparatus includes a light source emitting successive pulses of light having different wavelengths and a photodetector that detects both wavelengths of light. The pulses of light pass through the patient's body part may be at least partially absorbed by elements in the blood stream (e.g. oxygenated or deoxygenated hemoglobin). The amount of each wavelength that passes through the body is detected by the photodetector and used to determine data representing blood oxygen saturation of the patient in a known manner. The present embodiment advantageously includes the dynamic light filter positioned between the body part of the patient and the photodetector to filter wavelengths of light that are of interest. The dynamic light filter may be under control by a microcontroller or other processor that is able to selectively control the pixel densities (e.g. the number of mirrored pixels in the array) of the DMD to vary the wavelengths of light (e.g. red or IR) that may be reflected and thus detected by the photodetector. The controller may selectively modify the pixel densities with each successive pulse of light so that the type of light being reflected corresponds to the type of light being emitted. By automatically reflecting only a particular type of light, the dynamic light filter provides an enhanced set of light data able to be detected by the photodetector for use in determining the blood oxygen saturation data for the patient.

In another embodiment, the patient monitoring apparatus may include a device for separating light into its component wavelengths such as a prism or diffraction grading. In this embodiment, the light separation device is positioned between the patient's body part and the dynamic light filter and advantageously separates the ambient light into its component wavelengths prior to reflection by the pixels of the DMD. Once the light is separated, the controller may selectively control pixels or columns of pixels to reflect or absorb lights of different wavelengths thereby actively filtering out all ambient light and reducing the noise in the light signal being measured by the photodetector. The result is a higher quality set of light data being measured by the photodetector resulting in a more accurate determination of blood oxygen saturation level.

While the embodiment described above refers to the patient monitoring apparatus including the dynamic light filter being a pulse oximetry device, one skilled in the art will understand that any patient monitoring apparatus that utilizes pulsed light detection of at least one wavelength to derive a patient parameter may be used. For example, the patient monitoring apparatus may also include a continuous non-invasive blood pressure (CNAP) monitor that utilizes a single type of light of a particular wavelength (red) to determine data representing intraarterial pressure of the patient.

Figure 1 is an exemplary block diagram of a patient parameter monitoring device including the dynamic light filter 100. The device 100 includes a patient monitor 102 including a dynamic light filter 101 (shown within dashed lines) that selectively determines and monitors at least one type of patient parameter and a patient connector 104 coupled to the patient monitor 102 for sensing data used in deriving the at least one type of patient parameter. The patient connector 104 may include a housing that is selectively positionable on a part of a patient' s body such that the components therein (as described below) are positioned to sense information that may be used to determine the at least one type of patient parameter. In this embodiment, the patient monitor 102 is a pulse oximetry monitor and the patient connector 104 is a sensor housing (e.g. finger sensor) that is removably connected to a finger of the patient in order to determine data representing blood oxygen saturation associated with the patient. In another embodiment, the monitor may be a continuous non-invasive blood pressure monitor that measures the intra- arterial blood pressure of the patient and the patient connector 104 may also be a sensor housing.

The patient connector 104 may include components for generating and sensing a signal (e.g. particular wavelengths of light) used in determining the at least one type of patient parameter. In the embodiment, shown herein the patient monitor 102 is able to selectively determine the at least one type of patient parameter based on an amount of light that passes through an object 103, such as a finger of the patient. Thus, the patient connector 104 includes a light source 106 that selectively emits at least two types of light 107. In one embodiment, the first type of light may be light within a first range of wavelengths and the second type of light may include light of a different range of wavelength. For example, the light source 106 may be a light emitting diode (LED) light source that emits the first type of light in the red wavelength (~700nm - 635nm) range and the second type of light in infrared wavelengths (>1000nm). While two types of lights in two different wavelengths are discussed herein, one skilled in the art will understand that the LED may be able to emit any number of different types of light in different wavelengths. Additionally, the light source 106 may be able to selectively emit different types of light simultaneously. The patient connector 104 further includes a light separation device (e.g. diffraction grading) 108. The light separation device 108 selectively separates light into its component wavelengths. The light separation device 108 is positioned on a side of the object 103 opposite the light source 106 and selectively receives at least one of light 107 emitted by the light source 106 and ambient light 109. The light separation device 108 selectively separates the ambient light into a plurality of types of light having different wavelengths. Light 107 from the light source 106 is emitted in a predetermined wavelength and thus the light separation device 108 does not further break up the photon(s) of light 107. However, the ambient light 109 is generally white light and composed of a plurality of different photons of different wavelengths. The light separation device 108 separates ambient light 109 into a plurality of photons having different wavelengths and represented in Figure 1 by the different types of dashed lines emanating from the light separation device 108.

A digital micromirror device (DMD) 110 is part of the dynamic light filter 101 and is positioned adjacent to and downstream (with respect to the direction of light being emitted from light source 106) from the light separation device 108. The DMD 110 includes a plurality of micromirrors known as pixels that can be selectively controlled to operate in a desired manner to achieve a desired objective. The terms mirror and pixel may be used interchangeably throughout the detailed description. The individual pixels of the DMD 110 are selectively controllable using a microelectromechanical (MEMS) architecture that is responsive to a control signal 118 as will be discussed below. The control signal 118 may include instructions causing the MEMS to enable the state of each pixel (or groups of pixels) to be toggled between a first "ON" state where the pixel is reflective and a second "OFF" state whereby the pixel is non-reflective. Additionally, the control signal 118 may include instructions directing the MEMS to selectively control a position of the pixel (or groups of pixels) and determine an angle at which the pixel (or groups of pixels) sits in order to steer light 107 in a desired direction.

A sensor 112 (e.g. photodetector) is positioned adjacent to and downstream from the DMD 110 and selectively detects an amount of light 107 being steered by the DMD 110. The sensor 112 is further coupled to the patient monitor 102 as will be discussed below in order to provide data corresponding to the at least two types of light 107 sensed by the sensor 112 and used to determine the at least one type of patient parameter. By selectively controlling the state and position of the various pixels of the DMD 110, the sensor 112 is able to receive a higher quality signal comprising the first or second type of light 107 that is used by the patient monitor 102 to determine the at least one patient parameter. Additionally, a pixel (or groups of pixels) of the DMD 110 may be selectively controlled to be "OFF" for types of light other than the first or second type of light thereby filtering out undesirable types of light that are not being measured. This advantageously reduces noise in the signal including the first or second type of light that is being measured by the sensor 112.

The patient monitor 102 selectively controls the components of the patient connector 104 to generate and sense light signal data for use in determining at least one type of patient parameter. The patient monitor 102 includes a system controller 114 that executes a monitoring control algorithm to control the light source 106 to emit the first and second types of light 107 in a predetermined pattern which pass through the object 103. The light 107 passing through the object is processed by the light separation device 108 and the DMD 110 and detected by the sensor 112. In an embodiment where the patient monitor 102 is a pulse oximetry monitor, the monitoring control algorithm employs pulse oximetry techniques that are known in the art in order to derive the blood oxygen saturation level of the patient by sequentially passing light at the first wavelength and light at the second wavelength through the part of the body 103 to which the patient connector 104 is connected. By sequentially passing two different wavelengths of light through the body, the sensor is able to determine the ratio of changing absorbance of the two different wavelengths of light caused by the difference in color of oxygenated versus deoxygenated hemoglobin in the blood.

The patient monitor 102 also includes a mirror controller 116 that is coupled to the system controller 114. The mirror controller 116 is part of the dynamic light filter 101 and generates the control signal 118 that includes configuration data which is a set of instructions for controlling the DMD 110 in the patient connector 104 to steer the first and second types of light 107 towards the sensor 112 to improve the quality of the signal being sensed by the sensor 112. The system controller 114 provides light characterization data identifying the first and second types of light (including the wavelengths) that are to be measured by the sensor 112 as well as data representing other types of light that are not being measured by the sensor 112 so as to exclude the other non-measured types of light. In response to the light characterization data, the mirror controller 116 automatically generates the control signal 118 including instructions for controlling the operation of the pixels of the DMD 110. The control signal may include at least one of (a) information controlling an ON/OFF state of a particular pixel; (b) information controlling an ON/OFF state of a particular group of pixels; (c) information controlling at least one of a position and angle of a particular pixel; and (d) information controlling at least one of a position and angle of a particular group of pixels. The control signal may also include duration information identifying the duration during which the particular pixel or group of pixels is to operate in a particular manner. For example, the control signal may cause a group of pixels corresponding to the first type of light in the first wavelength (e.g. red wavelength) to be in a position to reflect the first type of light in a direction towards the sensor 112. The control signal may also simultaneously direct other pixels corresponding to any type of light other than the first type of light to be in a non-reflective state thereby minimizing any interference the other types of lights at other wavelengths may cause the first type of light. The mirror controller 116 may dynamically and automatically generate new control signals 118 depending on certain system conditions thereby enabling the DMD 110 to operate as a dynamic optical filter. This dynamic optical filtering advantageously provides greater flexibility in determining which signals may be used to monitor the at least one patient parameter. The dynamic optical filtering may also allow for multiple different types of light associated with different types of patient parameters to be sensed by sensor 112. The control signal 118 and the manner in which the pixels of the DMD are controlled will be discussed hereinafter with respect to Figures 2 and 3.

A parameter processor 120 is coupled between the system controller 114 and the sensor 112 and selectively receives data representing an amount of a particular type of light sensed by the sensor 112 at a given time. The parameter processor 112 may employ known algorithms using the type and amount of light sensed by the sensor 112 as inputs to a parameter determination algorithm in order to determine patient parameter data. The parameter processor 120 may also selectively determine that patient parameter data has fallen outside an accepted range of data values. Patient parameter data falling outside an acceptable range may indicate (a) components of the patient connector 104 have been displaced from an optimal position or (b) a change in patient condition that may require attention from a healthcare provider. The parameter processor 120 may signal the system controller 114 that the patient parameter data is outside an acceptable range resulting in the system controller 114 signaling the mirror controller 116 to generate a new control signal 118 including configuration data selectively modifying at least one of the state or position of a pixel or group of pixels of the DMD 110. Once the state and/or position of the pixels has been modified, the sensor can sense an updated set of light data which is provided to the parameter processor 120. Upon receiving the updated set of light data, the parameter processor 120 can determine the patient parameter data and compare it with patient parameter data that was originally outside the accepted range of values to determine if the repositioning of the DMD 110 has brought the patient parameter back within the accepted range. If not, the data processor 120 may determine that the change is associated with a patient condition and signals a healthcare professional to attend to the patient.

A memory 115 may be connected to the system controller 114 and the parameter processor 120. The memory 115 includes a data storage medium able to store at least one of analog or digital data therein. The parameter processor 120 selectively causes patient parameter data received from the sensor 112 to be stored in the memory 115 at predetermined time intervals for predetermined durations. The system controller 114 or the parameter processor 120 may selectively query data stored in memory 115 at predetermined intervals in order to determine if one of the respective parameter monitoring algorithm employed by the system controller 114 or the mirror control algorithm employed by the mirror controller 116 should be modified in any manner as will be discussed below.

A communication processor 122 may also be selectively coupled to each of the parameter processor 120, the system controller 114 and the memory 115. The system controller 114 or parameter processor 120 may generate communication control signals that control the communication processor 122 to selectively communicate data to at least one of a display unit 124, an alarm unit 126 and to a remote computing system 130 via a communications network 128. The data communicated by the communication processor 122 may include any data sensed or derived by the parameter processor 120. The communication processor 122 may also be caused to communicate mirror configuration data including data identifying the state and position of the pixels of the DMD 110. In one embodiment, parameter data and mirror configuration data may be selectively communicated at least one of (a) simultaneously; (b) sequentially; (c) in response to the parameter processor 120 determining that a type of data has reached, exceeded, or fallen below a threshold value; and (d) in response to receipt of an external request (user generated or automatically generated by a computing system) requesting a particular type of data be transmitted. In another embodiment, the parameter processor 120 may generate a communication control signal causing the communication processor 122 to query and communicate data stored in memory 115. In this embodiment, the communication processor 122 may cause a set of data sensed by the sensor 112 and that is stored in memory 115 to be selectively communicated via network 128 to a remote computing system 130 (e.g. hospital information system) to automatically update a patient record with patient parameter data at a particular time interval. The communication processor 122 may also be able to selectively receive control requests from remote computing systems 130 (or users thereof) that selectively modify the operation of the apparatus. In a further embodiment, the patient parameter processor 120 may automatically and in real-time compare patient parameter data to threshold parameter values and, if the sensed patient parameter data at least one of (a) equals a threshold; (b) exceeds a threshold; and (c) falls below a threshold. The patient parameter processor 120 may selectively control the communication processor 122 to signal at least one of the display unit 124 or alarm unit 126 to notify a healthcare professional that the patient may be in trouble and require assistance.

While the embodiment shown in Figure 1 includes certain components of the dynamic light filter 101 being distributed partially in the patient monitor 102 and the patient connector 104, one skilled in the art would appreciate that this is described for purposes of example only and in order to improve the understanding of how the respective apparatus functions and operates. Thus, one skilled in the art can appreciate that an in a further embodiment, the mirror controller 116 may be formed integral with the DMD 110 in the patient connector 104. Alternatively, it should be appreciated that the system controller 114 may perform any and all of the same functions described above and associated with the mirror controller 116.

