Method and devices for determining a treatment regimen for altering the treatment parameters when dialyzing a patient

Abstract

A method for determining a treatment regimen for altering the treatment parameters when dialyzing a patient over a plurality of treatment sessions taking place on future days includes determining a diffusive total target sodium balance; and determining a transitional treatment regimen by which the diffusive total target sodium balance is achieved over the plurality of future treatment sessions. A control device or closed-loop control device is configured to control a blood treatment apparatus using the method.

Claims

1. A method for altering treatment parameters of a treatment apparatus used for dialyzing a patient over a plurality of treatment sessions, the method comprising: determining a diffusive total target sodium balance; determining a transitional treatment regimen by which the diffusive total target sodium balance is achieved over the plurality of treatment sessions, wherein determining the transitional treatment regimen comprises: determining the diffusive total target sodium balance of a first treatment session of the plurality of treatment sessions; determining a target dry weight or another weight target value of the patient for the first treatment session; determining a first initial ultrafiltration volume to be achieved by ultrafiltration during the first treatment session, wherein a dry weight or another weight value of the patient at an end of the first treatment session is based on a first ultrafiltration volume achieved at the end of the first treatment session; and specifying, prior to starting the first treatment session, a first corrected volume by mathematically adjusting the value of the first initial ultrafiltration volume in order to achieve the target dry weight or the another weight target value; controlling, based on the determined transitional treatment regimen and while dialyzing the patient, at least one of: an ultrafiltration pump of the treatment apparatus; and a concentration of sodium chloride in a dialysis liquid used by the treatment apparatus; and adjusting a second initial ultrafiltration volume to be withdrawn during a second treatment session of the plurality of treatment sessions to a second corrected volume of the second treatment session in order to achieve a second ultrafiltration volume of the second treatment session, wherein: the second ultrafiltration volume of the second treatment session corresponds to an interdialytic weight increase of the patient, and the second corrected volume of the second treatment session of the plurality of treatment sessions is less than the first corrected volume of the first treatment session.

2. The method according to claim 1, wherein the diffusive total target sodium balance is between −300 mmol and +300 mmol.

3. The method according to claim 1, wherein the diffusive total target sodium balance is 0 mmol.

4. The method according to claim 1, wherein a respective initial ultrafiltration volume to be withdrawn during a respective treatment session is adjusted to a respective corrected volume for each of the plurality of treatment sessions following the first treatment session until a sum of each corrected volume of each treatment session of the plurality of treatment sessions reaches a total volume that assumes or exceeds the first ultrafiltration volume of the first treatment session.

5. The method according to claim 4, wherein the respective initial ultrafiltration volume to be withdrawn during the respective treatment session is adjusted to the respective corrected volume for a plurality of successive treatment sessions.

6. The method according to claim 1, wherein the step of determining the transitional treatment regimen comprises: determining a diffusive target sodium balance (M.sub.diff,target(d)) for an upcoming treatment session:
M.sub.diff,target(d)=M.sub.diff,tolerated(d−1)−M.sub.diff,minus(d), wherein the following applies: M.sub.diff,target(d) is a value of a diffusive sodium balance desired during the upcoming treatment session; M.sub.diff,tolerated(d−1) is a value of a diffusive sodium balance tolerated by the patient during the upcoming treatment session; and M.sub.diff,minus(d) is a determined value of a diffusive sodium balance by which M.sub.diff,tolerated(d−1) is mathematically reduced.

7. The method according to claim 6, wherein the following applies:
M.sub.diff,tolerated(d−1)−M.sub.diff,target(d−1) wherein the following applies: M.sub.diff,target(d−1) is the value of the desired, achieved, or adjusted diffusive sodium balance for a treatment session preceding the upcoming treatment session.

8. The method according to claim 6, wherein the steps of claim 6 are repeated for successive treatment sessions of the plurality of treatment sessions until the value of the diffusive sodium balance desired during the upcoming treatment session assumes, or is less than, the diffusive total target sodium balance.

9. The method according to claim 1, wherein the step of determining the transitional treatment regimen comprises: determining that the diffusive total target sodium balance is to be between −300 mmol and +300 mmol.

10. The method according to claim 1, wherein the step of determining the transitional treatment regimen comprises: determining that the diffusive total target sodium balance is 0 mmol.

