Patent Publication Number: US-2005119537-A1

Title: Method and apparatus for performing concurrent multiple measurements of relative hydration

Description:
BACKGROUND OF THE INVENTION  
      This invention generally relates to measurements of relative hydration of the human skin or physical substrate materials and more specifically to making multiple concurrent measurements of relative hydration in such environments.  
     DESCRIPTION OF RELATED ART  
      There is a continuing growing interest in measuring the relative hydration of a substrate, such as measurements on human skin. Such measurements can provide information about wound healing. There is also evidence that such measurements can predict certain diseases or the effectiveness of treatment.  
      U.S. Pat. No. 6,370,426 issued Apr. 9, 2002 for a method and apparatus for measuring relative hydration of a substrate discloses a probe and related equipment that provides such measurements. Such a probe is also known as a dermal phase meter, or DPM unit. This particular probe has an elongated probe housing. A sensor body mounted at one end of the probe housing has first and second concentric electrodes for contacting a substrate at the site for which a measurement of relative hydration is desired. An electrical impedance measurement circuit in the probe housing generates an impedance signal representing the impedance of the substrate between the first and second electrodes. This particular probe includes a temperature sensor, as an example of an environmental sensor, for generating a signal representing the temperature of the skin contacting the electrodes. A signal processor in the probe housing polls the impedance measurement circuit and the temperature sensor to generate processed impedance and temperature measurement signals. A connector at the other end of the probe housing enables communications between a data processing system and the signal processor. In this particular embodiment the data processing system issues commands to control the operation of the probe.  
      Over time these probes have been used in a wide variety of applications including the measurement of mean arterial pressure, neonatal skin maturation, burn treatment and others. In some applications diagnosis requires measurements at different locations on a patient. If a single device is used, the measurements are taken serially. While the test itself does not generally produce discomfort, a patient, particularly a burn patient, can experience discomfort merely from being positioned for an extended period of time in an uncomfortable position. Probes of this type have been used in clinical trials for ascertaining the efficacy of relative hydration motions as indicators or predictors of certain types of diseases or treatment. Clinical trials may involve many people. A single probe then requires each person to be measured separately. This increases the time required for handling multiple subjects.  
      What is needed is a method and apparatus that enables all the data to be gathered in a single data processing system to facilitate concurrent measurements on one or multiple subjects.  
     SUMMARY  
      Therefore it is an object of this invention to provide a method and apparatus for obtaining concurrent measurements of relative hydration with a single system with multiple probes.  
      In accordance with one aspect of this invention, readings from a plurality of probes are obtained in a data processing system with a corresponding plurality of serial ports and a display. A concordance establishes the relationship between each probe and one serial port. Each port and corresponding probe is then accessed to input data in accordance with the established concordance. The data is then read from the probe and displayed on a composite display. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The appended claims particularly point out and distinctly claim the subject matter of this invention. The various objects, advantages and novel features of this invention will be more fully apparent from a reading of the following detailed description in conjunction with the accompanying drawings in which like reference numerals refer to like parts, and in which:  
       FIG. 1  is a view of a system for measuring relative hydration in accordance with this invention;  
       FIG. 2  is an enlarged version of a display shown in  FIG. 1 ;  
       FIG. 3  is a block diagram that depicts the organization of the system shown in  FIG. 1 ; and  
       FIG. 4  is a flow chart depicting the operation of a control shown in  FIG. 3 . 
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS  
       FIG. 1  depicts one embodiment  10  of a system constructed in accordance with this invention that includes a data processing system in the form of a laptop computer  11  with a keyboard  12  and a screen  13 . The data processing system  11  includes a PCMCIA card  14  that can be a commercially available four-port asynchronous PCMCIA card that provides four inputs wherein each input can be treated as a serial port (e. g., a COM port).  
       FIG. 1  depicts four dermal phase meter (DPM) units  15  through  18  that comprise four probes  15 A,  16 A,  17 A and  18 A and corresponding interfaces  15 B,  16 B,  17 B and  18 B. Cables  20 ,  21 ,  22  and  23  connect each of the DPM units  15  through  18  to separate input channels of the PCMCIA card  14 .  FIG. 1  further defines the corresponding channels as channels A, B, C and D for the DPM units  15  through  18 , respectively. The data processing system  11  produces a display on the screen  13  that dynamically presents measurement results.  
      Referring to  FIG. 2 , the display  24  that appears on the screen  13  in  FIG. 1  has one vertical area or column for each channel. That is, vertical areas  25 ,  26 ,  27  and  28  correspond to channels A through D, respectively that, in turn, may correspond to DPM units  15  through  18 , respectively. As each vertical area is identical, only the vertical area for channel A, that is vertical area  25 , is described in detail. This vertical channel  25  includes, as particularly shown in  FIG. 2 , a numerical display  30  that depicts a number. That number is the instantaneous value of measurement and is an indicator of the relative hydration of the skin being monitored by the corresponding DPM unit, such as the DPM unit  15 . A graphical display  31  in a form of a dynamic bar graph display graphically depicts this level.  
      A status display  32  indicates whether sampling is continuing or whether the interval for which the test is being applied has been completed. In the particular display shown in  FIG. 2 , channels A, B and D are in the sampling mode while the sampling has been completed for channel C as depicted by the status display  33  in the vertical area  27  containing the message “OK”.  
      It will now be apparent that the information provided by the display  24  is a central display of four different measurements that can be taken concurrently. As previously indicated, these can represent the use of multiple DPM units in a single patient, or a single DPM unit on multiple patients or multiple DPM units on multiple patients.  
       FIG. 3  depicts one implementation of the data processing system  11  that includes a memory  34  organized with an input data buffer  35 , a concordance/status table  36  and a control  37 . This is a functional organization of the data processing system. The actual implementation may be varied depending upon the various capabilities and processes being run by the data processing system  11 .  FIG. 3  depicts the DPM units  15  through  18  as inputs through the PCMCIA card  14  and the display  13  in the form of the screen  24  shown in  FIGS. 1 and 2  as an output.  
      Still referring to  FIG. 3 , the input data buffer will receive data readings and any other selected information from the DPM units. In one embodiment the input data buffer can be partitioned into areas dedicated to each specific DPM unit and channel. In other embodiments the input data could be tagged with a channel marker or identifier thereby to allow the data to be stored in more random fashion or in an interlace fashion. Depending upon the particular application, the input data buffer could store all the readings. Alternately, the data could be stored in a separate file so that input data buffer  35  would be available for subsequent diagnoses.  
      The concordance/status table  36  establishes the correspondence or concordance between a probe, such as any one of the DPM units  15  through  18 , and a channel represented by a COM port. This table allows any arbitrary positioning of the probes of each DPM unit with respect to channels. As previously indicated, there are multiple states attained during a measurement. The status of each measurement can also be maintained in the concordance status table  36  or as a separate table.  
      The control  37  manages the operation of the data processing system for the purposes of implementing this invention.  FIG. 4  depicts one embodiment as a series of steps defining one functional implementation of the control  37  that has been found to be advantageous for implementing this invention. Referring to  FIG. 4 , steps  40  and  41  represent the processes for initializing a system. Step  40  specifically establishes the input data buffer as a work space within the memory  34  and establishes the concordance status table  36  including the correspondences between the ports and the DPM units. Step  40  also initializes the status for each DPM unit to an initial, or “READY”, state. Step  41  then selects a first probe or DPM unit.  
      Once the initialization is complete, the operation of  FIG. 4  enters a loop so the probes are polled in an iteration function. Step  42  determines whether the probe is in fact performing a test, i.e., is in a “testing” mode. If testing is not underway, step  42  transfers control to step  43  that, during an initial iteration, will transfer control to step  44  to select a next channel and a corresponding DPM unit and then transfer control back to step  42 . This effectively disables the remainder of the loop in  FIG. 4 . Step  43  performs this function because none of the DPM units will indicate an “OK” status at this initial iteration.  
      When a channel is in the testing mode, control transfers to step  45  that tests the status. Step  46  changes the status from a READY status to SAMPLING status during an initial iteration during the testing mode. Step  46  then transfers to step  47 . During subsequent iterations step  45  transfers control directly to step  47  because the corresponding DPM unit will be in a SAMPLING mode.  
      Step  47  reads the data from the selected DPM unit and records the reading in the input data buffer  35  of the memory  34 . Step  50  updates the display for the selected DPM unit thereby displaying the READY message for the DPM unit on a corresponding display.  
      Typically during a patient diagnosis readings are accumulated for a selected time interval. Step  51  determines the time that remains for such a testing interval for the selected DPM unit. If additional time remains, step  52  transfers control to step  43 . If the status for all the DPM units has shifted to an “OK” state, no additional recording is needed so step  43  transfers control to step  53  and terminates the measurement.  
      However, if at least one DPM unit is still in a sampling state, control passes from step  43  to step  44  to select a next active channel before control transfers back to step  42 . If a selected channel has completed the test, step  43  transfers directly to step  44 .  
      When the interval for testing has been completed, step  52  transfers control to step  54  to change the status for that DPM unit to “OK” to indicate completion of the test with that DPM unit. Step  54  also updates the status display for the corresponding DPM unit.  
      As will now be apparent, the configuration shown in  FIG. 3  taken in conjunction with the functional diagram of  FIG. 4  depicts one embodiment of a system that allows concurrent relative hydration measurements from multiple DPM units. More specifically, the procedure of  FIG. 4  obtains data sequentially from each of the DPM units during the operation of the iterative loop. During each operation the display  24  is updated. Consequently the display  24  provides a “real time” display for each DPM unit being monitored.  
      This invention has been disclosed in terms of certain embodiments. It will be apparent that many modifications can be made to the disclosed apparatus without departing from the invention. Therefore, it is the intent of the appended claims to cover all such variations and modifications as come within the true spirit and scope of this invention.