The patient monitoring apparatus 100 may employ known patient monitoring algorithms such as pulse oximetry algorithms and/or CNAP algorithms to derive and calculate patient parameter data in a known manner. However, the apparatus 100 includes the dynamic light filtering device 101 prior to sensing a signal from which the patient parameter data may be determined. The positioning and control of the dynamic light filtering device advantageously reduces noise and/or interference from the signal being sensed by the sensor 112 by separating light into its component wavelengths and automatically filtering out wavelengths of light not used to determine the patient parameter while simultaneously concentrating and reflecting the light having the wavelength used to determine the patient parameter. Thus, the dynamic light filter 101 is a modifiable optical filter enabling the sensor 112 to sense a filtered signal which is provided to a parameter processor 120 to determine the particular patient parameter. Additionally, the selective control of the position and state of the DMD advantageously enables the device to change position and state as needed to ensure the multiple types of light of different wavelengths can be concentrated and reflected towards the sensor at least one of simultaneously and sequentially as required by the patient parameter determination algorithm. For example, in the embodiment where the apparatus 100 is a pulse oximetry monitor, the light source emits sequential pulses of light having different wavelengths. The DMD 110 may be selectively controlled to sequentially (a) turn on the pixels able to reflect light having the first wavelength and position the pixels at an angle to steer the reflected light towards the sensor 112 and turn off all other pixels and (b) turn on the pixels able to reflect light having the second wavelength and position the pixels at an angle to steer the reflected light towards the sensor 112 and turn off all other pixels. This manner of operation is described for purposes of example only and the pixels of the DMD 110 may be controlled in any manner to dynamically filter light of different wavelengths in a particular manner.

Figure 2 is an illustrative block diagram of the DMD 110 shown in Figure 1. The DMD 110 includes an array 201 of a plurality mirrored pixels M0, Ml, M2...Mn (where n is an integer greater than 0) that are selectively controllable to reflect particular wavelengths of light. The DMD 110 including an array of four (4) mirrored pixels as shown herein is for purposes of example only and it is known that the DMD 110 may be formed from an array 201 of any number of mirrored pixels which may number in the many millions of mirrored pixels, each selectively controllable by the mirror controller 116. In a default position, the plurality of mirrored pixels form a substantially planar array. However, in operation each edge of each mirrored pixel may be selectively pivotable in relation to an adjacent edge thereof. For example, each edge of each mirrored pixel may pivot plus or minus twelve degrees with respect to the substantially planar arrangement and in relation to an adjacent edge of another mirrored pixel.

Each of pixels MO, Ml, M2...Mn has a respective address 202a...202n associated therewith. Each pixel in the array 201 includes a unique address enabling identification thereof. The address 202a...202n advantageously enables the mirror controller 116 (or system controller 114) to determine a respective position of a pixel in relation to all other pixels in the array. The address 202a...202n also enables the controller 116 to control at least one of (a) the state of the pixel; (b) a position of the respective pixel; (c) a duration that a respective pixel is in a particular state (ON or OFF); and (d) a duration that a respective pixel is in a particular position or orientation. In one embodiment, the addressing scheme for the pixels of the DMD 110 is similar to an address scheme used to allocate memory in a computing device. Information identifying a state of the pixel may include a pixel as being in a reflective state (ON) or a non-reflective state (OFF). Pixel position information may include information setting an angle at which the mirror is positioned to reflect light as well as information setting an orientation of a pixel with respect to other surrounding pixels.

