Extracellular fluid excessive amount calculation device

Abstract

To provide a device of calculating an excessive amount of an extracellular fluid at the time of completion of dialysis.SOLUTION: The extracellular fluid excessive amount calculation device comprises: a drain amount acquisition unit which acquires a drain amount by dialysis; a plasma amount ratio acquisition unit which acquires a ratio of a plasma amount at the time of the completion of the dialysis to that at the time of starting the dialysis; a healthy person plasma amount acquisition unit which acquires a plasma amount of a healthy person having a physique identical to that of a dialysis patient; a storage part which stores a relational expression between the ratio of the excessive amount of an interstitial fluid to the excessive amount of the plasma and the excessive amount of an extracellular fluid; and a calculation unit which calculates an excessive amount of the extracellular fluid at the time of the completion of the dialysis based on the drain amount, the ratio of the plasma amount at the completion of the dialysis to that at the time of starting the dialysis, the plasma amount of a healthy person, and the relational expression.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present specification relates to a technique for calculating the excess amount of extracellular fluid at the end of dialysis. [Background technology]

[0002] In dialysis patients, all water ingested accumulates in the body because renal function is abolished. Water accumulated in the body is removed by dialysis therapy. In theory, water removal is performed until the weight at the end of dialysis is the weight that the patient would have if his / her renal function were normal. However, in reality, there is no established method for knowing the weight of the patient if his / her renal function were normal. Therefore, at present, the weight of the patient if his / her renal function were normal is estimated by trial and error based on clinical symptoms such as the presence or absence of edema, blood pressure level, the presence or absence of blood pressure drop during dialysis, the presence or absence of fatigue after the end of dialysis, and the presence or absence of muscle cramps in the latter half of dialysis (Non-Patent Document 1). However, the evaluation results of these clinical symptoms are inaccurate (Non-Patent Document 2), and after a certain amount of time has passed, the amount of body fat and muscle mass change (Non-Patent Document 1). Therefore, the weight of the patient if his / her renal function were normal, estimated based on the evaluation results of clinical symptoms, is inaccurate. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Jaeger JQ and Mehta RL: Assessment of Dry Weight in Hemodialysis: An Overview. J Am Soc Nephrol 10: 392-403, 1999. [Non-Patent Document 2] Charra B, et al: Clinical assessment of dry weight. Nephrol Dial Transplant 11(Suppl 2): ​​16-19, 1996. Summary of the Invention [Problem to be solved by the invention]

[0004] Theoretically, the amount of excess water retained in the body at the end of dialysis is equal to the difference between the weight at the end of dialysis and the weight of the patient if the renal function of the patient were normal. All excess water in the body is retained in the extracellular compartment, and it is the water retained in the extracellular compartment that is removed during dialysis. Therefore, the amount of excess water retained in the body at the end of dialysis is theoretically equal to the difference between the amount of extracellular fluid at the end of dialysis and the amount of extracellular fluid if the renal function of the patient were normal. In other words, the amount of excess water retained in the body at the end of dialysis is the excess amount of extracellular fluid at the end of dialysis. However, in reality, there is no way to accurately know the weight if the renal function was normal, so the exact amount of excess extracellular fluid cannot be known. In other words, in dialysis therapy, the amount of water to be removed during dialysis cannot be accurately estimated.

[0005] Thus, there is no way to know the exact amount of excess extracellular fluid, and therefore there is a problem in dialysis therapy in that it is not possible to accurately estimate the amount of water that should be removed during dialysis.

[0006] This specification discloses a technique for calculating the amount of extracellular fluid excess at the end of dialysis. [Means for solving the problem]

[0007] In a first aspect of the technology disclosed in this specification, an apparatus for calculating an excess amount of extracellular fluid calculates an excess amount of extracellular fluid at the end of dialysis. The apparatus for calculating an excess amount of extracellular fluid includes a water removed amount acquisition unit that acquires an amount of water removed by dialysis, a plasma amount ratio acquisition unit that acquires a ratio of the amount of plasma at the end of dialysis to the amount of plasma at the start of dialysis, a healthy person plasma amount acquisition unit that acquires the amount of plasma of a healthy person with the same body type as the dialysis patient, a memory unit that stores a relational expression between the ratio of the amount of excess interstitial fluid to the amount of excess plasma and the amount of excess extracellular fluid, and a calculation unit that calculates the amount of excess extracellular fluid at the end of dialysis based on the amount of water removed, the ratio of the amount of plasma at the end of dialysis to the amount of plasma at the start of dialysis, the amount of plasma of the healthy person, and the relational expression between the ratio of the amount of excess interstitial fluid to the amount of excess plasma and the amount of excess extracellular fluid.

