Abstract:
Multiple different output signals for a polysomnograph (PSG) machine, the multiple different output signals including a first output indicative of an upper airway restriction (UAR), a second output indicative of an airway pressure during respiration, and a third output indicative of an airway air temperature during respiration, can be produced using a single sensor input.

Description:
CLAIM OF PRIORITY 
       [0001]    This patent application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/045,735, filed on Apr. 17, 2008, which application is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present subject matter relates generally to an electronic signal processing circuit for adapting a piezo/pyro electric sensor to a conventional polysomnograph (PSG) machine of the type commonly used in sleep laboratory applications, and more particularly to an adapter module that receives a single incoming sensor signal and creates multiple signal outputs with different waveform shapes based on selected filter cut-off frequencies. 
       BACKGROUND 
       [0003]    Sleep disorders have recently become the focus of a growing number of physicians. Many hospitals and clinics have established sleep laboratories (sleep labs) to diagnose and treat sleep disorders such as sleep apnea, insomnia, and other physiological events or conditions occurring during sleep. In the sleep laboratories, practitioners use instrumentation to monitor and record a patient&#39;s sleep patterns. Practitioners rely on these recorded sleep patterns to diagnose patients and prescribe proper therapies. 
         [0004]    The instrumentation used to record the sleep patterns generally includes sensors attached to a patient and connected via electrical leads to a polysomnograph (PSG) machine, which produces a waveform for interpretation by a practitioner. Several varieties of these sensors have been developed and commonly function by converting a mechanical bodily movement to an electrical signal related to the body movement. 
         [0005]    Air pressure transducers (APT) and thermistors (Thermo) represent the classical sensors used to record oral and nasal airflow. APT&#39;s are used in conjunction with a cannula attached to an air pressure hose. The APT cannula is placed under a patient&#39;s nose and measures differences in respiratory air pressure between inhaling and exhaling. Thermo sensors are placed under a patient&#39;s nose and measure differences in respiratory air temperature between inhaling and exhaling. As the classical sensors, both the APT and Thermo sensors produce a signal that presents a distinct and familiar waveform on the PSG machine. Unfortunately, due to their physical construction, chemical composition and solid state physics, neither of these sensors provide sufficient detail relating to upper airway restrictions (UAR). This makes it difficult or impossible for practitioners to recognize certain UAR events related to a patient&#39;s sleep disorder. 
         [0006]    As an alternative to APT and Thermo sensors, Dymedix Corporation, applicant&#39;s assignee, recently introduced a new piezo/pyro sensor comprising a polyvinylidene (PVDF) film that is found to exhibit both piezoelectric and pyroelectric properties. Information regarding this type of sensor may be found in U.S. Pat. No. 5,311,875 to Stasz and U.S. Pat. No. 6,254,545 to Stasz et al. Piezo/pyro sensors of the type described may be adapted to be affixed to a subject&#39;s upper lip. In this condition, airflow in and out of the nostrils of a patient, due to inspiration and expiration, impinges on the sensor, which produces an output signal related to temperature and pressure changes occasioned by the inspiratory and expiratory flow. This sensor provides more detailed information regarding UAR&#39;s. 
         [0007]    However, as a result of the more detailed information, one problem with this newly developed piezo/pyro sensor is that its signal produces a waveform on a PSG machine that is unfamiliar to sleep laboratory practitioners. Generally speaking, this is because the detailed information causes the waveform to differ from the distinct and familiar waveforms associated with the known APT and Thermo sensors discussed above. 
         [0008]    There is added value in the detailed information produced by the piezo/pyro sensor and thus there is a need in the art for making its associated waveform familiar to sleep laboratory practitioners. Additionally, to successfully market these new types of sensors, it is desirable that they be able to be used with existing PSG machines already in place in sleep laboratories. 