11. A control device or a closed-loop control device configured for performing a method comprising: determining a diffusive total target sodium balance; determining a transitional treatment regimen by which the diffusive total target sodium balance is achieved over a plurality of treatment sessions, wherein determining the transitional treatment regimen comprises: determining the diffusive total target sodium balance of a first treatment session of the plurality of treatment sessions; determining a target dry weight or another weight target value of a patient for the first treatment session; determining a first initial ultrafiltration volume to be achieved by ultrafiltration during the first treatment session, wherein a dry weight or another weight value of the patient at an end of the first treatment session is based on a first ultrafiltration volume achieved at the end of the first treatment session; and specifying, prior to starting the first treatment session, a first corrected volume by mathematically adjusting the value of the first initial ultrafiltration volume in order to achieve the target dry weight or the another weight target value; controlling, based on the determined transitional treatment regimen and while dialyzing a patient using a treatment apparatus, at least one of: an ultrafiltration pump of the treatment apparatus; and a concentration of sodium chloride in a dialysis liquid used by the treatment apparatus; and adjusting a second initial ultrafiltration volume to be withdrawn during a second treatment session of the plurality of treatment sessions to a second corrected volume of the second treatment session in order to achieve a second ultrafiltration volume of the second treatment session, wherein: the second ultrafiltration volume of the second treatment session corresponds to an interdialytic weight increase of the patient, and the second corrected volume of the second treatment session of the plurality of treatment sessions is less than the first corrected volume of the first treatment session.

12. A blood treatment apparatus comprising: a control device configured to control the blood treatment apparatus by executing a method, the method comprising: determining a diffusive total target sodium balance; determining a transitional treatment regimen by which the diffusive total target sodium balance is achieved over a plurality of treatment sessions, wherein determining the transitional treatment regimen comprises: determining the diffusive total target sodium balance of a first treatment session of the plurality of treatment sessions; determining a target dry weight or another weight target value of a patient for the first treatment session; determining a first initial ultrafiltration volume to be achieved by ultrafiltration during the first treatment session, wherein a dry weight or another weight value of the patient at an end of the first treatment session is based on a first ultrafiltration volume achieved at the end of the first treatment session; and specifying, prior to starting the first treatment session, a first corrected volume by mathematically adjusting the value of the first initial ultrafiltration volume in order to achieve the target dry weight or the another weight target value; controlling, based on the determined transitional treatment regimen and while dialyzing a patient, at least one of: an ultrafiltration pump of the blood treatment apparatus; and a concentration of sodium chloride in a dialysis liquid used by the blood treatment apparatus; and adjusting a second initial ultrafiltration volume to be withdrawn during a second treatment session of the plurality of treatment sessions to a second corrected volume of the second treatment session in order to achieve a second ultrafiltration volume of the second treatment session, wherein: the second ultrafiltration volume of the second treatment session corresponds to an interdialytic weight increase of the patient, and the second corrected volume of the second treatment session of the plurality of treatment sessions is less than the first corrected volume of the first treatment session.

13. The blood treatment apparatus according to claim 12, wherein the blood treatment apparatus is an apparatus for chronic renal replacement therapy or for continuous renal replacement therapy.

14. The blood treatment apparatus according to claim 12, wherein the blood treatment apparatus is a peritoneal dialysis apparatus, hemodialysis apparatus, hemofiltration apparatus, or hemodiafiltration apparatus.

15. The blood treatment apparatus according to claim 12, further comprising sensors arranged upstream and downstream of a dialyzer of the blood treatment apparatus for measuring the at least one of: an electrolyte balance, and a liquid balance.

16. The blood treatment apparatus according to claim 12, further comprising sensors arranged upstream or downstream of a dialyzer of the blood treatment apparatus for measuring the at least one of: an electrolyte balance, and a liquid balance.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a simplified illustration from a blood treatment apparatus having an extracorporeal blood circuit in a first embodiment;

(2) FIG. 2 shows a simulation of the tracking of the deviation from the diffusive sodium balance in an embodiment; and

(3) FIG. 3 shows another simulation of the tracking of the deviation from the UF volume in another embodiment.

DETAILED DESCRIPTION OF THE FIGURES

(4) FIG. 1 shows a greatly simplified illustration of a blood treatment apparatus 100 connected to an extracorporeal blood circuit 300 and an only indicated discharge hose system having an effluent bag 400.

(5) The extracorporeal blood circuit 300 comprises a first line 301, here an arterial line section.