A microelectromechanical (MEM) device 204 may be selectively connected to respective pixels M0...Mn and selectively controls the state and position of respective pixels M0...Mn in the array 201. The MEM device 204 is a known component of the DMD 110 to selectively change the reflectiveness of respective pixels M0...Mn and selectively change the angle, position and orientation of respective pixels M0...Mn in order to reflect the desired type of light in a desired manner. The MEM device 204 is responsive to the control signal 118 generated by the mirror controller 116 as shown in Figure 1. The format and information of the control signal will be discussed below with respect to Figure 3. Figure 3 shows an exemplary pixel control signal 118 generated by the mirror controller 116 of Figure 1. The pixel control signal 118 may include a plurality fields associated with respective types of control information used to control at least one of the state and position of a respective pixel in the array of pixels. The control signal 118 may include a mirror address data field 302 that includes address data identifying a pixel of the pixel array to be controlled. A pixel state data field 304 may include data identifying whether the pixel at the address in address field 302 should be in the "ON" reflective state or the "OFF" non-reflective state. The control signal may also include a pixel position data field 306 including data identifying a position of the pixel at the address in the address field 302. Data identifying a position of the pixel may include at least one of (a) angle information identifying an angle at which the pixel is to be positioned; (b) orientation information including an orientation of the pixel relative to other pixels in the array; and (c) an edge or edges of the pixel being positioned at an angle. The control signal 118 may also include a duration data field 308 including information identifying a duration for which the addressed pixel is to be in the identified state as per the information in field 304 and identified position as per the information in field 306. Additionally, duration data field 308 may include a first set of duration information identifying and controlling the duration for the state of the addressed pixel and a second set of duration information identifying and controlling the duration for the position of the addressed pixel. While the control signal 118 and respective data fields are described as controlling a single pixel within the pixel array 201, it should be appreciated that each field may include a set of data that corresponds to a group of pixels wherein each pixel of the group has a respective pixel address (e.g. columns of pixels) and information identifying the state and positions for at least one of (a) each individual pixel in the group of pixels; (b) the group of pixels in its entirety and (c) a combination thereof.

The format of the control signal 118 is described for purposes of example only and the use of individual data fields containing corresponding data values is similarly used for purposes of example only and to explain the types of information that may be included within the control signal 118. The control signal 118 may include any number of fields or none at all so long as data values corresponding to the above-described information is encompassed therein. The format of the control signal 118 is merely exemplary and the manner in which the types of information contained therein are encoded and/or transmitted may vary. One skilled in the art of DMD control may be able to readily configure a controller or processor to generate a control signal 118 in a different format but including similar information.

Exemplary operation of the DMD 110 shown in Figures 2 and 3 will now be discussed. The control signal 118 may selectively control the state and operation of certain or all of the pixels M0...Mn in the array 201 in Figure 2. In this example, the mirror controller 116 controls pixels MO to be in an "ON" reflective state and having a top edge 205 positioned at a negative 10 degree angle for a period of 20 microseconds. This result is accomplished by the controller 116 generating a control signal 118 that includes address data 202a associated with pixel M0 being included in data field 302. Data indicating that M0 is to be in the reflective ON state is included in pixel state data field 304. The angular position of edge 205 of M0 being negative ten degrees is included in position data field 306 and the duration data of 20 microseconds is included in duration data field 308. Upon receipt of this exemplary control signal 118, the MEM device 204 parses the control signal and determines that control is being exerted over pixel M0 in view of address data field including address data 202a. The MEM device 204 generates an electrical signal to change the state of pixel M0 at address 202a from OFF to ON thereby resulting in pixel M0 being reflective. The MEM device 204 also mechanically modifies the position of M0 to tilt the edge 205 a negative ten degrees. The MEM device 204 further parses the control signal 118 to identify the duration in the duration data field 308 and initiates countdown of the indicated duration by a timer. At the expiration of the timer, the MEM device 204 automatically resets pixel M0 to a default state. Alternatively, at the expiration of the timer, the MEM device 204 may determine if any further control signals 118 have been received and modify the pixels in the array accordingly.

The operation and control of a single pixel is describe for purposes of example only and for ease of understanding. Thus, as the array of pixels generally include many thousands or millions of pixels, it should be understood that the control signal and fields described therein may be used to control multiple pixels and/or groups of pixels in a similar manner and that the MEM device 204 may be able to process and control each pixel in the array in the desired manner. Figure 4 illustrates an exemplary operation of the dynamic light filter 101 including the light separation device 108, the DMD 110 and the sensor 112. In this embodiment, the DMD 110 includes an array 201 of mirrored pixels that are selectively controllable to (a) reflect at least one particular type of light and (b) absorb other types of light different from the at least one particular type of light. The mirrored pixels that form the array 201 may be controlled by the mirror controller 116 (Fig. 1) to form a plurality of groups of mirrored pixels 402 - 416. In one embodiment, each respective group of the plurality of groups 402 - 416 may be formed as columns wherein the pixel columns are defined by their locations within the "rainbow" of separated light that is created by the light separation device 108 as it falls upon the DMD 110. The groups of mirrored pixels 402 - 416 are shown as columns and, although, for simplicity, the individual pixels of which each group 402 - 416 are comprised are not shown in the figure, each group 402 - 416 is formed from a plurality of mirrored pixels.

In this embodiment, each column is able to at least one of reflect or absorb a particular range of wavelengths of light. In one embodiment, the groups of mirrored pixels 402-416 may reflect the component wavelengths that comprise visible light as well as infrared light. This association is shown below in Table 1.

Table 1

In exemplary operation, the light source 106 may emit at least one of the first and second type of light 107a and 107b. In the embodiment shown herein, the first type of light 107a is infrared light and the second type of light 107b is red light. The at least one of the first or second light 107a,b is passed through an object 103 as shown in Figure 1 and is at least partially absorbed by the object. The remaining light that passes through the object passes further through the light separation device 108. Ambient light 109 is combined with the at least one of the first and second types of light 107a,b and the light separation device 108 automatically separates the ambient light 109 from the at least one of the first and second types of light 107a,b. The light separation device 108 further automatically separates the ambient light 109 into individual component wavelengths 109 a - 109g along the visible light spectrum. Table 2 shows the correlation between the wavelengths and the component of visible light that is represented thereby.

Thus, upon being separated by the light separation device, each respective wavelength of light is directed towards the group of mirrored pixels able to reflect or absorb that particular type of light.

During exemplary operation wherein the apparatus is a pulse oximeter that determines blood saturation data for a patient, the light source emits sequential pulses of the first type light 107a and the second type of light 107b. The array 201 of the DMD 110 may be selectively controlled by the mirror controller to configure the first group 402 to be reflective upon emission of a pulse of the first type of light 107 (IR) and also to position the first group of mirrored pixels to steer the first type of light 107a towards the sensor 112 for use in determining at least one patient parameter. Additionally, the mirror controller 116 further configures the mirrored pixels in each of groups 404 - 416 to be non-reflective thereby filtering out types of light other than the first type of light 107a and focusing the first type of light 107 a towards the detector. During emission of a pulse of the second type of light 107b from the light source, the array 201 of the DMD 110 may be selectively controlled by the mirror controller 116 to configure the second group 404 to be reflective and also to position the second group of mirrored pixels 404 to steer the second type of light 107b towards the sensor 112 for use in determining at least one patient parameter. Additionally, the mirror controller 116 further configures the mirrored pixels in each of groups 402 and 406 - 416 to be non-reflective thereby filtering out types of light other than the second type of light 107b and focusing the second type of light 107b towards the detector. The result of this dynamic filtering produces an enhanced signal with reduced noise that may be sensed by the sensor 112 and used in determining blood saturation data for the patient.

The dynamic filtering described herein is described for purposes of example only and the mirror controller 116 may selectively generate a control signal 118 including configuration data that separates the plurality of mirrored pixels of the DMD into any number of groups of mirrored pixels. Any of these groups of mirrored pixels may be selectively configured to be reflect and steer any type of light or a plurality of types of light at a given time depending on the type of light emitted by the light emitted device 106 to be sensed by sensor 112.

An exemplary operation of the patient monitoring apparatus including the dynamic light filter will now be described with respect to the flow diagram in Figure 5 with reference numerals referring back to Figures 1 - 4. The flow diagram of Figure 4 describes the operation of the apparatus as a pulse oximetry monitor that selectively determines and monitors blood oxygen saturation data of a patient (Sp02 data). At step 502, the patient connector 104 such as a sensor housing is connected to a finger 103 of a patient. The cuff 104 is positioned so that the finger 103 is positioned between the light source 106 and a light separation device 108. At step 504 the system controller 114 identifies the type of light being sensed by the sensor 112 in the sensor housing and determines which pixels in the pixel array 201 are required to enhance the light sample sensed by the sensor 112 for use in determining Sp02 data. In step 506, the mirror controller generates a control signal 118 including at least one of (a) pixel address data identifying at least one pixel in the array of pixels to be controlled; (b) pixel state data identifying an operational state of the at least one pixel; (c) position data identifying a position of the at least one pixel of the pixel array; and (d) duration data identifying a duration that the at least one pixel is to be in the identified state and/or position. In one embodiment, generation of the control signal 118 by the mirror controller 116 includes (a) selecting a group of pixels (e.g. a column) that are able to reflect a particular type of light at a particular wavelength and setting each pixel in the group of pixels to be in a reflective state ("ON") and positioned at an orientation and angle that directly reflects the particular type of light at the sensor 112; and (b) selecting a group of pixels (e.g. column(s)) that reflect light at wavelengths other that the particular wavelength to be non-reflective thereby filtering out light having other wavelengths from being directed at the sensor 112. In another embodiment, the control signal may include two sets of control instructions that correspond to different types of light being sensed such that, a first set of pixels is controlled to reflect a first type of light for a first duration and a second set of pixels is controlled to reflect a second type of light for a second duration that occurs at the expiration of the first duration.