[0008] The inventors have found that the excess amount of extracellular fluid at the end of dialysis can be calculated from the amount of water removed by dialysis, the plasma volume of a healthy person who has the same height and weight as the dialysis patient (in the case of a dialysis patient, the weight at the end of dialysis) (i.e., the same body type as the dialysis patient), the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis, and the relationship between the ratio of the excess amount of interstitial fluid to the excess amount of plasma and the excess amount of extracellular fluid. The amount of water removed can be measured as an actual measurement value. In addition, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis and the plasma volume of a healthy person with the same body type as the dialysis patient can be calculated using various methods from various actual measurement values. Furthermore, the equation showing the relationship between the ratio of the excess amount of interstitial fluid to the excess amount of plasma and the excess amount of extracellular fluid can be derived from experimental results. In other words, the excess amount of extracellular fluid at the end of dialysis can be calculated using obtainable values. [Brief description of the drawings]

[0009] [Figure 1] Schematic diagram to explain water compartments in the body. [Diagram 2] Diagram showing the composition of plasma excess, interstitial fluid excess, and extracellular fluid excess at the start and end of dialysis. [Diagram 3] FIG. 13 is a graph showing the relationship between the excess amount of extracellular fluid after dialysis calculated assuming a=0.038 and the amount of extracellular fluid after dialysis measured by the impedance method. [Figure 4] A diagram showing overflow, proper fluid volume, and extracellular fluid excess in a dehydrated dialysis patient. [Diagram 5] FIG. 1 is a diagram showing the system configuration of an extracellular fluid excess calculation device. [Figure 6] 13 is a flowchart showing an example of a process for calculating an excess amount of extracellular fluid at the end of dialysis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The main features of the embodiments described below are listed below. Note that the technical elements described below are independent technical elements that exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0011] In a second aspect of the technology disclosed in the present specification, the device for calculating the excess amount of extracellular fluid in the first aspect described above may further include a plasma concentration acquisition unit that acquires the plasma concentration at the start of dialysis and the plasma concentration at the end of dialysis of a substance that is not removed by dialysis. Furthermore, the calculation unit may calculate the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis based on the plasma concentration at the start of dialysis and the plasma concentration at the end of dialysis of a substance that is not removed by dialysis. That is, while a part of the water in the plasma is removed by dialysis, the substances that are not removed by dialysis remain in the plasma, so that the plasma concentration of such substances is higher at the end of dialysis than at the start of dialysis. Therefore, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis can be calculated from the plasma concentration at the start of dialysis and the plasma concentration at the end of dialysis of a substance that is not removed by dialysis. Incidentally, the plasma concentration of a substance that is not removed by dialysis can be easily obtained as an actual measurement value. Therefore, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis can be calculated using the easily obtainable actual measurement value.

[0012] In a third aspect of the technology disclosed in this specification, the device for calculating an excess amount of extracellular fluid in the first aspect may further include a hematocrit value acquisition unit that acquires a hematocrit value at the start of dialysis and a hematocrit value at the end of dialysis. The calculation unit may calculate a ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis using a known formula from the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis.

[0013] In a fourth aspect of the technology disclosed in this specification, in the third aspect described above, the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis may be hematocrit values ​​converted from hemoglobin concentrations optically measured at the start of dialysis and the end of dialysis, respectively.

[0014] In a fifth aspect of the technique disclosed in the present specification, in any one of the first to fourth aspects, the extracellular fluid excess amount calculation device may further include a height acquisition unit that acquires the height of the dialysis patient, and a weight acquisition unit that acquires the weight of the dialysis patient at the end of dialysis. The calculation unit may calculate the plasma volume of a healthy person of the same height and weight as the dialysis patient based on the height and the weight at the end of dialysis, for example by a known formula.

