Method of determining a parameter indicative of the progress of an extracorporeal blood treatment
First Claim
1. Method of determining a parameter indicative of the effectiveness of an extracorporeal blood treatment, the parameter being chosen from the group consisting of D, K, Kt/v, Cbin, the method comprising:
- flowing blood through a first compartment of a membrane exchanger;
flowing treatment liquid through a second compartment of a membrane exchanger, the second compartment having an inlet connected to an upstream flow path and an outlet connected to downstream flow path;
controlling contents of the upstream flow path to cause an initial substantially constant conductivity value (Cd) in the upstream flow path;
measuring and storing in memory, data sufficient to define a downstream conductivity baseline;
purposefully inducing a conductivity perturbation in the second compartment by varying the conductivity value (Cd) in the upstream flow path for a discrete time period, after which discrete time period the upstream conductivity value is stabilized at the substantially constant conductivity value (Cd);
measuring and storing in memory, during the perturbation, a plurality of downstream perturbation conductivity values defining a downstream curve;
calculating with respect to the downstream baseline, an area bounded by the downstream curve; and
calculating, as a function of both the area bounded by the downstream curve and a known area associated with a corresponding upstream curve, the parameter indicative of the effectiveness of a treatment.
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Abstract
A method is disclosed for determining a parameter (D, K, Kt/v, Cbin) indicative of the effectiveness of an extracorporeal blood treatment carried out using a membrane exchanger. The method includes the steps of flowing through the exchanger a treatment liquid having a concentration characteristic (Cd) and of varying the value of the characteristic (Cd) upstream of the exchanger for a time at the end of which the characteristic (Cd) is returned to a nominal value. A plurality of values adopted by the characteristic (Cd) downstream of the exchanger in response to the upstream variation is measured and stored in memory. The area (Sout) of a downstream perturbation region is determined, which is bounded by a baseline and a curve representing the variation of the measured values with respect to time. Then, the parameter (D, K, Kt/v, Cbin) indicative of the effectiveness of the treatment is calculated using the area (Sin) beneath the upstream curve and an area beneath an upstream curve.
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Citations
20 Claims
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1. Method of determining a parameter indicative of the effectiveness of an extracorporeal blood treatment, the parameter being chosen from the group consisting of D, K, Kt/v, Cbin, the method comprising:
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flowing blood through a first compartment of a membrane exchanger; flowing treatment liquid through a second compartment of a membrane exchanger, the second compartment having an inlet connected to an upstream flow path and an outlet connected to downstream flow path; controlling contents of the upstream flow path to cause an initial substantially constant conductivity value (Cd) in the upstream flow path; measuring and storing in memory, data sufficient to define a downstream conductivity baseline; purposefully inducing a conductivity perturbation in the second compartment by varying the conductivity value (Cd) in the upstream flow path for a discrete time period, after which discrete time period the upstream conductivity value is stabilized at the substantially constant conductivity value (Cd); measuring and storing in memory, during the perturbation, a plurality of downstream perturbation conductivity values defining a downstream curve; calculating with respect to the downstream baseline, an area bounded by the downstream curve; and calculating, as a function of both the area bounded by the downstream curve and a known area associated with a corresponding upstream curve, the parameter indicative of the effectiveness of a treatment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification