Methods for estimating the duration of peritoneal dialysis treatment

Abstract

Dialysis device for performing peritoneal dialysis with at least one control unit, with at least one input unit for inputting one or more values, and with at least one processor, wherein the processor is designed to perform a method for estimating the treatment duration of a peritoneal dialysis treatment, wherein the estimation of the treatment duration is based on an ideal treatment duration, wherein the ideal treatment duration is increased by one or more delay values, characterized in that the delay values ​​depend on one or more patient-specific parameters.where a patient-specific parameter is catheter performance and the catheter performance is taken into account when estimating the infusion time and / or when estimating the outflow time and / or when estimating the duration of the last infusion, and the catheter performance, and in particular an absolute or relative increase thereof, is editable by a user.

Description

The present invention relates to a method for estimating the treatment duration of a peritoneal dialysis treatment. During peritoneal dialysis, a dialysis solution is introduced into the patient's abdominal cavity to remove waste products from the blood. This is done using a surgically implanted catheter through which the sterile dialysis solution is introduced. This solution absorbs waste products from the patient's blood via the peritoneum, which acts as a semipermeable membrane. Additionally, due to the glucose in the dialysis solution and the resulting osmotic pressure, water is removed from the patient. After a specific period of time in the abdominal cavity, the solution is drained through the catheter and replaced with fresh dialysis solution. Various peritoneal dialysis methods are known from current technology, such as continuous ambulatory peritoneal dialysis (CAPD), in which patients themselves change the dialysis solution approximately four to five times a day using a bag system. In automated peritoneal dialysis, this is done by a dialysis machine, the so-called cycler, making overnight treatment possible. To achieve better planning reliability for caregivers and patients (transportation services, machine times, etc.), it would be desirable to have a reliable method for estimating the total duration of a peritoneal dialysis treatment. The present invention therefore aims to provide a method for estimating the expected duration of a peritoneal dialysis treatment. This task is accomplished by a method having the features of claim 1. The plan is to estimate the treatment duration based on an ideal treatment duration, increasing the ideal treatment duration by one or more delay values ​​that depend on one or more patient-specific and / or procedure-specific and / or device-specific parameters. These delay values ​​can be absolute time periods or relative time periods, such as a percentage increase in the run-in or run-out time. According to the invention, an ideal treatment duration is first determined. For example, assuming that peritoneal dialysis treatment comprises an initial drainage, two cycles each with an enema, a residence time in the abdominal cavity, a drainage, and a final enema, the ideal treatment duration is determined by summing the duration of the initial drainage, the duration of one cycle multiplied by the number of cycles performed, and the duration of the final enema. Based on this value, according to the invention, surcharges—i.e., factors that extend the treatment duration—are taken into account in the form of delay values ​​to arrive at an estimate of the total treatment duration. The extent of the time difference between the actual treatment and the prescribed treatment typically depends on the patient's characteristics and / or the catheter's properties. For example, the expected flow rate may not be achieved. Another discrepancy arises from the patient generating ultrafiltration volume, thus increasing the expected outflow volume. Since no outflow volume is specified for pressure-controlled outlets, the volume within the patient is used to calculate the outflow volume. In a preferred embodiment of the invention, the ideal treatment duration comprises the ideal duration of the initial drainage, the ideal cycle duration multiplied by the number of cycles, and the ideal duration of the final enema. The ideal duration of the initial drainage can be assumed to be a specific value, e.g., 5 minutes, in the case of pressure-controlled drainage. With pressure-controlled drainage, no specific drainage volume is predetermined; rather, the patient is emptied until no further volume can be extracted from the abdominal cavity. The ideal cycle time preferably comprises the ideal run-in time, the ideal residence time, and the ideal run-out time. The ideal run-in time can be determined as the quotient of the run-in volume and the run-in rate. The residence time can be predefined. The ideal run-out time can be determined as the quotient of the prescribed run-out volume and the run-out rate. To account for the time-varying functional state of the catheter, a preferred embodiment of the invention provides that a patient-specific parameter, which can lead to a delay compared to the ideal treatment duration, is determined by the catheter performance. Even if the catheter performance during