[0015] In a sixth aspect of the technology disclosed herein, the relationship between the ratio of the excess amount of interstitial fluid to the excess amount of plasma and the excess amount of extracellular fluid may be expressed as an exponential function of the excess amount of extracellular fluid, i.e., the ratio of the excess amount of interstitial fluid to the excess amount of plasma increases exponentially as the excess amount of extracellular fluid increases. EXAMPLES

[0016] An extracellular fluid excess volume calculation device 10 according to this embodiment will be described with reference to the drawings. The extracellular fluid excess volume calculation device 10 is a device that calculates the excess volume of extracellular fluid in a dialysis patient at the end of dialysis.

[0017] First, a method for calculating the excess amount of extracellular fluid at the end of dialysis in this embodiment will be described. As shown in Fig. 1, the water compartments in the body are divided into an intracellular compartment 40 and an extracellular compartment 50, and the extracellular compartment 50 is further divided into an interstitial compartment 52 and an intravascular compartment 54. Ingested water is stored only in the extracellular compartment 50.

[0018] Here, the difference between the volume of the extracellular compartment 50 of a dialysis patient (hereinafter also referred to as the extracellular fluid volume) and the volume of the extracellular fluid if the renal function of the dialysis patient were assumed to be healthy is the excess amount of the extracellular fluid of the dialysis patient. Since there is no movement of water between the intracellular compartment 40 and the extracellular compartment 50 during dialysis, the amount of water removed from the body by dialysis (hereinafter also referred to as the amount of water removed) is equal to the amount of water removed from the extracellular compartment 50 by dialysis. In other words, the amount of water removed by dialysis is equal to the difference between the excess amount of extracellular fluid at the start of dialysis and the excess amount of extracellular fluid still present at the end of dialysis. Therefore, the following formula 1 is established. Note that exECVs indicates the excess amount of extracellular fluid at the start of dialysis, exECVe indicates the excess amount of extracellular fluid at the end of dialysis, and UFV indicates the amount of water removed by dialysis.

[0019]

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[0020] Figure 2 shows the composition of the excess amount of extracellular fluid at the start and end of dialysis. The excess amount of extracellular fluid at the start of dialysis, exECVs, is the sum of the excess amount of plasma at the start of dialysis, exPVs, and the excess amount of interstitial fluid at the start of dialysis, exISVs. Therefore, the following formula 2 is established.

[0021]

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[0022] Similarly, the excess extracellular fluid (ECVe) at the end of dialysis is the sum of the excess plasma (exPVe) at the end of dialysis and the excess interstitial fluid (exISVe) at the end of dialysis. Therefore, the following formula 3 is established.

[0023]

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[0024] Next, the ratio of the plasma volume at the end of dialysis (PVe) to the plasma volume at the start of dialysis (PVs) was calculated as R PV Then, the following equation 4 holds true.

[0025]

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[0026] The plasma volume at the start of dialysis, PVs, is the sum of the plasma volume nPV of a healthy person with the same height and weight (for dialysis patients, the weight at the end of dialysis) and the excess plasma volume exPVs at the start of dialysis. Therefore, the following formula 5 is established.

[0027]

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[0028] Similarly, the plasma volume at the end of dialysis, PVe, is the sum of the plasma volume nPV of a healthy person with the same height and weight (for dialysis patients, the weight at the end of dialysis) and the excess plasma volume exPVe at the end of dialysis. Therefore, the following formula 6 is established.

[0029]

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[0030] By substituting the above expressions (5) and (6) into the above expression (4), the following expression (7) is obtained.

[0031]

number

[0032] Here, a method for calculating the plasma volume nPV of a healthy person will be described. It is known that the plasma volume nPV of a healthy person can be calculated from the body surface area (Pearson TC, et al: Interpretation of measured red cell mass and plasma volume in adults: Expert Panel on Radionuclides of the International Council for Standardization in Haematology. Br J Haematol 89: 748-756, 1995.). The following formula 8 shows a method for calculating the plasma volume nPV of a male healthy person, and the following formula 9 shows a method for calculating the plasma volume nPV of a female healthy person. Note that BSA indicates body surface area.

[0033]

number

[0034]

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[0035] It is also known that the body surface area BSA can be calculated using the following formula (Du Bois D, Du Bois EF: A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 17:863-871, 1916.).

[0036]

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[0037] In other words, the plasma volume nPV of a healthy person can be calculated from the weight and height at the end of dialysis.

