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US 4,668,400 AGranted
Hemodialysis processes and hemodialysis solutions
OwnerRichard L. Veechinventor
Life of this patent
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Abstract
Techniques for predicting the respective concentrations and distributions of diffusible materials in solutions on opposing sides of a semi permeable membrane are provided. Unique compositions for hemodialysis using the mathematical relationships involved are provided. Also processes are provided for controlling the rate of change in concentration of a diffusible material in and fluid into another fluid on an opposing side of semi-permeable membrane are provided. Apparatus for practicing such processes are described.
Claims13
A process for determining the permeant ion composition in a complex physiological electrolyte solution existing on each side of a dialysis membrane, such solution on one side of such membrane corresponding to a dialyzing fluid, and such solution on the other side of such membrane corresponding to blood plasma from a patient whose blood is being hemodialyzed through such membrane, said process accomplishing both:
- (1) adjusting the charge on at least one non permeant polyionic material existing on one side of the membrane by regulating the pH on at least one side of the membrane, and
- (2) determining the ionic composition of permeant ions on one side of the membrane by selecting the permeant ion concentrations on the other side of the membrane,
- said process comprising the steps of:
- (A) estimating the approximate molar concentration of albumin in said blood plasma,
- (B) selecting a particular pH value for said blood plasma, thereby to make the electrolyte solution existing on one side of said membrane have such pH and consequently thereby to set the approximate anionic valence of said albumin in said blood plasma, and where, in equation (3), Z is defined as the valence of the non permeant polyionic material, mainly serum albumin, whose valence varies with pH in accordance with the following approximately linear relationship:
- ______________________________________ Z.sup.- Charge on 1 mole pH serum albumin ______________________________________ 5.1 0 5.6 -7.5 6.6 -13.5 7.4 -20.5 8.0 -27 8.8 -33.2 ______________________________________
- and further where said selected pH value determines the value of Z as represented in said relationship,
- (C) specifying the desired ion concentrations in millimoles per liter of fluid water of permeant ions present in the electrolyte solution existing on one side of said membrane in accord with the following equation (1) ##EQU3## wherein:
- subscript .sub.i designates a permeant ion in said plasma,
- subscript .sub.o designates a permeant ion in said dialyzing fluid, and
- each chemical symbol in square bracket designates concentration in millimole per liter of fluid water
- provided that, when any given ion specified in said equation (1) is not present, then that ratio which incorporates such ion is dropped and said equation (1) is thereby amended, thus, to identify all permeant ions to be considered in both electrolyte solutions, and further, provided that, if the chosen so specified ion concentrations are in dialysis fluid, the sum charge of all cations equals the sum charge of anions in conformity with following equation (2):
- ##STR1## or, if the chosen so specified ion concentrations are in plasma, the sum charge of all cations equals sum charge of all anions in conformity with following equation (3):
- ##EQU4## which such equations (2) and (3) state that electrical neutrality exists in both solutions,
- (D) multiplying each specified ion concentration by a ratio of one chosen pair of ions appearing in said amended equation (1),
- (E) substituting these resulting so multiplied specified ion concentrations into either said equation (2) or said equation (3), depending upon whether the ion composition being determined is for a dialyzing fluid or for a hemodialyzed said blood plasma, and regrouping the terms of the resulting equation,
- (F) effecting an algebraic solution for the unknown ion ratio so selected, and
- (G) using the said algebraic solution of said ion ratio by substituting said algebraically solved ratio into equation (1), thus identifying the concentration of each of the unknown ions.
15 more elements
A process for establishing the pH of a bicarbonate containing physiological electrolyte solution with gaseous CO.sub.2 comprising the steps of:
- (A) dissolving CO.sub.2 gas in an aqueous medium in a total quantity sufficient to achieve a predetermined concentration in accordance with the relationship:
- ##EQU9## wherein:
- pCO.sub.2 is defined as the partial pressure of the CO.sub.2 gas being dissolved in mm of Hg,
- .alpha. is defined as the milliliters CO.sub.2 dissolved in one milliliter of solution, and
- [CO.sub.2 ] is defined as concentration of carbon dioxide in said solution expressed as millimoles per liter solution water, and
- (B) adding sufficient bicarbonate in said solution so as to achieve a concentration thereof which is sufficient together with said dissolved CO.sub.2 concentration to produce a specified pH in the range from about 5 to 9 in accordance with the relationship ##EQU10## wherein:
- pKa' is defined as the apparent dissociation constant of carbonic acid under physiological conditions,
- [CO.sub.2 ] is as defined above,
- [HCO.sub.3 ] is defined as the concentration in millimoles per liter of bicarbonate present in said solution.
6 more elements
A process for establishing the pH of a bicarbonate containing electrolyte solution with gaseous CO.sub.2 comprising the steps of:
- (A) adding sufficient bicarbonate into an aqueous solution in a total quantity sufficient to achieve a predetermined concentration, and
- (B) dissolving sufficient CO.sub.2 gas in such resulting solution to produce a specified pH in the range from about 5 to 9 in accordance with the relationship ##EQU11## wherein:
- pCO.sub.2 is defined as the partial pressure of the CO.sub.2 gas being dissolved in mm of Hg,
- .alpha. is defined as the milliliters CO.sub.2 dissolved in one milliliter of solution, and
- [CO.sub.2 ] is defined as the concentration of carbon dioxide in said solution expressed as millimole per liter solution water,
- thereby to produce a solution having a pH as defined in accordance with the relationship:
- ##EQU12## wherein:
- pKa' is defined as the apparent dissociation constant of carbonic acid under physiological conditions,
- [CO.sub.2 ] is as defined above, and
- [HCO.sub.3 ] is defined as the concentration in millimoles per liter of bicarbonate present in said solution.
7 more elements
In a hemodialysis delivery apparatus of the type which delivers hemodialysis fluid to a hemodialyzer and which incorporates in addition to a hemodialyzer
- (a) dialysis fluid supply pump means,
- (b) dialysis fluid supply pressure regulating means,
- (c) dialysis fluid supply temperature regulating means,
- (d) dialysis fluid supply flow regulating means,
- (e) dialysis fluid supply means, and
- (f) conduit means interconnecting said pump means, said regulating means, and said supply means,
- the improvement which comprises incorporating into said supply means:
- (A) means for dissolving CO.sub.2 gas in said hemodialysis fluid,
- (B) means for regulating the dissolved CO.sub.2 concentration in said hemodialysis fluid at a predetermined pH.
6 more elements
Dependencies are inferred from the claim text.