enema is less dependent on the individual patient, it is nevertheless considered a patient-specific parameter, since the catheter is, in the broadest sense, a part of the patient. Preferably, the catheter performance is taken into account when estimating the inflow time and / or when estimating the outflow time and / or when estimating the duration of the last inflow. It is conceivable that catheter performance could be taken into account by an absolute or relative increase in the ideal infusion time and / or the ideal drainage time and / or the ideal duration of the last infusion. For example, assuming an ideal infusion time of 4 minutes (infusion volume: 1000 ml; infusion rate: 250 ml / min), catheter performance could be factored in by a factor of 110%, resulting in an estimated infusion time of 264 seconds. A similar approach is conceivable for the run-out duration as well as for the duration of the final run-in. If no fixed time period is assumed for the duration of the initial run-out, i.e., if the initial run-out is volume-controlled, a corresponding increase in the ideal time periods is also conceivable. Catheter performance, and in particular the absolute or relative increase, can be edited so that a user can adjust these values. It is conceivable that different values ​​could be assigned to different phases. For example, the relative delay during inflow could be 10%, but 50% during outflow. It is also possible to predefine default values ​​that can then be modified by the user as needed. The delay in enema due to a failure to achieve the ideal enema rate is less dependent on the patient, so it may be intended that this is not editable on the device, i.e., not changeable by a user, but is fixed based on empirical values, such as the aforementioned value of 10%. The invention covers the case where only some of the parameters relevant to the delay are user-modifiable, or where all or none of these parameters are user-modifiable. In the latter case, all delay values ​​are fixed by the machine. As explained above, the initial discharge can be pressure-controlled, and its duration can be predetermined by the device or set by the user. For example, a value of 5 minutes can be set for the initial discharge. The invention also encompasses the case where the initial outflow is volume-controlled and where the duration of the initial outflow is determined from an (estimated) initial outflow volume and an outflow rate. The duration of the initial outflow can also be increased by an absolute or relative delay value to account for catheter performance. The process-specific parameter could be, for example, an absolute or relative delay at the inlet and / or a delay at the outlet. These values ​​can also be fixed or user-adjustable. For instance, a delay of 1 minute per outlet and a delay of 2 minutes per inlet could be set. These process-related delays are therefore independent of the conveyed volume. For example, if an ideal insertion time of 4 minutes is assumed, the catheter performance can be increased by a margin of, say, 10%. Assuming a procedure-related delay of, say, 120 seconds, the insertion time would be 384 seconds (= 240 seconds * 110% + 120 seconds). One unknown factor is the volume of the initial drainage if it is prescribed as a pressure-controlled drainage. In this case, the patient is emptied until no more fluid is drawn through the catheter into the drainage system. If a specific duration is assumed for the initial drainage, such as 5 minutes, a theoretical volume that can be drained during this duration can be calculated based on this assumption and the drainage rate. The volume of the initial drainage can thus be determined from the effective duration of the initial drainage and the effective drainage rate. The duration of the initial run-out can be determined from a given time plus a procedural delay, e.g., of 1 minute. Furthermore, it may be provided that the effective leakage rate is determined from the specified leakage rate and a value that takes catheter performance into account, which is recorded, for example, in the form of a percentage surcharge. The volume of the initial outflow determined in this way can be used to create a graph showing the volume of dialysis fluid in the patient over time. Furthermore, it may be stipulated that the prescribed duration be used for the estimated residence time of the solution in the patient and / or for the estimated duration of a treatment break. For example, if a residence time of 60 minutes is prescribed, this value can also be used for the estimate, as it is not expected that the residence time will be extended. The same applies to treatment breaks. The estimated duration of a notification can be assumed to be zero, since a notification has no impact on the treatment duration. According to a preferred embodiment of the invention, the estimated treatment duration is composed of the following estimated times, wherein the specified durations or phases may not occur at all, exactly once, or multiple times depending on the course of treatment: initial withdrawal duration, induction duration, withdrawal duration, dwell time in the patient, final withdrawal duration, duration of the treatment break, duration of notifications, wherein the value for the latter is preferably assumed to be zero, and wherein the prescribed, i.e., known, values ​​are preferably used for the dwell time in the patient and for the duration of the treatment break. In a further embodiment of the invention, it is provided that effective inflow and / or outflow rates are determined and that, for the purpose of creating a trend analysis, changes in catheter performance are determined by recording this data over time. If the volume of treatment fluid in the patient is plotted over time, the slope of the graph represents the inflow or outflow rate. If recording takes place over a longer period, conclusions can be drawn as to whether the rates, and thus the catheter performance, have changed. To provide the most realistic estimates possible for subsequent treatments, it may be possible to base the estimation of treatment duration on the changed catheter performance. For example, it is conceivable to use a factor of 160% for the outflow delay instead of 150% if it has been shown that the catheter performance has decreased accordingly. It is also conceivable that the estimated treatment duration is compared with an upper and / or lower limit, and that a notification is issued to the user if the estimated treatment duration exceeds the upper limit or falls below the lower limit. In this way, it can be determined whether the planned treatment should be carried out under realistic parameters or whether a correction of one or more parameters is necessary. In a further embodiment of the invention, it is provided that the residence time of the treatment is either modified or remains unchanged within the estimated treatment duration. During treatment, residence times—i.e., the periods during which the dialysis fluid is located in the abdominal cavity—can thus be shortened if necessary. For example, if a specific total treatment duration is predetermined and the estimated treatment duration exceeds this predetermined duration, the residence time(s) can be shortened accordingly so that the predetermined duration is met. This means that the estimate, with corrected residence times, corresponds exactly or largely to the predetermined duration, which also implies that the estimate lies within an acceptable range. If, however, the estimated duration is within a permissible range or corresponds to a permissible value, no change to the waiting times is necessary and the treatment can be carried out as planned. The present invention further relates to a dialysis machine for performing peritoneal dialysis, comprising at least one control unit, at least one input unit for entering one or more values, and at least one processor, wherein the processor is programmed to perform a method according to any one of claims 1 to 14. Furthermore, the dialysis machine preferably has one or more memory locations for storing, for example, limit values ​​of permissible ranges or for storing predefined values, such as a device-defined value for a delay, e.g., during the infusion process. The memory can also serve to store user-entered data. In a preferred embodiment of the invention, the dialysis machine is provided with at least one device configured to determine the temporal profile of the volume of the dialysis solution in the patient. This temporal profile can then, for example, be printed out or displayed for a user to see. It is also conceivable that the device incorporates features designed to determine the rate of volume increase (during inflow) and / or volume decrease (during outflow) and to compare several time-spaced measurements of these rates. This comparison would then allow the device to determine whether a change in rate of change has occurred, indicating a change in catheter performance. If so, the device could adjust default values ​​or suggest a value for catheter performance to the user. The statements concerning the dialysis machine apply accordingly to the method according to the invention. Further details and advantages of the invention are explained in more detail with reference to an embodiment illustrated in the drawing. The single figure shows a time course of the volume of dialysis solution administered to a patient according to an estimate, as well as the actual time course of the volume of dialysis solution administered to the patient. According to the example described below, a standard prescription is given with the following parameters: • Performance of two cycles • Pressure-controlled initial drainage • Residence time of 60 min each • Enema of 1000 ml each • Final enema of 1250 ml • Enema rate of 250 ml / min • Drainage rate of 200 ml / min The calculation of the ideal treatment time, i.e., the treatment time in which there are no delays due to the procedure, the patient, or any other reasons, is as follows: The initial ideal run-off time is assumed to be 5 minutes: This value can be adjustable or preset by the device. The ideal enema duration is calculated by dividing the volume to be administered to the patient by the prescribed or set enema rate: The ideal drainage time is determined by the quotient of the volume of dialysis solution to be drained with the prescribed or set drainage rate. Assuming that the volume to be removed is equal to the volume administered, the following results: A cycle consists of an inlet, a residence period, and an outlet. The ideal cycle duration Δt_cycle, ideally, is: The ideal duration of the last enema is calculated from the quotient of the enema volume (1250 ml) and the enema rate (250 ml / min): This results in the total treatment duration ΔtTotal, ideally as follows: The ideal total treatment time for this example is therefore 148 minutes. This treatment time results when there are no procedure-related delays, such as breaks or delays during entry or exit, and no non-procedure-related delays, such as delays caused by the patient or the equipment used. Taking into account expected procedural and patient-related delays, the estimated total treatment duration for the same treatment course (2 cycles) is as follows: A time period of 5 minutes is again assumed for the duration of the initial run-out. The cycle duration ΔtCycle is again derived from ΔtInlet + ΔtDwell time + ΔtOutlet. For the insertion, a procedure-related delay ΔtInsertion of 120 s is assumed. Furthermore, a delay due to reduced catheter performance by a factor of 110% is assumed for the insertion; that is, the insertion time is 10% longer than in the ideal state where this property is absent, due to a characteristic of the catheter. If we define the catheter parameter FΔtInsertion, which relates to the insertion delay, the insertion time is given by: The value for FΔtInlet can be preset to 110% by the device. However, it is also conceivable that the value can be adjusted by a user. For the outflow duration ΔtOutflow, the following results apply in the case of a delay FΔtOutflow caused by the catheter during outflow and in the case of a procedure-related delay ΔtOutflow, delay of 60 s: If we again assume a value FΔtEinlauf of 110% and a delay of 120 s for the duration of the last entry, the following results: The values ​​ΔtInflow, delay and ΔtOutflow, delay may be caused by process-related delays, such as measuring the patient pressure, changing the bag during the enema, etc. The values ​​FΔtInlet and FΔtOutlet can, for example, fluctuate between a minimum value (100%) and a maximum value (200%). A default value, such as 130%, can be specified or suggested for both values. The cycle duration, assuming a dwell time of 60 minutes, is now: With two cycles, the total treatment duration is then calculated as follows: Assuming that the value for FΔtExit is editable, i.e., user-changeable, the following table results for the expiry time and the estimated total treatment duration for different values ​​for FΔtExit. 100360157 110390158 120420159 130450160 140480161 150510162 160540163 170570164 180600165 190630166 200660167 If it is assumed that additional time periods for one or more breaks ΔtPause and / or messages ΔtMessage must be taken into account, the estimated cycle duration and the estimated total duration are extended accordingly. The estimated duration of a break can correspond to the prescribed duration of a break. The same applies to the residence time of the dialysis solution in the patient. The duration of a message can be assumed to be zero. As explained above, the initial discharge volume Vdischarge,initial can be estimated for a pressure-controlled initial discharge. This estimation can be performed using the following relationship. The effective discharge rate Qdischarge,initial is derived from the prescribed discharge rate Qdischarge,initial according to: The effective drain time ΔtDrain,initial, effer is derived from For FΔtOutflow and for ΔtOutflow,initial, the above-mentioned values ​​of 110% and 5 min can be used, for example. Based on this relationship, the initial discharge volume Vdischarge,initial can be determined. Figure A shows the course estimated using the inventive method, and curve A' shows the actual course of the volume of dialysis solution in the patient over time. The markings P symbolize pressure events. As can be seen from the figure, course A begins with a dotted line that starts with the calculated initial discharge volume and extends over a fixed time period of 5 minutes. After an initial infusion phase, the solution remains in the patient for a period of time, followed by a withdrawal phase until the volume reaches zero. The infusion, withdrawal, and withdrawal phases then repeat, as shown in the diagram. Line B indicates the maximum permissible volume of dialysis solution in the patient, line C indicates the maximum permissible volume remaining in the patient. Area D indicates the volume of ultrafiltration removed during treatment. The initial outflow phase is not taken into account when determining the ultrafiltration volume. A trend analysis over longer periods could reveal whether and how the catheter's properties change over time. The effective flow rates at outflow and inflow correspond to the slopes of curve A'. If the slope is zero, neither outflow nor inflow occurs. This is the case, for example, during dwell times, treatment breaks, or procedure-related downtime. Preferably, each treatment is logged. The log may include the mean effective flow rate for inlet and outlet, i.e., the mean effective inlet and outlet rates calculated over the entire treatment. The calculated values ​​only consider the flow rates at which volume was effectively delivered into or out of the body, i.e., the times when the pumps were in operation. The effective flow rates can also be recorded for all phases. As explained above, comparing different effective flow rates at different time points allows conclusions to be drawn about catheter performance.

