Abstract:
User interfaces for medical perfusion systems that provide oxygenation, filleting, and recirculation of blood in connection with various medical procedures are provided. In particular, methods of displaying and communicating a desired target flow rate and cardiac index during cardiopulmonary bypass surgeries are provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to U.S. Provisional Application No. 60/905,747, filed Mar. 8, 2007, the entire contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is directed to user interfaces for medical perfusion systems that provide oxygenation, filtering, and recirculation of blood in connection with various medical procedures. In particular, the present invention is directed to methods of displaying and communicating a desired target flow and cardiac index during cardiopulmonary bypass surgeries. 
       BACKGROUND 
       [0003]    Cardiac index is a tool often used by healthcare providers such as perfusionists. Cardiac index is a cardiodynamic measure based on cardiac output, which is the amount of blood pumped by the heart per unit time, measured in liters per minute (l/min). The cardiac output can also be thought of as the amount of blood the heart pumps through the circulatory system in a minute. To provide the cardiac index, cardiac output is in to a patient&#39;s body size by dividing the cardiac output by the body surface area (BSA) of the patent. Thus, the cardiac index is typically provided as (l/min)/m 2 . There are several algorithms to calculate a patient&#39;s body surface area, such as DuBois, Boyd and infant algorithms, for example. Typically, these algorithms are provided in large tables in reference books that can be utilized by the appropriate health care provider. Target cardiac flow rates are typically calculated by perfusionists using a combination of a body surface area equation and desired cardiac index values. 
       SUMMARY 
       [0004]    The present in provides methods of displaying and communicating a desired cardiac index during cardiopulmonary bypass surgeries. Cardiac index is a calculated value based on a patient blood flow and body surface area calculation. The present invention also preferably provides indicators or indicia on a flow display to communicate a visual or tactile indication of a desired flow rate to achieve a desired cardiac index. The present invention automates the calculation of target flow and supplies the perfusionist with a real-time indication of actual cardiac index and a graphical indicator of target flow versus current cardiac flow. The present invention assists the user in achieving desired cardiac index during cardiopulmonary bypass. The combination of automated calculation, real-time display of actual cardiac index and display of target cardiac flow on a flow graph significantly simplifies the task of managing patient blood flow to achieve a desired cardiac index. 
         [0005]    In an aspect of the present invention a method of graphically displaying target blood flow rate on a display screen of a user interface during cardiopulmonary bypass surgery is provided. The method comprises the steps of providing patient data including height, weight, and a desired cardiac index to the user interface, display a first graphical indicator of actual blood flow rate in real time on the display screen, calculating target blood flow rate with the user interface, wherein the target blood flow rate is at least partially based on the patient data, and displaying a second graphical indicator of the calculated target blood flow rate on the display screen. 
         [0006]    In another aspect of the present invention, a user interface for graphically providing a target blood flow rate during cardiopulmonary bypass surgery is provided. The user interface comprises a display screen, a first graphical indicator of actual real time blood flow rate displayed on the display screen, a second graphical indicator of target blood flow rate displayed on the display screen, wherein the target blood flow rate is based on a desired cardiac index, and as numerical value of actual real time cardiac index displayed on the display screen. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate several aspects of the invention and together with description of the embodiments serve to explain the principles of the invention. A brief description of the drawings is as follows: 
           [0008]      FIG. 1  is a perspective view of an exemplary pump console according to an aspect of the present invention showing a user interface and a base unit. 
           [0009]      FIG. 2  is a schematic block diagram of the pump console of  FIG. 1 . 
           [0010]      FIG. 3  is a schematic diagram of a safety module that can he used with the base unit according to an aspect of the present invention. 
           [0011]      FIG. 4  is an exemplary main screen of a user interface in accordance with the present invention. 
           [0012]      FIG. 5  is an exemplary settings screen of a user interface in accordance with the present invention. 
           [0013]      FIG. 6  is a flow chart showing an exemplary process for determining and displaying target flow in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]      FIG. 1  is an exemplary perspective View and  FIG. 2  is a schematic block diagram of a pump console  10  in accordance with the present invention. As shown, the pump console  10  comprises two primary components, including a base unit  12  and a user interface  14  that can communicate via communication link  13 . The pump console  10  may comprise a stand-alone centrifugal pump control system or it may comprise an add-on module to commercially available heart-lung machines or blood pumps. The base unit  12  provides functionality for controlling pump speed, monitoring flow/pressure, battery backup, and providing communications to the user interface  14 , for example. The user interface  14  includes a display  16  and user controls for operating and/or interfacing with the user interface  14 . Display  16  preferably comprises a touch display/screen or other display device that allows input to be provided to an icon displayed on the screen by touching, contacting, or otherwise identifying the icon. Components of the base unit  12  and/or user interface  14  preferably comprise microcontrollers that provide communications through an asynchronous serial interface (RS232) or suitable communications protocol. 