       SUMMARY 
       [0009]    An adaptor module can be provided for interfacing a piezo/pyro electric film sensor to a PSG machine. In some embodiments, the adaptor module comprises a differential input amplifier having a pair of input terminals that are adapted to be coupled to the piezo/pyro electric film sensor and an output terminal. The differential input amplifier may be configured to significantly attenuate common-mode noise while providing a predetermined gain factor by which the sensor output signal is amplified. The output of the differential amplifier may be fed into a filter bank of multiple filter circuits. 
         [0010]    In one embodiment the waveform of the piezo/pyro electric sensor output signal is shaped to resemble the waveform of an air pressure transducer and a thermistor that a diagnosing sleep disorder professional would see and recognize on a PSG. 
         [0011]    In another embodiment, a differential input amplifier with a predetermined gain factor and appropriate conditioning of the amplified piezo/pyro sensor output signal allows three different filters to be readily matched to existing PSG electronic head boxes already on hand in most sleep laboratories. 
         [0012]    In an example, multiple different output signals for a polysomnograph (PSG) machine, the multiple different output signals including a first output indicative of an upper airway restriction (UAR), a second output indicative of an airway pressure during respiration, and a third output indicative of an airway air temperature during respiration, can be produced using a single sensor input. 
         [0013]    In Example 1, an apparatus for creating multiple filtered outputs for a polysomnograph (PSG) machine from a single sensor input includes an electronic signal processing circuit configured to receive a single sensor input and to produce, using the single sensor input, multiple different output signals, the multiple different output signals including a first output indicative of an upper airway restriction (UAR), a second output indicative of an airway pressure during respiration, and a third output indicative of an airway air temperature during respiration. 
         [0014]    In Example 2, the second output of Example 1 is optionally indicative of a difference in the airway pressure during respiration, and the third output is indicative of a difference in the airway air temperature during respiration. 
         [0015]    In Example 3, the electronic signal processing circuit of any one or more of Examples 1-2 is optionally configured to receive the single sensor input from a piezo/pyro sensor, sized and shaped to be affixed to a subject&#39;s upper lip and configured to receive respiration information from the subject. 
         [0016]    In Example 4, the electronic signal processing circuit of any one or more of Examples 1-3 is optionally configured to provide information about at least one of the produced multiple different output signals to a user. 
         [0017]    In Example 5, the electronic signal processing circuit of any one or more of Examples 1-4 is optionally configured to produce the multiple different output signals for a polysomnograph (PSG) machine from the single sensor input. 
         [0018]    In Example 6, the electronic signal processing circuit of any one or more of Examples 1-5 optionally includes a differential amplifier configured to amplify the single sensor input and to attenuate common-mode noise. 
         [0019]    In Example 7, the electronic signal processing circuit of any one or more of Examples 1-6 optionally includes a UAR shape filter configured to produce the first output, an air pressure transducer (APT) shape filter configured to produce the second output, and a thermistor (Thermo) shape filter configured to produce the third output. 
         [0020]    In Example 8, the UAR shape filter of any one or more of Examples 1-7 optionally includes a first low-pass filter having a cut-off frequency between 1.5 Hz and 10 Hz, the APT shape filter of any one or more of Examples 1-7 optionally includes a second low-pass filter having a cut-off frequency between 0.5 Hz and 1.5 Hz, and the Thermo shape filter of any one or more of Examples 1-7 optionally includes a third low-pass filter having a cut-off frequency between 0.01 Hz and 0.5 Hz. 
         [0021]    In Example 9, the electronic signal processing circuit of any one or more of Examples 1-8 is optionally configured to produce the second output to resemble an air pressure transducer (APT) waveform on a polysomnograph (PSG) machine, and to produce the third output to resemble a thermistor (Thermo) waveform on the PSG machine. 
         [0022]    In Example 10, the electronic signal processing circuit of any one or more of Examples 1-9 is optionally configured to be integrated into a cable coupling a piezo/pyro sensor to a polysomnograph (PSG) machine. 
         [0023]    In Example 11, a system for creating multiple filtered outputs for a polysomnograph (PSG) machine from a single sensor input includes a piezo/pyro sensor, sized and shaped to be affixed to a subject&#39;s upper lip, the piezo/pyro sensor configured to receive respiration information from the subject. The system also includes an electronic signal processing circuit configured to receive information from the piezo/pyro sensor and to produce, using the piezo/pyro sensor input, multiple different output signals, the multiple different output signals including a first output indicative of an upper airway restriction (UAR), a second output indicative of an airway pressure during respiration, and a third output indicative of an airway air temperature during respiration. Further, the system includes a polysomnograph (PSG) machine configured to receive the multiple different output signals from the electronic signal processing circuit and to display information about at least one of the received first output, the received second output, or the received third output to a user. 
         [0024]    In Example 12, the system of Example 11 optionally includes a cable configured to couple the piezo/pyro sensor to the PSG machine, wherein the electronic signal processing circuit is configured to be integrated into the cable. 
         [0025]    In Example 13, a method for creating multiple filtered outputs for a polysomnograph (PSG) machine from a single sensor input includes receiving a single sensor input, producing, using the single sensor input, multiple different output signals, the producing including producing a first output indicative of an upper airway restriction (UAR), producing a second output indicative of an airway pressure during respiration, and producing a third output indicative of an airway air temperature during respiration. 
         [0026]    In Example 14, the receiving the single sensor input of Example 13 optionally includes receiving a single sensor input from a piezo/pyro sensor, sized and shaped to be affixed to a subject&#39;s upper lip and configured to receive respiration information from the subject. 
         [0027]    In Example 15, the producing the multiple different output signals of any one or more of Examples 13-14 optionally includes using an electronic signal processing circuit integrated into a cable coupling the piezo/pyro sensor to a polysomnograph (PSG) machine. 
         [0028]    In Example 16, the method of any one or more of Examples 13-15 optionally includes providing information about at least one of the produced multiple different output signals to a user. 
         [0029]    In Example 17, the method of any one or more of Examples 13-16 optionally includes receiving the produced multiple different output signals using a polysomnograph (PSG) machine and providing information about at least one of the received multiple different output signals to a user. 
         [0030]    In Example 18, the producing the first output of any one or more of Examples 13-17 optionally includes using a first UAR shape filter, the producing the second output includes using an air pressure transducer (APT) shape filter, and the producing the third output includes using a thermistor (Thermo) shape filter. 
         [0031]    In Example 19, the using the UAR shape filter of any one or more of Examples 13-18 optionally includes using a first low-pass filter having a cut-off frequency between 1.5 Hz and 10 Hz, the using the APT shape filter of any one or more of Examples 13-18 optionally includes using a second low-pass filter having a cut-off frequency between 0.5 Hz and 1.5 Hz, and the using the Thermo shape filter of any one or more of Examples 13-18 optionally includes using a third low-pass filter having a cut-off frequency between 0.01 Hz and 0.5 Hz. 
         [0032]    In Example 20, the producing the second output of any one or more of Examples 13-19 optionally includes producing output to resemble an air pressure transducer (APT) waveform on a polysomnograph (PSG) machine, and the producing the third output of any one or more of Examples 13-19 optionally includes producing output to resemble a thermistor (Thermo) waveform on the PSG machine. 
         [0033]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0034]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0035]    The forgoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like the numerals in the several views refer to the corresponding parts: 
           [0036]      FIG. 1  is a configuration diagram of an adapter module, according to certain embodiments. 
           [0037]      FIG. 2  is a block diagram of an adapter module, according to certain embodiments. 
           [0038]      FIG. 3  is a schematic diagram of a detailed implementation of an adapter module, according to certain embodiments. 
           [0039]      FIG. 4  is a display on a PSG machine receiving multiple input signals from an adapter module, according to certain embodiments. 
       
    
    
     DETAILED DESCRIPTION  
       [0040]    The following detailed description relates to an adapter module directed toward monitoring patients with sleep disorders in sleep laboratories. The adapter module is more particularly directed at use between a sensor affixed to a patient and a polysomnograph (PSG) machine. The adapter module may be used to receive a signal from a sensor and then convert the signal into multiple signals for display in separate waveforms on a PSG machine. The separate waveforms may include varying levels of detail and may also present waveforms familiar to sleep laboratory practitioners. 
