A Comparative Study of the Physiological Parameters and Efficiency of the Various Types of Hemodialyzers

Transcription

1 American Journal of Bioscience an Bioengineering 2015; 3(2): 8-16 Pulishe online June 29, 2015 ( oi: /j.io ISSN: (Print); ISSN: (Online) A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers Alert E. Yousif 1, Farah M. Aul-Kareem 2, Ali J. Muhaffer 3 1 Professor, Meical Engineering Department, College of Engineering, alnahrain University, Bagha, Iraq 2 Grauate stuent, Meical Engineering Department, College of Engineering, alnahrain University, Bagha, Iraq 3 Consultant Internist-Nephrologists, Kiney Disease an ransplant Center, the Meical City Hospital, Bagha, Iraq aress: farah.mohana88@gmail.com (F. M. Aul-Kareem) o cite this article: Alert E. Yousif, Farah M. Aul-Kareem, Ali J. Muhaffer. A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers. American Journal of Bioscience an Bioengineering. Vol. 3, No. 2, 2015, pp oi: /j.io Astract: he work presente in this paper is intene to compare the physiological parameters an ''efficiency'' (the capacity to remove Urea, while ''Flux'' refers to the capacity to remove water, an inirectly, the capacity to remove molecules of mile molecular weight for the three asic types of ialyzer (twin coil, parallel plate, an hollow fier). A comparative stuy of the operational parameters,that is, ( clearance, resistance, permeaility (which means efficiency with removing molecules of small molecular weight ),memrane surface area, time, an clearance ratio (extraction ratio). he most esirale property of a hemoialysis memrane is high mass transfer of toxic solutes to reuce the ialysis time, loo compatiility an limite protein asorption capacity. his was achieve in the hollow fier ialyzer which has relatively high mass transfer as compare to that of the parallel plate an also for the twin coil ialyzer all having aout the same memrane surface area. Dialysis treatment was given to 65 patients with kiney failure; 25 patients for the stuy of clearance an permeaility, an 40 patients for the stuy of ialysis aequacy. he treatment time was foun to e approximately aout half the time for the hollow fier ialyzer as compare to the Kiil an Kolff ialyzers of aout the same memrane surface area. his reuction in treatment time is extremely avantageous for the patient enurance an comfort. Keywors: Dialyzer Efficiency, Kolff Dialyzer, Kiil Dialyzer, Hollow Fier Dialyzer, Urea Clearance 1. Introuction An unerstaning of osmosis, iffusion, an semipermeale memranes egan to emerge in the mi-1800s. here are two ways solutes can e move through a memrane: iffusion an convection. Diffusion means small solute transport across the ialysis memrane in a irection ictate y the concentration graient estalishe across the memrane of the hemoialysis. Urea moves from loo to the ialysate, while calcium an acetic aci move from the ialysate to loo. he concentration graient across the memrane rives the movement of solutes. Diffusion is affecte y loo, ialysate flow rates, temperature, an surface area of the ialyzer an thickness of the memrane. Assuming that all other factors are constant, the iffusion process is asically epenent on the concentration graient etween loo an ialysate. his is strongly affecte y the loo an ialysate flow rates an y the istriution of the countercurrent flows in their relative compartments [1, 2]. Ultrafiltration is the passage of flui uner pressure ifference across a semi-permeale memrane where solutes are carrie along with the flui y solvent rag (convection), where the convection pulls solution an solutes across a memrane [3]. he positive pressure of loo is higher than the negative pressure of the ialysate an y ajusting the negative pressure, the amount of filtrate water may e controlle [1]. homas Graham, a professor of chemistry in Glasgow, first coine the phrase ialysis in 1854 when he escrie the movement of various types of solutes through a memrane force y osmotic pressures [3]. Although various iseases of the kiney may initially attack a specific area of the organ (e.g., the glomeruli, the tuules) progression of the iseases often leas ultimately to severe general impairment of kiney function. When sustantial or total inaility of the kineys to remove water, metaolic wastes, an excess electrolytes from the oy exists, eath is normally only a matter of ays away [4]. he techniques use to perform the kineys excretory functions

