New artificial kidney has high filtration rate
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TECHNOLOGY New artificial kidney has high filtration rate Monsanto-developed kidney with membrane material of modified acrylic polymer is nonthrombogenic, holds promise for home use of disposable units * CHICAGO «g a **Π£ characterize a new artificial kidney de- veloped at Monsanto Research Corp. The developers, under the direction of Dr. I. O. Salyer, have also overcome limitations of cellulosic membrane ma- terials in the project, which has been under way for three years. After systematic study of candidate materials for membranes, Dr. Salyer and his associates concentrated on vinyl addition and condensation poly- mers. The final choice was a modi- fied acrylic produced by quaterniz- ing the amino groups of polyacryloni- trile and subsequent ionic coupling with heparin. The result, described by Dr. Salyer to the Division of In- dustrial and Engineering Chemistry, is a nonthrombogenic material that ex- hibits water ultrafiltration rates an order of magnitude higher than those of cellophane, the most common ma- terial used to date. One obstacle overcome in develop- ing the Monsanto kidney was pro- ducing hollow fibers of the desired size and structure. Fibers with an inside diameter of less than 300 mi- crons and wall thicknesses under 100 microns were ultimately achieved. The in vitro characteristics of these fibers showed that urea transport de- pended greatly on the fiber spinning conditions and the structure of the resulting material. The effects of structure were so pronounced that thick wall fibers actually had higher permeation rates than comparable thin wall fibers. Rates. In the best fiber system, the Monsanto investigators obtained blood-urea-nitrogen permeabilities be- tween 0.008 and 0.015 cm. per min- ute, and water ultrafiltration rates of 11 ml. per minute per square meter with a transmembrane pressure drop of 45 mm. Hg. These rates are about 20% of those obtained with film mem- branes of the same material. Using these parameters, the investigators calculated that a dialysis area of 2 square meters would require approxi- mately 7000 fibers each 17 cm. in length. Such values were necessary for clinical use. For in vivo tests, a fiber bundle with about 2000 individual fibers in parallel was prepared. The fiber dialysis length was 15 cm. In vivo tests were conducted at Peter Bent Brigham Hospital in Boston. Initial results show that the device achieved the expected dialysance of 20 to 30 ml. per minute, was nonthrombogenic, and allowed for necessary clinical con- trol of water ultrafiltration rate. The Monsanto development was carried out as part of the artificial kidney-chronic uremia research and development program of the National Institute of Arthritis and Metabolic Diseases (NIAMD). About two dozen contracts have been negotiated for various phases of the program, which is aimed at developing a sim- pler and less expensive kidney than is now available. The ultimate goal is a device that can be used conven- iently at home by the 5000 to 6000 people in the U.S. that experience chronic kidney failure each year. Periodic. Until it is possible to solve the problem of tissue rejection of transplanted human kidneys, those suffering from chronic kidney disease must rely on periodic treatment of their blood with an artificial kidney (hemodialysis). This usually means a hospital visit of six to 12 hours twice weekly. During the patient's visit his blood is passed through a dialyz- ing unit (artificial kidney) which per- forms two of the three major func- tions of the normal human kidney. The unit removes end products of metabolism from the blood and regu- lates the body's electrolyte composi- tion and acid-base balance. It doesn't regulate blood pressure, how- ever. Small size and simplicity characterize new artificial kidney from Monsanto Unfortunately not all people suf- fering from kidney disease can obtain the treatment, either because of re- moteness from a treatment center or because of the expense. It is esti- mated by Dr. Β. Τ. Burton, chief of the artificial kidney program at NIAMD, that annual costs for treat- ment range from $10,000 to $30,000 per patient, depending on the equip- ment required and the location of the patient. NIAMD expects to main- tain support of the artificial kidney program at the present level of $4.6 million per year through 1971. Among the various types of dia- lyzers already developed are a unit from the Atomic Energy Commission's Argonne National Laboratory, pro- duced under the direction of Dr. F. W. Markley (C&EN, July 14, 1969, page 10), and a cellulose fiber device developed by Dow Chemical Co. (C&EN, Sept. 1, 1969, page 12). Dr. Salyer believes that the Mon- santo kidney is superior to any yet developed because of the better per- meation characteristics of the fibers, the smaller size and the simplicity, and costs low enough to allow for dis- posable fiber cartridges. 50 C&EN SEPT. 28, 1970
Transcript of New artificial kidney has high filtration rate
TECHNOLOGY
New artificial kidney has high filtration rate
Monsanto-developed kidney with membrane material of modified acrylic polymer is nonthrombogenic, holds promise for home use of disposable units
* CHICAGO « g a * * Π £ characterize a new artificial kidney developed at Monsanto Research Corp. The developers, under the direction of Dr. I. O. Salyer, have also overcome limitations of cellulosic membrane materials in the project, which has been under way for three years.
After systematic study of candidate materials for membranes, Dr. Salyer and his associates concentrated on vinyl addition and condensation polymers. The final choice was a modified acrylic produced by quaterniz-ing the amino groups of polyacryloni-trile and subsequent ionic coupling with heparin. The result, described by Dr. Salyer to the Division of Industrial and Engineering Chemistry, is a nonthrombogenic material that exhibits water ultrafiltration rates an order of magnitude higher than those of cellophane, the most common material used to date.
One obstacle overcome in developing the Monsanto kidney was producing hollow fibers of the desired size and structure. Fibers with an inside diameter of less than 300 microns and wall thicknesses under 100 microns were ultimately achieved. The in vitro characteristics of these fibers showed that urea transport depended greatly on the fiber spinning conditions and the structure of the resulting material. The effects of structure were so pronounced that thick wall fibers actually had higher permeation rates than comparable thin wall fibers.
Rates. In the best fiber system, the Monsanto investigators obtained blood-urea-nitrogen permeabilities between 0.008 and 0.015 cm. per minute, and water ultrafiltration rates of 11 ml. per minute per square meter with a transmembrane pressure drop of 45 mm. Hg. These rates are about 20% of those obtained with film membranes of the same material. Using
these parameters, the investigators calculated that a dialysis area of 2 square meters would require approximately 7000 fibers each 17 cm. in length. Such values were necessary for clinical use.
For in vivo tests, a fiber bundle with about 2000 individual fibers in parallel was prepared. The fiber dialysis length was 15 cm. In vivo tests were conducted at Peter Bent Brigham Hospital in Boston. Initial results show that the device achieved the expected dialysance of 20 to 30 ml. per minute, was nonthrombogenic, and allowed for necessary clinical control of water ultrafiltration rate.
The Monsanto development was carried out as part of the artificial kidney-chronic uremia research and development program of the National Institute of Arthritis and Metabolic Diseases (NIAMD). About two dozen contracts have been negotiated for various phases of the program, which is aimed at developing a simpler and less expensive kidney than is now available. The ultimate goal is a device that can be used conveniently at home by the 5000 to 6000 people in the U.S. that experience chronic kidney failure each year.
Periodic. Until it is possible to solve the problem of tissue rejection of transplanted human kidneys, those suffering from chronic kidney disease must rely on periodic treatment of their blood with an artificial kidney (hemodialysis). This usually means a hospital visit of six to 12 hours twice weekly. During the patient's visit his blood is passed through a dialyz-ing unit (artificial kidney) which performs two of the three major functions of the normal human kidney. The unit removes end products of metabolism from the blood and regulates the body's electrolyte composition and acid-base balance. It doesn't regulate blood pressure, however.
Small size and simplicity characterize new artificial kidney from Monsanto
Unfortunately not all people suffering from kidney disease can obtain the treatment, either because of remoteness from a treatment center or because of the expense. It is estimated by Dr. Β. Τ. Burton, chief of the artificial kidney program at NIAMD, that annual costs for treatment range from $10,000 to $30,000 per patient, depending on the equipment required and the location of the patient. NIAMD expects to maintain support of the artificial kidney program at the present level of $4.6 million per year through 1971.
Among the various types of dia-lyzers already developed are a unit from the Atomic Energy Commission's Argonne National Laboratory, produced under the direction of Dr. F. W. Markley (C&EN, July 14, 1969, page 10), and a cellulose fiber device developed by Dow Chemical Co. (C&EN, Sept. 1, 1969, page 12). Dr. Salyer believes that the Monsanto kidney is superior to any yet developed because of the better permeation characteristics of the fibers, the smaller size and the simplicity, and costs low enough to allow for disposable fiber cartridges.
50 C&EN SEPT. 28, 1970
