Apparatus and method of controlling an extracorporeal blood treatment
First Claim
1. An apparatus for extracorporeal blood treatment comprising:
- at least a treatment unit having at least a first chamber and at least a second chamber separated from one another by a semipermeable membrane;
at least a blood removal line connected to an inlet port of the first chamber and predisposed to remove blood from a patient;
at least a blood return line connected to an outlet port from the first chamber and predisposed to return treated blood to the patient;
at least an expansion chamber placed at least in one of the blood removal line and the blood return line, the expansion chamber being arranged in use to contain a predetermined quantity of gas in an upper portion and a predetermined quantity of blood at a predetermined level in a lower portion thereof, the blood removal line, the blood return line, the first chamber and the at least an expansion chamber being part of an extracorporeal blood circuit;
at least a blood pump operating at the extracorporeal blood circuit such as to move the blood in the circuit;
at least a pressure sensor associated to the expansion chamber and configured to enable determining pressure values internally of the expansion chamber;
at least a fluid evacuation line connected to an outlet port of the second chamber; and
a control unit connected to the at least a pressure sensor, with the pump, and configured to;
move the blood pump to generate a variable blood flow comprising a constant flow component equal to a desired value of blood flow and a variable flow component oscillating about the constant component and having a substantially nil average value, the variable blood flow component generating, at least in the expansion chamber, a pressure progression that is variable over time comprising a pressure component oscillating about an average value;
receive from the at least a pressure sensor a plurality of measured pressure values for a time period comprising a plurality of oscillations of the pressure about the average value, the pressure values being measured in successive time instants;
calculate, as a function of the pressure values, an average value of the pressure;
acquire an estimated volume variation value in the expansion chamber linked to the variable flow component;
calculate, as a function of the pressure values, an estimated pressure variation in the expansion chamber representing the oscillating pressure component; and
determine a representative magnitude of a blood level in the expansion chamber as a function of the average value of the pressure, the estimated volume variation value and the value of the estimated pressure variation in the expansion chamber.
1 Assignment
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Accused Products
Abstract
An apparatus is described for extracorporeal blood treatment (1), comprising a treatment unit (2), an extracorporeal blood circuit (8) and a fluid evacuation line (10). The apparatus comprises a control unit (21) connected with a pressure sensor (13, 14) and with a blood pump (9) and configured to move the blood pump (9), generating a variable flow (Q(t)) with a constant component (Qb) and a variable component (Qvar(t)) having a nil average value; the variable flow generates, in the expansion chamber (11, 12), a progression of the pressure that is variable over time (P(t)) with a pressure component (Pvar(t)) oscillating about an average value (Pavg). The control unit receives, from the sensor, a plurality of values (Pj) and calculates the average value of the pressure (Pavg), acquires an estimated value of volume variation (AP) in the expansion chamber (11, 12) connected to the variable flow component (Qvar(t)), calculates, as a function of the pressure values (Pj), an estimated value of pressure variation (AP) in the expansion chamber (11; 12) that is representative of the oscillating pressure component (Pvar(t)) and determines a representative magnitude of a blood level (L) in the expansion chamber (11, 12) as a function of the average value (Pavg) of the pressure (P(t)), of the estimated value of volume variation (AV) and of the estimated pressure variation (AP) in the expansion chamber.
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Citations
20 Claims
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1. An apparatus for extracorporeal blood treatment comprising:
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at least a treatment unit having at least a first chamber and at least a second chamber separated from one another by a semipermeable membrane; at least a blood removal line connected to an inlet port of the first chamber and predisposed to remove blood from a patient; at least a blood return line connected to an outlet port from the first chamber and predisposed to return treated blood to the patient; at least an expansion chamber placed at least in one of the blood removal line and the blood return line, the expansion chamber being arranged in use to contain a predetermined quantity of gas in an upper portion and a predetermined quantity of blood at a predetermined level in a lower portion thereof, the blood removal line, the blood return line, the first chamber and the at least an expansion chamber being part of an extracorporeal blood circuit; at least a blood pump operating at the extracorporeal blood circuit such as to move the blood in the circuit; at least a pressure sensor associated to the expansion chamber and configured to enable determining pressure values internally of the expansion chamber; at least a fluid evacuation line connected to an outlet port of the second chamber; and a control unit connected to the at least a pressure sensor, with the pump, and configured to; move the blood pump to generate a variable blood flow comprising a constant flow component equal to a desired value of blood flow and a variable flow component oscillating about the constant component and having a substantially nil average value, the variable blood flow component generating, at least in the expansion chamber, a pressure progression that is variable over time comprising a pressure component oscillating about an average value; receive from the at least a pressure sensor a plurality of measured pressure values for a time period comprising a plurality of oscillations of the pressure about the average value, the pressure values being measured in successive time instants; calculate, as a function of the pressure values, an average value of the pressure; acquire an estimated volume variation value in the expansion chamber linked to the variable flow component; calculate, as a function of the pressure values, an estimated pressure variation in the expansion chamber representing the oscillating pressure component; and determine a representative magnitude of a blood level in the expansion chamber as a function of the average value of the pressure, the estimated volume variation value and the value of the estimated pressure variation in the expansion chamber. - 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