Abstract:
Methods and systems for monitoring erectile function or dysfunction provide for determining concentration data of biochemical compounds in a subject&#39;s erectile tissues; and analyzing the concentration data to yield values indicative of the subject&#39;s erectile function. The concentration of biochemical compounds may be measured using Near Infrared Spectroscopy (NIRS). The biochemical compounds may comprise at least one compound from the group consisting of Hemoglobin, Oxygenated Hemoglobin, Cytochromes and Myoglobin.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from United States patent application No.  60 / 888012  filed Feb. 2, 2007 and entitled SYSTEMS AND METHODS FOR DIAGNOSING ERECTILE DYSFUNCTION. For purposes of the United States of America, this application claims the benefit under 35 U.S.C. § 119 of United States patent application No. 60/888012 filed Feb. 2, 2007 and entitled SYSTEMS AND METHODS FOR DIAGNOSING ERECTILE DYSFUNCTION which is hereby incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates to methods and systems for monitoring erectile function and diagnosing erectile dysfunction. 
       BACKGROUND 
       [0003]    Erectile dysfunction (“ED”) affects a significant section of the male population. Some available methods for diagnosing ED involve:
       using Doppler ultrasound to measure blood flow in the penis; or   using snap gauges or strain gauges to measure changes in penile circumference.
 
A disadvantage of ultrasonic Doppler measurements is that it can be hard to maintain intimate contact between an ultrasound probe and the penis to obtain measurements over an extended period. It is also difficult to keep an ultrasound probe positioned so as to obtain consistent measurements over an extended period. Because of these issues, it is difficult to use ultrasonic monitoring to monitor a subject overnight.
       
 
         [0006]    Near Infrared Spectroscopy (“NIRS”) is a technique which involves emitting near infrared (“NIR”) light and receiving the NIR light after it has passed through a tissue or other medium of interest. NIRS can be applied to study and monitor biochemical compounds in the body. Emitted NIR light penetrates skin and other tissues and some of it is absorbed by biochemical compounds which have an absorption spectrum in the NIR region. NIR light which is not absorbed is scattered. Each biochemical compound has a different absorption spectrum. It is possible to estimate the concentration of biochemical compounds in the tissues by measuring characteristics of NIR light that has been detected after it has passed through the tissues. 
         [0007]    There is a need for practical and cost-effective systems for measuring erectile function and diagnosing erectile dysfunction. 
       SUMMARY 
       [0008]    This invention provides methods and systems for monitoring erectile function. 
         [0009]    One aspect of the invention provides methods which monitor erectile function by measuring the concentration of biochemical compounds in tissues of the penis or clitoris through the use of NIRS. The biochemical compounds may comprise one or more compounds from the group consisting of deoxygenated hemoglobin (Hb), Oxygenated Hemoglobin (HbO 2 ), Cytochromes (Cyt), and Myoglobin (Mb). Trends in the concentration data can be correlate to changes in erectile state. An analysis of trends in the concentration data may be used to diagnose erectile dysfunction. 
         [0010]    Another aspect of the invention provides systems for monitoring erectile function and/or diagnosing erectile dysfunction. The systems comprise a data monitoring subsystem which processes and analyses concentration data of biochemical compounds in tissues of the penis or clitoris or adjacent tissues. The concentration data may be obtained through a data acquisition subsystem, such as a NIRS subsystem. The biochemical compounds which are monitored may include at least one compound from the group consisting of Hb, HbO 2 , Cyt and Mb. The data monitoring subsystem stores concentration data at periodic intervals. The data monitoring subsystem monitors trends in the concentration data and may perform other analyses of the concentration data. 
         [0011]    Further aspects of the invention and features of specific embodiments of the invention are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In drawings which illustrate non-limiting embodiments of the invention, 
           [0013]      FIG. 1  is a flow chart illustrating a method for monitoring erectile function; 
           [0014]      FIG. 2  is a plot showing a concentration of oxygenated hemoglobin in a subject&#39;s penis as a function of time; 
           [0015]      FIG. 2A  is an example plot which includes a curve which indicates the concentration of HbO 2  during the onset of an erection in a subject having normal erectile function; 
           [0016]      FIG. 3  is a block diagram illustrating a system for monitoring erectile function; 
           [0017]      FIG. 3A  is a schematic illustration of a display in an example embodiment of the invention; 
           [0018]      FIG. 4  is a block diagram illustrating a specific implementation of the system of  FIG. 3 ; 
           [0019]      FIG. 5  is a block diagram illustrating a data monitoring subsystem which may be used in the system of  FIG. 4 ; and, 
           [0020]      FIG. 6  is a block diagram of a system for monitoring erectile function that includes a separable data acquisition and collection system. 
       
    
    
     DESCRIPTION 
       [0021]    Throughout the following description, specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
         [0022]      FIG. 1  illustrates a method  100  for monitoring erectile function. At block  102 , spectroscopy, preferably absorption spectroscopy, is conducted on a subject to detect and measure concentrations of one or more biochemical compounds in the tissues of the subject&#39;s penis or clitoris. NIRS is a form of absorption spectroscopy which may be used for detecting biochemical compounds which have an absorption spectrum in the NIR region. 
         [0023]    In one embodiment of the invention, NIRS may be conducted on a subject by directing NIR light at the skin of the subject&#39;s penis or clitoris, and detecting and measuring the NIR light that is scattered back through the skin. As discussed in further detail below, this may be achieved by placing an NIR transmitter and an NIR receiver close together on the surface of the skin, so as to detect NIR back scattered light from the tissues of the subject&#39;s penis or clitoris. 
         [0024]    Method  100  proceeds to block  104 , where the scattered light that is detected at block  102  is analysed to obtain concentration data for biochemical compounds in the tissues. The compounds may comprise one or more compounds from the group consisting of Hb, HbO 2 , Cyt, and Mb, for example. 
         [0025]    The concentration data is analysed at block  106 . The analysis may comprise monitoring trends in the data, for example, monitoring a change in concentration value relative to an initial concentration value, or monitoring the first derivative of the concentration with respect to time. Such trends (particularly trends in the concentration of Hb or HbO 2  or a function of one or more of the concentrations of Hb and HbO 2 ) generally correlate to changes in erectile state. Therefore, based on an analysis of these trends, one can obtain information about the subject&#39;s erectile performance. 
         [0026]    The steps described above may be repeated continuously for so long as it is desired to monitor the subject. In some embodiments, monitoring may be performed over an extended period, such as overnight. 
         [0027]      FIG. 2  is a plot which includes a curve  200  which indicates the concentration of HbO 2  in tissues of a subject&#39;s penis as a function of time. Curve  200  is typical of a subject having normal erectile function and experiencing an erection. Curve  200  is a schematic illustration and does not represent actual data. A number of features of curve  200  may be measured. Such measurements may be performed automatically by a system according to the invention as described in more detail below. 
         [0028]    Examples of features of curve  200  that may be measured include:
       a baseline level  204  of the concentration of HbO 2  in the absence of an erection;   a total erection time T Total  which may be measured between an onset time  206  at which the concentration first drops below the baseline level  204  by more than a threshold amount, and an end time  208  at which the concentration returns to the baseline level after having risen to a peak  210  of curve  200  that is above the baseline level;   a peak concentration, which may be measured as the difference between a value of the concentration at peak  210  during the erection and baseline value  204 ;   a “half-time” TB 1  between onset time  206  and the time of peak  210 ;   a “half-time” TB 2  between the time of peak  210  and end time  208 ;   an onset time Tonset between onset time  206  and a time at which the concentration exceeds a threshold value  212 ;   an onset rate, which may be measured as the first derivative of the concentration during a period  214  just after onset time  206 ;   an area under curve  200  during all of or a selected part of the erection.       
 
         [0037]      FIG. 2A  is a plot which includes a curve  200  which indicates the concentration of HbO 2  during the onset of an erection in a subject having normal erectile function. As shown in  FIG. 2A , at the onset of the erection, the concentration measured by curve  200  dips below baseline  204  during a period  216  and then increases to values greater than baseline  204 . The method may detect the onset of an erection by monitoring the concentration over time and identifying this signature (a dip in concentration followed by an increase in concentration). 
         [0038]    Onset time  206  and end time  208  may be used to represent an approximation of the times of the onset and end of an erection, respectively. However, a different determination may be used to approximate the onset and end of an erection. For example, the time of onset may be determined to be the time at which the concentration of HbO 2  has the overall lowest value of curve  200 . 
         [0039]      FIG. 3  illustrates a system  300  for monitoring erectile function. System  300  comprises a data acquisition subsystem  302  to detect biochemical compounds in the tissues. Data acquisition subsystem  302  may use absorption spectroscopy techniques, for example, NIRS, to detect biochemical compounds. Subsystem  302  may comprise one or more sources  303 A of NIR light and one or more detectors  303 B for the NIR light. subsystem  302  may also comprise a support  303 C for holding the source(s)  303 A and detector(s)  303 B in place on the subject&#39;s anatomy. Source(s)  303 A, detector(s)  303 B and support  303 C (if present) may be described as a probe  303 . 
         [0040]    Any suitable means may be used to hold light source(s)  303 A and light detector(s)  303 B against the subject&#39;s anatomy. For example:
       In some embodiments, support  303 C comprises a wrap that can be wrapped around the subject&#39;s penis.   In some embodiments, support  303 C may comprise an adhesive patch which can hold source(s)  303 A and/or detector(s)  303 B against the subject&#39;s penis. The light source(s) and detector(s) may be located such that light from the light source(s) is transmitted through the subject&#39;s penis and received at the light detector(s); the light is back scattered in tissues of the subject&#39;s penis and received at the light detector(s) or some combination thereof. The light source(s) and detector(s) may be located at any suitable location along the subject&#39;s penis. In some embodiments, sets of light sensor(s) and light detector(s) are placed at multiple locations along the subject&#39;s penis.       
 
         [0043]    Data acquisition system  302  may comprise a commercially-available NIRS system connected to receive data from probe  303 , for example. 
         [0044]    The data which is acquired by data acquisition subsystem  302  is analysed by a concentration analysis subsystem  304  to determine the concentration of one or more biochemical compounds in the tissues or some function thereof. The compounds may comprise at least one compound from the group consisting of Hb, HbO 2 , Cyt, and Mb. It is not necessary that the concentration of any of these compounds be determined in any particular units. 
         [0045]    The concentration data is input to a data monitoring subsystem  306  which stores the data at periodic intervals. Data monitoring subsystem  306  analyses the data to detect parameters that may be indicative of erectile function or dysfunction (the parameters may include one or more of the features of curve  200  that are discussed above). 
         [0046]    Data monitoring subsystem  306  is connected to a display  308  for displaying the data. Data monitoring subsystem  306  may also be connected to a user interface  325  which a user can operate to input instructions to data monitoring subsystem  306  and to control the output to display  308 . For example, a user may input instructions to:
       calculate and display one or more of the parameters that may be indicative of erectile function or dysfunction;   zoom in to or zoom out from a portion of curve  200  visible on display  308 ;   scroll forward or backward in time along curve  200 ;   determine and display the time between selected features of curve  200 , for example, the time between the onset and end of an erection; or   provide an assessment of whether the data indicates normal or abnormal erectile function.
 
Moveable cursors on display  308  may be provided to facilitate such user input.
       
 
         [0052]    In an example embodiment, shown in  FIG. 3A , display  308  displays curve  200  and includes one or more cursors that can be moved by operating user interface  325  to measure times between different portions of curve  200  and/or differences in concentration between different points on curve  200  and/or between a point on curve  200  and baseline level  204 . In the illustrated embodiment, two cursors  309 A and  309 B are shown. Display  308  also has marks  309 C and  309 D respectively indicating the start and end points of the erection as determined by data monitoring subsystem  306 . In the illustrated embodiment, display  308  displays values for a number of parameters  309 E,  309 F,  309 G that are calculated by data monitoring subsystem  306 . 
         [0053]    Data monitoring subsystem  306  may also be connected to a user interface  325  which allows a user to perform such functions as:
       manipulating one or more cursors;   highlighting portions of a concentration curve;   zooming in on a selected portion of a concentration curve;   entering notes or other information about the subject;   storing data;   retrieving comparison data and optionally displaying the comparison data on display  308  to permit comparison of curve  200  to the comparison data; and   the like.
 
The results may be output to display  308 .
       
 
         [0061]    System  300  may incorporate an alarm  312  that may comprise, for example, an audible alarm (e.g. bell or beep), visual alarm (e.g. light), a tactile alarm (e.g. a vibrator) or a combined alarm. Alarm  312  may be actuated automatically by an alarm trigger  310  if system  300  fails to detect a reliable signal from probe  303  (as could be the case if probe  303  somehow came off of the subject&#39;s penis or other erectile tissue). Alarm trigger  310  may be wired to alarm  312  or it may transmit a wireless message which activates alarm  312  on a wireless receiving device (e.g. Personal Digital Assistant, pager, or cellular phone). Other types of alarms are possible. 
         [0062]      FIG. 4  illustrates a specific implementation of system  300 . Data acquisition subsystem  302  is provided to conduct NIRS on a patient. Data acquisition subsystem  302  comprises an NIR transmitter  306  and an NIR receiver  309 , each connected to an NIR controller  318 . Although only one NIR receiver is illustrated, data acquisition subsystem  302  may comprise more than one NIR receiver  309 . In some embodiments, NIR transmitter  306  comprises an optical fibre that carries NIR light to the subject by way of an optical fiber or other light guide. This can be beneficial if the light source operates at a temperature such that it would be noticeable or uncomfortable to a subject. 
         [0063]    Preferably, NIR transmitter  306  and NIR receiver  309  are contained in a probe or probes placed on the patient&#39;s skin. NIR transmitter  306  directs NIR light at the patient&#39;s skin. The NIR light may have one or more bands in the spectrum range of 700 to 950 nm. The transmitted NIR light penetrates the skin and other tissues and some of it is absorbed by biochemical compounds, such as proteins, which each have a different absorption spectrum in the NIR region. The NIR light which is not absorbed is either scattered back through the skin or transmitted through the tissues to skin on the far side of the subject&#39;s penis or clitoris. Some of this back scattered and/or transmitted light is detected by NIR receiver  309 . 
         [0064]    NIR controller  318  may determine the intensity of the NIR light transmitted by NIR transmitter  306 . 
         [0065]    The NIR light which is detected and received by NIR receiver  309  is output by NIR receiver  309  in the form of an analog signal. This signal is sent to concentration analysis subsystem  304 . A signal conditioner  315  conditions the analog signal to prepare it for analog to digital conversion by converter  317 . For example, signal conditioner  315  may amplify and/or filter the signal at the frequencies of interest. 
         [0066]    After the conditioned analog signal is converted to a digital signal by converter  317 , digital processor  319  may perform further filtering of the signal, such as to remove signals attributable to background NIR radiation. 
         [0067]    Digital processor  319  analyses the signal to determine concentration data  330  for biochemical compounds. The compounds may comprise at least one compound from the group consisting of Hb, HbO 2 , Cyt, and Mb. Each of these biochemical compounds absorbs NIR light at a different spectrum. Thus, by comparing the spectrum of the NIR light transmitted by NIR transmitter  306  with the spectrum of the NIR light received by NIR receiver  309 , concentration data  330  may be determined. For example, concentration data  330  may be determined by transmitting NIR light having a set of discrete wavelengths, and monitoring the wavelengths contained in the output signal of NIR receiver  309 . Concentration data  330  is then sent to data monitoring subsystem  306 . 
         [0068]      FIG. 5  illustrates, in further detail, data monitoring subsystem  306 . Data monitoring subsystem  306  receives a subset of concentration data  330 , namely concentration data  330 A for HbO 2 . Although not illustrated, data monitoring subsystem  306  may also receive concentration data  330  for one or more of Hb, Cyt and Mb. In some embodiments, parameters indicative of erectile function or dysfunction may involve concentrations or concentration trends of two or more of HbO 2 , Hb, Cyt and Mb. 
         [0069]    Data monitoring subsystem  306  comprises a processor  340 , which executes instructions contained in software  350  and reads/writes data to/from memory  360 . Memory  360  stores, for example, a plurality of functions  380  which can compute parameters relating to an erection from concentration data  330 A obtained during the erection. Memory  360  may also store a baseline concentration value  383  of concentration data  330 A, and a number of values  382  of concentration data  330 A, recorded at periodic intervals, such as a few times each second, once every few seconds or once every few minutes. In some embodiments, measurements are made at a rate of at least 0.5 Hz. In some embodiments the rate of measurements is in the range of 0.1 Hz to 100 Hz. 
         [0070]    Processor  340  calls and executes functions in software  350  with selected information from memory  360  as inputs to the functions. 
         [0071]    Although not illustrated, a device for printing out information may be provided. The device may print information displayed by display  308  or other information related to the subject&#39;s erectile status. 
         [0072]    Software  350  may include functions for automatically detecting and counting erections; functions for automatically computing parameters indicative of a subject&#39;s erectile function; and/or functions for collecting statistical information regarding a subject&#39;s erections. 
         [0073]    In some embodiments, as illustrated, for example, in  FIG. 6 , apparatus according to the invention comprises a data acquisition and collection unit  501  that is separable from a data analysis unit  502 . Data acquisition and collection unit  501  may comprise a relatively small battery-powered unit that connects to a probe  503  to acquire NIRS data during a monitoring period (such as overnight). Data acquisition and collection unit  501  may comprise an alarm  512  that vibrates, makes a sound, or otherwise alerts a subject if a signal from probe  503  is not detected. A processor  505  manages the operation of data acquisition and collection unit  501  and stores NIRS data in a memory  507 . 
         [0074]    After collection unit  501  has collected data during one or more monitoring periods, the data can be uploaded to data analysis unit  502 . Data analysis unit  502  may comprise a specialized unit or a personal computer or the like executing suitable software. Data analysis unit  502  can analyze the data that has been collected by data acquisition and collection unit  501  as described above. In some embodiments, data analysis unit  502  can download to data acquisition and collection unit  501  operating parameters that affect the operation of data acquisition and collection unit  501 . The parameters may include, for example, a rate of data acquisition. 
         [0075]    Certain implementations of the invention comprise data processors which execute software instructions which cause the data processors to perform a method of the invention. For example, one or more processors in an apparatus for monitoring erectile function may implement the methods of  FIG. 1  by executing software instructions in a program memory accessible to the data processors. The data processors may comprise one or more microprocessors, embedded processors, computer systems, digital signal processors or the like. The invention may also be provided in the form of a program product. The program product may comprise any medium which carries a set of computer-readable instructions which, when executed by one or more data processors, cause the one or more data processors to execute a method of the invention. Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like. The computer-readable instructions on the program product may optionally be compressed or encrypted. 
         [0076]    As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example, an apparatus may be provided which contains one or more subsystems or devices described above, such as a data monitoring subsystem  306 , display  308 , alarm trigger  310  and alarm  312 . Some embodiments described herein may provide more than one data processor. In other embodiments, the functions of two or more such data processors are combined in one data processor. 
         [0077]    While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.