Apparatus for extracorporeal blood treatment

Patent metadata

Field	Value
Publication number	US-11883571-B2
Application number	US-202016849456-A
Country	US
Kind code	B2
Filing date	Apr 15, 2020
Priority date	May 25, 2015
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

An extracorporeal blood treatment apparatus includes a filtration unit (2) connected to a blood circuit (17) and a dialysate circuit (32), a preparation device (9) for preparing and regulating the composition of the dialysis fluid, and a sensor (11) for measuring conductivity of the dialysate (i.e. spent dialysis fluid); a control unit (12) configured for setting a sodium concentration in the dialysis fluid and after setting the dialysis fluid at the initial set point, circulating the dialysis fluid and blood through the filtration unit (2), measuring an initial conductivity value of the dialysate at the beginning of the treatment, and calculating, based on the measured initial conductivity value and on the corresponding conductivity value of the dialysis fluid, the value of the initial plasma conductivity, said circulating of the dialysis fluid up to the calculating of the initial plasma conductivity performed by maintaining the dialysis fluid conductivity substantially constant.

First claim

The invention claimed is:

1. A method for setting parameters in an apparatus for extracorporeal blood treatment, the apparatus comprising:
a filtration unit having a primary chamber and a secondary chamber separated by a semi-permeable membrane;
a blood withdrawal line in fluid communication with an inlet of the primary chamber;
a blood return line in fluid communication with an outlet of the primary chamber, the blood withdrawal line and the blood return line configured for connection to a patient cardiovascular system;
a dialysis supply line in fluid communication with an inlet of the secondary chamber;
a dialysis effluent line in fluid communication with an outlet of the secondary chamber;
a preparation device for preparing dialysis fluid, the preparation device in fluid communication with the dialysis supply line and including a regulating device for regulating composition of the dialysis fluid;
a sensor for measuring a parameter value of dialysate in the dialysis effluent line, the parameter value of the dialysate being at least one chosen from a group consisting of: (i) conductivity of the dialysate; (ii) a conductivity-related parameter of the dialysate; (iii) concentration of at least a substance in the dialysate; or (iv) a concentration-related parameter of at least a substance in the dialysate; and
a control unit communicating with the sensor to receive the parameter value of the dialysate, the control unit further communicating with the regulating device and calculating a value representative of plasma conductivity,
the method comprising:
setting a parameter value for dialysis fluid in the dialysis supply line at an initial set point, the parameter value of the dialysis fluid being at least one chosen from a group consisting of: (i) conductivity of the dialysis fluid; (ii) a conductivity-related parameter of the dialysis fluid; (iii) concentration of at least a substance in the dialysis fluid; or (iv) a concentration-related parameter of at least a substance in the dialysis fluid;
after setting the parameter value of the dialysis fluid at the initial set point, circulating the dialysis fluid through the secondary chamber of the filtration unit so as to exchange with blood;
circulating blood through the primary chamber of the filtration unit;
measuring at least an initial value of the dialysate downstream of the secondary chamber at the beginning of the treatment; and
calculating, based on the measured initial value of the dialysate, and on a corresponding parameter value of the dialysis fluid in the dialysis supply line, an initial plasma conductivity,
wherein the circulating of the dialysis fluid through the secondary chamber up to the measuring of the initial value of the dialysate used for calculating the initial plasma conductivity is performed while maintaining the parameter value of the dialysis fluid to be substantially constant.

2. The method according to claim 1 , wherein the regulating device modifies a dialysis fluid composition by changing the conductivity of the dialysis fluid or by changing the concentration of at least one substance in the dialysis fluid, and wherein the preparation device prepares a dialysis fluid containing at least a substance, the substance including sodium, and the regulating device regulating the concentration of at least the substance in the dialysis fluid.

3. The method according to claim 2 , wherein the parameter value for the dialysis fluid is set at the initial set point so that a dialysis fluid conductivity matches a first estimate of plasma conductivity of the blood, the method further comprising:
calculating an initial set point of a substance concentration in the dialysis fluid, wherein a regulation of dialysis fluid conductivity in the supply line by the regulating device is derived from the calculated initial set point of the substance.

