Medical apparatus for extracorporeal treatment of fluid and a process of calculating set flow rates in a medical apparatus for delivery or collection of fluids

Abstract

An apparatus for extracorporeal treatment of fluid and a process of setting up a medical apparatus for the delivery or collection of fluids are disclosed. According to the apparatus and the process, a control unit ( 10 ) is configured calculate set values of two or more of the fluid flow rates by imposing that an emptying time of containers of fresh fluid ( 16, 20, 21, 26 ) and/or a filling time of a waste container is substantially same as, or multiple of the emptying time of one or more of the other containers of fresh fluid.

1 . An apparatus for extracorporeal treatment of fluid comprising:
 a filtration unit having a primary chamber and a secondary chamber separated by a semi-permeable membrane;   a blood withdrawal line connected to an inlet of the primary chamber, and a blood return line connected to an outlet of the primary chamber said blood lines being configured for connection to a patient cardiovascular system;   a blood pump configured to control the flow of blood through the blood lines;   an effluent fluid line connected, at one end thereof, to an outlet of the secondary chamber and at its other end to a waste container;   at least two further fluid lines selected in the group of fluid lines comprising:
 a pre-dilution infusion fluid line connected at one end thereof to the blood withdrawal line and at its other end to a first container of fresh fluid, 
 a post-dilution infusion fluid line connected at one end thereof to the blood return line and at its other end to a second container of fresh fluid, 
 a dialysis fluid line connected at one end thereof to the inlet of the secondary chamber and at its other end to a third container of fresh fluid, 
 a pre-blood pump infusion fluid line connected at one end thereof to a fourth container of fresh fluid and at its other end to the blood withdrawal line in a region of this latter which is positioned in use upstream the blood pump, 
 one or more syringe lines connected at one end thereof either to the blood withdrawal line or to the blood return line or directly to the patient, and at its other end to a syringe container, 
   means for regulating the flow of fluid through one or more said fluid lines; and   a control unit connected to the means for regulating, the control unit being configured to:   calculate set values (Q iset ) of two or more fluid flow rates selected in the group of fluid flow rates including:
 a fluid flow rate (Q rep1 ) through the pre-dilution infusion fluid line, 
 a fluid flow rate (Q rep2 ) through the post-infusion fluid line, 
 a fluid flow rate (Q pbp ) through the pre-blood pump infusion fluid line, 
 a fluid flow rate (Q dial ) through the dialysis liquid fluid line, 
 a fluid flow rate (Q syr ) through the syringe fluid line, 
 a fluid flow rate (Q eff ) through the effluent fluid line, 
   by imposing that at least of an emptying time of the first container, an emptying time of the second container, an emptying time of the third container, an emptying time of the fourth container, an emptying time of the syringe container, and a filling time of the waste container are multiples of a same reference time (T r ).   
     
     
         2 . (canceled) 
     
     
         3 . The apparatus according to  claim 1 , wherein the control unit is configured to:
 calculate the set values of N−1 of said fluid flow rates (Q iset ) by imposing that an emptying time of at least one among the containers of fresh fluid is substantially the same as, or a multiple of the emptying time of one or more of the other containers of fresh fluid, said reference time (T r ) being the shortest among said empting times, and   calculate the remaining of said fluid flow rates (Q iset ) by applying a fluid balance equation imposing that the sum of the fluid flow rates through fluid lines coming from fresh fluid containers (Q rep1 , Q rep2 , Q dial , Q pbp ) and of a patient fluid removal rate (Q pfr ) is equal to the effluent fluid line flow rate (Q eff ):
   Σ( Q   rep1   +Q   dial   +Q   pbp   +Q   pfr )= Q   eff .
 
