Hemofiltration system and safety system therefor

Claim 1

Apparatus for hemofiltration of a supply of blood withdrawn from a patient and for the return to the patient of an infusate solution and filtered blood after hemofiltration, said apparatus comprising purified water supply means for purifying an impure supply of water provided from a source of impure water which is separate from said supply of blood and adding concentrate thereto so as to provide a replacement liquid stream comprising a purified water stream including said concentrate, the amount of said replacement liquid stream being such that substantially the entire infusate solution to be returned to the patient is derived from said replacement liquid stream; filtration means for filtering said supply of blood and said replacement liquid stream, said filtration means comprising a first semipermeable hemofiltration membrane for hemofiltration of said supply of blood and a second semipermeable membrane for filtration of said replacement liquid stream; contact means for contacting said supply of blood and said replacement liquid stream with said filtration means so as to produce a filtered blood stream and an ultrafiltration stream from said supply of blood and an infusate filtrate stream from said replacement liquid stream, said contact means including blood inlet means for supplying said supply of blood to said first semipermeable hemofiltration membrane, replacement liquid inlet means for supplying said replacement liquid stream to said second semipermeable membrane, filtered blood outlet means for withdrawing said filtered blood stream from said first semipermeable hemofiltration membrane, ultrafiltrate outlet means for withdrawing said ultrafiltration stream from said first semipermeable hemofiltration membrane, filtrate outlet means for withdrawing said infusate filtrate stream from said second semipermeable membrane, and replacement liquid outlet means for withdrawing said replacement liquid stream which does not pass through said second semipermeable membrane from said second semipermeable membrane; return means for returning said filtered blood stream and said infusate filtrate stream to said patient whereby substantially the entire infusate solution returned to said patient is derived from said replacement liquid stream; and recirculation means for recirculating said replacement liquid stream withdrawn from said replacement liquid outlet means to said replacement liquid inlet means, said recirculation means including safety means for detecting failures in said second semipermeable membrane, said safety means comprising indicator supply means for supplying an indicator which will not normally pass through said second semipermeable membrane to said replacement liquid stream in said recirculation means, and detector means associated with said filtrate outlet means, said detector means being capable of detecting the presence of said indicator in said infusate filtrate stream.

Claim 25

A method for monitoring the filtration of a replacement fluid for use in connection with the hemofiltration of blood withdrawn from a patient by means of a filter comprising a semipermeable filtration membrane, said method comprising supplying said replacement fluid to said filter whereby at least a portion of said replacement fluid may be contacted with said semipermeable membrane so as to produce a filtrate therethrough, withdrawing said replacement fluid from said filter subsequent to said contacting with said semipermeable filtration membrane, withdrawing said filtrate produced in said filter therefrom, adding said filtrate to said blood withdrawn from said patient, and returning said blood including said filtrate to said patient, recirculating said replacement fluid withdrawn from said filter for mixture with said fluid supply to said filter, supplying an indicator which will not normally pass through said semipermeable membrane to said recirculating fluid, and detecting the presence of said indicator in said filtrate.

Claim 26

A method for monitoring the filtration of a replacement fluid for use in connection with the hemofiltration of blood withdrawn from a patient by means of a filter comprising a semipermeable filtration membrane, said method comprising supplying said replacement fluid to said filter whereby at least a portion of said replacement fluid may be contacted with said semipermeable membrane so as to produce a filtrate therethrough, withdrawing said replacement fluid from said filter subsequent to said contacting with said semipermeable filtration membrane, withdrawing said filtrate produced in said filter therefrom, adding said filtrate to said blood withdrawn from said patient, and returning said blood including said filtrate to said patient, recirculating said replacement fluid withdrawn from said filter for mixture with said fluid supply to said filter, supplying an indicator which will not normally pass through said semipermeable membrane to said recirculating fluid, and detecting the presence of said indicator in said filtrate.