[0038] Next, the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis in the above formulas 4 and 7 is PV For example, the ratio of plasma volume at the end of dialysis to plasma volume at the start of dialysis R PV can be calculated as follows: Ratio of plasma volume at the end of dialysis to plasma volume at the start of dialysis, R PV is equal to the reciprocal of the ratio of the concentration of a solute not removed by dialysis at the end of dialysis to the concentration at the start of dialysis. Examples of substances not removed by dialysis include albumin, gamma globulin, and total protein. The following explanation uses albumin as an example. Since albumin is not removed by dialysis, the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis is PV is equal to the reciprocal of the ratio of the plasma albumin concentration at the end of dialysis to the plasma albumin concentration at the start of dialysis. Plasma albumin concentration can be measured using blood collected from dialysis patients. In other words, the plasma albumin concentration at the start of dialysis and the plasma albumin concentration at the end of dialysis can be easily obtained. Therefore, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis, R PV can be easily obtained.

[0039] In addition, the ratio of plasma volume at the end of dialysis to plasma volume at the start of dialysis, R PV It is known that it can also be calculated from the hematocrit value Hs at the start of dialysis and the hematocrit value He at the end of dialysis using the formula shown in the following equation 11 (Jaffrin MY, et al: Continuous monitoring of plasma, interstitial, and intracellular fluid volumes in dialyzed patients by bioimpedance and hematocrit measurements. ASAIO J 48(3): 326-333, 2002.).

[0040]

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[0041] The hematocrit value can be measured using blood collected from a dialysis patient. In other words, both the hematocrit value at the start of dialysis, Hs, and the hematocrit value at the end of dialysis, He, can be easily obtained. Therefore, the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis is PV can be easily obtained from the hematocrit value Hs at the start of dialysis and the hematocrit value He at the end of dialysis using the formula (11).

[0042] The hematocrit value Hs at the start of dialysis and the hematocrit value He at the end of dialysis may be measured using a measuring device such as a blood volume monitor. The blood volume monitor measures the hemoglobin concentration by infrared absorption. The blood volume monitor continuously measures the hematocrit value of blood during dialysis.

[0043] Incidentally, there is an exponential relationship between the ratio R of the excess interstitial fluid volume exISV to the excess plasma volume exPV and the excess extracellular fluid volume exECV. In other words, in mild cases of overflow, the ratio R of the increase in plasma volume to the increase in interstitial fluid volume remains almost constant even as overflow progresses, but in severe cases of overflow, the ratio R of the increase in plasma volume to the increase in interstitial fluid volume increases as overflow progresses, and in cases where the amount of extracellular fluid increases by 30-50% or more, most of the increased amount of extracellular fluid is stored in the interstitium (John E. Hall. Edema: Distribution of Extracellular Fluid Between the Interstitial Spaces and Vascular System. In: Guyton and Hall Textbook of Medical Physiology, pp.373). This means that the ratio R of the excess amount of interstitial fluid exISV to the excess amount of plasma exPV increases only slowly in the case of mild overflow, but when the excess amount of extracellular fluid exECV exceeds a certain level, the ratio R of the excess amount of interstitial fluid exISV to the excess amount of plasma exPV increases rapidly with the increase in the excess amount of extracellular fluid exECV. Therefore, the relationship between the ratio R of the excess amount of interstitial fluid exISV to the excess amount of plasma exPV and the excess amount of extracellular fluid can be best approximated by the exponential function shown in the following equation 12. Note that a and b in the equation 12 are constants.

[0044]

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[0045] For example, the value reported by Jaffrin et al. can be used as the value of b in the above formula 12. Jaffrin et al. reported that the ratio R of the excess interstitial fluid volume exISV to the excess plasma volume exPV in an average dialysis patient was 1.56 (Jaffrin MY, et al.: Continuous monitoring of plasma, interstitial, and intracellular fluid volumes in dialyzed patients by bioimpedance and hematocrit measurements. ASAIO J 48(3): 326-333, 2002.). Therefore, the value of b, which is the ratio of the excess interstitial fluid volume exISV to the excess plasma volume exPV when excess water starts to accumulate, i.e., when the excess extracellular fluid volume exECV is close to zero, may be set to 1.56. The value of b in the above formula 12 may be calculated from the values ​​of the interstitial fluid loss due to dialysis and the plasma loss due to dialysis of a dialysis patient who is not in a flooded state.

