Experimental effect of negative pressure on ultrafiltration in hemodialysis

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Recently a quad-coil ‘washing-machine artificial kidney’ for home dialysis was developed by Kolff and his associates.1, 2 One of the main advantages of this artificial kidney is that it makes possible a modest maintenance cost of home dialysis. Moreover, the cost of the unit itself is only about $350, an amount that is much less than other commercially available artificial kidneys. However, there have been several disadvantages to this artificial kidney.

This dialysis system was designed to be operated without a blood pump, to simplify the procedure of home dialysis. The coils were made to produce a flow rate of from 250 to 300 ml per minute; a low ultrafiltration pressure is produced by only arterial pressure. To increase ultrafiltration, a high concentration of dextrose was added to the rinsing fluid. Khastagir and associates2 reported adverse effects of this method. For intermittent hemodialysis, at least three pounds of water should be removed during each period of dialysis. For those patients whose kidneys still can produce urine, a quad-coil artificial kidney is effective, since they do not need additional ultrafiltration, only removal of waste products such as urea and creatinine.

At this time the Kiil artificial kidney3 and the Kolff twin-coil artificial kidney4 are the most popular artificial kidneys for home dialysis. Both types of artificial kidney have good ultrafiltration capabilities. The Kolff twin-coil artificial kidney has a high resistance: to obtain a flow of 150 ml per minute a pressure of more than 200 mm Hg is required. The high pressure . . .



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