Surgery – Blood drawn and replaced or treated and returned to body – Constituent removed from blood and remainder returned to body
Patent
1988-11-03
1992-03-24
Hafer, Robert A.
Surgery
Blood drawn and replaced or treated and returned to body
Constituent removed from blood and remainder returned to body
604 4, 604 6, A61M 3700
Patent
active
050983725
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a machine based on blood separation by filtration for plasma exchange treatment, plasma donation and cytapherasis such as platelet apheresis.
For plasma exchange treatment of a patient, whereby plasma is separated from the patient's blood (because the plasma may lack a certain substance or alternatively may contain substances(s) that cause(s) disease or may be generated by the disease and in turn give rise to significant troubles) and substitution fluid is added to the patient's blood, until now one has been forced to use machinery requiring two separate blood vessel connections through intravenous needles, catheters or the like, one connection for blood flow out from the patient and the other for the return flow back to the patient. This holds true irrespective of the principle applied for separation of blood, centrifugation or filtration. Dual connection has been the only feasible arrangement when running continuous blood separation processes by using equipment without reservoir functions. One special embodiment of plasma donation is so called plasma exchange donation wherein plasma is donated in exchange for the bulk of plasma collected from the donor at a preceding session, these plasma donors returning for donation once a month or much more often. Inbetween sessions the procured plasma is subjected to a sterile fractionation procedure such as taking out a so called cryoprecipitate, where concentrated coaguloation factor VIII may be found. Then the rest of the plasma may be returned without risk of any severe side effect to the donor. Therefore, thanks to the fully compatible exchange fluid being plasma, large volumes up to a few liters may be collected at advantage during each session.
An example of machinery that is capable of satisfactorily performing single-needle plasma donation using filtration as the principle for separating blood, is Autopheresis-C.RTM. made by Hemascience Inc., since 1986 Fenwal Automated Systems, Div. of Travenol Laboratories. It appears to represent the state of the art of blood filtration in applying modern computer control simultaneously of pump speeds, pressures, air in donor blood line etc and comprising a novel design of a filtration unit in which the membrane is rotating to minimize particle coating during filtration. Although the Autopheresis-C would fit the purpose of plasma exchange as far as drawing blood and filtration of blood for the collection of plasma for donation or as part of patient treatment, means and control means for infusing fluid in exchange for the relatively large volumes of plasma that may have to be taken out are lacking. Then, exchange fluid such as normal donor plasma might be given back through a separate needle or through a branch of the single blood line between the donor/patient and the machine, e.g. as a separate step manually controlled during or after return of concentrated blood. Aside from the manual control the drawbacks of designs like these are manifest by the return flow speed being limited, partly because the high viscoisity of (the first fraction of retransfused) packed red cells causes increased friction of flow and consequently increased internal pressure in the tubing and the receiving blood vessel, and partly because of the limited capacity of donors/patients to metabolize the calcium ion-binding citrate (admixed to blood during draw or generally to donated blood, inter alia as an inhibitor to coagulation), present in the plasma given (back) to the donor/patient (in exchange). A significant drawback of present single-needle techniques is the long time required for retransfusion.
During recent years a related medical procedure, viz. plasma donation as an alternative to whole blood donation, also has been automated with similar machines, which require but one syringe for vascular access, just as previously established as the routine for manual plasma donation. In such equipment, means for storing packed blood cells and means for periodically repeated retransfusion are mandatory, irrespective of the choi
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FIG. 9G, Making Platelet Cut, p. 9.12 (Jan. 1977), Haemonetics Brochure, "Extended Storage Platelet ESP Pack".
Hafer Robert A.
Owens Kerry
Stafilum AB
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