Dialysis Device for Performing A Dialysis Treatment

Abstract

A dialysis device for performing a dialysis treatment can include a liquid conducting system, which comprises a first section and a second section. A differential pressure sensor can be included for measuring a differential pressure p.sub.diffm between a first pressure (p.sub.1) in the first section of the liquid conducting system and a second pressure (p.sub.2) in the second section of the liquid conducting system. A monitoring unit is also provided, which is configured to determine an operating status based on the measured differential pressure p.sub.diffm. A control device is also provided, which is configured to interrupt and/or block the dialysis treatment according to the determined operating status. A display device is also provided, which is configured to output a notification based on the determined operating status.

Claims

1. A dialysis device for performing a dialysis treatment, the dialysis device comprising: a liquid conducting system comprising a first section and a second section; a differential pressure sensor arranged for measuring a differential pressure p.sub.diffm between a first pressure (p.sub.1) in the first section of the liquid conducting system and a second pressure (p.sub.2) in the second section of the liquid conducting system; a monitoring unit configured to determine an operating status based on the measured differential pressure p.sub.diffm;and a control device configured to interrupt and/or block the dialysis treatment according to the determined operating status, and/or a display device configured to output a notification based on the determined operating status.

2. The dialysis device according to claim 1, further comprising: a first pressure sensor arranged for measuring a pressure (p.sub.1) in the first section; and a second pressure sensor arranged for measuring a pressure (p.sub.2) in the second section, and wherein the monitoring unit is configured to calculate a differential pressure p.sub.diffb between the first measured pressure (p.sub.1) in the first section and the second measured pressure (p.sub.2) in the second section.

3. The dialysis device according to claim 2, wherein the determined operating status indicates an incorrect functioning of the first and/or second pressure sensor.

4. The dialysis device according to claim 2, wherein the monitoring unit is configured to determine the operating status based on the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm.

5. The dialysis device according to claim 4, wherein the monitoring unit is configured to determine a difference p.sub.res between the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm and to compare the determined difference p.sub.res with a nominal value to determine the operating status.

6. The dialysis device according to claim 1, wherein the first section and the second section of the liquid conducting system comprise portions of an extracorporeal blood circuit that includes a dialysis filter, wherein the first section corresponds to a blood feed line and the second section corresponds to a blood return line.

7. The dialysis device according to claim 6, wherein the monitoring unit is configured to detect a needle disconnection as an operating status based on the measured differential pressure p.sub.diffm and/or a change of the measured differential pressure p.sub.diffm.

8. A method for monitoring an operating status of a dialysis device comprising a liquid conducting system with a first section and a second section, the method comprising: measuring a differential pressure p.sub.diffm between a first pressure (p.sub.1) in the first section and a second pressure (p.sub.2) in the second section using a differential pressure sensor, determining an operating status based on the measured differential pressure p.sub.diffm, and interrupting a dialysis treatment and/or blocking a dialysis treatment and/or outputting a notification based on the determined operating status.

9. The method according to claim 8, further comprising: measuring a pressure (p.sub.1) in the first section using a first pressure sensor), measuring a pressure (p.sub.2) in the second section using a second pressure sensor, calculating a differential pressure p.sub.diffb between the measured pressure (p.sub.1) in the first section and the measured pressure (p.sub.2) in the second section, determining an operating status based on the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm.

10. The method according to claim 9, wherein the operating status indicates an incorrect functioning of the first and/or second pressure sensor.

11. The method according to any of the claims 8 to 10, characterized in that the determining of the operating status comprises the following steps: calculating a resulting pressure .sub.Pres from the difference between the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm, and analyzing the behavior of the pressure p.sub.res.

12. The method according to claim 11, wherein the analysis is a comparison with a nominal value and/or an analysis of the change over time.

13. The method according to claim 12, wherein an error volume is accumulated from the resulting pressure p.sub.res when the resulting pressure p.sub.res deviates from the nominal value, and the notification is provided and/or the dialysis treatment is interrupted and/or the start of the treatment is blocked when a predefined maximum error volume is exceeded.