The system controller 114 executes the Sp02 monitoring algorithm which requires the successive emission of two different types of light having different wavelengths. Thus, the control signal 118 generated in step 506 includes pixel configuration data to configure respective pixels of the pixel array in an optimal position to reflect the particular type of light being emitted by the light source 106. In step 508, light 107 is emitted by light source 106 and passes through the finger 103. The light 107 may be the first type of light having a first wavelength (e.g., Red) or a second type of light having a second different wavelength (e.g., infra-red - IR). As light passes through the finger 103, it is partially absorbed by the oxygenated and deoxygenated hemoglobin in the blood vessels at that given time. The light 107 combines with ambient light 109 to pass through a light separation device 108 in step 510 which separates the light 107 and 109 into its component wavelengths and is provided to the DMD 110 in step 512.

A determination is made in step 514 as to whether light 107 is of the first type or the second type of light. If the light 107 is the first type of light, the MEMS employs the first set of pixel configuration data to (a) configure respective pixels in the pixel array to reflect the first type of light and position respective pixels to steer the reflected first type of light towards the detector 112; and (b) configure respective pixels of the pixel array to reflect all other types of light to be non-reflective as shown in step 515. If the light 107 is the second type of light, the MEMS employs the second set of pixel configuration data to (a) configure respective pixels in the pixel array that reflect the second type of light and position respective pixels to steer the reflected second type of light towards the detector 112; and (b) configure respective pixels of the pixel array that reflect all other types of light to be non-reflective as shown in step 516.

The light 107 that is reflected by the DMD is detected in step 518 and provided to the parameter processor 120 for use in determining Sp02 data associated with the patient in step 520. By automatically configuring the pixels in the DMD 110 to reflect only the types of light that is used in determining Sp02 data at a given time, the dynamic light filter 101 is able to enhance the quality of the signal being sensed by sensor 112 and used by the parameter processor 120 to determine the Sp02 data values.

The apparatus described above with respect to Figures 1 - 5 advantageously digitally controls the pixel densities in an array of mirrored pixels to vary the wavelengths of light that can be selected and steered towards a detector and used in determining patient parameter data for a particular patient. By applying the automatic and dynamic wavelength selection in conjunction with existing patient parameter determination algorithms such as Sp02 data and CNAP data, an enhanced signal having less noise may be detected for use in determining the patient parameter.

Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention. This disclosure is intended to cover any adaptations or variations of the embodiments discussed herein.

Claims

1. An apparatus for measuring at least one patient parameter comprising:

a connector connecting the apparatus to the patient, the connector including

a light emitting device; and

a sensor that senses light emitted by the light emitting device for use in calculating the at least one patient parameters;

a dynamic light filtering device for filtering light from the light emitting device to be sensed by the sensor

a controller coupled to the dynamic light filtering device that selectively controls the dynamic light filtering device to dynamically steer a particular type of light emitted by the light emitting device in a direction towards the sensor and other types of light away from the sensor, the sensor sensing of the particular type of light used in determining the at least one patient parameters.

2. The apparatus as recited in claim 1 , wherein

said light emitting device emits a first type of light having a first wavelength and a second type of light having a second different wavelength.

3. The apparatus of claim 2, wherein

said light emitting device emits sequential pulses of light having different wavelengths, the first pulse being light emitted at the first wavelength and the second, sequential pulse being light emitted at the second different wavelength.

4. The apparatus of claim 3, wherein

In response to emission of the first pulse of light by the light emitting device, said controller selectively controls the dynamic light filtering device to steer the first type of light towards the sensor; and

In response to emission of the second pulse of light by the light emitting device, said controller selectively controls the dynamic light filtering device to steer the second type of light towards the sensor.

5. The apparatus of claim 2, wherein

the first type of light is red light and the second type of light is infrared light.

6. The apparatus of claim 1, further comprising

a light separating device positioned between the light emitting device and the dynamic light filtering device, the light separating device selectively separates ambient light that combines with the particular type of light into a plurality of component wavelengths, wherein each wavelength represents a band of light in the light spectrum.

7. The apparatus of claim 1, wherein

said controller selectively controls the dynamic light filtering device to filter out wavelengths of light other than the particular wavelength.

