Blood feeding flow rate-controlling device and extracorporeal circulation device

1. A blood supply flow rate controlling device for use in an extracorporeal circulation device connected to a living body, the extracorporeal circulation device comprising a centrifugal pump for circulating blood through a blood circulation circuit, the blood supply flow rate controlling device comprising:

rotational frequency detecting means that detects a rotational frequency of the centrifugal pump;

inlet pressure detecting means and outlet pressure detecting means that detect an inlet pressure and an outlet pressure of the centrifugal pump, respectively;

flow rate regulating means that regulates a flow rate of blood supplied to the living body by adjusting a flow path cross section area of the blood circulation circuit; and

controlling means that controls the flow rate regulating means, wherein

the flow rate regulating means is located downstream of the centrifugal pump,

the controlling means comprises an inputter, a storage, a processor, and an outputter,

the inputter is configured to receive inputs of a desired target blood supply flow rate entered by an operator, an inlet pressure detection value and an outlet pressure detection value respectively detected by the inlet pressure detecting means and the outlet pressure detecting means, a detected rotational frequency of the centrifugal pump detected by the rotational frequency detecting means, and an estimated blood flow rate equation for calculating an estimated blood flow rate of blood passing through the blood circulation circuit from the inlet pressure detection value, the outlet pressure detection value, and the detected rotational frequency,

the storage is configured to store the target blood supply flow rate, the inlet pressure detection value, the outlet pressure detection value, the detected rotational frequency, and the estimated blood flow rate equation,

the processor is programmed to calculate a differential pressure by subtracting the inlet pressure detection value from the outlet pressure detection value, the estimated blood flow rate from the differential pressure and the detected rotational frequency by the estimated blood flow rate equation, and a flow rate differential by subtracting the estimated blood flow rate from the target blood supply flow rate, and

the outputter is configured to output to the flow rate regulating means a control signal that reduces the flow path cross section area when the flow rate differential has a negative value, a control signal that increases the flow path cross section area when the flow rate differential has a positive value, and a control signal that reduces the flow path cross section area to zero when the estimated blood flow rate has a negative value.

2. The blood supply flow rate controlling device according to claim 1 , wherein the estimated blood flow rate equation is expressed by the following equation 1:

Qe ( f )=α( f )·Δβ+β( f )  (equation 1)

where Qe is the estimated blood flow rate, f is the detected rotational frequency of the centrifugal pump, ΔP is the differential pressure by subtracting the inlet pressure detection value from the outlet pressure detection value, and α and β are respectively a slope and an intercept of a linear function of the flow rate of the centrifugal pump as a function of the differential pressure ΔP at the rotational frequency of the centrifugal pump.

3. The blood supply flow rate controlling device according to claim 2 , wherein the outputter is configured to output to the flow rate regulating means a control signal that reduces the flow path cross section area to zero when the estimated blood flow rate is above a predetermined threshold flow rate.

4. The blood supply flow rate controlling device according to claim 1 , comprising:

a display configured to display the target blood flow rate and the estimated blood flow rate,

the blood supply flow rate controlling device comprising a power supply independent of a power supply to the centrifugal pump.

5. An extracorporeal circulation device comprising the blood supply flow rate controlling device according to claim 1 .