US3795318A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of ultrafiltration rates during hemodialysis with highly permeable membranes
Assignee: Dow Chemical Co
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Filing: 1972-05-26
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Granted: 1974-03-05
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Expires: 1992-05-26
Abstract
Abstract A system for carrying out hemodialysis with high flux membranes without incurring the risk of excessive ultrafiltration rates or reverse ultrafiltration is disclosed. The transmembrane pressure differential is held constant, despite changes in pressure on the blood side of the membrane. The actual differential is sensed, compared to a desired positive magnitude and the pumping rate of a positive displacement, discharge pump adjusted to alter the proportion of the dialysate which passes through a restricted shunt path around the pump, thereby altering the back-pressure on the dialysate side of the membrane until the differential has the desired magnitude.
Inventors
- 👤 R Crane
- 👤 B Lipps
- 👤 J Sargent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:13
CPC Classifications
A; A61; A61M; A61M1/00; A61M1/14; A61M1/16; A61M1/1601; A61M1/34; A61M1/3403; A61M2205/00; A61M2205/33; A61M2205/3331; A61M2205/50; Y; Y10; Y10S; Y10S210/00; Y10S210/929
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
168 words
A hemodialysis system comprising a. a hemodialysis device comprising a dialysis membrane capable of passing at least 0.05 cc of ultrafiltrate per minute per millimeter of Hg transmembrane pressure differential; b. feed means adapted to introduce dialysis solution to said hemodialysis device at a preselected constant volume rate (QD) and at an inlet pressure PDi; c. a variable speed, positive displacement discharge pump adapted to receive dialysate from said device at an outlet pressure PDo, said pump having a displacement volume Vp and being adapted to displace therethrough dialysate at a volume rate Qp nVp, n being displacements per unit time; d. restricted conduit means adapted to shunt dialysate around said displacement volume at a volume rate Qs QD- Qp, determinative of said pressure PDo; and e. control means for sensing the magnitude of the difference between the pressure at which blood is discharged from said device and a dialysateside pressure therein, said control means being adapted to adjust n to maintain said difference at a preselected value.
Claim 2
Dependent Claim
168 words
A hemodialysis system comprising a. a hemodialysis device comprising a dialysis membrane capable of passing at least 0.05 cc of ultrafiltrate per minute per millimeter of Hg transmembrane pressure differential; b. feed means adapted to introduce dialysis solution to said hemodialysis device at a preselected constant volume rate (QD) and at an inlet pressure PDi; c. a variable speed, positive displacement discharge pump adapted to receive dialysate from said device at an outlet pressure PDo, said pump having a displacement volume Vp and being adapted to displace therethrough dialysate at a volume rate Qp nVp, n being displacements per unit time; d. restricted conduit means adapted to shunt dialysate around said displacement volume at a volume rate Qs QD- Qp, determinative of said pressure PDo; and e. control means for sensing the magnitude of the difference between the pressure at which blood is discharged from said device and a dialysateside pressure therein, said control means being adapted to adjust n to maintain said difference at a preselected value.
Claim 3
Dependent Claim
21 words
The system of claim 1 in which the dialysis feed means is the combination of a flow controller and a pump.
Claim 4
Dependent Claim
44 words
The system of claim 1 in which the dialysis membrane is in the form of fine hollow fibers so disposed in the hemodialysis device that blood passes through the lumen of the fibers and dialysis solution passes around the exterior surfaces of the fibers.
Claim 5
Dependent Claim
16 words
The system of claim 1 adapted to pass blood and dialysate co-currently through said dialysis device.
Claim 6
Dependent Claim
20 words
The system of claim 4 wherein said preselected value is equal to the sum: (PDi - PDo) + oncotic pressure.
Claim 7
Dependent Claim
18 words
The system of claim 1 adapted to pass blood and dialysate in counter-current flow through said dialysis device.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |