Plasmapheresis by reciprocatory pulsatile filtration
AssigneeE. I. Du Pont de Nemours and Company
InventorRay B. Duggins
Life of this patent
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Abstract
A process for continuous plasmapheresis, which process comprises conducting blood over a microporous membrane in reciprocatory pulsatile flow, and preferably further comprises reducing the transmembrane pressure difference to below zero during each forward and reverse flow. Apparatus for carrying out the process are also disclosed.
Claims36
Improved method for plasmapheresis wherein whole blood is introduced and conducted in a forward direction from an upstream area of a first surface of each of one or more membranes having cell-retaining pores to a downstream area of the first surface, plasma-depleted blood is collected from the downstream area of the first surface, and plasma is separately collected from a second surface of each of the one or more membranes, in a system closed off from the atmosphere, comprising:
- (a) while maintaining a net positive transmembrane pressure difference across said one or more membranes, conducting plasma-depleted blood in the reverse direction over the first surface by delivering collected plasma-depleted blood to the downstream area of the first surface and reducing the transmembrane pressure difference across said one or more membranes in the upstream area whereat whole blood is introduced to about .ltoreq.0 by either withdrawing and collecting blood from the upstream area of the first surface or increasing the pressure on a second surface of the one or more membranes, while collecting blood from the upstream area of the first surface, so that blood in the upstream area of the first surface is at a pressure which is lower than the downstream plasma-depleted blood pressure;
- (b) terminating the reverse conducting of step (a);
- (c) while maintaining the net positive transmembrane pressure difference across the membrane, conducting whole blood in the forward direction over the first surface by delivering collected blood from step (a) to the upstream area of the first surface and reducing the transmembrane pressure difference across said one or more membranes in the downstream area whereat plasma-depleted blood is collected to about .ltoreq.0 by either withdrawing and collecting plasma-depleted blood from the downstream area of the first surface or increasing the pressure on a second surface of the one or more membranes, while collecting plasma-depleted blood from the downstream area of the first surface, so that plasma-depleted blood in the downstream area of the first surface is at a pressure which is lower than the upstream blood pressure;
- (d) repeating steps (a) to (c) in sequence;
- and
- (e) collecting plasma at a rate of at least about 0.01 mL/min/cm.sup.2 of membrane and plasma-depleted blood having a hematocrit of at least about 60%.
Improved plasmapheresis apparatus comprising one or more membranes having cell-retaining pores, means for conducting blood through a blood flow path forward at a net positive transmembrane pressure difference and reverse over a first surface of each membrane, means for reducing the transmembrane pressure difference during the forward and reverse conducting of blood, means for collecting plasma which passes through each membrane from a second surface thereof, means for withdrawing and collecting blood from each said first surface, means for withdrawing and collecting plasma-depleted blood from each said first surface, means for delivering collected blood to each said first surface, means for delivering collected plasma-depleted blood to each said first surface and means for operating the apparatus closed off from the atomosphere.
Improved apparatus including a plasmapheresis membrane filter module comprising:
- first and second opposing module housing plates having circular recesses within opposing surfaces so as to form a blood flow region between two plasma flow regions;
- said plates defining a central blood inlet port connected to the blood flow region, a plasma depleted blood outlet port, a blood collection channel, around the blood flow region, connected to said plasma-depleted blood outlet port, a plasma output port and a plasma collection channel around each plasma flow region connected to said plasma outlet port;
- a plasma-side support within each plasma flow region;
- a pair of membranes, having cell-retaining pores, between each plasma flow region and the blood flow region, there being an elastomeric seal between each membrane and each plate and a blood flow path between the membranes;
- means for conducting blood forward at a net positive transmembrane pressure difference and reverse over a first surface of each membrane;
- means for reducing the transmembrane pressure difference during the forward and reverse conducting of blood;
- means for collecting plasma which passes through each membrane from a second surface thereof;
- means for withdrawing and collecting blood from the blood flow region;
- means for delivering collected blood to the blood flow region;
- means for withdrawing and collecting plasma-depleted blood from the blood flow region;
- means for delivering plasma-depleted blood to the blood flow region;
- and
- means for operating the apparatus closed off from the atmosphere.
The apparatus of clalim 28 in which the membranes are comprised of polyester or polycarbonate and are less than about 1 mil (25 .mu.m) thick.
Dependencies are inferred from the claim text.