14. The method according to claim 12, wherein the notification is provided and/or the dialysis treatment is interrupted and/or the start of the treatment is blocked, when a persisting deviation of the resulting pressure p.sub.res from the nominal value is provided and a minimum trigger level is reached.

15. The method according to claim 10, wherein, after determining of an incorrect functioning of the first pressure sensor in a first section, a pressure (p.sub.1) is determined in the first section from the measured differential pressure p.sub.diffm and the measured pressure (p.sub.2) in a second section.

16. The method according to claim 8, wherein the liquid conducting system is an extracorporeal blood circuit with a dialysis filter, wherein the first section corresponds to a blood feed line and the second section corresponds to a blood return line.

17. The method according to claim 8, wherein a needle disconnection is detected as an operating status based on the measured differential pressure p.sub.diffm.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0075] Example embodiments are described in further detail in the following description in connection with the accompanying drawings, in which it is shown:

[0076] FIG. 1 shows a dialysis device with an extracorporeal blood circuit of a dialysis device with a differential pressure sensor between a blood feed and a blood return,

[0077] FIG. 2 is a diagram, which depicts a desirable and an undesirable operating status of the dialysis device of FIG. 1,

[0078] FIG. 3 shows a dialysis device with an extracorporeal blood circuit of a dialysis device having a first pressure sensor in a blood feed and a second pressure sensor in a blood return and a differential pressure sensor between the blood feed and the blood return,

[0079] FIG. 4 is a diagram, which indicates an exemplary pressure course of the dialysis device of FIG. 3 with correctly measuring pressure sensors,

[0080] FIG. 5 is a diagram, which indicates an exemplary pressure course of the dialysis device of FIG. 3, wherein a second pressure sensor incorrectly measures in the blood return,

[0081] FIG. 6 shows a dialysis device with an extracorporeal blood circuit of a dialysis device, wherein various arrangement possibilities of pressure sensors, which may measure the pressure in various sections, are illustrated,

[0082] FIG. 7 shows a dialysis device with an extracorporeal blood circuit of a dialysis device, wherein further arrangement possibilities of the differential pressure sensor are illustrated,

[0083] FIG. 8 is a schematic representation of the method for monitoring an operating status of a dialysis device based on a measured differential pressure, and

[0084] FIG. 9 is a schematic representation of the method for monitoring an operating status of a dialysis device based on a calculated and a measured differential pressure.

DETAILED DESCRIPTION OF THE FIGURES

[0085] In the following, further example embodiments will be explained in more detail with reference to the accompanying Figures. In the various Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

[0086] In the following description, a dialysis device 1 for performing a dialysis treatment and a method for monitoring at least one operating status of the dialysis device 1 are described. The dialysis device 1, which has already been described in general in the above, is depicted in the Figures very schematically and exemplary in regard to an extracorporeal blood circuit 10 with at least a dialysis filter 5 and a liquid conducting system 2.

[0087] Accordingly, a dialysis device 1 with a liquid conducting system 2 is schematically shown in FIG. 1, wherein the liquid conducting system 2 is an extracorporeal blood circuit 10. For the further description, a blood feed corresponds to a first section 3 of the liquid conducting system 2 and a blood return corresponds to a second section of the liquid conducting system 2.

[0088] The dialysis device 1 furthermore comprises a dialysis filter 5, which is arranged between the blood feed line 13 and the blood return line 14. The blood feed line 13, also called arterial feed line, is connected to the patient via a connection, not shown, to withdraw blood from the circuit or circulation of the patient. By the same token, the blood return line 14, also called venous return line, is also connected to the patient via a connection, not shown, to return the blood treated in the dialysis filter 5 to the circuit or circulation of the patient.

[0089] The dialysis device 1 furthermore comprises a pump 9, which is depicted in the form of a flexible tube or peristaltic pump, in order to feed the blood withdrawn from the patient through the extracorporeal blood circuit 10.

[0090] The dialysis device 1 furthermore comprises a control device 100, which is configured to control the treatment of a patient. The control device 100 controls, for example, the functioning of the pump 9 and/or switches the clamp 12.

[0091] Furthermore, an indicating or display device 110 is provided, by which operating statuses of the dialysis device 1 may be displayed. The display device 110 in the depicted exemplary embodiment is schematically shown in the form of a monitor. However, other display devices or indicating devices are possible, such as acoustic or haptic devices.

[0092] In order to treat the blood of a prescribed dialysis patient with the dialysis device, the blood feed line 13 is connected with the circulation of the patient, for example, via a cannula. The withdrawn blood is fed via the pump 9 to the dialysis filter 5, wherein the blood is treated by means of known dialysis methods. For example, a hemodialysis, a hemofiltration, a Hemodiafiltration, or another known dialysis method may be performed in the dialysis filter 5. The treated blood is then returned to the patient via the blood return line 14, which is also connected to the circulation of the patient.

[0093] A differential pressure sensor 6 measures a differential pressure Nam between the pressure p.sub.1 in the blood feed line 13, which corresponds to an arterial pressure, and the pressure p.sub.2 in the blood return line 14, which corresponds to a venous pressure. The measured differential pressure Nam can be used e.g. to determine an operating status of the dialysis device 1, for example, to monitor a correct functioning of the dialysis device 1 with regard to the functioning of further pressure sensors, which are not shown in FIG. 1.

[0094] In FIG. 1, a configuration of the dialysis device 1 is schematically shown, wherein only the differential pressure sensor 6 and a monitoring unit 11, which is configured to determine an operating status based on the differential pressure p.sub.diffm measured by the differential pressure sensor 6, are provided.

[0095] Depending on the determined operating status based on the measured differential pressure p.sub.diffm, the dialysis treatment is either continued in this operating status or an error notification occurs and/or the blood flow in the extracorporeal blood circuit is stopped. For this purpose, the operating status determined by the monitoring unit 11 may be communicated to the control device 100 and the control device 100 accordingly ends the treatment or blocks the beginning of a treatment. The determined operating status may, alternatively, or in addition, also be communicated to a display device 110 to be displayed thereon.

[0096] When the measured differential pressure Nam corresponds, for example, to a nominal value of a normal dialysis procedure, the dialysis procedure is continued. However, if the measured differential pressure p.sub.diffm deviates from this nominal value, for example, in the case, wherein the venous needle, which returns the treated blood to the patient, is dislocated or slid out or another form of needle disconnection has occurred, thereby causing a pressure drop in the blood return line 14, this is noticed by the monitoring unit 11 and an error notification to the user occurs and/or the extracorporeal blood circuit is immediately stopped to avoid a safety hazard for the patient due to a potential high blood loss.

[0097] This alarm threshold may not only be exceeded in the case of said deviation from a nominal value, but also upon a corresponding change of the differential pressure p.sub.diffm, such that also in the case of a change of the differential pressure Nam an alarm may be triggered or the dialysis may be stopped. For example, in case of a sudden change of the differential pressure p.sub.diffm, it may be assumed that an irregularity relating to the integrity of the connection of the extracorporeal blood circuit with the patient exists and hence a needle disconnection may have occurred.

[0098] The evaluation of the course of the differential pressure p.sub.diffm over time or the comparison of the measured differential pressure p.sub.diffm with a nominal value is provided by the monitoring unit 11, which is configured to perform the corresponding analyses. The monitoring unit 11 may e.g. be provided in the form of a hardware module and/or in the form of a software module. According to the result of the evaluation the monitoring unit 11 then sends an alarm notification and/or a command to abort or stop the dialysis treatment, when an alarm condition is achieved or exceed.

[0099] Furthermore, a control device 100 and/or a display device 110 of the dialysis device 1 may be provided. The control device 100 may be configured to interrupt or stop a dialysis treatment and/or block a future treatment based on a message from the monitoring unit 11. The display device 110 may be configured to output a notification based on the determined operating status.

[0100] The monitoring unit 11 and/or the control device 100 and/or the display device 110 may also be formed as a common unit, for example, in the form of a control device of a dialysis device with a common processor.

[0101] The monitoring unit 11 may e.g. be formed such that it may receive the signal of the differential pressure sensor 6 and may e.g. comprise one or more processors and a storage to store a program, by which the monitoring steps may be performed on the processor. The monitoring unit 11 may accordingly be realized as a computer with corresponding buses integrated in the dialysis device 1.

[0102] The control device 100 may also be provided such that only the program code for the control is different from the program code of the monitoring unit 11, wherein at least partly the same hardware is used, e.g. a common processor. The control device 100 and the monitoring unit 11 may also be present in different software modules, for example.

[0103] The control device 100 may be programmed to block or stop a treatment with the dialysis device 1, to avoid a starting of, or to stop, a blood pump. The blocking may also be provided by depicting that an action to be performed by a user is not performable. For example, an actuation field on the machine or on a display of the machine may not be activatable.

[0104] The display device 110 may be present in the form of a display screen, for example in the form of a touch screen, and/or a loud speaker to output acoustic signals and/or an optical transducer, such as a lamp.

[0105] In FIG. 2 a diagram is shown, which depicts a desirable operating status A and an undesirable operating status B of the dialysis device 1 from FIG. 1. Here, the schematic course of the pressure p [mmHg] of the measured differential pressure p.sub.diffm and the schematic course of the pressure p.sub.1 in the blood feed line 13 and the pressure p.sub.2 in the blood return line 14 over time t [5] are plotted. The values of the pressure p.sub.1 in the blood feed line 13 and the pressure p.sub.2 in the blood return line 14 are only schematically depicted for illustration and are not necessarily measured directly by means of the dialysis device from FIG. 1—accordingly, no pressure measuring devices for the pressures in the blood feed line 13 and in the blood return line 14 are shown in FIG. 1.

[0106] For a simplified representation the shown pressures are depicted linearly, which may correspond e.g. to an average value of the pressures. The actual pressures may obviously vary periodically with the heart beat and the pumping movement of the pump 9. In the desired operating status A, the pressure p.sub.1 in the blood feed line 13 and the pressure p.sub.2 in the blood return line 14 essentially run constant at least with respect to their average value, such that also the differential pressure Nam measured by means of the differential pressure sensor 6 is essentially a constant value. In such a case, no error or failure alarm and/or command to stop the treatment is generated by the monitoring unit 11.

[0107] The undesirable operating status B schematically shows the case of an error, wherein the venous needle, which should return the purified blood to the patient, is dislocated or disconnected from the vein of the patient (VND, Venous Needle Disconnect). When a connection between the needle, i.e. the exit of the blood return line 14, and the vein of the patient no longer exists, a (marginal) pressure drop of the pressure p.sub.2 in the blood return line 14 occurs. Based on said pressure drop, the differential pressure p.sub.diffm measured by the differential pressure sensor 6 also changes. The monitoring unit 11 detects this change of the pressure drop of the differential pressure p.sub.diffm and sends an error notification and/or initiates an immediate interruption of the dialysis process or the pump 9.

[0108] In FIG. 3 a dialysis device 1 is shown with an extracorporeal blood circuit 10 having a first pressure sensor 7 arranged in a first section 3, which is arranged here at a blood feed line 13, and a second pressure sensor 8 arranged in a second section 4, which is arranged here at a blood return line 14. A differential pressure sensor 6 is depicted between the first section 3 and the second section 4. In addition, the dialysis device comprises a monitoring unit 11, which is configured to determine a correct functioning of the first and/or second pressure sensor 7, 8, and accordingly determines the operating status in this manner.

[0109] By means of the dialysis device 1 shown in FIG. 3 it is hence possible to verify or check the functioning of the first and/or second pressure sensors 7, 8.

[0110] The dialysis device 1 comprises again a pump 9 to feed the blood withdrawn from a patient and a dialysis filter 5. To treat the blood of a patient prescribed with dialysis by means of the dialysis device 1, the blood feed line 13 is connected to a vein of the patient.

[0111] The blood withdrawn from the patient is fed via the pump 9 to the dialysis filter 5, wherein the blood of the patient is purified by means of known dialysis methods, for example, a hemodialysis, a hemofiltration, a hemodiafiltration, or another dialysis method.