         [0041]    The following detailed description includes discussion of sensors affixed to patients, adapter modules, and PSG machines. Additionally, various components of an adapter module are discussed. These include a differential input amplifier, a power supply, and various wave shape filters. These shape filters include an upper airway restriction (UAR) shape filter, an air pressure transducer (APT) filter, and a Thermistor (Thermo) filter. 
         [0042]    One embodiment of use and configuration of the adapter module is shown with the aid of  FIG. 1 . A sleep laboratory patient  1  has been outfitted with a sensor  2 . A pair of sensor output wire leads  3  connects the sleep laboratory patient  1  to the adapter module  4  for creating multiple filtered outputs from a single sensor. The present embodiment also shows three filtered output wire pairs  5 ,  6 , and  7  connecting the adapter module  4  to a PSG machine  8 . 
         [0043]    In the present embodiment, the adapter module  4  produces three signals for waveform displays on the PSG machine  8 . Each of these signals is transmitted to the PSG machine  8  by an output wire pair. Filter output wire pair  5  transmits a UAR indicating signal showing the most detail on the PSG waveform display. Filter output wire pair  6  transmits an APT type signal showing slightly less detail on the PSG waveform display. Filter output wire pair  7  transmits a Thermo type signal showing minimal detail on the PSG waveform display. 
         [0044]    Those skilled in the art will understand and appreciate that various configurations of the apparatuses shown are possible. The adapter module may provide for any number of outputs and inputs. The patient may be fitted with multiple sensors. To the extent necessary to display all of the necessary data, multiple PSG machines could also be used. Additionally, those skilled in the art will understand that various lead configurations are available and that multiple adapter modules could be used. 
         [0045]    Another embodiment is shown in  FIG. 2 , which specifically depicts the functional components of an adapter module  10 . In this embodiment, a differential input amplifier  30  is shown having a pair of input terminals  12  and  14  to which the leads of a piezo/pyro sensor  20  are connected and an output signal  32 . The piezo/pyro sensor  20  is preferably constructed in accordance with the teachings of U.S. Pat. No. 6,491,642, to Stasz and entitled “Pyro/Piezo Sensor,” the teachings of which are hereby incorporated by reference as if fully set forth herein. The sensor  20  is adapted to be placed on a subject&#39;s upper lip so that inspiratory and expiratory airflow through the nostrils impinges thereon. Also shown is a power supply  80  and three wave shape filters. The three wave shape filters include a UAR wave shape filter  40 , an APT wave shape filter  50 , and a Thermo wave shape filter  60 . Further included are lines  42 ,  44 ,  52 ,  54 ,  62 ,  64 , and PSG machine  70 . 
         [0046]    The differential input amplifier  30  comprises an instrumentation-type amplifier which functions to increase the common-mode rejection of the adapter system to make it less susceptible to 60 Hz noise present in the environment as well as to motion artifacts. Without limitation, the differential input amplifier may have a gain in the range of 2 to 10 with about 6.2 being quite adequate. 
         [0047]    The output signal  32  from the differential input amplifier  30  is applied to a bank of three third order Butterworth low pass filters  40 ,  50 , and  60 . The inputs of the third order Butterworth filters  40 ,  50 , and  60  are connected to the output terminal of the differential input amplifier  30 . Those skilled in the art understand that the literature covering filter responses is vast and that the type of filter response is neither limited to a third order filter nor is it limited to a Butterworth response. Other filter responses may be used such as, but not limited to, Bessel, Elliptic, Chebyshev, BiQuad, State Variable, Infinite Impulse, or Finite Impulse. 
         [0048]    In the present embodiment, the cut-off frequency for the UAR wave shaped third order Butterworth low pass filter 40 is 2 Hz creating a PSG display waveform that allows for the indication and diagnosis of UAR&#39;s in sleeping patients. Those skilled in the art will understand and appreciate that the cut-off frequency for the UAR filter, while not limited to this range, may vary from 1.5 Hz to 10 Hz. 