Claims

Dialysis device for performing peritoneal dialysis, comprising at least one control unit, at least one input unit for inputting one or more values, and at least one processor, wherein the processor is designed to perform a method for estimating the treatment duration of a peritoneal dialysis treatment, wherein the estimation of the treatment duration is based on an ideal treatment duration, the ideal treatment duration being increased by one or more delay values, characterized in that the delay values ​​depend on one or more patient-specific parameters.where a patient-specific parameter is catheter performance and the catheter performance is taken into account when estimating the infusion time and / or when estimating the outflow time and / or when estimating the duration of the last infusion, and the catheter performance, and in particular an absolute or relative increase thereof, is editable by a user. Dialysis device according to claim 1, characterized in that the ideal treatment duration comprises the ideal duration of the initial drainage, the ideal cycle duration multiplied by the number of cycles, and the ideal duration of the final drainage. Dialysis device according to claim 1, wherein it is provided that the catheter performance is taken into account in the form of an absolute or relative increase in the ideal inflow time and / or the ideal outflow time and / or the ideal duration of the last inflow. Dialysis device according to one of the preceding claims, characterized in that the initial outflow is pressure-controlled and that the duration of the initial outflow is predetermined by the device, or that the initial outflow is volume-controlled and that the duration of the initial outflow is determined from an initial outflow volume and an outflow rate, wherein it is preferably provided that the value determined in this way is increased to take into account the catheter performance. Dialysis device according to one of the preceding claims, characterized in that the process-specific parameter is an absolute or relative delay in the inflow and / or outflow. Dialysis device according to one of the preceding claims, characterized in that the volume of the initial outflow is determined from the effective duration of the initial outflow and from the effective outflow rate. Dialysis device according to claim 6, characterized in that the effective duration is a predetermined duration plus a time delay and / or that the effective outflow rate is determined from the predetermined outflow rate and a value taking into account the catheter performance. Dialysis device according to one of the preceding claims, characterized in that the prescribed duration is used for the estimated duration of the residence time of the solution in the patient and / or for the estimated duration of a treatment break and / or that the value zero is assumed for the estimated duration of a notification. Dialysis device according to one of the preceding claims, characterized in that the estimated treatment duration is composed of the following estimated times: initial drain time, inflow time, drain time, dwell time in the patient, duration of treatment break, duration of notifications, final inflow time. Dialysis device according to one of the preceding claims, characterized in that the effective inflow rates and / or outflow rates are determined and that, for the purpose of creating a trend analysis, a change in catheter performance is determined by recording this data over time, wherein it is preferably provided that the changed catheter performance is used as the basis for estimating the treatment duration of future treatments. Dialysis device according to one of the preceding claims, characterized in that the dwell time of the treatment is changed or remains unchanged depending on the estimated treatment duration. Dialysis device according to one of the preceding claims, characterized in that the estimated treatment duration is compared with an upper and / or a lower limit and that a notification is issued to the user if the estimated treatment duration exceeds the upper limit or falls below the lower limit.

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