2 9 Alert E. Yousif et al.: A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers are hemoialysis an peritoneal ialysis an others. he general term ialysis means to separate sustances using a memrane. he artificial kiney is an apparatus that utilizes a process terme hemoialysis to remove excess sustances from the loo [5]. here are various types of artificial kiney ut the asic types that stuie in the presente work are: the hollow fier, parallel plate, an twin coil ialyzers. heir operational factors an efficiencies are compare ase on theoretical consierations an actual ialysis treatment results. 2. Experimental Work 2.1. Dialysis reatment: his Requires a Hemoialysis Machine, Dialyzer, Dialysate Flui, an Bloo Sample he ialysis treatment was given to 65 patients with kiney failure; 25patients for the stuy of clearance an permeaility, an 40 patients for the stuy of ialysis aequacy (Kt/V). hey were connecte to the artificial kiney evice for a perio of 2-4 hours, three times a week at the Meical City Hospital in Bagha. he ialyzer was of the hollow fier type. he hemoialysis machine allows ialysis treatment without any aitional equipment.he machine operates an monitors the ialysate circuit an the extracorporeal loo circuit. he require treatment parameters can e entere via various menus provie for programming an isplaying on a high resolution LC isplay.he current treatment ata are shown on the isplay. he ialyzer (memrane): is a part in the artificial kiney system in which the treatment actually takes place an the loo is free from the waste proucts. It is the meeting point of two circuits, one in which the loo circulates an the other in which ialysis flui flows. hese two compartments are separate y a semipermeale memrane an form a close self-containe system. here are various types of ialyzers with ifferent areas. hese are: (i) Fresenius meical care (F): F4 (A=0.8 m2); F5 (A=1 m2); F6 (A=1.3 m2); F7 (A=1.6m²); F8 (A=1.8m2); F10 (A=2.2m2). (ii) Gamro polyflux (L): 17L (A=1.7 m²), 21L (A=2.1 m²). he ialysis machine mixes the icaronate an aci concentrates an water which contain concentrates an water at ratio 1:35 to form the ialysate which is use to clean the patient loo from waste prouct. 2cm3 loo samples for urea measurement were taken after 15 min from the 25 patient connecte to the evice, some of them gave four samples, two at specific loo flow rate efore an after ialyzer, an two after nearly 1 hour at another loo flow rate efore an after ialyzer, patients gave two samples at specific loo flow rate efore an after ialyzer. As follow: 1. Dialyzer with area1m²: 6 patients were utilize, two patients with 150 an 200 ml/min; two patients with 250 an 300ml/min; 1 patient with 250ml/min, 1 patient with 200 an 300ml/min flow rates. 2. Dialyzer with area0.8m², one patient was examine at 200,300 ml/min flow rates. 3. Dialyzer with area1.3m², three patients were examine at 200 an 300 ml/min flow rates. 4. Dialyzer with area1.6m², 2 patients were teste at 200 an 300 ml/min an one at 250 ml/min flow rates respectively. 5. Dialyzer with area1.8m², two patients were teste with 200,300 ml/min flow rates respectively. 6. Dialyzer with area2.2m², 1patient was teste at 200ml/min, 1 at 200 an 350 ml/min, an 1 at 200 an 300 ml/min flow rates. 7. Dialyzer with area2.1m², four patients were examine, one at 200, an two at 300 an the fourth at 350 ml/min flow rates. 8. Dialyzer with area1.7m², three patients were examine, one at 200ml/min, another at 250 an 300ml/min, an the thir at 300 ml/min flow rates. he loo samples were use with heparin to prevent loo clotting. hey were taken efore ialyzer from the arterial line, an after leaving the ialyzer, taken from the venous line y tues use to collect the loo sample for laoratory tests Dialysis Factors Clearance Bloo samples have een rawn from the patients at the eginning of ialysis session (Pre-ialysis), an at the en of ialysis (Postialysis) immeiately, an applying them in equation (1) [6] for clearance with loo flow rates 150, 200, 250, 300, 350ml/min for ifferent areas (0.8, 1, 1.3, 1.6, 1.8, 2.2, 1.7, 2.1m²), the clearance values for hollow fier ialyzer were otaine. For Kiil an Kolff ialyzer, the clearance values were taken from literature in orer to compare them with those of the hollow fier ialyzer ecause they are not availale at present in the local hospitals. Qi ( Ci Co ) K = (1) C Where K is the clearance in ml/min, Ci, Co are the loo concentrations inlet an outlet the ialyzer taken from the patient loo an Q is the loo flow rate Dialysis ime Depening on the ata in the literature (KₒA) for coil, parallel plate an hollow fier ialyzer, with selecte set for parameters ( Ci, Co, Q, A, V ) equal (150mg %, 50mg%, 200ml/min, 1m², ml) respectively [4], his ata was fixe for (coil, parallel plate an hollow fier ialyzer) for the purpose of comparison of the operational parameters an the efficiency of the three types of ialyzers. he ialysis session time was otaine y applying equation (2) elow: K A Where β = exp( ο ) Q i Ci V t = ln o. Ci Q ( β 1) (2)

