Apparatus for extracorporeal treatment of blood
First Claim
1. In a hemodialysis apparatus comprising a first chamber, a second chamber, a dialysis solution circuit, a blood circuit, means for preparing a fresh dialysis solution, and means for withdrawing ultrafiltrate from said dialysis circuit, said first chamber being separated by means of a membrane from said second chamber, said first chamber being connected into said dialysis solution circuit, and said second chamber being connected into said blood circuit, said blood circuit including a first blood side upstream of said second chamber and a second blood side downstream of said second chamber, the improvement comprising:
- a single sensor coupled between a single connection with a patient and a branch of said blood circuit into said first and second blood sides, said sensor alternately sensing inflowing blood quantities and outflowing blood quantities;
an ultrafiltrate controller coupled to said sensor for receiving signals from said sensor and being operative during a first time interval to recognize a first output signal from said sensor representing outflowing blood quantities and being operative during a second time interval to recognize a second output signal from said sensor representing inflowing blood quantities and being operative after said first and second time intervals to compare said first output signal with said second output signal to determine the actual ultrafiltration rate;
a control unit connected to said ultrafiltrate controller, said control unit having input means for inputting a predetermined ultrafiltration rate; and
a dialysis solution pump coupled in said dialysis circuit downstream of said first chamber and operatively coupled to said ultrafiltrate controller for changing the pressure in said dialysis solution circuit, thereby changing the transmembrane pressure to cause the actual ultrafiltration rate to approach said predetermined ultrafiltration rate.
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Abstract
An apparatus for controlling the ultrafiltration rate in machines for the extracorporeal purification of blood in which the difference obtained in the blood circuit by an electromagnetic flow meter is used for controlling the ultrafiltration rate.
The ultrafiltration rate is controlled by controlling the transmembrane pressure across the membrane separating the blood chamber from the dialysis fluid chamber in a dialyzer. In one embodiment, the pressure in the blood circuit is varied to change the transmembrane pressure. In a second embodiment, the pressure in the dialysis solution circuit is varied.
164 Citations
13 Claims
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1. In a hemodialysis apparatus comprising a first chamber, a second chamber, a dialysis solution circuit, a blood circuit, means for preparing a fresh dialysis solution, and means for withdrawing ultrafiltrate from said dialysis circuit, said first chamber being separated by means of a membrane from said second chamber, said first chamber being connected into said dialysis solution circuit, and said second chamber being connected into said blood circuit, said blood circuit including a first blood side upstream of said second chamber and a second blood side downstream of said second chamber, the improvement comprising:
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a single sensor coupled between a single connection with a patient and a branch of said blood circuit into said first and second blood sides, said sensor alternately sensing inflowing blood quantities and outflowing blood quantities; an ultrafiltrate controller coupled to said sensor for receiving signals from said sensor and being operative during a first time interval to recognize a first output signal from said sensor representing outflowing blood quantities and being operative during a second time interval to recognize a second output signal from said sensor representing inflowing blood quantities and being operative after said first and second time intervals to compare said first output signal with said second output signal to determine the actual ultrafiltration rate; a control unit connected to said ultrafiltrate controller, said control unit having input means for inputting a predetermined ultrafiltration rate; and a dialysis solution pump coupled in said dialysis circuit downstream of said first chamber and operatively coupled to said ultrafiltrate controller for changing the pressure in said dialysis solution circuit, thereby changing the transmembrane pressure to cause the actual ultrafiltration rate to approach said predetermined ultrafiltration rate. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a hemodialysis apparatus comprising a first chamber, a second chamber, a dialysis solution circuit, a blood circuit, means for preparing a fresh dialysis, solution, and means for withdrawing ultrafiltrate from said dialysis circuit, said first chamber being separated by means of a membrane from said second chamber, said first chamber being connected into said dialysis solution circuit, and said second chamber being connected into said blood circuit, said blood circuit including a first blood side upstream of said second chamber and a second blood side downstream of said second chamber, the improvement comprising:
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a single sensor coupled between a single connection with a patient and a branch of said blood circuit into said first and second blood sides, for alternately sensing inflowing blood quantities and outflowing blood quantities; an ultrafiltrate controller coupled to said sensor for receiving signals from said sensor and being operative during a first time interval to recognize a first output signal representing outflowing blood quantities and being operative during a second time interval to recognize a second output signal representing inflowing blood quantities and being operative to compare said first output signal with said second output signal to determine the actual ultrafiltation rate; a control unit connected to said ultrafiltrate controller, said control unit having input means for inputting a desired ultrafiltration rate; a first pump connected in said first blood side and operatively coupled to said control unit; a second pump connected in said second blood side and operatively coupled to said control unit; and a pressure sensor connected in said first blood side downstream of said first pump and coupled to said control unit; said control unit being operative during said first time interval to activate said first pump and to deactivate said second pump and being operative during said second time interval to deactivate said first pump and to activate said second pump, said control unit being operative to effectuate a switchover from said first time interval to said second time interval when said pressure sensor indicates to said control unit a pressure value which matches an excess pressure value, said control unit being further operative to determine said excess pressure value by comparing said actual ultrafiltration rate and said desired ultrafiltration rate. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification