METHOD OF DISPLAYING MULTIPLE NON-INTERACTING LAYERS OF PATIENT DATA USING A SINGLE PLANE VIDEO SCREEN

Abstract: A method and apparatus of displaying multiple layers of patient data, including waveform data and background data, using a single plane video monitor is claimed. A patient waveform is generated on the display of a video monitor. A background display data array is generated for producing a background display on the video monitor. At least a portion of the background display data array is copied to the video monitor such that the background display is regenerated at substantially the same time as the patient waveform is generated on the video monitor.

Description: WO 00/42913 PCTtUSOO/00463 METHOD OF DISPLAYING MULTIPLE NON-INTERACTING LAYERS OF PATIENT DATA USING A SINGLE PLANE VIDEO SCREEN RELATED APPLICATIONS This application claims the benefit under 37 C.F.R. §119 of prior filed, co- pending Provisional Application No. 60/072,248, filed on January 23, 1998. BACKGROUND OF THE INVENTION The invention relates to a method and apparatus for displaying patient data on a video monitor. More particularly, the invention relates to a method and apparatus for displaying multiple layers of patient data using a single plane video monitor. Video monitors generate images on a cathode ray tube (CRT) or a liquid crystal display (LCD) by energizing one or more pixels on the CRT or LCD to generate light visible to the user of the monitor. A line, for example, is represented by illuminating a series of adjacent pixels. Pixels are the fundamental building blocks from which all computer graphics are created. A pixel is the smallest possible dot that can be represented on a given video monitor. The display of real-time patient monitoring data is divided into two forms. The first is graphical data, such as waveforms, which consist of real-time plots of physiological measurements taken from various sensors. The second is textual information, consisting of general information such as the patient's name, alarm indicators, labels, units, and numerical measurements, graduation marks, messages or other parameters. Typical prior art display products display both graphical and textual data on the same overlapping display space. Waveform data constantly moves across the screen, either by scrolling or by use of an eraser bar mechanism. Textual data, however, is often placed in the same position on the screen and does not frequently change. As a result, graphical and textual data may physically overlap each other. Display of graphical and textual data as overlapped data is typically accomplished using dual-plane hardware. The first plane is dedicated to the moving waveform plots. The second plane is used for textual information. Either plane of information is independently updated without concern of destroying the information of the other plane. The two resulting images are then transparently merged in the video hardware. Standard PC hardware does not typically support dual-plane video hardware. Thus, a solution is needed to display overlapping information using single-plane hardware in an organized, efficient and effective manner. » In a single-plane hardware system, a problem encountered when displaying overlapping information is that when new information is written onto the screen, the new information permanently alters the previous information on the screen. In the case of waveform data, depending on the algorithm used, the new waveform information will appear to go either under, over, or blend in with textual information. Thus, as the eraser bar moves across an area, the erasing of the old waveform blanks pixels of the old waveform and destroys the textual information on the screen. A typical method to erase old data or lines on the display is to redraw the old data in the same color as the background. However, redrawing the old waveform in same color as the background leaves holes in the textual information where the waveform overlapped the textual information. It is possible to redraw the text onto the screen, however, the process of erasing and redrawing text is highly noticeable, uses significant CPU time, and gives the appearance of the screen flickering. Also, the text may appear to "jump" from behind the waveform to in front of the waveform as the textual information is rewritten onto the video monitor. Another prior art approach used is to erase all of the data in the eraser bar area and redraw all of the textual and fixed position information. However, such an approach also uses significant CPU time and causes screen flickering. Another method for drawing and updating graphical information overlapping textual information is to use an "exclusive OR" (XOR) approach. On a monochrome screen, old waveform or textual data is erased by toggling the bits on or off. Accordingly, pixels on the screen that were black turn white and pixels on the screen that were white turn black. A problem occurs in that, whenever two white lines cross one another, the crossing point turns black when erased. Thus, a "hole" is formed in the non-erased line. Further, the XOR approach does not work well with color monitors using colored graphics. Since the XOR approach only accommodates a toggle situation, and the use of color graphics allows a pixel to be more than just black or white, using an XOR approach for color graphics may turn a pixel to any random color. Another common method is to scroll the waveform from right to left on the screen. A block transfer may be used to shift an area of the screen, or window, some distance to the left, and then draw the new data to the right. In this manner, the fixed textual information shifts along with the waveform. SUMMARY OF THE INVENTION Accordingly, the invention provides a method and apparatus of displaying multiple layers of patient data using a single plane video monitor in a patient monitoring system. The patient monitoring system includes a central processor for receiving patient data and for generating display signals. The video monitor receives the display signals and generates a video display including patient data waveforms and background information. The video display is updated with new patient data waveform information without erasing the background information. Specifically, patient waveforms or waveform data and patient textual data are simultaneously displayed on the video monitor. The patient waveform is generated directly on the display of the video monitor, and the waveform is constantly updated as new patient data is acquired. A background display data array (comprising the textual data) is generated for producing the textual data display on the video monitor. At substantially the same time as the patient waveform is updated on the video monitor at least a portion of the background display data array is copied to the video monitor to create the illusion of an eraser bar and to regenerate the background display data within the area of the eraser bar. In this way, an eraser bar effectively precedes the new waveform across the screen to "erase" the old waveform data without affecting the background information. It is an advantage of the invention to provide a method and apparatus to display multiple layers of patient data using a single plane video monitor. It is another advantage of the invention to provide a method and apparatus to update waveform and textual information without visible flickering on the video display. It is another advantage of the invention to provide a method and apparatus to update textual information without erasing the waveform. Other features and advantages of the invention are set forth in the following drawings, detailed description and claims. DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a patient monitoring system according to the invention. FIG. 2 is a diagram illustrating a block transfer of information from the background data display array to the video monitor. FIG. 3 is a flowchart illustrating the method of updating the waveform without erasing the background textual information. FIG. 4 is a flowchart illustrating the updating of background textual information without erasing the waveform. Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and are carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for purpose of description and should not be regarded as limiting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a patient monitoring system 10 embodying the invention. The patient monitoring system 10 acquires and displays physiological patient data. While the monitoring system 10 can be used in connection with monitoring any kind of physiological parameter, in the preferred embodiment, the monitoring system 10 is for monitoring a patient's electrical cardiac activity and blood pressure. Monitoring system 10 is coupled to the patient 14 by an array of sensors or transducers which may include, for example, electrodes 18 mounted on the patient's chest and arm for electrocardiogram testing. Hereinafter, the term sensor and transducer will be used synonymously, and each term will be defined as including the subject matter of the other term. The patient monitoring system 10 includes a computer 20 connected to the sensors 18 and a video display monitor 30 connected to the computer. The computer includes an analog-to-digital converter (A/D) 22 and a central processing unit (CPU) 26. The signals derived from the sensors are converted from analog form to digital form by A/D 22 and provided to the CPU 26. CPU 26 prepares the data for display on the video monitor 30. The video monitor 30 is a conventional computer style display monitor having a generally rectangular cathode ray tube (CRT). FIG. 2 illustrates how patient information is displayed on the video monitor 30. The screen of the video monitor 30 is divided into windows 31, each window having a textual information region 32 and a waveform region 36. The textual information region 32 and the waveform region 36 can be viewed as planes of data that overlap in areas of the screen of the video monitor 30. For each textual information region 32 generated, an internal background data array or background (BG) bitmap 40 is also generated, having the same dimensions as the window 31. The BG bitmap 40 serves as an intermediate step for textual information to be drawn on the window 31, and is simply a two-dimensional (X-Y) data array. FIG. 3 illustrates the method of the present invention. While other embodiments are possible, in the preferred embodiment, the method is effected by software that is stored in or programmed into CPU 26. Background and other textual information is written onto the BG bitmap 40 (60). The X-Y coordinates for the background and textual information are stored