(6) The first line 301 is in fluid communication with a blood treatment apparatus, here exemplarily a blood filter or dialyzer 303. The blood filter 303 comprises a dialysis fluid chamber 303a and a blood chamber 303b, which are separated from each other by a mostly semi-permeable membrane 303c.

(7) The extracorporeal blood circuit 300 further comprises at least a second line 305, here a venous line section. Both the first line 301 as well as the second line 305, can serve as connection to the patient's vascular system (not shown).

(8) The first line 301 is optionally connected with a (first) hose clamp 302 for blocking or closing line 301. The second line 305 is optionally connected with a (second) hose clamp 306 for blocking or closing line 305.

(9) The blood treatment apparatus 100 which is represented, only by some of its devices and merely schematically, in FIG. 1, comprises a blood pump 101. During the patient's treatment, the blood pump 101 conveys blood towards the blood filter or dialyzer 303. This is illustrated by the small arrows, which are used in each of the figures to generally indicate the direction of flow.

(10) Fresh dialysis liquid is pumped from a source 200 along the dialysis liquid inlet line 104 into the dialysis liquid chamber 303a, by a pump for dialysis liquid, which may be designed as a roller pump or as an otherwise occluding pump. The dialysis liquid leaves the dialysis liquid chamber 303a in the direction of the basin 600 as dialysate possibly enriched by filtrate, and is herein referred to as effluent.

(11) The source 200 may be, for example, a bag or a container. The source 200 may also be a fluid line through which online and/or continuously generated or mixed liquid is provided, for example, a hydraulic output or connection of the blood treatment apparatus 100.

(12) A further source 201 with substituate may be optionally provided. It may correspond to the source 200 or be a separate source. The substituate may be optionally heated, e.g., in the optional bag heating H1.

(13) In addition to the aforementioned blood pump 101, the arrangement in FIG. 1 further includes an optional series of further pumps. The series of pumps include the pump 111 for substituate, the pump 121 for dialysis liquid, and the pump 131 for the effluent, each pump being optional.

(14) The pump 121 is provided to supply dialysis liquid from a source 200, for example a bag, via an optional existing bag heater with a bag H2 to the dialyzer 303, via a dialysate liquid inlet line 104.

(15) The supplied dialysis liquid exits from dialyzer 303 via a dialysate outlet line 102, supported by the pump 131, and may be discarded.

(16) Upstream of the blood pump 101, an optional arterial sensor PS1 is provided. During a patient's treatment it measures the pressure in the arterial line.

(17) Downstream of the blood pump 101, but upstream of the blood filter 303 and if provided, upstream of an addition site 25 for heparin, a further optional pressure sensor PS2 is provided. The pressure sensor PS2 measures the pressure upstream of the blood filter 303 (“pre-hemofilter”).

(18) Again, a further pressure sensor to measure the filtrate pressure or the membrane pressure of the blood filter 303 may be provided as PS4 downstream of the blood filter 303, however, preferably upstream of the pump 131 in the dialysate outlet line 102.

(19) Blood, which leaves the blood filter 303, passes through an optional venous blood chamber 29, which may comprise a ventilation device 31 and can be in fluid communication with a further pressure sensor PS3.

(20) The exemplary arrangement shown in FIG. 1 comprises a control or closed-loop control device 150. It may be in cable or wireless signal communication to any of the components referred to herein—in particular or at least to the blood pump 101—in order to control or regulate the blood treatment apparatus 100. It is optionally configured to carry out the herein described method.

(21) Alternatively to the embodiment shown herein, the blood treatment apparatus may comprise a device for the online mixing of dialysis liquid consisting of a plurality of components which may include an acidic concentrate, a bicarbonate component and reverse osmosis water.

(22) Using the device for the online mixing, a variation of the sodium content of the dialysis liquid, controlled by the control device 150, is possible within certain limits.

(23) Furthermore, the blood treatment apparatus 100 optionally comprises a device for the exact balancing of the dialysate flow flowing into and out of the dialyzer 303.

(24) The blood treatment apparatus 100 further comprises devices, such as an ultrafiltration pump 131, for the exact removal of a liquid volume V.sub.UF, predetermined by the user and/or by the control device 150, from the balanced circuit.

(25) Sensors 106 and 108 serve to determine the conductivity, which is in some embodiments temperature-compensated, and the liquid flow upstream and downstream of the dialyzer 303. The sensors 106, 108 may also be a suitable, and having the same effect, combination of actuators such as calibrated pumps, balancing chambers and pressure sensors. Instead of an optional determination of the temperature-compensated conductivity, devices for ion-selective measurement are optionally also possible.