8. The apparatus of claim 1, wherein

said dynamic light filtering device includes a plurality of mirrored pixels arranged in an array, wherein at least one of a position and a reflectivity of respective ones of said plurality of mirrors are selectively controllable by the controller.

9. The apparatus of claim 8, wherein

said controller selectively controls a first group of mirrored pixels associated with the particular wavelength of light in a reflective state and controls a second group comprising others of said plurality of mirrored pixels associated with wavelengths of light other than the particular wavelength to be in a non- reflective state.

10. The apparatus of claim 8, wherein

said controller generates configuration data used for controlling a reflectivity and position of respective ones of said plurality of mirrored pixels.

11. The apparatus of claim 10, wherein

each mirrored pixel of the plurality of mirrored pixels includes a unique address associated therewith, the controller able to selectively control each pixel using said unique address.

12. The apparatus of claim 11, wherein

the unique address associated with a respective pixel of the plurality of pixels enables control of at least one of (a) a reflectivity state of the respective pixel and (b) a position of the respective pixel.

13. The apparatus of claim 12, wherein

the position of the respective pixel includes at least one of (a) an orientation of the respective pixel relative to others of the plurality of mirrored pixels; (b) an angular position of the respective mirrored pixel; and (c) an orientation of a particular edge of the respective mirrored pixel.

14. The apparatus of claim 1, wherein

said controller controls the dynamic light filtering device to dynamically steer light towards the sensor for a predetermined duration of time.

15. The apparatus of claim 10, wherein

configuration data includes duration information

identifying a duration of time associated with reflectivity and position of respective ones of the plurality of mirrored pixels.

16. A method for monitoring at least one patient parameter comprising the activities of:

configuring a dynamic light filtering device to steer at least one type of light towards a sensor;

emitting light from a light source through a patient; dynamically filtering the emitted light towards the sensor;

sensing the dynamically filtered light by the sensor; and determining data representing the at least one patient parameter based on the dynamically filtered light data.

17. The method of claim 16, wherein said activity of configuring a dynamic light filtering device includes:

determining at least one of the reflectivity and position of the dynamic light filtering device.

18. The method of claim 17, wherein said activity of dynamically filtering includes:

focusing the at least one type of light emitted from a light emitting device to be steered in a direction towards the sensor using at least one of the determined reflectivity and position of the dynamic light filtering device.

19. The method of claim 16, further comprising the activity of

separating the at least one type of light and ambient light into component wavelengths prior to said activity of dynamically filtering.

20. The method of claim 16, wherein the activity of emitting light further includes:

emitting a first type of light from a light source, the first type of light including a pulse of light having a first wavelength and a pulse of light having a second wavelength;

passing successive pulses of light having the first wavelength and second wavelength through a digit of a patient; and said activity of sensing further includes

detecting amounts of light having the first wavelength and light having the second wavelength that has been absorbed by the digit of the patient; and

providing absorption data to a processor for use in calculating the at least one patient parameter.

21. The method of claim 16, wherein the dynamic light filtering device includes a plurality of mirrored pixels formed in an array, each pixel including a unique address associated therewith enabling configuration thereof.

22. The method of claim 21, wherein said activity of configuring further includes:

determining at least one of a reflectivity and position for respective ones of said plurality of mirrored pixels.

23. The method of claim 22, wherein said activity of dynamically filtering further includes:

using at least one of the determined reflectivity and position associated with respective ones of said plurality of mirrored pixels to steer the at least one type of light towards the sensor.

24. The method of claim 21, wherein said activity of configuring further includes:

generating, by a controller, configuration data in response to the type of light, the control signal data representing

a unique address associated with respective ones of the plurality of mirrored pixels able to focus the at least one type of light;

a reflectivity state for the respective one of the plurality of mirrored pixels for focusing the at least one type of light; and

a position of the respective ones of the plurality at least one mirrored pixel to steer the focus at least one type of light in a direction towards a sensor; and

providing configuration data to the dynamic light filtering device; and

configuring the respective ones of the plurality of mirrored pixels using the configuration data.

25. The method as recited in claim 24, wherein the activity of generating configuration data further comprises the activity of identifying the respective pixels of the plurality of pixels and configuring the respective ones of the plurality of pixels to be reflective.

26. The method as recited in claim 25, wherein the activity of generating configuration data further comprises the activity of

Identifying others of the plurality of pixels that correspond to another type of light different from the at least one type of light and configuring the others of the plurality of pixels to be non-reflective.