   
     
     
         4 . The apparatus of  claim 1  comprising at least four fluid lines selected in said group of fluid lines, the control unit being configured to:
 calculate set values (Q iset ) of two or more of:
 a fluid flow rate (Q rep1 ) through the pre-dilution infusion fluid line, 
 a fluid flow rate (Q rep2 ) through the post-infusion fluid line, 
 a fluid flow rate (Q pbp ) through the pre-blood pump infusion fluid line, 
 a fluid flow rate (Q dial ) through the dialysis liquid fluid line, 
 a fluid flow rate (Q syr ) through the syringe fluid line, 
 a fluid flow rate (Q eff ) through the effluent fluid line, 
 
 by imposing that at least one of the following conditions is met:
 at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, the emptying time of the syringe container, and the filling time of the waste container are multiples of a same reference time (T r ), or at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, the emptying time of the syringe container, and the filling time of the waste container are multiples of a first reference time (T r1 ) while imposing that at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, the emptying time of the syringe container, and the filling time of the waste container that are not multiples of the first reference time (T r1 ) are multiples of a second reference time (T r2 ), 
 or that at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, and the emptying time of the syringe container are multiples of a same reference time (T r ), 
 or that at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, and the emptying time of the syringe container are multiples of a first reference time (T r1 ) while imposing that at least two of the emptying time the first container, the emptying time of the second container, the emptying time of the third container, the emptying time of the fourth container, and the emptying time of the syringe container that are not multiples of the first reference time (T r1 ) are multiples of a second reference time (T r2 ). 
 
 
     
     
         5 . The apparatus of  claim 1  wherein the control unit is further configured to control said means for regulating based on said calculated set values, either automatically or after receipt of a confirmation signal. 
     
     
         6 . The apparatus according  claim 1  comprising at least the following fluid lines:
 the pre-dilution infusion fluid line, 
 the post-dilution infusion fluid line, 
 the dialysis fluid line ( 19 ); 
 
       wherein the control unit is configured to calculate the set value for the fluid flow rate through each of the pre-dilution and the post-dilution infusion fluid lines and the dialysis fluid line by imposing that the emptying time of each of said first, second and third containers is a multiple of the same reference time (T r ). 
     
     
         7 . The apparatus according to  claim 8  wherein:
 the blood pump is active in correspondence of a segment of the blood withdrawal line, 
 the pre-dilution infusion fluid line is connected to the blood withdrawal line between the blood pump segment and the filtration unit, 
 the pre-blood pump infusion fluid line is connected to the blood withdrawal line in a region of this latter which is positioned between the blood pump segment and an end of the blood withdrawal line opposite the end connected to the filtration unit, and 
 the control unit is configured to calculate the set value for the fluid flow rate through each of the infusion fluid lines and the dialysis fluid line by imposing that the emptying time of each given of said first, second, third, and fourth containers is a multiple of the same reference time (T r ). 
 
     
     
         8 . The apparatus according to  claim 1  wherein the waste line is connected to the waste container and wherein the control unit is configured to calculate the set value for the fluid flow rate through each of the fluid lines by imposing that the emptying time of each given of said containers of fresh fluid and the filling time of the waste container are multiple of the same reference time (T r ) and are same as or multiple of the emptying time of one or more other containers of fresh fluid. 
     
     
         9 . The apparatus according to  claim 1  wherein the control unit is configured to store in a memory connected to the control unit at least one of a total volume and a total weight of fluid which may be contained in each of said container of fresh fluid and in said waste container, said total volume or total weight of fluid being one of:
 detected by a sensor associated to each respective container and connected to the control unit, 
 entered by an operator for each respective container through a user interface connected to the control unit, 
 determined by the control unit associating an identification code on each respective container to a respective volume, 
 pre-stored in said memory; 
 
       and wherein the control unit is further configured to receive a set value for at least one of:
 a treatment time (T) and weight loss (WL) to be achieved during said treatment time; 
 a treatment dose (D set ) to be delivered to the patient during the treatment, which comprises a prescribed value for one selected in the group including:
 an effluent dose flow rate (D eff     —     set ), which is the prescribed mean value of the flow rate through the effluent line ( 13 ), 
 a convective dose flow rate (D conv     —     set ), which is the prescribed mean value of the sum of the flow rates through any infusion fluid line (Q rep , Q pbp ) and the patient fluid removal rate (Q pfr ), 
 a diffusive dose flow rate (D dial     —     set ), which is the prescribed mean value of the flow rate through the dialysis fluid line (Q dial ), 
 an urea dose (D urea     —     set ), which is a prescribed mean value for an estimated urea clearance, 
 a clearance dose (K solute     —     set ), which is a prescribed mean value for an estimated clearance for a given solute; 
 