[0046] Next, we will explain how to calculate the value of a in the above formula (12). The post-dialysis extracellular fluid volume hdECVe of a dialysis patient is the sum of the excess extracellular fluid volume exECVe after dialysis and the extracellular fluid volume nECV of a healthy person, as shown in the following formula (13).

[0047]

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[0048] This means that in the regression line between the excess amount of extracellular fluid after dialysis exECVe and the post-dialysis extracellular fluid volume hdECVe measured by a bioimpedance method or the like, the slope of the regression line is "1.0" and the intercept of the regression line is the extracellular fluid volume nECV of a healthy person. Therefore, when the simultaneous equations consisting of the above formulas 1 to 3, the formulas 7 to 11, and the formula 12 in which various values ​​are substituted for a and 1.56 is substituted for b are solved by a computer to calculate the excess amount of extracellular fluid after dialysis exECVe at each value of a, the value of a when the regression line with the slope closest to "1.0" is calculated is the value of a to be substituted into formula 12.

[0049] That is, the value of a in the above formula (12) can be obtained, for example, by the following method. The present inventors measured the post-dialysis extracellular fluid volume hdECVe of 12 dialysis patients by the bioimpedance method, and simultaneously measured the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis. The post-dialysis extracellular fluid volume hdECVe was measured using a BCM manufactured by Fresenius, and the hematocrit values ​​at the start and end of dialysis were measured using a crit line monitor manufactured by JMS. Then, the measured hematocrit values ​​at the start and end of dialysis were substituted into the above formula (11) to obtain the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis. PVwas calculated. The height and weight of the dialysis patient were substituted into the formula represented by the above formula 10 to calculate the body surface area BSA, and the BSA calculated in this way was substituted into the formula represented by the formula 8 and the formula represented by the formula 9 to calculate the plasma volume nPV of a healthy person. Next, simultaneous equations consisting of the formulas represented by the above formulas 1 to 3, the formulas represented by the formulas 7 to 11, and the formula represented by the formula 12 in which various values ​​are substituted for a and 1.56 is substituted for b were solved by a computer to calculate the excess amount of extracellular fluid after dialysis exECVe at each value of a. Then, the value of a when the regression line between the excess amount of extracellular fluid after dialysis exECVe at each value of a and the amount of extracellular fluid after dialysis hdECVe measured by the bioimpedance method or the like was calculated, the value of a to be substituted into the formula 12 was determined to be the value of a.

[0050] As shown in Figure 3, when a = 0.038, the slope of the regression line between the excess amount of extracellular fluid after dialysis exECVe and the amount of extracellular fluid after dialysis hdECVe was 1.0046, which was the closest to 1.0. Therefore, by substituting 0.038 for a and 1.56 for b into the formula (12) above, the following formula (14) was newly obtained.

[0051]

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[0052] From the above, the excess amount of extracellular fluid exECVe at the end of dialysis can be calculated by solving the simultaneous equations represented by the above formulas 1 to 3, the formulas represented by the above formulas 7 to 11, and the formula represented by the formula 14 using a computer. Specifically, the amount of water removed by dialysis UFV is substituted into the above formula 1, the hematocrit value Hs at the start of dialysis and the hematocrit value He at the end of dialysis are substituted into the above formula 11, and height and weight are further substituted into the formula represented by the formula 10, and then the simultaneous equations represented by the above formulas 1 to 3, the formulas represented by the above formulas 7 to 11, and the formula represented by the formula 14 are solved by a computer, whereby the excess amount of extracellular fluid exECVe at the end of dialysis can be calculated.

[0053] The present inventors verified the clinical usefulness of the extracellular fluid excess volume (exECVe) at the end of dialysis calculated by the above method. That is, the present inventors divided dialysis patients into overhydrated patients, patients with adequate body fluid volume, and dehydrated patients, and compared the extracellular fluid excess volume (exECVe) at the end of dialysis corrected for body surface area among each patient group.

[0054] The inventors considered that the state immediately before the first reduction of dry weight in patients whose dry weight was reduced at least once in a month was an overflow state, and patients in this state were classified as overflow patients. In addition, patients whose dry weight had not changed for more than six months, whose systolic blood pressure had not decreased by 40 mmHg or more during dialysis in one month, and whose muscle cramps had not been recorded during dialysis, and whose fatigue had not been recorded after dialysis, were classified as patients with appropriate body fluid volume. Furthermore, the state immediately before the first increase of dry weight in patients whose dry weight was increased at least once in a month was considered to be a dehydrated state, and patients in this state were classified as dehydrated patients. As a result, 18 patients were assigned to the overflow group, 11 patients to the appropriate body fluid group, and 10 patients to the dehydration group.

[0055] The results, as shown in Figure 4, showed that the postdialysis extracellular fluid excess (exECVe) corrected for body surface area in the overflow group was 3.22 ± 2.0 L / m 2 The postdialysis extracellular fluid excess (exECVe) corrected for body surface area in the appropriate body fluid volume group was 1.18±0.35 L / m 2 The postdialysis extracellular fluid excess (exECVe) corrected for body surface area in the dehydrated group was -0.49 ± 1.96 L / m 2 There was a significant difference (p<0.001) between the overflow group and the appropriate body fluid volume group in the post-dialysis extracellular fluid excess volume (exECVe) corrected for body surface area, and there was also a significant difference (p<0.001) between the appropriate body fluid volume group and the dehydration group in the post-dialysis extracellular fluid excess volume (exECVe) corrected for body surface area.

[0056] Next, the configuration of the extracellular fluid excess amount calculation device 10 will be described. As shown in Fig. 5, the extracellular fluid excess amount calculation device 10 includes a calculation device 12, an input unit 20, and a display unit 22. The calculation device 12 can be configured, for example, by a computer including a CPU, ROM, RAM, etc. The calculation device 12 is connected to the input unit 20 and the display unit 22. The calculation device 12 includes a memory unit 14 and a calculation unit 16.

[0057] The memory unit 14 stores information acquired from the input unit 20, as well as various mathematical expressions and numerical values. The mathematical expressions stored in the memory unit 14 include, for example, a mathematical expression for calculating the plasma volume nPV of a healthy person from height and weight (expressed by the above formulas 8 to 10), a mathematical expression for calculating the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis from the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis, and a mathematical expression for calculating the plasma volume at the end of dialysis from the hematocrit value at the start of dialysis. PV (expressed in the above formula 11), and a formula showing the relationship between the excess amount of extracellular fluid and the ratio R of the excess amount of interstitial fluid to the excess amount of plasma (expressed in the above formula 14).

[0058] The calculation unit 16 uses the information acquired from the input unit 20 to solve simultaneous equations consisting of the various mathematical expressions stored in the memory unit 14, thereby calculating the excess volume exECVe of extracellular fluid at the end of dialysis.

[0059] The input unit 20 accepts instructions and information from an operator. For example, the input unit 20 accepts input of various information related to dialysis and dialysis patients (e.g., hematocrit value at the start of dialysis and hematocrit value at the end of dialysis, amount of water removed UFV, weight and height at the end of dialysis, etc.). The input information is output from the input unit 20 to the calculation device 12. The display unit 22 displays the excess amount of extracellular fluid exECVe at the end of dialysis calculated by the extracellular fluid excess amount calculation device 10.

[0060] Next, a process for calculating the extracellular fluid excess volume exECVe at the end of dialysis will be described using the extracellular fluid excess volume calculation device 10. In the following, the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis is calculated using the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis measured by the blood volume monitor device. PV A method for calculating the above will be described below as an example.

[0061] As shown in Fig. 6, first, the calculation device 12 acquires information on the amount of water removed by dialysis UFV (S12). The information on the amount of water removed UFV is input from the input unit 20. The calculation device 12 stores the information on the amount of water removed UFV input to the input unit 20 in the memory unit 14.

[0062] Next, the calculation device 12 acquires the height and weight at the end of dialysis of the dialysis patient (S14). The height and weight at the end of dialysis of the dialysis patient are input from the input unit 20. The calculation device 12 stores the height and weight at the end of dialysis of the dialysis patient input to the input unit 20 in the memory unit 14.

[0063] Next, the calculation device 12 acquires the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis measured by the blood volume monitor device (S16). The hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis measured by the blood volume monitor device are input from the input unit 20. The calculation device 12 stores the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis input to the input unit 20 in the memory unit 14.