         [0049]    In the present embodiment, the cut-off frequency for the APT wave shaped third order Butterworth low pass filter 50 is 1 Hz. This creates a PSG display waveform that would have been produced had an APT sensor been used directly with a PSG machine  70  in lieu of the piezo/pyro sensor in conjunction with the adapter module  10 . Those skilled in the art will understand and appreciate that the cut-off frequency for the APT filter, while not limited to this range, may vary from 0.5 HZ to 1.5 Hz. 
         [0050]    In the present embodiment, the cut-off frequency for the Thermo wave shaped third order Butterworth low pass filter 60 is 0.125 Hz. This creates a PSG display waveform that would have been produced had a Thermo sensor been used directly with a PSG machine  70  in lieu of the piezo/pyro sensor in conjunction with the adapter module  10 . Those skilled in the art will understand and appreciate that the cut-off frequency for the Thermo filter, while not limited to this range, may vary from 0.01 HZ to 0.5 Hz. 
         [0051]    In the present embodiment, the third order low pass filter  40 , or UAR filter, is effective to pass the UAR type signal relating to respiratory activity directly to an input jack of the PSG machine  70  by way of lines  42  and  44  respectively. The third order low pass filter  50 , or APT filter, is effective to pass the APT type signal relating to respiratory activity directly to an input jack of the PSG machine  70  by way of lines  52  and  54  respectively. The third order low pass filter  60 , or Thermo filter, is effective to pass the Thermo type signal relating to respiratory activity directly to an input jack of the PSG machine  70  by way of lines  62  and  64  respectively. 
         [0052]    Those skilled in the art will understand and appreciate that various functional components could be re-arranged and different numbers of these components used. Various types of sensors can be used and the current disclosure is not limited to a piezo/pyro electric sensor. Any number of filters could be used with various frequency cut-offs, which would produce various filter responses. The current disclosure is not limited to producing UAR, APT, and Thermo type signals. The cut-off frequency can be adjusted to provide for a wide range of filter responses and thus a wide range of signals that may be desired by sleep physicians to experiment with other yet unknown and undetermined filter types and responses in order to advance the science of sleep medicine. 
         [0053]    Having described one embodiment of an overall configuration of the adapter module  10  with the aid of  FIG. 2 , a more detailed explanation of a specific embodiment of the adapter module  10  will now be presented. In that regard, reference is made to the block diagram of  FIG. 3 , which describes in greater detail, certain embodiments of the building blocks of the adapter module  10 . 
         [0054]    In one embodiment, the adapter module  10  may be integral with the cable used to couple a piezo/pyro sensor to a PSG machine. In this embodiment, it incorporates its own power supply and virtual ground generator  80 . A single lithium battery  82  with a positive battery voltage terminal  84  and a negative battery voltage terminal  96  is included. Also included is a resistor  88  connecting the positive battery voltage terminal to a virtual ground point  90 . Further included is a resistor  92  connecting the negative battery voltage terminal to the virtual ground point  90 . In the present embodiment, the resistors  88  and  92  are equal in value in the virtual ground point  90  configuration. In this embodiment, a polarized capacitor  86  is included connected in parallel with resistor  88  to form a low alternate current (ac) impedance return path from the positive battery terminal  84  to the virtual ground point  90 . A polarized capacitor  94  is also included and is connected in parallel with resistor  92  to form a low alternating (ac) impedance return path from the negative battery terminal  96  to the virtual ground point  90 . 
         [0055]    Those skilled in the art will understand and appreciate that other arrangements are available for creating a virtual ground. For example, an off-the-shelf integrated circuit could be used such as the TLE2426 Virtual Ground Generator IC available from Texas Instruments. Yet another way of creating a virtual ground is to use a standard operational amplifier in a unity non-inverting gain configuration with the non-inverting input to be the summing node for two equal resistors with their remaining leads tied to the positive voltage terminal  84  and the negative battery voltage terminal  96  respectively. 