4. The method according to claim 3 , wherein the initial set point of the substance in the dialysis fluid is calculated as a function of: (i) the concentration of at least a further substance in the dialysis fluid, the substance, whose concentration is to be set, being different from the further substance, wherein the further substance is selected from the group consisting of bicarbonate, potassium, calcium, magnesium, acetate, lactate, citrate, phosphate, and sulphate, or (ii) the concentration of at least two substances selected from the group consisting of bicarbonate, potassium, acetate, and citrate.

5. The method according to claim 3 , wherein the initial set point of the substance in the dialysis fluid is calculated as a function of an estimated plasma concentration of one or more substances selected from the group consisting of sodium, potassium, calcium, magnesium, bicarbonate, acetate, lactate, citrate, phosphate, and sulphate.

6. The method according to claim 3 , wherein the initial set point of the substance in the dialysis fluid is calculated as a function of at least one of the group consisting of:
(i) a weighted difference in concentration of at least one further substance in the dialysis fluid and in the plasma, the substance, whose concentration is to be set, being different from the at least one further substance, the at least one further substance chosen from a group consisting of bicarbonate, potassium, calcium, magnesium, acetate, lactate, citrate, phosphate, and sulphate,
(ii) a molar conductivity of at least one substance in the dialysis fluid chosen from a group consisting of acids and salts of bicarbonate (HCO 3 − ), chloride (Cl − ), acetate (CH 3 COO − ), lactate (C 3 H 5 O 3 − ), citrate (C 6 H 5 O 7 3− ), phosphate (PO 4 3− ) and sulphate (SO 4 2− ), wherein the salts are formed with sodium, potassium, calcium, or magnesium,
(iii) at least a flow rate of dialysate at the outlet of the secondary chamber, or
(iv) at least an efficiency parameter of the filtration unit.

7. The method according to claim 1 , further comprising, after calculating the initial plasma conductivity, causing the regulating device to change a content of a substance in the dialysis fluid to reach a set point for the substance, the set point being a function of the calculated initial plasma conductivity.

8. The method according to claim 1 , further comprising measuring at least the initial parameter value of the dialysate in the dialysis effluent line downstream of the secondary chamber as soon as the exchange process in the filtration unit reaches stable conditions, the method determining that stable conditions for the exchange process have been reached when one or more of the following conditions occurs:
a first derivative of a median or average value of the conductivity of the dialysate is lower than a first threshold for a specified time window,
a first derivative of a value of conductivity of the dialysate is lower than a first threshold for a specified time window,
a first derivative of a filtered value of conductivity of the dialysate is lower than a first threshold for a specified time window, the filtered value being a value filtered either by a median filter, a linear filter, a finite impulse response filter, or an infinite impulse response filter,
a second derivative of the median or average value of the conductivity of the dialysate is lower than a second threshold for a specified time window,
a second derivative of the value of conductivity of the dialysate is lower than a first threshold for a specified time window,
a second derivative of the filtered value of conductivity of the dialysate is lower than a first threshold for a specified time window,
a change or a relative change of the value of conductivity of the dialysate or a filtered version of the value of the conductivity with respect to a fixed previous point in tim

Assignees

• Gambro Lundia Ab

Inventors

• Rovatti Paolo
• Surace Alessandro
• Lodi Carlo Alberto
• Wallenborg Anders
• Nilsson Anders
• Solem Kristian
• Sternby Jan
• Hertz Thomas

Classifications

• A61M1/1607 Primary

  before use, i.e. upstream of dialyser · CPC title

• A61M1/1609

  after use, i.e. downstream of dialyser · CPC title

• A61M1/1613

  Profiling or modelling of patient or predicted treatment evolution or outcome · CPC title

• A61M1/3609

  Physical characteristics of the blood, e.g. haematocrit, urea · CPC title

• A61M2205/3317

  Electromagnetic, inductive or dielectric measuring means · CPC title