3 American Journal of Bioscience an Bioengineering 2015; 3(4): Extraction Ratio (E) Extraction ratio or clearance ratio is the fraction of solute removal. By applying equations (3) an (4) an using the ata in the literature for ifferent area, loo an ialysate flow rates ( Q, Q ), an mass transfer coefficient, the values of E otaine with Z=0, 1, 2.for ifferent N values, all eing imensionless [4, 7]. For countercurrent flow: Or, if Z=1, 1 exp N (1 Z ) E = Z exp N (1 Z ) (3) N E = (4) 1 + N Where Z= Q / Q ; N = KₒA/ Q he results otaine y taking KₒA with ifferent values from manufacturer ata sheet ivie y the loo flow rate 100,200,300,400 ml/min, for the hollow fier ialyzer, however,for Kiil an Kolff ialyzers these values were taken from the literature. he results otaine were compare with (E) against (Z) for countercurrent flow in the literature Permeaility (P) aking the result of concentrations ( Ci, C o ) of loo sample efore an after ialyzer, an applying them in equation (5) an (6) to otain permeaility value (P) ( min ml ) an equation (7) to otain (Pm²) value [8]. A R D = Q = Q. E A U (5) P = ln(1 E ) Q (6) 2 Q Pm = ln(1 E ) (7) A [9, 10], URR [11], e Kt/V [12]) which etermine the ialysis aequacy.bloo samples for Kt/V iffer from loo samples for clearance ecause they nee special technique.hese samples were taken at loo flow rate 200 an 300 ml/min to show the effect of Q on the Kt/V values. he values of (sp Kt/V, URR, e Kt/V) were rawn against four groups of ialyzer types (Group 1: ialyzer with area 1m², Group 2: ialyzer with area 1.3 m², Group 3: ialyzer with area 1.7m², Group 4: ialyzer with area 2.1m²) to show the effect of surface area on the Kt/V values, using equations (9), (10), an (11): 3. Results 3.1. Clearances spkt / Vurea = ln( R t ) + (4 3.5 R ) UF / W (9) 100( Co Ct ) URR = (10) Co ekt / Vurea = spkt / Vurea 0.6( K / V ) (11) he clearance values otaine for the hollow fier ialyzer with area 1 m², at Q =200 ml/min, was ml/min. At Q =300ml/min., the clearance value was ml/min. as shown in figure (1- a) compare with (1 ) an (1c) for the Kiil an Kolff ialyzer. Clearance values of hollow fier ialyzer with memrane from polysulfone material for ifferent areas are shown in figure (2). Clearance values of hollow fier ialyzer with memrane from polyflux material for ifferent areas are shown in figure (3). Comparison etween polyflux (A=2.1m²) an polysulfone memrane (A=2.2m²) shown in figure (4). he clearance value increases with increasing the ialyzer surface area with ifferent loo flow rates as shown in figure (5). As oth values of KₒA an Q increase; the clearance values increase, as shown in figure (6) elow, for Q =200 ml/min an 300 ml/min Overall Resistance (Rₒ) he overall mass transfer coefficient (Kₒ) is the inverse of an overall resistance which in turn is the sum of the loo sie, memrane, an ialysate sie mass transfer resistance, as shown in equation (8). the values of the overall resistance was otaine for the hollow fier ialyzer with areas (0.8,1,1.3,1.4,1.6,1.7,1.8,2.1,2.2 m²) an with values of (KₒA) from the manufacturer ata sheet for each area. An these compare with the overall resistance values for the Kiil an Kolff ialyzer from the literature [4, 6]. 1 x x x B M D = R = R + R + R = = = ο B M D D kd D ο B M D K (8) Dialysis Aequacy 40 patients were taken to otain the values of Kt/V (sp Kt/V (a)