(26) Based on the measurement of the sensors 106 and 108, the control device 150 determines, in some embodiments, the electrolyte and/or liquid balance. Also, the control device 150 optionally determines, based on user specifications and stored algorithms, the default value for the electrolyte and liquid balance, in particular the diffusive target sodium balance M.sub.diff,target(d) and/or the diffusive total target sodium balance M.sub.diff,target_total, to be achieved in the ongoing or current treatment.

(27) User specifications and/or the display of calculated values and/or the treatment of progress are possible via an optional user interface (not shown).

(28) An internal or external computing unit and/or storage unit (not shown) may also be provided. It may be able to store and evaluate the historical data necessary for calculating the current electrolyte and liquid balance. In this, for example, it may only provide the raw data for a calculation running in the control device 150. Alternatively, the calculation in the computing unit and/or storage unit (not shown) may also already be carried out based on an algorithm, e.g., implemented in it, such that only the end result from the computing unit and/or storage unit (not shown) is transmitted in form of guidelines specification to the control device 150.

(29) Although the blood treatment apparatus is shown in FIG. 1 as an apparatus for hemo(dia)filtration, however, peritoneal dialysis apparatuses are also contemplated, even though not specifically illustrated by a figure.

(30) FIG. 2 and FIG. 3 show in simulations, how a patient is stepwise continuously or progressively transferred over a transitional period of several days d from a previous regimen, the treatment regimen 1, in which the patient is being treated, in FIG. 2 and FIG. 3 until (including) day 5, with a high dialysis liquid sodium—relative to the patient's plasma sodium—to the desired or new treatment regimen, the regimen 2, comprising a dialysis liquid sodium which is low or adapted to the patient's plasma sodium, which regimen 2 begins on day 19 (FIG. 2) and on day 27 (FIG. 3).

(31) It is assumed that the model patient has a distribution volume V.sub.TBW of 40 l, ingests 140 mmol NaCl through diet each day, is dialyzed three times a week (e.g., Monday, Wednesday, Friday) and drinks so much liquid between each treatment sessions that his plasma sodium reaches the setpoint of 130 mmol/l before the next dialysis or treatment session.

(32) In the simulations, until the beginning of the fourth treatment, (day 8, which corresponds to d=1, after the long interval, i.e. on Monday, i.e. with two dialysis-free days (Saturday and Sunday) instead of one dialysis-free day such as between Monday and Wednesday or Wednesday and Friday) the previous treatment regimen or the standard regimen is assumed as follows. Due to the constant concentration of the dialysis liquid sodium, the patient's plasma sodium is raised to ca. 130 to 138 mmol/l under consideration of the typical dialysis efficiency for his treatment. The herewith associated diffusive salt transfer is determined using the sensors 106, 108 of the blood treatment apparatus 100. The UF volume V.sub.UF is adjusted, respectively, so that the liquid feed triggered by the salt ingestion is completely balanced again between the treatment sessions. Therefore, UF volume and predialytic overhydration in regimen 1 are identical. Thus, the patient reaches his dry weight m.sub.dry at the end of each treatment regimen. This previous treatment session was tolerated free of symptoms by the patient. The values for dry weight m.sub.dry and intradialytic diffusive NaCl removal are stored during this previous treatment regimen 1. An averaging of M.sub.diff over one week results in a diffusive sodium infusion of 220 mmol (see the bottom illustration of FIGS. 2 and 3), so that in this case

(33) M.sub.diff,tolerated=220 mmol.

(34) FIG. 2 shows the tracking of the deviation from the diffusive sodium balance in a simulation of the method.

(35) FIG. 2 (top) shows the plasma sodium [mmol/l] over consecutive days, which also include the treatment days d, wherein the predialytic sodium of the plasma is indicated by small diamonds, the postdialytic plasma by squares.

(36) FIG. 2 (middle) shows the ultrafiltration volume UF [l] over the consecutive days. In this, the ultrafiltration volume UF [l] corresponds to the respective, intradialytic weight increase on each day of the treatment.

(37) FIG. 2 (bottom) shows the diffusive sodium balance over consecutive days, respectively.

(38) FIG. 2 illustrates the step-by-step achievement of a diffusive intradialytic sodium zero-balance as an example of a desired diffusive total target sodium balance M.sub.diff,target_total. In FIG. 2, the dialysis liquid sodium is stepwise adapted.