[0112] The purified blood is then returned to the patient via a blood return line 14, which is also connected with this vein of the patient. The differential pressure p.sub.diffm between the pressure p.sub.1 in the blood feed line 13, i.e. the first section 3 of the liquid conducting system 2, and the pressure p.sub.2 in the blood return line 14, i.e. the second section 4 of the liquid conducting system 2, is measured via the differential pressure sensor 6. In addition, the pressure p.sub.1 in the first section 3 is measured by the first pressure sensor 7 and the pressure p.sub.2 in the second section 4 is measured by the second pressure sensor 8.

[0113] If the measured differential pressure Nam is considered individually, an assessment may be made regarding the operating status of the dialysis device 1 and the dialysis method may be accordingly continued or interrupted, as already described in view of FIG. 1.

[0114] In order to carry out a monitoring of the first and/or second pressure sensor 7, 8, a differential pressure p.sub.diffb is calculated in the monitoring unit 11 from the measured pressure p.sub.1 in the first section 3 and the measured pressure p.sub.2 in the second section 4. Then, the differential pressure p.sub.diffm as measured by the differential pressure sensor 6 and the calculated differential pressure p.sub.diffb are compared with each other, for example, subtracted from each other. From the comparison between the measured differential pressure Nam and the calculated differential pressure p.sub.diffb a resulting pressure pies is obtained.

[0115] In the case, wherein both pressure sensors 7, 8 are functioning correctly, i.e. wherein the pressure sensor 7 correctly measures the pressure p.sub.1 in the first section 3 and the pressure section 8 correctly measures the pressure p.sub.2 in the second section 4, the measured differential pressure and the calculated differential pressure correspond to each other, i.e. the resulting pressure pies is zero or at least constant over time.

[0116] In the case wherein both pressure sensors 7, 8 are not functioning correctly, i.e. wherein the pressure sensor 7 does not correctly measure the pressure p.sub.1 in the first section 3 and the pressure section 8 does not correctly measure the pressure p.sub.2 in the second section 4, the measured differential pressure p.sub.diffm and the calculated differential pressure p.sub.diffb do not correspond to each other, i.e. the resulting pressure p.sub.res does not equal zero or changes over time. The evaluation of the resulting pressure p.sub.res, i.e. the calculation of the resulting pressure p.sub.res from the measured differential pressure p.sub.diffm and the calculated differential pressure p.sub.diffb and the comparison to a nominal value (for example zero) is performed by the monitoring unit 11. When a deviation of the resulting pressure p.sub.res from the nominal value is detected, an error notification occurs and/or the extracorporeal blood circuit 10 is stopped.

[0117] An exemplary pressure course is schematically shown in FIG. 4 for the case wherein both pressure sensors 7, 8 are measuring correctly. The diagram in FIG. 4 shows the measured pressure p.sub.1, p.sub.2, p.sub.diffm, and the calculated pressures p.sub.diffb and p.sub.res. The pressure course p [mmHg] over time t [s] is plotted for each pressure. As evident from the diagram, do the calculated differential pressure p.sub.diffb and the measured differential pressure Nam correspond to each other, i.e. the difference between the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm is zero. In this case, no error notification is provided by the monitoring unit 11 and the dialysis method is continued.

[0118] In the case, wherein the pressure sensors 6, 7, 8 having a level of tolerance are used, a difference will exist between the measured and hence tolerance containing differential pressure p.sub.diffm and the calculated differential pressure p.sub.diffb, which also comprises a tolerance, as it is calculated from two tolerance containing measurement values p.sub.1, p.sub.2, such that the resulting pressure does not equal zero, but is essentially constant over time. The analysis by the monitoring unit 11 may take this into account and may hence still consider a deviation from the resulting pressure from the zero-line in the range of a predefined tolerance to not constitute an error.

[0119] In FIG. 5 a schematic diagram is depicted, which shows an exemplary pressure course for the case, wherein the second pressure sensor 8, which should measure the pressure p.sub.2 in the blood return, does not measure correctly. The diagram in FIG. 5 shows the measured pressures p.sub.1, p.sub.2, p.sub.diffm and the calculated pressures p.sub.diffb and p.sub.res. The pressure course p [mmHg] is plotted over time t [5].

[0120] As evident from the diagram, the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm do not correspond to each other, i.e. the difference between the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm does not equal zero and the deviation exceeds a predefined tolerance. The monitoring unit 11 detects said deviation of the measured differential pressure p.sub.diffm from a nominal value and sends an error notification or stops the extracorporeal blood circuit 10.

[0121] In each of the FIGS. 6 and 7 a dialysis device 1 is shown with an extracorporeal blood circuit 10 having a first pressure sensor 7 arranged in a first section 3, which corresponds to the blood feed line 13, and a second pressure sensor 8 arranged in a second section 4, which corresponds to the blood return line 14. As described in the above, differential pressure sensors may be arranged between different or various sections of the liquid conducting system 2 and the functioning of the pressure sensors arranged at said sections may accordingly be monitored by the respective differential pressure sensor.

[0122] Accordingly, various different sections of the liquid conducting system 2 as well as pressure sensors measuring the pressure in said sections are exemplary shown in FIG. 6.

[0123] Hence, pressure sensors are shown in the form of a pressure sensor 7 for determining a pressure p.sub.1 between an arterial end of the arterial feed 13 and the blood pump 9, a pressure sensor 8 for determining the pressure p.sub.2 between a venous end of the venous blood return 13 and the dialyzer or dialysis filter 5, a pressure sensor 7a for determining a pressure p.sub.3 in a section 20 of the liquid conducting system 2 between the blood pump 9 and the dialyzer or dialysis filter 5, a pressure sensor 7b for determining a pressure p.sub.4 in a dialysate line downstream of the dialyzer 5, and/or a pressure sensor 7c for determining a pressure p.sub.5 in the dialysate line upstream of the dialyzer 5. The dialyzer 5 forms a dialysis liquid circuit 50 with its feed lines and return lines.

[0124] In FIG. 7 various sections of the liquid conducting system 2 and corresponding differential pressure sensors for measuring the differential pressure between said sections are shown in FIG. 7.

[0125] In this Figure, various arrangement possibilities of differential pressure sensors 6a to 6c are illustrated. The pressure sensors 6a to 6c may be positioned in sections of ranges with various pressure regimes. The dialysis device 1, which is shown in FIGS. 6 and 7, comprises according to the pressure sensors 7a to 7c and the differential pressure sensors 6a to 6c respective individual or combined monitoring units, which are, however, not depicted to provide a better overview.

[0126] In the sections between which a differential pressure sensor 6a to 6c is arranged, an element may be positioned, which may influence, due to its resistance, the pressure transmission from a first section, e.g. a blood feed line 13, to a second section 4, e.g. a blood return line 14. This element may be e.g. a pump, in particular a peristaltic pump, hollow fibers of a dialysis membrane, a dialysis membrane, a flow reducer, a valve, a chamber that is partly filled during operation, or a similar element. Said element may also be a pressure generating element, for example, a pump, wherein the pressure fluctuations before and after said element are in phase to each other.

[0127] If said pressure influencing elements are passive elements and if the pressures in both of the sections 3, 4, are generated by completely different pressure generators, e.g. by two pumps that operate independently from each other, it may be required to average the signal over a predefined time in order to average these independent fluctuations of the pressure signals to a stable value. This may e.g. be the case, when the first section is positioned in the extracorporeal blood circuit 10 and the second section is positioned on the side of the dialysis liquid circuit 50.

[0128] The dialysis device 1 may also comprise a differential pressure sensor 6a to 6c, which is connected to more than two sections 3, 4. Furthermore, a control (not shown) may be provided, which is configured to respectively connect exactly two sections 3, 4 via the differential pressure sensor 6a to 6c and to perform one of the described monitoring methods for these sections 3, 4 and/or the pressure sensors 7a to 7c connected with said sections.

[0129] In the storage unit (memory) of the dialysis device 1 it may be stored how long or for how many measurement values the averaging must be applied, dependent on the respectively connected sections or pressure sensors.

[0130] A further parameter, which is stored in the storage unit, for the duration or the number of the measurement values for the averaging, may also be the velocity, with which the pumps of the dialysis device transport the liquid through the respective sections 3, 4. For this purpose, e.g. a chart or table or an equation may be stored in the storage unit. In the case, wherein the pressures of the individual sections 3, 4 are each measured by independent pressure sensors, the pressure courses may be averaged by means of a program being run by a processor in the dialysis device until the fluctuations of the pressure courses have dropped below a predefined threshold stored in the storage unit.