         [0056]    Referring now to the differential input amplifier  30 , in one embodiment, the input terminals  12  and  14  are respectively coupled, via resistors  104  and  124  to the non-inverting inputs of operational amplifiers  110  and  130 . Those skilled in the art will appreciate that the operational amplifiers (OpAmps), configured as shown, are typical instrumentation type amplifiers designed to produce a predetermined gain while rejecting common-mode noise. In this embodiment, the output from the differential input amplifier circuit  30  appears at junction  32  and feeds the three third order Butterworth low-pass filter circuits  40 ,  50 , and  60 . 
         [0057]    Reference is now made to filter circuit  40 . In one embodiment, the input appearing at junction  32  is applied, via series connected resistors  202 ,  206  and  208 , to the non-inverting input of an operational amplifier  214 . The resistors  202 ,  206 , and  208  along with capacitors  204 ,  210 , and  212  cooperate with the operational amplifier  214  to function as a low-pass filter. The output of the  214  operational amplifier feeds an AC/DC (alternate current/direct current) coupling circuit consisting of a resistor  222  and a capacitor  224 . When the adapter module operates with a PSG machine input that requires AC coupled signals only, resistor  222  is not populated in the adapter but ac-coupling capacitor  224  is populated. When the adapter operates with a PSG machine input that requires DC coupled signals, resistor  222  is populated and capacitor  224  is not populated. 
         [0058]    The AC/DC coupling circuit, being populated either with resistor  222  or capacitor  224  connects to a voltage divider. The voltage divider includes resistors  226  and  228  and is used to drop the piezo/pyro based signal component to acceptable levels of a PSG machine  80 . 
         [0059]    The cut-off frequency of the low pass filter circuit  40 , or the UAR filter, may be established by setting the values of the resistors  202 ,  206  and  208  and the capacitors  204 ,  210  and  212 . As discussed, in one embodiment, this cut-off frequency may be set to about 2 Hz. 
         [0060]    Reference is now made to filter circuit  50 . In one embodiment, the input appearing at junction  32  is applied, via series connected resistors  302 ,  306  and  308 , to the non-inverting input of an operational amplifier  314 . The resistors  302 ,  306 , and  308 , along with capacitors  304 ,  310  and  312  cooperate with the operational amplifier  314  to function as a low-pass filter. The output of the  314  operational amplifier feeds an AC/DC (alternate current/direct current) coupling circuit consisting of a resistor  322  and a capacitor  324 . When the adapter operates with a PSG machine input that requires AC coupled signals only, resistor  322  is not populated in the adapter but ac-coupling capacitor  324  is populated. When the adapter operates with a PSG machine input that requires DC coupled signals, resistor  322  is populated and capacitor  324  is not populated. 
         [0061]    The AC/DC coupling circuit, being populated either with resistor  322  or capacitor  324  connects to a voltage divider. The voltage divider includes resistors  326  and  328  and is used to drop the piezo/pyro based signal component to acceptable levels of a PSG machine  80 . 
         [0062]    The cut-off frequency of the low pass filter circuit  50 , or the APT filter, may be established by setting the values of the resistors  302 ,  306  and  308  and the capacitors  304 ,  310  and  312 . As discussed, in one embodiment, this cut-off frequency may be set to about 1 Hz. 
         [0063]    Reference is now made to filter circuit  60 . In one embodiment, the input appearing at junction  32  is applied, via series connected resistors  402 ,  406  and  408 , to the non-inverting input of an operational amplifier  414 . The resistors  402 ,  406 , and  408 , along with capacitors  404 ,  410  and  412  cooperate with the operational amplifier  414  to function as a low-pass filter. The output of the  414  operational amplifier feeds an AC/DC (alternate current/direct current) coupling circuit consisting of a resistor  422  and a capacitor  424 . When the adapter operates with a PSG machine input that requires AC coupled signals only, resistor  422  is not populated in the adapter but ac-coupling capacitor  424  is populated. When the adapter operates with a PSG machine input that requires DC coupled signals, resistor  422  is populated and capacitor  424  is not populated. 
