Circulating dialyser fluid through an artificial kidney - via directional valve diverting flow from pumps under pilot control

Abstract

Abstract A switching mechanism, for use in an appts. for the circulation of dialyser fluid through an artificial kidney, works with two double-acting, synchronously running plunger pumps of identical capacity. The pump compartments act alternately as suction and pressure vessels, so that dialyser fluid is drawn into them from one direction and expelled from them in another. Lines connect through the switching mechanism to and from the artificial kidney, from a supply of fresh fluid and to drain for wasting the used material. The switching mechanism is an hydraulic directional valve comprising a spindle with the necessary bored passages, moved by the pressure in a control circuit which also operates the plunger pumps, in a cylinder so as to link ports to pipelines for transporting the fluid as required. There is no risk of ultrafiltration due to malfunctioning of limit switches, etc., esp. of water from the patient. The dialysing fluid can flow in open circuit and only one pipeline is necessary for each pump compartment. The alternate connecting of the plunger pump to the artificial kidney, to the source of fresh dialyser fluid or to the waste for used fluid, takes place without electrically controlled valves or limit switches.

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