Abstract:
A means, apparatus, and system for reducing the net fluid volume deficiency in a patient during a medical treatment process. The invention seeks to modify a batch-type process to achieve the efficiency of a continuous process by precisely measuring the net change in fluid volume within a patient and dispensing the appropriate amount of biological fluids to a patient via IV lines or by recycling blood components into the patient while biological fluids are being withdrawn. The apparatus includes subcomponent lines, valving means, pumping means, load cells, storage chambers, a centrifuge, and centrifuge bowls. The system may have numerous feedback components to accurately measure and control the flow rates and amount of fluid dispensed to a patient.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to systems and apparatus that facilitate a precise process by which a batch-type process may achieve the efficiency of a continuous process, reducing the net fluid volume deficiency in a patient during a medical treatment process where fluid must be removed from a patient. 
     2. Description of the Prior Art 
     Growth in technology has allowed the medical profession to measure the precise natural fluid ratios found in the human body. Consequently, preserving these ratios during medical treatments is desirable, particularity in treatments such as photophoresis, which is discussed and claimed in U.S. Pat. No. 5,984,887 and U.S. application Ser. No. 08/832,219, which are expressly incorporated herein by reference. By way of example, a photophoresis process such as the UVAR® process (Therakos, Inc., West Chester, Pa.) removes blood from a patient, separates the buffy coat from the plasma and red blood cells and replaces the biological fluids in a batch process. When blood is removed from the patient, however, a volume deficit is created within the patient. This volume deficit is particularly detrimental in small children and the elderly or in patients that suffer from certain illnesses or diseases because their blood has a higher percentage of plasma relative to the cellular components. This volume imbalance requires that a greater volume of blood be drawn from the patient to obtain the required amount of red blood cells. This especially impacts infants and sick children who may have low body weight and hemocrit percentages of 25-30% which is significantly lower than the normal average of 45%. The need thus arose to be able to detect small incremental changes in natural fluid ratios within the body and to use these measurements to create a process by which the net fluid volume collected or removed from a patient may be reduced during-a medical treatment process. 
     SUMMARY OF THE INVENTION 
     The objects of the present invention include providing systems and apparatus for increasing the efficiency of a continuous process through a modified batch-type process, using a biological fluid and one or more centrifuge bowls to reduce the net fluid volume deficiency in a patient during a medical treatment process. An additional object may be to alleviate the difficulty in finding multiple proper insertion sites by requiring only one insertion site. 
     The present invention solves the inadequacies of the prior art by being able to detect small incremental changes in fluid volumes and by achieving the results of a continuous process. An efficient batch process or other Latham bowl batch-type technique is used to simulate a continuous process by which fluid is continually added and removed from a patient to account for any net fluid volume deficiency at any point in time within a medical treatment process and yet achieve higher separation and treatment efficiencies than, for example, a continuous flow separation treatment. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the present invention may include, in one or more embodiments, a method, apparatus, and system, and in a preferred embodiment an automated system, for reducing the net fluid volume change of a biological fluid within a patient during a treatment cycle by determining the net fluid volume change in the patient, adjusting the net fluid volume deficiency in the patient to obtain a minimal net fluid volume deficiency, and maintaining a minimal net fluid volume deficiency. 
     Additionally, determining the net fluid volume deficiency may be achieved through the use of a load cell, designed to measure the change in weight of a storage chamber. Adjusting the net fluid volume deficiency to obtain a minimal net fluid volume deficiency may involve increasing or decreasing the amount of biological fluid returned to a patient through use of a valving means and/or a pumping means to adjust the flow of a biological fluid. Maintaining the net fluid volume deficiency may also involve using one or more of the following: a load cell, pumping means, and valving means. Maintaining a minimal net fluid volume deficiency may also involve monitoring the net fluid volume deficiency. 
     The automation of the system may be accomplished by a computer system. Such a system may comprise a computer processor with memory which is coupled to the computer processor, and a computer process that is stored in the memory that includes obtainers and controllers configured to obtain, adjust and maintain a minimal net fluid volume deficiency. The obtainer may be associated with a load cell and the controllers may be associated with valving means and/or pumping means designed to adjust the minimum net fluid volume deficiency. The pumping means may be designed to increase or decrease the flow of biological fluids to be delivered to a patient. 
     Alternatively, the system for determining, adjusting, and maintaining the minimal net fluid volume deficiency may be a controller that communicates with the load cell, valving means, and pumping means. This controller may be a computer that controls the load cell, valving means, and pumping means. 