[0131] In FIG. 8 a method for monitoring an operating status of a dialysis device is shown in a schematic depiction. The method is preferably performed with a dialysis device 1 as described in the above, which comprises a liquid conducting system 2 with a first section 3 and a second section 4.

[0132] In a first step Si of the depicted method, a differential pressure p.sub.diffm is measured between a first pressure p.sub.1 in the section 3 and a second pressure p.sub.2 in the second section by means of a differential pressure sensor 6.

[0133] In a second step S2 an operating status is determined based on the measured differential pressure p.sub.diffm.

[0134] When an undesirable operating status is determined in step S2, e.g. in the case, wherein the venous needle, by which the purified blood is returned to the patient, is accidentally disconnected from the venous patient access of the patient (VND, Venous Needle Disconnect), the treatment is either immediately interrupted to avoid a safety hazard for the patient and/or a notification is outputted, e.g. via a display device 110, in step S4.

[0135] When the determining of the operating status in step S2 results in the presence of a desirable operating status, e.g. in the case, wherein the differential pressure is essentially constant and the dialysis may hence be safely and effectively performed, the treatment is continued.

[0136] In FIG. 9 a schematic depiction of the method for monitoring an operating status of a dialysis device 1 based on a calculated differential pressure p.sub.diffb and a measured differential pressure Nam is shown.

[0137] In a step S4 a first pressure p.sub.1 is measured in a first section 3. In a step S5, a second pressure p.sub.2 is measured in a second section 4. By means of the measured first pressure p.sub.1 and the measured second pressure p.sub.2 a differential pressure p.sub.diffb is calculated in a step S6.

[0138] In a step S1, a differential pressure p.sub.diffm between the first pressure p.sub.1 in the section 3 and the second pressure p.sub.2 in the second section 4 is measured by means of the differential pressure sensor 6, either in parallel, thereafter, or also beforehand.

[0139] By means of the calculated differential pressure p.sub.diffb and the measured differential pressure p.sub.diffm a resulting pressure p.sub.res is calculated in a step S8.

[0140] Based on the calculated resulting pressure p.sub.res, the operating status of the dialysis device 1 is determined in a step S7 and an analysis is performed in a step S9. When the analysis provides that an undesirable operating status exists, the dialysis treatment is interrupted.

[0141] Where applicable, all of the individual features that are depicted in the exemplary embodiments may be combined and/or replaced without leaving the scope of the present disclosure.

List of Reference Numerals

[0142] 1 Dialysis device

[0143] 2 Liquid conducting system

[0144] 3 First section

[0145] 4 Second section

[0146] 5 Dialysis filter

[0147] 6 Differential pressure sensor

[0148] 6a-6c Differential pressure sensor

[0149] 7 First pressure sensor

[0150] 7a-7c Pressure sensor

[0151] 8 Second pressure sensor

[0152] 9 Pump

[0153] 10 Extracorporeal blood circuit

[0154] 11 Monitoring unit for determining an operating status

[0155] 12 Clamp

[0156] 13 Blood feed

[0157] 14 Blood return

[0158] 100 Control device

[0159] 110 Display device

[0160] p.sub.1 First pressure

[0161] p.sub.2 Second pressure

[0162] p.sub.art Arterial pressure

[0163] p.sub.ven Venous pressure

[0164] p.sub.diffm Measured differential pressure

[0165] p.sub.diffb Calculated differential pressure

[0166] p.sub.res Resulting differential pressure

[0167] A Desired operating status

[0168] B Undesired operating status

[0169] S1 Measuring differential pressure p.sub.diffm

[0170] S2 Determining the operating status

[0171] S3 Interrupting a dialysis treatment

[0172] S4 Measuring of the pressure p.sub.1

[0173] S5 Measuring of the pressure p.sub.2

[0174] S6 Calculating the differential pressure p.sub.diffb

[0175] S7 Determining the operating status

[0176] S8 Calculating a resulting pressure pies

[0177] S9 Analysis