Artificial Internal Organs and Related Fields

Artificial Internal Organs and Related Fields.— There has been a marked increase in certain aspects of the literature here, notably in the haemoperfusion field and in total artificial heart replacement. Some recent advances in haemodialysis techniques have been described involving high rates of ultra-filtration combined with optimal diffusion, the use of a resin-sorbent system for dialysate regeneration and the use of urease (E.C. 3.5.1.5) and an expanded polytetrafluoroethylene membrane in the development of a new method of urea removal. The effects of different membranes in the onset of haemodialysis-induced leucopenia have been discussed.  

Haemoperfusion is a subject of considerable interest. A series of papers in Artificial Organs indicated present and future perspectives of the topic in 

Zartnack, W. Dunkel, K. Affeld, and E. S. Bucherl, Trans. Am. Soc. Artif. Intern. Organs, 1978, 24,600. 

Hanzelka, V. Krcma, P. Svoboda, V. Trbusek, P. Urbanek, J. Vaskon, E. Urbanek, and M. Dostal, 

Techniques used in the microencapsulation of charcoal and of ion-exchange resin beads are described, notably by Courtney and his co-workers. who also present results of their clinical work. The major reason for encapsulating the adsorbent particles is to improve blood compatibility. The behaviour of a polystyrene-based adsorbent in this respect has been discussed together with its ability to remove bile acids.  

Artificial Internal Organs and Related Fields.—A useful and up to date guide to present work in this area can be found from the appropriate collections in ref. 3. 

The general question of the filtration of blood has been discussed and the effectiveness of various microporous blood filters (polyurethane, nylon, polyester) have been evaluated, Guidain and his co-workers have described banked blood microfiltration using a microfilter composed of five polyurethane foam layers with graded pore size. 

In the field of membrane dialysis the results of an evaluation study for the artificial kidney-chronic uremia programme have been reported (15 contributors). Comparative clinical studies are concerned principally with the relative merits of celiulosic and polyacrylonitrile-based membranes. New membranes based on poly(vinyl alcohol) modified in various ways and on ethylene-vinyl acetate copolymers have been described. The manufacture, and influence of manufacturing parameters, on the structure and function of membranes for artifical kidneys have been discussed. The use of assymmetric hollow fibre haemodialysers (polyamide, polyurethane, polyester) has been considered in some detail.  

Further work on the use of microencapsulated charcoal and polymeric adsorbents in haemoperfusion has been reported. Clinical studies which are concerned primarily with uremia and specific cases of detoxification (such as methotrexate removal) have been carried out with ion-exchange resins (e.g. Amberlite XE-336, XAD-2, and R-004 ). It is apparent that the problems associated with the development and trial of systems for use in the wider aspects of acute liver failure discussed in the 1974 Symposium on artificial liver support still await solution. Further contributions in this area have been made by Williams 

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