 a fluid flow rate (Q rep1 ) through the pre-dilution infusion fluid line; 
 a fluid flow rate (Q rep2 ) through the post-infusion fluid line; 
 a fluid flow rate (Q pbp ) through the pre-blood pump infusion fluid line; 
 a fluid flow rate (Q dial ) through the dialysis liquid fluid line; 
 a fluid flow rate (Q eff ) through the effluent fluid line; 
 a fluid removal rate (Q pfr ) from the patient. 
 
     
     
         10 . The apparatus of  claim 1  comprising one or more scales weighing one or more of said containers, said one or more scales being connected to the control unit and sending to the control unit corresponding weight signals, wherein the control unit is configured to:
 receive an initial weight or volume (W i , V i ) of one or more of said containers, 
 calculate the set value of the fluid flow rate (Q iset ) in one or more of said fluid lines by dividing a weight or volume (W i , V i ) of the respective container by the value of the reference time (T r ) using one of the following formulas:
     Q   iset   =W   i   /T   r  or  Q   iset   =V   i   /T   r . 
 
 
     
     
         11 . The apparatus of  claim 31 , wherein the control unit is configured to:
 receive an initial weight or volume (W i , V i ) of one or more of said containers,   receive proposed values (Q i ) of the flow rates for said fluid lines;   calculate the set value of the fluid flow rate (Q iset ) in one or more of said fluid lines by dividing a weight or volume (W i , V i ) of the respective container by the value of the reference time (T r ) multiplied by a respective weighing coefficient (c) for each respective container using one of the following formulas:
     Q   iset   =W   i /( T   r   ·c   i ), or  Q   iset   =V   i /( T   r   ·c   i ), 
 where the weighing coefficient (c i ) for each respective container is calculated as a function of an intermediary factor (b i ) obtained by dividing either the dose or the sum of said proposed values (Q i ) of the flow rates by the respective proposed value (Q i ). 
   
     
     
         12 . The apparatus of  claim 1  wherein the control unit is configured to:
 receive an initial weight or volume (W i , V i ) of one or more of said containers, 
 receive proposed values (Q i ) of the flow rates for said fluid lines; 
 receive the value of an adjustment parameter (A) defined as maximum relative change allowed on container change periods; 
 calculate the set values of said fluid flow rates (Q iset ) based on the proposed values (Q i ), the initial weight or volume (W i , V i ) of each container and the value of the adjustment parameter (A). 
 
     
     
         13 . The apparatus of  claim 1  wherein the control unit is configured to:
 receive an initial weight or volume (W i , V i ) of one or more of said containers; 
 receive proposed values (Q i ) of the flow rates for said fluid lines; 
 for each pair of lines and respective containers, generate ratios of interest R0 k , which are reference ratios between change periods of pairs of containers and are defined for each pair of lines and respective containers, K being an integer from 1 to M, with the value of M pre-stored in memory connected to the control unit or receivable from a user input; 
 calculate the containers change periods T i =V i /Q i  or T i =W i /Q i , and rank each circuit according to the calculated container change period, where i=1 to N with T i  increasing with i; 
 compute all period ratios R ij =T i /T j , with i>j; 
 compare each period ratio R ij  to the ratios of interest R0 k ; 
 for each ratio R ij  where a k value exists verifying tolerance relation: (1−A)·R0 k <R ij <(1+A)·R0 k , computing the number of daily saved container changes; 
 select the ratios R ij  providing the largest number of saved container changes; 
 apply the ratios of interest corresponding to the selected ratios to compute the optimized flow rates (Q iset ). 
 
     
     
         14 . The apparatus of  claim 1  wherein said control unit is configured to:
 allow entry of the treatment time (T), 
 calculate the reference time (T r ) either as the treatment time (T) or as a sub-multiple of the treatment time (T). 
 
     
     
         15 . The apparatus of  claim 1 , wherein the control unit is configured to:
 receive one set value set by an operator for one fluid flow rate selected in the group comprising:
 a fluid flow rate (Q rep1 ) through the pre-dilution infusion fluid line, 
 a fluid flow rate (Q rep2 ) through the post-infusion fluid line, 
 a fluid flow rate (Q pbp ) through the pre-blood pump infusion fluid line, 
 a fluid flow rate (Q dial ) through the dialysis liquid fluid line; 
   identify the container associated to the fluid line for which the fluid flow rate has been set by the operator; and   calculate the reference time (T r ) dividing the initial weight or volume (W i , V i ) of the identified container by the set value of the fluid flow rate set by the operator.   
     
     
         16 . The apparatus according to  claim 1 , wherein the control unit is configured to compute the reference time (T r ) using one of the following:
 dividing the sum of the initial weights or volumes (W i , V i ) of a plurality of said containers by the prescribed dose flow rate value which is set to be delivered in total through the lines (D conv     —     set ) leading to the same plurality of containers,   dividing the sum of the initial weights or volumes (W i , V i ) of all said containers by the total prescribed dose flow rate (D eff     —     set ),   dividing the weighed sum of the initial weights or volumes (W i ) of a plurality of said containers by the prescribed dose flow rate value which is set to be delivered in total through the lines (D conv     —     set ) leading to the same plurality of containers, using formula:
     T   r   =ΣW   i   ·c   i /Dose 
   
       where c i  is an weighing coefficient to be multiplied by the initial weight or volume of each container;
 dividing the weighed sum of the initial weights or volumes (W i , V i ) of all said containers by the total prescribed dose flow rate (D eff     —     set ), using formula:
     T   r   =ΣW   i   ·c   i /Dose 
 
 
       where c i  is the weighing coefficient to be multiplied by the initial weight or volume of each container. 
     
     
         17 . (canceled) 
     
     
         18 . The apparatus of  claim 1  wherein the control unit is configured to:
 associate to each container a reference volume or a reference weight which, when reached by the respective container, triggers a container change signal, and 
 compare a measured volume or weight of each container to the respective reference volume or reference weight to trigger a container change signal container when the container reaches the respective reference volume or a reference weight; 
 further wherein the control unit is configured to impose on one or more containers of fresh fluid a reference volume or reference weight which is different from zero and/or on the waste container a reference volume or weight which is less than the maximum volume or weight of the waste container. 
 
     
     
         19 . The apparatus of  claim 18  wherein the control unit is further configured to calculate a set value (V eff-change ) of the waste container reference volume or weight, at which the control unit considers that the waste container is full, by imposing that the filling time of the waste container is one of: substantially the same as, proportional to, a multiple of the emptying time of one or more of the other containers of fresh fluid. 
     
     
         20 . The apparatus of  claim 1  wherein:
 the means for regulating the flow of fluid through said fluid lines comprises a pre-dilution pump for regulating the flow through said pre-dilution fluid line and a post-dilution pump for regulating the flow through said post-dilution fluid line, 
 a dialysis fluid line is connected to the inlet of the secondary chamber, and the means for regulating the flow of fluid through said fluid lines comprises at least a dialysis fluid pump for regulating the flow through said dialysis fluid line, 
 said one or more infusion fluid lines comprise a pre-blood pump infusion line connected to the blood withdrawal line in a region of this latter which is positioned in use upstream the blood pump, and the means for regulating the flow of fluid through said fluid lines comprises at least a pre-blood infusion pump for regulating the flow through said pre-blood pump infusion line. 
 
     
     
         21 . The apparatus of  claim 1  any one of the preceding claims, wherein said control unit is configured to allow entry of at least one of:
 a) a fluid removal rate (Q pfr ) from the patient, 
 b) a treatment time (T) and of a weight loss (WL) to be imposed over said treatment time (T) and calculate the patient fluid removal rate (Q pfr ) as a ratio of weight loss divided by treatment time (WL/T),
 and wherein the control unit is further configured to calculate the set values (Q iset ) of the fluid flow rates through said fluid lines by imposing that:
 the emptying times of the containers of fresh fluid are multiples of a same reference time (T r ), and 
 the sum of the fluid flow rates (Q rep1 , Q rep2 , Q pbp ) through the infusion fluid lines present in the apparatus plus the fluid flow rate (Q dial ) through the dialysis line, if present, plus the fluid removal rate (Q pfr ) from the patient equals (Q eff ) the fluid flow rate through the effluent fluid line. 
 
 
 
     
     
         22 . The apparatus of  claim 1  any one of the preceding claims wherein said fourth container contains an anticoagulant, optionally a regional anticoagulant comprising a citrate solution, and the second container leading to said post-dilution infusion fluid line includes an ionic balance solution comprising a calcium ion based solution, the control unit being configured to calculate the fluid flow rate through said pre-blood pump infusion fluid line and through said post-dilution infusion fluid line based on a pre-defined algorithm. 
     
     
         23 . (canceled) 
     
     
         24 . The apparatus of  claim 1  wherein all of the containers of fresh fluid comprise a fluid having a same composition. 
     
     
         25 . Apparatus according to  claim 1  wherein the control unit is configured to store a maximum volume of fluid which may be contained in each container of fresh fluid and a maximum volume of fluid which may be contained in said waste container, and wherein the control unit is configured to generate an alarm signal or to stop the treatment when one of the following events happens:
 the minimum quantity of fluid in one fresh fluid containers is detected, 
 the maximum volume of fluid in the waste container is detected. 
 
     
     
         26 - 28 . (canceled) 
     
     
         29 . The apparatus according to  claim 1 , wherein the control unit is configured to:
 calculate the set values of N−1 of said fluid flow rates (Q iset ) by imposing that an emptying time of at least one among the containers of fresh fluid is substantially the same as, or a multiple of one time selected among: the emptying time of one or more of the other containers of fresh fluid, and the filling time of the waste container, said reference time being the shortest among said empting times and the filling time, and   calculate the remaining of said fluid flow rates (Q iset ) by applying a fluid balance equation imposing that the sum of the fluid flow rates through fluid lines coming from fresh fluid containers (Q rep1 , Q rep2 , Q dial , Q pbp ) and of a patient fluid removal rate (Q pfr ) is equal to the effluent fluid line flow rate (Q eff ):
   Σ/( Q   repi   +Q   dial   +Q   pbp   +Q   pfr )= Q   eff .
 
   
     
     
         30 . The apparatus according to  claim 1 , wherein the control unit is configured to::
 calculate the set values of N−1 of said fluid flow rates (Q iset ) by imposing that an emptying time of at least one among the containers of fresh fluid is substantially the same as, or a multiple of the filling time of the waste container, and   calculate the remaining of said fluid flow rates (Q iset ) by applying a fluid balance equation imposing that the sum of the fluid flow rates through fluid lines coming from fresh fluid containers (Q rep1 , Q rep2 , Q dial , Q pbp ) and of a patient fluid removal rate (Q pfr ) is equal to the effluent fluid line flow rate (Q eff ):
   Σ( Q   repi   +Q   dial   +Q   pbp   +Q   pfr )= Q   eff .
 
   
     
     
         31 . The apparatus of  claim 1  comprising one or more scales weighing one or more of said containers, said one or more scales being connected to the control unit and sending to the control unit corresponding weight signals, wherein the control unit is configured to:
 receive an initial weight or volume (W i , V i ) of one or more of said containers, 
 calculate the set value of the fluid flow rate (Q iset ) in one or more of said fluid lines by dividing a weight or volume (W i , V i ) of the respective container by the value of a reference time (T r ) multiplied by a respective weighing coefficient (c) for each respective container using one of the following formulas:
     Q   iset   =W   i /( T   r   ·c   i ) or  Q   iset   =W   i /( T   r   ·c   i ).