Part I
Regression analyses are performed on in vivo hemodialysis datafor the transfer of creatinine, urea, uric acid and inorganic phosphateto determine the effects of variations in certain parameters on theefficiency of dialysis with a Kiil dialyzer. In calculating the masstransfer rates across the membrane, the effects of cell-plasma masstransfer kinetics are considered. The concept of the effective permeabilitycoefficient for the red cell membrane is introduced toaccount for these effects. A discussion of the consequences of neglectingcell-plasma kinetics, as has been done to date in the literature, ispresented.
A physical model for the Kiil dialyzer is presented in order tocalculate the available membrane area for mass transfer, the linearblood and dialysate velocities, and other variables. The equationsused to determine the independent variables of the regression analysesare presented. The potential dependent variables in the analyses arediscussed.
Regression analyses were carried out considering overall mass-transfercoefficients, dialysances, relative dialysances, and relativepermeabilities for each substance as the dependent variables. Theindependent variables were linear blood velocity, linear dialysatevelocity, the pressure difference across the membrane, the elapsedtime of dialysis, the blood hematocrit, and the arterial plasmaconcentrations of each substance transferred. The resulting correlationsare tabulated, presented graphically, and discussed. The implicationsof these correlations are discussed from the viewpoint of a researchinvestigator and from the viewpoint of patient treatment.
Recommendations for further experimental work are presented.
Part II
The interfacial structure of concurrent air-water flow ina two-inch diameter horizontal tube in the wavy flow regime hasbeen measured using resistance wave gages. The median waterdepth, r.m.s. wave height, wave frequency, extrema frequency,and wave velocity have been measured as functions of air and waterflow rates. Reynolds numbers, Froude numbers, Weber numbers, andbulk velocities for each phase may be calculated from these measurements. No theory for wave formation and propagation availablein the literature was sufficient to describe these results.
The water surface level distribution generally is not adequatelyrepresented as a stationary Gaussian process. Five typesof deviation from the Gaussian process function were notedin this work. The presence of the tube walls and the relativelylarge interfacial shear stresses precludes the use of simplestatistical analyses to describe the interfacial structure. Adetailed study of the behavior of individual fluid elements nearthe interface may be necessary to describe adequately wavy two-phaseflow in systems similar to the one used in this work.