(39) For the patient, the physician determines by which amount M.sub.diff,minus(d) at each treatment session should be deviated from the diffusive sodium balance M.sub.diff,tolerated(d−1) tolerated in the respective previous treatment session BS_d−1 towards the balancing target in the transitional treatment regimen.

(40) In general, this results in a target value, either in this way or in another way, for each treatment day d. The value may be as follows for the diffusive intradialytic sodium balance:
M.sub.diff,target(d)=M.sub.diff,tolerated(d−1)−M.sub.diff,minus(d)  Formula 3

(41) In the simplest case, M.sub.diff,minus(d) may be a constant value. This amount may be expressed as an absolute amount (in mmol or g) or an expected change in the concentration of postdialytic plasma sodium c.sub.plasma,post. For example, it may be medically assumed that a deviation of the plasma sodium concentration at the end of the dialysis session (i.e. the postdialytic plasma sodium concentration c.sub.plasma,post) by 1.0 mmol/l from the final value reached in the tolerated previous treatment regimen (regimen 1) is possible without symptoms. In this case, it would be

(42) $M_{\mathrm{diff},\mathrm{minus}}\left(d\right)=V_{\mathrm{TBW}}*1.0\frac{m\mathrm{mol}}{1},$
thus, it is 40 mmol in the present example.

(43) The approximation to the desired treatment regimen (regimen 2) then results, e.g., from the iteration:
M.sub.diff,tolerated(d)=M.sub.diff,target(d−1)  Formula 4

(44) This iteration is repeated until the following applies:
M.sub.diff,target(d)=M.sub.diff,target(Regime 2)=M.sub.diff,target_total.

(45) Generally however, e.g., in case of oscillation of M.sub.diff,tolerated(d) in the previous treatment regimen (regimen 1), complicated courses of M.sub.diff,tolerated(d) when approximating M.sub.diff,target(Regime 2) are possible.

(46) In the transitional phase or the transitional regimen (starting with day 8), instead of a fixed specification of the dialysis liquid sodium a regulation of the dialysis liquid sodium based on the balancing of the salt transfer between blood and dialysis liquid is now activated, as described in EP 2 413 991 A1. This regulation measures, preferably continuously, the salt balance at the dialyzer 303 and regulates the dialysis liquid sodium in such a way that respectively at the end of the current treatment session BS_d, the predetermined target value M.sub.diff,target(d) for the salt transfer of this treatment session is reached. Since in the present example the intradialytic diffusive salt intake becomes always smaller, the plasma sodium increases during the treatment session less from session to session. The patient has to drink less between treatment sessions as a physiological reaction, so that the interdialytic weight increase (i.e. between two consecutive treatment sessions) and thus the UF volume V.sub.UF(d) to be prescribed in the following treatment session continuously decreases. Thus, the above-described critical concurrence of a high UF volume with the abrupt discontinuation of the intradialytic diffusive salt intake along with the known associated symptoms are avoided.

(47) At the end of the transitional phase or the transitional regimen (starting from day 19), a new osmotic equilibrium without intradialytic diffusive salt intake and with low UF volume is achieved in the new regimen (the desired treatment regimen).

(48) FIG. 3 shows the tracking of the deviation of the UF volume in another simulation of the method.

(49) FIG. 3 (top) shows the plasma sodium [mmol/l] over consecutive days which encompass also the treatment days d, wherein the predialytic sodium of the plasma is indicated by small diamonds, the postdialytic plasma by squares.

(50) FIG. 3 (middle) shows the ultrafiltration volume UF [1] (indicated by small diamonds) and the overhydration (indicated by squares) over the consecutive days.

(51) FIG. 3 (bottom) shows the diffusive sodium balance over the consecutive days, respectively.

(52) In FIG. 3 the dialysate sodium is adapted to the plasma sodium already from day 8 (inclusive) continuing from then until the last treatment session of the method. Hereby, the ultrafiltration volume UF[1] is tracked stepwise.