     In an alternative embodiment, the biological fluid may be primer fluid. Preferably, the primer fluid may contain red blood cells, plasma, or red blood cells and plasma. 
     It is understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings illustrate several embodiments of the invention and together with the description serve to explain the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of a specific embodiment of a low extracorporeal volume system. 
     FIG. 2 is a schematic diagram of an alternative embodiment of a low extracorporeal volume system that utilizes multiple centrifuge bowls. 
     FIG. 3 is a schematic diagram of an alternative embodiment of a low extracorporeal volume system in a one-needle configuration. 
     FIG. 4 is a schematic diagram of an alternative embodiment of a low extracorporeal volume system that utilizes multiple centrifuge bowls in a one-needle configuration. 
     FIG. 5 is a flowchart diagram of the blood removal and transportation process for use in low extracorporeal volume systems. 
     FIG. 6 is a flowchart diagram of the priming process for use in low extracorporeal volume systems. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred or exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. 
     In a specific embodiment, the present invention relates to methods, apparatus, and systems that facilitate a process which reduces the net volume of a biological fluid removed from a patient during a medical treatment process. Biological fluids encompass fluids that comprise, exist in, or are used in or delivered to living organisms. Indeed, biological fluids may comprise bodily fluids and their components, such as blood cells, plasma, and other fluids that comprise biological components, including living organisms such as bacteria, cells, or other cellular components. Biological fluids may also comprise whole blood or specific whole blood components, including red blood cells, platelets, white blood cells, and precursor cells. In particular, it may be desirable to remove blood from a patient without creating a volume deficit within the patient in situations where a patient may have low body weight or lower hemocrit percentages than normal. Pumping primer fluid into the patient as blood is removed or recycling the red blood cell and plasma portions of the blood back into the patient reduces the net fluid volume deficiency. The primer fluid may comprise a saline solution, blood components or other biocompatible or sterile fluids with compositions, osmolality, and viscosities similar to those of biological fluids. 
     To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, for example, FIG. 1 depicts a specific embodiment of the invention. The embodiment of the present invention depicted in FIG. 1 comprises a first line  120  connected to a patient  100 . Line  120  may comprise a conventional intravenous (“IV”) line or cannula and associated needle, which is used to remove blood from a patient  100  at first insertion site  101 . The line  120  is preferably in fluid communication with a centrifuge  160  which is preferably operable at a speed of 4800 rpm +/−5%. 
     Additionally, a pumping means  205  may be located on line  120  to assist in drawing blood from patient  100 . This pumping means  205  may be any type of pump, such as, for example, a peristaltic pump or Kamen type pump. Pumping means  205  preferably has a range of 0 to 150 ml/min with flow accuracy of +/−10 ml/min. 
     Blood  110  flows from the patient  100  through line  120  to centrifuge  160 . Centrifuge  160  is located on and is in fluid communication with line  120  and contains a centrifuge bowl  161  that separates the buffy coat from the other components of the blood. The centrifuge bowls are preferably disposable bowls, which are most preferably capable of containing 125 ml of fluid. The buffy coat is transferred from centrifuge bowl  161  and is stored in buffy coat chamber  180 , which is located on and in fluid communication with line  121 , where it awaits photophoresis treatment. Line  121  is preferably made of sterile material, similar to that used for line  120 , and connects line  120  to buffy coat chamber  180 . Buffy coat chamber  180  is preferably a sealed flexible sterile chamber which preferably has associated with it means to add or remove fluids. Plasma  115  flows out of centrifuge  160  into line  130 , which preferably extends from and is in fluid communication with line  120  and is in fluid communication with storage chamber  170 . Both lines  120  and  130  may be made of any type of flexible or rigid tubing (such as medical tubing) or other such device providing a sealed passageway for the flow of fluids into or out of a reservoir of any sort, and which preferably can be disposable and sterilizable. Storage chamber  170  is preferably a flexible sterile chamber which has a means to add or remove fluids, such as for example the red blood cells captured by centrifuge  160 , and stores the separated red blood cells and plasma. Storage chamber  170  may also be used to contain a primer (e.g. blood, packed cells, anti-coagulant, saline, albumin, etc.) that can be pumped by pumping means  200  into the patient  100 . 
     Load cell  175  is associated with storage chamber  170 , associated with line  130 . Load cell  175  can be a strain gauge type load cell or any type of load cell that is designed to weigh volumes of fluid. Load cell  175  is associated with and measures the weight of storage chamber  170  and may provide feedback to control system  300 . Also located on line  130  is valving means  190 . Valving means  190  controls the flow of plasma and red blood cells out of storage chamber  170 . 
     Pumping means  200  is located on and in fluid communication with line  130  and may be any type of pump such as, for example, a peristaltic pump or Kamen type pump that is constructed of appropriate material to pump biological fluids and maintain the sterility of the system and is preferably of a type that allows continuous fluid flow from storage chamber  170  through lines  130 ,  140  and  150  into the patient  100 . The pumping means is preferably used to draw primer fluid from storage chamber  170  and pump primer fluid at the appropriate rate, which is dependant on the amount of fluid needed to reduce the net fluid volume deficiency, into a patient. Alternatively, a continuous flow type pumping means may be used instead of pumping means  200 , such as, for example the inclusion of rigid chambers as disclosed in U.S. Pat. No. 4,573,992, disposed about chambers  170  and  180 . Pumping means  200  preferably has a range of 0 to 150 ml/min with flow accuracy of +/−10 ml/min. Pumping means  200  is adapted to pump primer fluid, including red blood cells and plasma, through line  130  to conduit juncture  145 . 
     Conduit juncture  145  joins lines  130 ,  140  and  150 , is preferably made of a sterile material, similar to that used for lines  120  and  130 , and may be y-shaped. Line  140  is in fluid communication with line  120  and conduit juncture  145 . A valving means  210  which may be, for example, a solenoid valve or any other type of valve capable of maintaining the sterility of bodily fluids, is located on line  140  and controls the flow of blood  110  between lines  120  and line  130  as shown in FIGS. 1 and 2. Line  150  is in fluid communication with conduit juncture  145  and patient  100  and may be made of the same material as lines  130  and  140  and may comprise a conventional IV line or cannula and associated needle that connects to a patient  100  at second insertion site  102 . A valving means  220  is located on line  150  and is in fluid communication with conduit juncture  145  and patient  100 . Valving means  220  controls the flow of fluids (e.g., blood, plasma, red blood cells, or primer fluid) to patient  100 . 
     In a particular embodiment of the present invention, there may be a pause in the process, preferably a very slight pause. This pause occurs if the flow of blood from a patient must be stopped to allow the red blood cells and/or buffy coat to be emptied from a full centrifuge bowl  161  into storage chamber  170  and/or buffy coat chamber  180 , respectively. In an alternative embodiment, the pause in the treatment process caused by emptying the red blood cells in centrifuge bowl  161  into storage chamber  170  may be eliminated by implementing additional centrifuge bowls as illustrated in FIG. 2, which addition allows the flow of blood to continue into the additional centrifuge bowl(s) while first centrifuge bowl  161  is emptied. A valving means  185  is located on line  120  before centrifuge bowl  161  and is used to control the flow of blood  110  into first centrifuge bowl  161 . A second centrifuge bowl  162  is placed in a parallel combination with centrifuge bowl  161  on line  125 . A valving means  186  is located on line  125  before second centrifuge bowl  162  and is used to control the flow of blood  110  into second centrifuge bowl  162 . When first centrifuge bowl  161  is ready to be emptied into storage chamber  170 , valving means  185  shuts, causing blood  110  to flow into line  125 . Blood  110  flows through line  125  into second centrifuge  162 , which then. separates the blood into its components. When second centrifuge bowl  162  is ready to be emptied into storage chamber  170 , valving means  186  shuts and valving means  185  opens, causing blood  110  to flow into first centrifuge bowl  161 . 
     Centrifuge bowls may be emptied in any acceptable means such as, for example, by providing a vacuum whereby the contents of a centrifuge bowl are drawn into a chamber and the contents are replaced by sterile air from another chamber or any other acceptable source. For example, in the system depicted by FIG. 2, sterile air can be provided from either storage chamber  170  or buffy coat chamber  180  and the vacuum could be drawn from the remaining chamber on the centrifuge bowl. An additional conduit or conduits, such as, for example, between storage chamber  170  and first centrifuge bowl  161 , may be provided for an additional or separate path for this flow of air and chamber contents. 
     In yet another alternative embodiment, only one insertion site is needed. This is useful in situations where a small child or elderly person, due to the symptoms and effects of their illness, have weak or collapsed veins that make drawing blood through an IV difficult. As demonstrated in FIG. 3, a one-needle configuration can be used to alleviate the difficulty in finding a proper insertion site. A dual cannula needle, for example, may be used for this embodiment that is in fluid communication with insertion site  101  and line  120 . Blood  110  flows through the first cannula of the IV needle and through line  120  into centrifuge  160 . Once primer fluid is needed to prevent or correct a net volume deficiency within a patient, as indicated by load cell  175 , the system and apparatus work similarly to the embodiment described above, until the fluid passes through pumping means  200 . 
