Dialyzing apparatus

1. A dialyzing apparatus comprising:

a dialyzer which removes water from blood of a patient at a water-remove rate during a dialysis operation;

a blood-pressure-change-related-information obtaining device which obtains a plurality of sorts of blood-pressure- change-related information each of which is related to a change of a blood pressure of the patient during the dialysis operation; and

a water-remove-rate control device which comprises (a) a weighted-value determining means for determining, for each of the plurality of sorts of blood-pressure-change-related information, a weighted value corresponding to a change of said each sort of blood-pressure-change-related information; (b) a water-remove-rate-control-amount determining means for determining a water-remove-rate control amount based on a sum of the respective weighted values determined for the plurality of sorts of blood-pressure-change-related information; and (c) a control means for controlling the water-remove rate of the dialyzer, according to the water-remove-rate control amount determined by the water-remove-rate-control-amount determining means.

2. A dialyzing apparatus according to claim 1 , wherein the blood-pressure-change-related-information obtaining device obtains a blood-flow parameter that reflects a flow rate of a blood of the patient; an autonomic-nerve parameter that reflects an activity of an autonomic nerve of the patient; a blood-vessel parameter that reflects a degree of expansion of a blood vessel of the patient; and a blood-viscosity parameter that reflects a viscosity of the blood of the patient.

3. A dialyzing apparatus according to claim 2 , wherein the blood-flow parameter comprises at least one of a systemic-circulation blood volume that is estimated based on a hematocrit that is optically detected from the blood circulating during the dialysis operation, and an amplitude of a volumetric pulse wave, such as a photoelectric pulse wave, a finger-tip pulse wave, or an impedance pulse wave, that is detected by a sensor which is adapted to be worn on a skin of the patient.

4. A dialyzing apparatus according to claim 2 , wherein the autonomic-nerve parameter comprises at least one of a low-frequency component of fluctuations of respective blood-pressure values that are determined in synchronism with respective heartbeats of the patient, a high-frequency component of fluctuations of respective pulse-period values that are determined in synchronism with the respective heartbeats of the patient, and a pressoreceptor-reflex sensitivity that is defined as a ratio of one of the high-frequency component and the low- frequency component to the other of the high-frequency component and the low-frequency component.

5. A dialyzing apparatus according to claim 2 , wherein the blood-vessel parameter comprises at least one of an estimated blood-pressure value that is determined based on a pulse-wave propagation velocity at which a pulse wave propagates through an artery of the patient, in synchronism with each heartbeat of the patient, and a pulse-wave propagation time, and a pulse-wave propagation velocity, that are determined by a pulse-wave propagation-velocity determining means in synchronism with each heartbeat of the patient.

6. A dialyzing apparatus according to claim 2 , wherein the blood-viscosity parameter comprises a hematocrit that is optically detected from the blood circulating during the dialysis operation.