(53) Thus, FIG. 3 shows another way to avoid the critical concurrence of a high UF volume with the discontinuation of the intradialytic diffusive salt intake. This procedure proposes, when stopping the salt intake on treatment day d=1, to decrease the UF volume V.sub.UF, contrary to the usual setting at which the patient would reach his dry weight m.sub.dry at the end of the treatment session (see FIG. 3). However, this reduction causes that the patient does not reach his dry weight m.sub.dry at the end of the treatment session BS_d. Instead, the missing ultrafiltration volume is distributed over the following treatment sessions BS_d (with d=2, . . . , n) in which, in addition to balancing of the interdialytic weight increase V.sub.IDWG, the associated overhydration V.sub.OH is reduced gradually.

(54) The reduction of the UF volume V.sub.UF which has to be undertaken at the beginning and/or during the transitional phase or the transitional regimen may be determined by various physiological models.

(55) Most simply, a volume of liquid is calculated or otherwise determined (e.g., via a table) for the amount of salt diffusively administered in the previous treatment sessions, which volume of liquid compensates the salt intake such that the concentration of plasma sodium remains unchanged. If M.sub.diff,tolerated(Regime 1) and c.sub.plasma,pre(Regime 1) have been determined in regimen 1, optionally depending on the parameter constellation Ψ.sub.j, then the reduction of UF volume V.sub.UF,minus is as such

(56) $\begin{array}{cc}{V}_{\mathrm{UF},\mathrm{minus}}=\frac{M_{\mathrm{diff},\mathrm{tolerated}}\left(\mathrm{Regime}1\right)}{c_{\mathrm{plasma},\mathrm{pre}}\left(\mathrm{Regime}1\right)}& \mathrm{Formula}5\end{array}$

(57) Alternatively, models which determine e.g., the osmotic volume shift between intra- and extracellular volume (see Guyton & Hall, Textbook of Medical Physiology) are possible:

(58) Predialytic bioimpedance measurements are used to determine extracellular and intracellular volume V.sub.EC and V.sub.IC as well as total body water volume V.sub.TBW and the overhydration V.sub.OH.

(59) For the total body water volume V.sub.TBW the following applies
V.sub.TBWV.sub.EC+V.sub.IC  Formula 6

(60) Considering the simplification that only sodium chloride contributes to osmolality, the latter is in each compartment (EC and IC) equal to twice the respective sodium concentration:
c.sub.osm,j=2c.sub.j  Formula 7

(61) In the osmotic equilibrium, the following applies:

(62) $\begin{array}{cc}{c}_{\mathrm{osm},\mathrm{EC}}=c_{\mathrm{osm},\mathrm{IC}}=c_{\mathrm{osm},\mathrm{TBW}}\frac{M_{\mathrm{EC}}}{V_{\mathrm{EC}}}=\frac{M_{\mathrm{IC}}}{V_{\mathrm{IC}}}& \mathrm{Formula}8\end{array}$

(63) At constant total body water volume, the osmolality in the total body water TBW changes by M.sub.diff due to the change in the amount of sodium caused by the dialysis

(64) $\begin{array}{cc}{\hat{c}}_{\mathrm{osm},\mathrm{TBW}}=c_{\mathrm{osm},\mathrm{TBW}}+\frac{2M_{\mathrm{diff}}}{V_{\mathrm{TBW}}}& \mathrm{Formula}9\end{array}$

(65) In the new osmotic equilibrium the following applies because
ĉ.sub.osm,EC=ĉ.sub.osm,TBW

(66) $\begin{array}{cc}{\stackrel{.Math.}{V}}_{\mathrm{EC}}=V_{\mathrm{TBW}}\frac{V_{\mathrm{EC}}{c}_{\mathrm{osm},\mathrm{TBW}}+2M_{\mathrm{diff}}}{V_{\mathrm{TBW}}{c}_{\mathrm{osm},\mathrm{TBW}}+2M_{\mathrm{diff}}}& \mathrm{Formula}10\end{array}$
with that, the extracellular volume changes by

(67) $\begin{array}{cc}\Delta V_{\mathrm{EC}}={\stackrel{.Math.}{V}}_{\mathrm{EC}}-V_{\mathrm{EC}}=V_{\mathrm{TBW}}\frac{V_{\mathrm{EC}}{c}_{\mathrm{osm},\mathrm{TBW}}+2M_{\mathrm{diff}}}{V_{\mathrm{TBW}}{c}_{\mathrm{osm},\mathrm{TBW}}+2M_{\mathrm{diff}}}-V_{\mathrm{EC}}& \mathrm{Formula}11\end{array}$

(68) Thus, in a complete omission of the diffusive intradialytic salt intake, the UF volume should be reduced by V.sub.UF,minus=ΔV.sub.EC.