[0064] Next, the calculation unit 16 calculates the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis from the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis obtained in step S16. PV Specifically, the calculation unit 16 calculates the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis from the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis using the formula represented by equation 11 stored in the storage unit 14.PV Calculate.

[0065] Next, the calculation unit 16 calculates the plasma volume nPV of the healthy person from the weight and height at the end of dialysis acquired in step S14 (S20). Specifically, the calculation unit 16 calculates the plasma volume nPV of the healthy person using the formulas represented by the above numbers 8 to 10 stored in the storage unit 14.

[0066] Next, the calculation unit 16 calculates the excess amount of extracellular fluid exECVe at the end of dialysis by solving simultaneous equations consisting of the equations represented by equations 1 to 3, the equations represented by equations 7 to 11, and the equation represented by equation 14, which are stored in the memory unit 14 (S22). The calculated excess amount of extracellular fluid exECVe at the end of dialysis is stored in the memory unit 14 and is displayed on the display unit 22.

[0067] In this embodiment, various values ​​used to calculate the excess amount of extracellular fluid exECVe at the end of dialysis do not need to be obtained by special measurements, and actual measured values ​​or calculated values ​​can be easily obtained. In other words, the excess amount of extracellular fluid exECVe at the end of dialysis can be calculated using only values ​​that can be obtained every time dialysis is performed.

[0068] In this embodiment, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis R was calculated using the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis measured by a blood volume monitor. PV However, the present invention is not limited to such a configuration. The ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis PV can be calculated by a method other than the method using the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis measured by a blood volume monitor. For example, the ratio R of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis may be calculated using the concentration at the start of dialysis of a substance that is difficult to remove during dialysis to the concentration at the end of dialysis.

[0069] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility. [Explanation of symbols]

[0070] 10:Extracellular fluid excess calculation device 12: Arithmetic device 14: Storage part 16: Calculation section 20: Input section 22: Display section

Claims

1. An apparatus for calculating the excess amount of extracellular fluid at the end of dialysis, A water removal amount acquisition unit that acquires the amount of water removed by dialysis; a plasma volume ratio acquiring unit for acquiring a ratio of a plasma volume at the end of dialysis to a plasma volume at the start of dialysis in a dialysis patient; A healthy person's plasma volume acquisition unit for acquiring the plasma volume of a healthy person having the same body type as the dialysis patient; a memory unit that stores a relational expression between the ratio of the excess amount of interstitial fluid to the excess amount of plasma and the excess amount of extracellular fluid; an extracellular fluid excess amount calculation device comprising a calculation unit that calculates the excess amount of extracellular fluid at the end of dialysis based on the amount of water removed, the ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis, the plasma volume of the healthy person, and the relational equation.

2. A plasma concentration acquisition unit is further provided for acquiring a plasma concentration of a substance that is difficult to remove during dialysis at the start of dialysis and a plasma concentration of the substance at the end of dialysis, 2. The extracellular fluid excess calculation device according to claim 1, wherein the calculation unit calculates a ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis based on a ratio of the plasma concentration of the substance at the start of dialysis to the plasma concentration of the substance at the end of dialysis.

3. The device further includes a hematocrit value acquisition unit that acquires a hematocrit value at the start of dialysis and a hematocrit value at the end of dialysis, 2. The device for calculating an extracellular fluid excess amount according to claim 1, wherein the calculation unit calculates a ratio of the plasma volume at the end of dialysis to the plasma volume at the start of dialysis based on the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis.

4. 4. The device for calculating an extracellular fluid excess according to claim 3, wherein the hematocrit value at the start of dialysis and the hematocrit value at the end of dialysis are each a hematocrit value converted from a hemoglobin concentration optically measured during dialysis.

5. A height acquisition unit that acquires the height of a dialysis patient; A weight acquisition unit that acquires the weight of the dialysis patient at the end of dialysis, The device for calculating an extracellular fluid excess amount according to claim 1 , wherein the calculation unit calculates the plasma volume of the healthy individual based on the height and the weight at the end of dialysis.

6. 6. The apparatus for calculating an extracellular fluid excess according to claim 1, wherein the relational expression is an exponential function of the amount of extracellular fluid excess.

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