     After the biological fluid flows through pumping means  200 , it continues through line  130 . Valving means  210  is in fluid communication with line  130  and is used to regulate the flow of the fluid back into patient  100 . The fluid enters patient  100  through the second cannula of the IV needle at insertion site  101 . 
     FIG. 4 depicts another alternative embodiment of the present invention which eliminates the pause in the treatment process caused by emptying the red blood cells from centrifuge bowl  161  into storage chamber  170  in the same manner as FIG.  2 . FIG. 4, in contrast to FIG. 2, is in a one-needle configuration, like FIG. 3, which may be used to alleviate the difficulty in finding proper insertion sites. Oftentimes, as a result of an illness, a patient&#39;s veins may be weak or collapsed which may make drawing or distributing blood into the vein difficult. The difficulty in finding a strong vein is increased when more than one vein is needed. 
     FIGS. 5 and 6 are flowchart diagrams that depict the blood removal and transportation portion of an embodiment of the present invention. First, in step  1000 , blood is collected from the patient  100  via the first insertion site  101  and flows into line  120 . If the presence of blood is visually or electronically detected within line  120  in step  1010 , valving means  210  closes in step  1020 . Blood then flows into centrifuge  160  to be separated by centrifuge bowl  161  into the three required components (plasma, red blood cells, and buffy coat) in step  1030 . Plasma  115  preferably automatically flows out of centrifuge  160  into storage chamber  170 . The buffy coat and red blood cells remain in centrifuge bowl  161  until centrifuge bowl  161  is full and the components are manually removed. Upon removal, the buffy coat is emptied into buffy coat chamber  180  where it awaits treatment. The red blood cells are emptied into storage chamber  170 . 
     In step  1040 , load cell  175  measures the weight of storage chamber  170 . Any change in the weight of storage chamber  170  indicates a net volume change within the patient. If the weight of storage chamber  170  changes positively, valving means  190  and  220  are opened in step  1050 . In step  1060 , the fluid contained in storage chamber  170  is pumped according to the incremental change in weight of storage chamber  170 , as shown by load cell  175 , into line  130 . In step  1070 , primer is pumped by pumping means  200  through conduit juncture  145  and valving means  220 , and returns to the patient via line  150  and second insertion-site  102 . If the weight of storage chamber  170  changes negatively, valving means  190  closes and fluid is collected in storage chamber  170  until there is a positive change in the weight of storage chamber  170 , indicating that there may be a net fluid volume deficiency in the patient. 
     The above system mechanisms are preferably operated by a digital control system  300  that provides a means of electronically activating valving means  190 ,  210 ,  220  and pumping means  200  and may also include electronic circuitry and a microprocessor coupled to any necessary indicators and including an input for command control signals. Control system  300  may also receive and transmit data to and from possible pressure indicators, flow indicators, valving means, microprocessors, and any other electronic data transport means and may be configured in various ways depending upon the degree of control and information needed in a particular application. 
     Control system  300  is optionally arranged to monitor the entire process and obtain data regarding the level of fluid dispensed to the patient. The user may then download information for statistical analysis and obtain system diagnostics information for maintenance and repair purposes. This arrangement may include a setup program that allows the user to modify various variables that will be used by the control system in determining net fluid volume deficiency, mechanism calibration, error tolerances, etc. The arrangement may also provide a means to automate or direct a user in the preliminary calibration of any relevant instrumentation. 
     The microprocessor is preferably able to control many treatment parameters simultaneously. Functions that are critical to a medical treatment process are preferably redundantly monitored with back-up circuits. The in-process memory may retain information on treatment parameters in a battery-packed memory to enable the continuation of the medical treatment process in the event of a transient power loss. All communications between control system  300  and the mechanical system are preferably centralized with positive action buttons and an alphanumeric message center. Microprocessor-controlled fluid volumes collected and distributed are preferably clearly displayed. Controls may be arranged so that the medical treatment process phase is visible at a glance. 
     This control system  300  and its operation may be monitored and controlled remotely, including via communication through modem connection by telephone lines or via the internet. Additionally, data related to patient conditions or medical treatment processes may be downloaded for use as direct input for control system  300  via Internet or any other network system connection. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and the practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.