         [0015]    As illustrated, the base unit  12  comprises plural functional modules including a system controller module  18 , motion/pressure module  20 , flow module  22 , and safety module  24 . The safety module  24  is schematically shown in further detail in  FIG. 3  and preferably comprises a safety module bus interface  41 , system bus interface  26 , watchdog timer  28 , and motor controller servo interface  30 , which motor controller includes speed control input  39  and speed control output  37 . The safety module  24  also preferably includes interfaces to safety systems such as a bubble detector interface  32 , level sensor interface(s)  34  and an arterial clamp interface  36 , which comprise inputs  31 ,  33 , and  35 , respectively. The bubble detector interface  32  provides an alarm to the operator when it detects the presence of bubbles or gross air in the tubing of the flow circuit. The level sensor interface(s)  34  provide an alarm or alert to the operator preferably based upon two separate level detectors placed on the patient blood reservoir. The arterial clamp interface  36  provides automated arterial line occlusion in the event of retrograde flow as determined by operator setup. 
         [0016]      FIG. 4  illustrates an exemplary main screen  38  for the user interface  14  in accordance with the present invention. In use, main screen  38 , as well as any other screen or screens of the user interface  14 , are displayed on display  16  and are preferably capable of receiving touch inputs such as with a finger or appropriate stylus. Main screen  38  is preferably configured to display information related to operating parameters such as alert and alarm status, blood flow and pump speed, line pressure, user configurable timers, safety systems (if installed), and power status, for example. 
         [0017]    Main screen  38  includes a flow display portion  50  that includes a flow gauge  52  that provides flow graphically, a first readout  54  that provides a numeric indication of blood flow, a low flow alert marker  56 , a high flow alert marker  58 , a second readout  60  that provides a numeric indication of cardiac index, and a target flow bar  62 . The flow gauge  52 , first readout  54 , and second readout  60  each provide real time actual dynamic information regarding flow conditions. The low flow alert marker  56  and the high flow alert marker  58  are set by the user and trigger alarms that alert the user of the occurrence of low or high flow conditions. The target flow bar  62  represents the nominal rate of flow needed to achieve a desired cardiac index for a specific patient. It is displayed on the main screen  38  as a vertical green marker on the flow gauge  52 . 
         [0018]    In  FIG. 5 , an exemplary settings screen  40  is illustrated. Settings screen  40  provides the capability to set parameters such as blood flow range and upper/lower alert/alarm limits, target blood flow rate with cardiac index and height/weight calculator, pressure transducer zeroing and upper/lower alert/alarm limits, plural timer presets, and screen backlight intensity, for example. These settings can be adjusted by the operator by lightly touching or otherwise contacting a corresponding area on a screen. In many cases, this adjustment can be accomplished by contacting the up/down arrows associated with that particular parameter, for example. Settings screen  40  includes scale settings  64  for setting the scale of the flow gauge  52  of the main screen  38 , a to flow setting  66  for setting the low flow alert marker  56  of the flow gauge  52 , a high flow setting  68  for setting the high flow alert marker of the flow gauge  52 , and a flow readout  70  that displays real tune actual flow rate. Settings screen  40  also includes as body height setting  72 , a body weight setting  74 , a cardiac index setting  76 , a body surface area algorithm setting  78 , and a calculated target flow readout  80 . 
         [0019]    Settings screen  40  is used to calculate a target flow rate needed to achieve a desired cardiac index based on inputs entered into the settings screen  40 . An exemplary process for calculating target flow is schematically illustrated in the flow chart of  FIG. 6 . Patient height, weight, and a desired cardiac index are entered onto the settings screen  40  by adjusting the corresponding settings. The user also selects the desired body surface area algorithm such as the DuBois algorithm, Boyd algorithm, infant algorithm or other known body surface area algorithms. The DuBois algorithm provides body surface area in square meters by taking 0.007184×height (cm) 0.725 ×weight (kg) 0.425 . The Boyd algorithm provides body surface area in square meters by taking 0.0003207×height (cm) 0.3 ×weight (gm) [0.7285−(0.0188×Log (gm)] . The infant algorithm provides body surface area in square meters by taking 0.024265×height (cm) 0.3964 ×weight (kg) 0.5378 . The settings screen  40  than displays target flow at the target flow readout  80  on the settings screen. This same target flow is also displayed on main screen  38  as target flow bar  62 , which is preferably a vertical green bar overlayed on the flow gauge  52  as illustrated. Although a green bar is described herein because the color green often signifies a “go” or positive situation, it is possible for the target flow bar  62  to be any desired color, where this color may optionally be selectable by the user. In any case, the color of the target flow bar  62  can be visually distinct from other surrounding colors on the main screen  38 , or the color can be relatively similar to the colors of the items that are near to it. The present invention this advantageously automates the calculation of target flow and provides the user with a real-time indication of actual cardiac index and a graphical indicator of target flow versus current cardiac flow. Such a display assists the user in achieving desired cardiac index during cardiopulmonary bypass because it eliminates hand calculation while providing a simple, real-time visual indicator of the target blood flow. The combination of automated calculation, real-time display of actual cardiac index and display of target cardiac flow on a flow graph significantly simplifies the task of managing patient blood flow to achieve a desired cardiac index. 
         [0020]    The present invention has now been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is hereby incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Thus, the scope of the present invention should not be limited to the structures described herein, but only by the structures described by the language of the claims and the equivalents of those structures.