in a two-dimensional data array. A block of data 44 corresponding to a portion of the screen is defined (64). As shown in FIG. 2, the block of data 44 is typically a column of data which, when displayed, has a left edge 48, a right edge 52 and a width (W) between the left edge 48 and the right edge 52. The block of data 44 may vary in size depending, in part, upon the desired sweep rate of the eraser bar 48. In the preferred embodiment, the block of data, when displayed, has a width "W" of approximately 5 mm. The defined block 44 of the BG bitmap 40 is then copied to the display of the video monitor (68) to overwrite old waveform data (thereby creating an "eraser bar" on the display) and, at the same time, preserve the textual information and background data. At approximately the same time, new waveform data is plotted directly onto the video display (72) at approximately the left edge 48 of the block of data 44. Specifically, the new waveform data is plotted about two pixels to the left of the left edge 48. After the waveform is plotted on the screen, the next block of data is defined (76). In the preferred embodiment, the next block of data is offset to the right of the right edge 52 of the current block of data by a predetermined amount so that, as the software cycles through the acts specified herein, the position on the display of the defined block, i.e., the eraser bar, "moves" across the display from left to right. The defined block appears to move across the display due to the incrementing of the X- coordinate of the two-dimensional data array of the BG bitmap 40. For example, if the current defined block has X-coordinates ranging from XI to XI 6, the next defined block has X-coordinates ranging from X2-X 17. and so on. The next block 44 is then copied from the BG bitmap 40 to the display monitor (80). Waveform data acquired between act 72 and act 80 is then plotted onto the display monitor (84) at approximately the left edge 48 of the next block 44. After the new waveform is plotted, the next block of data is defined again (76), and the loop continues. In a preferred embodiment, about 60 blocks are defined per second (i.e., the data is displayed at a 60 Hertz rate). The total number of blocks is dependent on the size of the window(s) 31 on the screen of the video display, the update rate of the waveform, and the sweep rate. The update rate is preferably about 60 Hertz, although it is contemplated that other rates can be used. The sweep rate is preferably in the range of about 12.5 millimeters/second (mm/sec) to about 50 mm sec. In a preferred embodiment, a sweep rate of 25 mm sec is used. Stated differently, textual or "background" information is not immediately drawn onto the window 31. Rather, the new data is first drawn to the BG bitmap 40 and then copied, or block transferred to the window 31. When the eraser bar 48 passes an area of the window 31 , rather than blanking out an area of the display, the appropriate area of the BG bitmap is copied onto the window 31 with an eraser bar passing across the window to erase the oldest waveform data just to the right of the new waveform data. From the user's view, the textual region 32 appears to remain in place while the waveform region 36 is updated directly onto the window 31. By using the BG bitmap 40, there is no observable flicker on the screen of the video monitor 30 since the textual region 32 is not first erased and then redrawn, but simply copied onto the window 31. In another embodiment (not shown), instead of transferring an additional 5 mm of data from the BG bitmap 40, a new column of data along the right edge of the block o data 44 is defined as the eraser bar moves to the right. The left most column of data of the current defined block is excluded from the next defined block as the eraser bar moves to the right. The column immediately to the right of the right most column of data of the current defined block is included in the next defined block as the eraser bar moves to the right. FIG. 4 illustrates a method of updating background textual information that has changed in a given position in window 31 between each pass of the eraser bar past that position. The background textual information is preferably updated asynchronously as needed. Accordingly, a block of data (100) is defined corresponding to the position in window 31 where the textual background information has changed. The new textual information is then written on the background data array (104). The new textual information is then copied onto the display screen (108) in a block transfer of the defined block. If the changing text or background information is in a defined block that includes waveform information, then the block transfer will erase that waveform and the waveform must be regenerated. Therefore, after the new textual information is written onto the screen, the current waveform is rewritten onto the screen (112). More specifically, a list of all the X-Y coordinates of the waveform are stored in memory as they are drawn onto the display. When a waveform needs to be redrawn onto the screen, the memory is searched to find the appropriate set of X-Y coordinates for the defined block of data. Thus, the waveform is redrawn on the same location from which the waveform was erased. Various features and advantages of the invention are set forth in the following claims.

Claims: CLAIMS 1. A method of displaying multiple layers of patient data, including waveform data and background data, using a single plane video monitor, the method comprising the acts of: generating a patient waveform on the display of the video monitor; generating a background display data array for producing a background display on the video monitor; and copying at least a portion of the background display data array to the video monitor to regenerate the background display at substantially the same time as the patient waveform is generated on the video monitor. 2. The method as set forth in claim 1 , wherein the act of generating a patient waveform occurs at a predetermined sweep rate. 3. The method as set forth in claim 2, wherein the sweep rate is about 25 millimeters per second. 4. The method as set forth in claim 1 , wherein the act of generating a patient waveform occurs at a predetermined update rate. 5. The method as set forth in claim 4, wherein the update rate is about 60 Hertz. 6. The method as set forth in claim 1, wherein the act of generating the background display data array includes the act of subdividing the background display data array into a plurality of blocks, defining a first block, and block transferring background display data from the first block to the video monitor to overwrite a portion of the patient waveform without erasing the background display thereby creating an eraser bar. 7. The method as set forth in claim 6, wherein each block has a left edge and wherein the act of generating a patient waveform includes the act of displaying waveform data at approximately the left edge of each block after each respective block transfer. 8. The method as set forth in claim 7, further comprising the act of defining the next block adjacent and to the right of the first block and block transferring background display data from the next block to the video monitor after block transferring background display data from the first block. 9. The method as set forth in claim 6, wherein each block has a width. 10. The method as set forth in claim 9, wherein the width is greater than 0.416 millimeters. 11. The method as set forth in claim 1, wherein each block of the background display data array has a left edge and wherein the act of generating the patient waveform on the display of the video monitor includes the act of displaying the most recent waveform data at approximately the left edge of the most recent block transferred. 12. A patient monitoring system comprising: a central processor for receiving patient data and for generating therefrom display signals; a video monitor for receiving the display signals and generating therefrom a video display including at least one patient data waveform and background information; and means for updating the video display of the patient data waveforms without erasing the background information. 13. The system as set forth in claim 11, the means for updating includes software for controlling the function of the central processor. 14. The system as set forth in claim 12, further comprising means for updating the video display of the background information without erasing the patient data waveform. 15. The system as set forth in claim 12, wherein the patient data waveform is written directly onto the video monitor. 16. The system as set forth in claim 12, further comprising a background display data array, wherein the background display data array contains background information. 17. The system as set forth in claim 16, wherein at least a portion of the background display data array is copied onto the video monitor. 18. The system as set forth in claim 17, wherein each portion of the background display data array has a width. 19. The system as set forth in claim 18, wherein each portion of the background display data array has a width greater than about 0.416 millimeters. 20. The system as set forth in claim 19, wherein each portion of the background display data array has a width of about 5 millimeters. 21. The system as set forth in claim 12, wherein the display signals generated by the central processor are displayed on the video monitor at a predetermined sweep rate. 22. The system as set forth in claim 21 , wherein the sweep rate is about 25 millimeters per second. 23. The system as set forth in claim 12, wherein the display signals generated by the central processor are displayed on the video monitor at a predetermined update rate. 24. the system as set forth in claim 23, wherein the update rate is about 60 Hertz. 25. A method of updating textual information on a single plane video monitor, the method comprising the acts of: generating a patient waveform on the display of the video monitor; generating a background display data array for producing a background display on the video monitor; copying at least a portion of the background display data array to the video monitor; and regenerating the patient waveform onto the display of the video monitor. 26. The system as set forth in claim 25, wherein coordinates of the patient waveform are stored in memory. 27. The system as set forth in claim 25, wherein the act of regenerating the patient waveform includes the acts of defining a portion of the waveform corresponding to the portion of the background display data array, retrieving the coordinates of the portion of the patient waveform from memory and plotting the portion of the waveform on the display monitor.

Inventors: RADEZTSKY JOHN H, RADEZTSKY, JOHN, H.
Applicants: GE MARQUETTE MEDICAL SYS INC, GE MARQUETTE MEDICAL SYSTEMS, INC.
Application year: 2000
Main classification: A61B5
IPC codes: A61B5, G09G5