Ultrafiltration regulation by differential weighing

Hemodialysis ultrafiltration apparatus comprising:

• hemodialysis means;
• means for supplying fresh dialysate to and for removing spent dialysate, including ultrafiltrate, from said hemodialysis means;
• means for supplying and removing blood from said hemodialysis means;
• and
• differential weighing receptacle means for allowing a first amount of fresh dialysate, by weight, to flow into said hemodialysis means and for weighing a second amount of spent dialysate flowing out of said hemodialysis means corresponding thereto, said means further comprising means for determining from the weight differential between the first and second amounts of dialysate the amount and rate of ultrafiltrate removed from the blood in said hemodialysis means.

A method for regulating ultrafiltration during hemodialysis comprising:

• supplying blood to and removing blood from a hemodialyzer;
• supplying fresh dialysate to an inlet chamber of a differential weighing receptacle and concurrently removing spent dialysate from an outlet chamber of said receptacle;
• weighing said fresh dialysate in said receptacle, and, upon reaching a pre-selected weight level when said outlet chamber is substantially empty, preventing the further flow of fresh dialysate into said inlet chamber;
• allowing only said fixed amount of fresh dialysate, by weight, to flow through said hemodialyzer;
• collecting spent dialysate including ultrafiltrate, emerging from said hemodialyzer into said outlet chamber and weighing it over a time period not greater than the time period for said fixed amount of dialysate to flow through said hemodialyzer;
• determining the weight differential between said fixed amount of fresh dialysate and said spent dialysate to monitor and control the amount and rate of ultrafiltrate removed from blood in the hemodialyzer.

A method of hemodialytic ultrafiltration comprising:

• supplying fresh dialysate to and removing spent dialysate, including ultrafiltrate, from hemodialysis means;
• supplying and removing blood from said hemodialysis means;
• periodically allowing a known amount of fresh dialysate, by weight, to flow into said hemodialysis means;
• periodically weighing with a differential weighing receptacle means the amount of spent dialysate associated with said known amount which flows out of said hemodialysis means;
• and
• determining the weight differential between the known amount of fresh dialysate and the associated amount of spent dialysate so as to allow the amount and rate of ultrafiltrate removed from the blood in said hemodialysis means to be monitored and controlled.