(69) The described, greatly simplified osmotic model may be extended to include other osmotically active substances as well as volume and substance removal by ultrafiltration.

(70) When the volume withdrawal is reduced by V.sub.UF,minus in the first treatment session BS_d on day d=1 of the transitional phase or the transitional regimen (corresponds to day 8 in FIG. 2 or FIG. 3), the patient is overhydrated about V.sub.UF,minus at the end of the dialysis session. This overhydration is stepwise reduced in the following dialysis sessions.

(71) For this purpose, e.g., a priori, a liquid volume V.sub.UF,extra may be determined for the patient. the liquid volume V.sub.UF,extra should be additionally withdrawn from the patient in each dialysis session; it is namely to be additionally withdrawn in addition to the already required balance V.sub.UF of the interdialytic weight increase.

(72) This may be a fixed value or a value which is determined in relation to a maximum tolerated ultrafiltration volume V.sub.UF,max e.g., determined from the time-series analysis of the parameter sets Ψ.sub.j in the previous treatment regimen, the regimen 1.

(73) Alternatively, this volume V.sub.UF,extra may be dynamically determined, e.g., by observing the relative blood volume RBV, wherein in each treatment as much volume is withdrawn until either a critical value of the RBV, a maximum value of V.sub.UF,extra or the dry weight m.sub.dry, in particular calculated, is reached. The maximum value of V.sub.UF,extra may be e.g., a patient-specific or a center-specific definition. It may be specified by the user. The maximum value may be reached if a maximum ultrafiltration rate, determined by a specified ultrafiltration volume and the duration of treatment, is reached. Alternatively, the maximum ultrafiltration rate may be technically limited by the dialysis machine or will be limited for medical reasons. An example of the latter option is e.g., 10 ml/min/kg body weight.

(74) Basically, the interdialytic weight increase or liquid increase V.sub.IDWG between the end of the dialysis on the previous treatment day d−1 and the beginning of the dialysis on the treatment day d is required in order to prescribe the UF volume V.sub.UF:

(75) $\begin{array}{cc}{V}_{\mathrm{IDWG}}=\left[m_{\mathrm{pre}}\left(d\right)-m_{\mathrm{post}}\left(d-1\right)\right]\frac{1}{\mathrm{kg}}& \mathrm{Formula}12\end{array}$

(76) If the patient in the previous treatment regimen (regimen 1) has reached his dry weight m.sub.dry at the end of the dialysis session on the treatment day d−1, he will also reach it by the prescription V.sub.UF=V.sub.IDWG on the following treatment day d.

(77) The following applies for the predialytic overhydration V.sub.OH of the patient on treatment day d.

(78) 0$\begin{array}{cc}{V}_{OH}=\left[m\left(d\right)-m_{\mathrm{dry}}\right]\frac{1}{\mathrm{kg}}& \mathrm{Formula}13\end{array}$

(79) Therefore, m(d) corresponds to the weight of the patient on day d before the beginning of the dialysis session.

(80) In FIG. 3, as an example, a linear return to the dry weight m.sub.dry at a constant value of V.sub.UF,extra=0.2 l is illustrated:

(81) On the first day d=1 of the transitional regimen (or the transitional phase), in which e.g., a diffusive sodium zero balance (M.sub.diff,target_total=0 mmol/l) is prescribed, a reduced UF volume
V.sub.UF(d)=V.sub.IDWG−V.sub.UF,minus
is prescribed. Due to the omitted intradialytic salt supply to the patient starting from this treatment session BS_d (with d=1), the liquid intake, starting from this treatment session, is already reduced in the interdialytic interval (i.e. until the treatment session BS_d+1) and is only determined by the salt content of the intradialytic nutrition or ingested by the patient. However, as the patient was still overhydrated by V.sub.UF,minus at the end of the treatment, the interdialytic liquid increase V.sub.IDWG determined one the following treatment day d+1 is less than the measurable overhydration V.sub.OH. There will be now prescribed an UF volume
V.sub.UF=V.sub.IDWG+V.sub.UF,extra
over so many treatment sessions BS_d with d=1, d=2, d=3, and so on, until the overhydration V.sub.OH at the end of one of the following dialysis sessions is completely depleted, i.e. the patient finally reaches his dry weight m.sub.dry.

