An example medical system includes a hemodialysis device configured to receive blood from vasculature of a patient via an arterial line and to deliver blood to the vasculature of the patient via a venous line. The medical system includes a hematocrit sensor configured to generate a signal indicative of a hematocrit level of blood in at least one of the arterial line or the venous line. The medical system also includes processing circuitry configured to determine a change in blood volume of the patient over time based on the signal indicative of the hematocrit level, determine a threshold blood volume reduction over time for the patient, compare the change in the blood volume of the patient over time to the threshold blood volume reduction over time, and based on the comparison, generate an indication of vascular access recirculation.

The invention relates to a blood treatment device having an extracorporeal blood circuit which comprises an arterial line, a blood pump, a blood treatment unit and a venous line, wherein the arterial and venous lines can be connected to a blood vessel of a patient, and wherein the blood treatment device has an evaluation and control unit, wherein the evaluation and control unit is configured to carry out the following steps: (a1) determining the blood recirculation in a blood vessel of the patient connected to the extracorporeal blood circuit; and (b) calculating the blood flow in the blood vessel using the blood recirculation determined in accordance with (a1) and using a provided value or a value likewise previously determined for the cardiac output of the patient.

The invention relates to a device for extracorporeal blood treatment, comprising a blood treatment unit 1 that comprises at least one compartment 4. The invention further relates to a method for determining a hemodynamic parameter during an extracorporeal blood treatment by means of an extracorporeal blood treatment device. In order to determine the hemodynamic parameter, the conveying direction of the blood pump 10 is reversed from a “normal” blood flow to a “reversed” blood flow. In practice, it has been found that reversing the conveying direction of the blood pump for a measurement for determining a hemodynamic parameter carries the risk of blood clots reaching the patient, despite the dialyser holding back blood clots. The blood treatment device comprises an input unit 23 for inputting a time interval which can be specified by the user, taking into account the patient-specific and system-specific factors. The control and evaluation unit 12 of the blood treatment device is configured such that the operation of the blood pump 10 in the operating mode involving a reversed blood flow is only enabled during the time interval input by means of the input unit, the start of the time interval being determined from the point at which the blood treatment starts.

A monitoring method for an extracorporeal blood treatment machine, a monitoring device of an extracorporeal blood treatment machine, and an extracorporeal blood treatment machine including a monitoring device. The monitoring device is configured to detect a signal representing a concentration of pollutants in a used dialysis liquid, to automatically evaluate a signal course with respect to at least one predetermined indicator for an existing recirculation, and to automatically initiate a recirculation measurement or automatically output a request for initiating a recirculation measurement to a user upon determination of the at least one indicator.

The invention relates to an apparatus for extracorporeal blood treatment, comprising a blood treatment unit 1 that comprises at least one compartment 3. The invention further relates to an apparatus 15A, 15B for collecting blood clots for a blood line 5, 7 for supplying blood to or removing blood from a blood treatment unit 1 of an extracorporeal blood treatment apparatus, and to a method for determining a hemodynamic parameter during extracorporeal blood treatment using an extracorporeal blood treatment apparatus. In order to determine the hemodynamic parameter, the conveying direction of the blood pump 10 is reversed from a “normal” blood flow to a “reversed” blood flow. It has been found in practice that, in the event of a reversal in the conveying direction of the blood pump in order to carry out a measurement for determining a hemodynamic parameter, there is a risk of blood clots reaching the patients, although the dialyser traps blood clots. The apparatus according to the invention provides an apparatus 15A for catching blood clots, at least in the blood line of the extracorporeal blood circuit I that leads to the blood treatment unit 1 during a “normal blood flow”. The blood treatment unit traps blood clots during blood treatment having a “normal” blood flow. In the case of a “reversed” blood flow, the apparatus for catching blood clots in the blood line that leads to the blood treatment unit 1 during a “normal blood flow” traps blood clots that may have previously accumulated at the inlet of the blood treatment unit.

A control device for a blood treatment machine performs a connection test (50) by causing the blood treatment machine to switch (51, 53) between a first and a second operating state by reversing a blood pump so as to change a flow direction of blood through both a dialyzer and access devices connected to a patient. Based on an output signal of at least one sensor in the blood treatment machine (52, 54), the control device computes (55) an efficiency change parameter that represents a change in in-vivo clearance of the blood treatment machine during the switch of the blood treatment machine between the first and second operating states. The control device evaluates (56) the efficiency change parameter to jointly detect connection errors at the dialyzer, resulting in co-current flow of treatment fluid and blood through the dialyzer, and at the access devices, resulting in access recirculation of blood.

An object is to provide a blood purifying device and an access flow rate measuring method enabling easy and accurate measurement of an access flow rate of an access vessel. A blood purifying device includes a flow rate calculating unit calculating the access flow rate of an access vessel based on an initial blood indicator for blood distributed through a vein side circuit and flowing through the access vessel of a patient, the flow rate distributed through measuring means when a pump is reversed to cause the priming solution to flow out from an artery side circuit, and a blood indicator for the blood diluted with the priming solution which is obtained when the pump is reversed to dilute, with the priming solution, the blood distributed through the vein side circuit.

Techniques and apparatuses for access recirculation of a patient during dialysis treatment are described. In one embodiment, for example, an apparatus may include at least one memory, and logic coupled to the at least one memory. The logic may be configured to determine a first hemoglobin concentration for a dialysis system, determine a change in an ultrafiltration rate, determine a second hemoglobin concentration modified due to the change in the ultrafiltration rate based on a dialysis system model of the dialysis system, and determine an access recirculation value for the dialysis system. Other embodiments are described.

A dialysis device having an extracorporeal blood circuit which has an arterial line having a blood pump and an arterial needle for connection to a patient, a venous line having a venous needle for connection to a patient and a dialyzer arranged between the arterial line and the venous line and having a blood chamber and a dialysis fluid chamber is provided. The dialysis device furthermore has a control unit and an extracorporeal blood pressure sensor which is arranged at the suction side of the blood pump. The control unit is configured such that a signal output takes place which indicates the presence of recirculation when a change in the signal of the sensor following a trigger event exceeds a threshold value.

An apparatus for measuring recirculation using thermodilution during extracorporeal blood treatment including a temperature varying unit arranged to cyclically heat and/or cool blood in a venous tube segment of the blood tube system for a quasi-continuous recirculation measurement; and a detecting device configured to measure a variation of a physical parameter resulting from the heating and/or cooling. The detecting device is arranged to detect, in a case free from recirculation, a first physical parameter and to detect, in a case afflicted with recirculation, a physical parameter varied by the cooling and/or heating of the blood by the temperature varying unit as a second physical parameter in the blood tube system. A method for measuring recirculation carries out appropriate steps.