         [0064]    The AC/DC coupling circuit, being populated either with resistor  422  or capacitor  424  connects to a voltage divider. The voltage divider includes resistors  426  and  428  and is used to drop the piezo/pyro based signal component to acceptable levels of a PSG machine  80 . 
         [0065]    The cut-off frequency of the low pass filter circuit  60 , or the Thermo filter, may be established by setting the values of the resistors  402 ,  406  and  408  and the capacitors  404 ,  410  and  412 . As discussed, in one embodiment, this cut-off frequency may be set to about 0.125 Hz. 
         [0066]    The list of specific components used to assemble a printed circuit board assembly is known in the industry as a Bill-of-Materials (BOM). Below is an example of a BOM for one embodiment of the components of  FIG. 3 .
   B 1  BR2330A/FA   R 6  100   R 16  100   R 25  100   C 8  0.056 uF   C 12  0.056 uF   C 18  0.056 uF   C 3  0.1 uF   C 5  0.1 uF   C 7  0.39 uF   C 13  0.39 uF   C 17  0.39 uF   R 4  100 k   R 5  100 k   R 13  100 k   R 15  100 k   C 6  100 pF   C 14  100 pF   C 1  10 uF   C 2  10 uF   R 12  1 k   R 22  1 k   C 4  1 uF   C 10  1 uF   C 15  1 uF   R 8  24.3 k   R 18  24.3 k   R 24  24.3 k   R 9  270 k   R 10  270 k   R 11  270 k   R 27  3.3 M   R 28  3.3 M   R 29  3.3 M   R 2  330 k   R 3  330 k   R 1  47.5 k   C 9  47 uF   C 11  47 uF   C 16  47 uF   R 14  5.1 M   R 23  5.1 M   R 19  560 k   R 20  560 k   R 21  560 k   R 7  6.8 M   R 17  6.8 M   R 26  6.8 M   U 1 : A LMC6442AIM   U 1 : B LMC6442AIM   U 2 : A LMC6442AIM   U 2 : B LMC6442AIM   U 3 : A LMC6442AIM   
 
         [0120]    Those of skill in the art will understand and appreciate that this BOM is simply exemplary and a wide array of values and a wide array of combinations of the above elements can be used. 
         [0121]    Referring now to  FIG. 4 , in one embodiment, three signals received by a PSG machine are simultaneously displayed in waveform on a PSG screen. In the present embodiment, a waveform  1000  produced from a UAR filter is shown. Also shown is a waveform  2000  produced from an APT filter and a waveform  3000  produced from a Thermo filter. In the present embodiment the input signals from the various filters provide varying levels of detail. Waveform  1000  from the UAR filter provides the most detail and includes detailed UAR information. Waveform  2000  from the APT filter shows slightly less detail and waveform  3000  shows minimal detail. In the present embodiment, waveforms  2000  and  3000  are more likely to be familiar waveforms to sleep disorder practitioners and waveform  1000  is less likely to be a familiar waveform. 
         [0122]    Those of skill in the art will understand and appreciate that any number of waveforms could be produced using a larger number of filters in the adapter module. Moreover, the waveforms produced can vary and are not limited to UAR, APT, and Thermo type waveforms. 
         [0123]    During operation, in one embodiment, a sleep laboratory patient may be fitted with a piezo/pyro electric film sensor that includes a circuit similar to that described in detail here. The circuit may then be further connected to a PSG machine. As the patient breathes and/or sleeps, sleep scientists, sleep physicians, and sleep technicians may then be able to see, detect and properly diagnose specific sleep disorders and diseases. These disorders may include abnormal respiratory events. Moreover, the present embodiment provides the ability to review familiar waveforms which may signify familiar sleep disorders, but also provides the ability to review more detailed information regarding UAR&#39;s at the same time. Thus, the present embodiment may allow practitioners to more thoroughly understand the disorders of patients and provide better care. 
         [0124]    This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself. 
         [0125]    The description of the various embodiments is merely exemplary in nature and, thus, variations that do not depart from the gist of the examples and detailed description herein are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.