(82) At the end of the transitional regimen (or the transitional phase) (day 27), a new equilibrium, with which the patient reaches his/her dry weight m.sub.dry at the end of the future dialysis session without intradialytic diffusive salt supply, is now achieved in the desired treatment regimen (regimen 2), as shown in FIG. 3 in the middle.

(83) Both methods, on the one hand the stepwise reduction of the diffusive salt supply, as exemplarily described in FIG. 2, and on the other hand the initial reduction of the UF volume at the beginning of the transitional phase with subsequent return to the dry weight, as exemplarily described in FIG. 3, may be combined together.

(84) In addition to a linear distribution of reduction of salt supply or return to the dry weight, more complicated algorithms are encompassed. If periodicities are recognized, e.g., when analyzing the diffusive salt intake in the previous treatment regimen, e.g., that the salt intake deviates after the long dialysis interval from the one in the short intervals, then this analysis may be transferred onto the specification of the diffusive salt intake. Likewise, the return to the dry weight may be done in a manner other than linear (rather e.g., exponential) or taking into consideration the presence of a long or short interval. For example, it may be in that a return to dry weight is only effected after the short interval, so that the UF volume, which anyhow has increased after the long interval, is not further increased.

(85) In further modifications of the method, the residence time for a peritoneal dialysis liquid in the abdomen is changed over several treatment sessions. Setting the transitional treatment regimen thus encompasses or is the setting of different residence times of the introduced fluid. The residence time is related to the diffusive sodium balance.

(86) TABLE-US-00001 Table of the used parameters BS_d treatment session wherein d = 1, . . . , n with n is the number of the treatment days of the transitional regimen BS_d with d = 1 the treatment session upcoming as first M.sub.diff, target_total total target sodium balance M.sub.diff, minus(d) diffusive sodium balance on day d M.sub.diff, target(d) target sodium balance (target value for the diffusive intradialytic sodium balance) for the treatment day d M.sub.diff, tolerated(d) value of a sodium balance tolerated by the patient on treatment day d V.sub.UF ultrafiltration volume, UF volume V.sub.UF(d) ultrafiltration volume (UF volume), which should be withdrawn in the treatment session on day d V.sub.UF, max maximal tolerated ultrafiltration volume V.sub.UF, minus correction value (downwards) V.sub.UF, extra correction value (upwards) V.sub.IDWG interdialytic weight or liquid increase V.sub.OH “overhydration” predialytic overhydration V.sub.EC extracellular volume V.sub.IC intracellular volume m.sub.dry dry weight, target dry weight V.sub.TBW, dry total body water volume belonging to the dry weight V.sub.TBW total body water volume c.sub.j concentration of all ions contributing to the total conductivity c.sub.plasma, pre predialytic plasma sodium concentration c.sub.plasma, post post dialytic plasma sodium concentration c.sub.di medium dialysis sodium; sodium concentration in the dialysis liquid upstream of the dialyzer c.sub.do sodium concentration in the dialysate downstream of the dialyzer c.sub.osm, j osmotic equilibrium σ temperature-compensated total conductivity σ.sub.Ofs Offset γ.sub.j (known) specific conductivity Ψ.sub.j parameter constellation or parameter set Q.sub.d total flow of fresh dialysis liquid RBV relative blood volume ξ intradialytic symptoms d − 1 the treatment day preceding the treatment day d d treatment day, day, date d + 1 treatment day following the treatment day d EC extracellular compartment, extracellular space IC intracellular compartment, intracellular space Kt/V dialysis efficiency measure

LIST OF REFERENCE NUMERALS

(87) 25 addition point for heparin (optional) 29 venous blood chamber (optional) 31 ventilation device 100 blood treatment apparatus 101 blood pump 102 dialysate outlet line, effluent inlet line 104 dialysis liquid inlet line 106 sensor 108 sensor 111 pump for substituate 121 pump for dialysis liquid 131 pump for dialysate or effluent 150 control device or closed-loop control device 200 source containing dialysis liquid 201 source containing substituate, optional 300 extracorporeal blood circuit 301 first line (arterial line section) 302 (first) tube clamp 303 blood filter or dialyzer 303a dialysis liquid chamber 303b blood chamber 303c semi-permeable membrane 305 second line (venous line section) 306 (second) tube clamp 400 effluent bag 600 sink or basin H1 bag heating with bag (substituate) H2 bag heating with bag (dialysis liquid) PS1, PS2 arterial pressure sensor (optional) PS3 pressure sensor (optional) PS4 pressure sensor for measuring the filter pressure