4 11 Alert E. Yousif et al.: A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers () Fig. (3). Shows the clearance against loo flow rate for the capillary ialyzer polyflux memrane. (c) Fig. (1). Basic types of artificial kineys.(a) hollow fier ialyzer () Kiil ialyzer (c) Kolff ialyzer, oth () an (c) from [13]. Fig. (4). Shows the clearance against loo flow rate for the capillary ialyzer show the ifferences etween polyflux an polysulfone memrane approximately with the same surface area. Fig. (2). Shows the clearance against loo flow ialyzer with polysulfone memrane. rate for the capillary Fig. (5). Shows the effect of increasing ialyzer surface area on the clearance value with ifferent loo flow rate for the capillary ialyzer.

5 American Journal of Bioscience an Bioengineering 2015; 3(4): Extraction Ratio (E) he values of E were otaine for the Hollow fier ialyzer as in figure (9), Kiil ialyzer as in figure (10), an Kolff ialyzer as in figure (11). Fig. (6). Shows the effect of increasing Q = 200ml / min, an 300 ml/min. KoA with the clearance at 3.2. Session imes (t) he values of time for the ialyses session was preicte for the Kiil, Kolff an Hollow fier ialyzer as in figure (7), the ifferences in time etween the polysulfone an polyflux materials use in the hollow fier ialyzer are not very large an it is convergent as in figure (8). Fig. (9). Shows extraction ratio (E) against Z flow ratio for ifferent N values for Hollow fier ialyzer. Fig. (10). Extraction ratio (E) against Z flow ratio with ifferent N values for Kiil ialyzer Fig. (7). Shows the variation in times for the asic three types of ialyzer (Kiil, Kolff an Hollow fier ialyzer). Fig. (11). Extraction ratio (E) against Z flow ratio with ifferent N values for Kolff ialyzer. Fig. (8). Show the ifferences in time etween the polysulfone an polyflux materials use in the hollow fier ialyzer. Curves (9), (10) an (11) for countercurrent flow can e compare with figure (12), given in [4] for general agreements.

6 13 Alert E. Yousif et al.: A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers Fig. (12). Shows the variation of the extraction ratio (E) against Z flow ratio ( Q / Q ) representing the performance profiles for a countercurrent flow ialyzer [4] he Permeaility (P) he values of permeaility for Hollow fier ialyzer was otaine as figure (13), an compare these results with the results of Kiil an Kolff ialyzer as shown in tale( A-1) in the appenix an in figure (14) he overall Resistance (Rₒ) he values of the overall resistance (Rₒ) are otaine as shown in figure (15) epening on the overall mass transfer-area coefficient (KₒA) for the hollow fier ialyzer with ifferent areas an for Kiil an Kolff ialyzer is as in the literature. Fig. (15). Shows the effect of increasing ialyzer surface area (m²) on overall resistance Rₒ (min/cm). Fig. (13). Shows the permeaility variation with loo flow rate at ifferent areas Dialysis Aequacy he results otaine are presente in figures (16), (17), (18): Fig. (14). Relations of permeaility (P) to loo flow rate, the numers in circles enote the same as in tale (A-1) in the appenix [8]. Fig. (16). Shows the effect of ialyzer type (each type have a ifferent area) an loo flow rate on the single pool Kt/V (sp Kt/V).

7 American Journal of Bioscience an Bioengineering 2015; 3(4): Fig. (17). Shows the effect of ialyzer type (each type have a ifferent area) an loo flow rate on the Urea reuction ratio (URR). Fig. (18). Shows the effect of ialyzer type (each type have a ifferent area) an loo flow rate on the equilirate Kt/V (ekt/v). 4. Discussion One of the most important parameters for comparing the efficiency (capacity to remove urea) etween the ifferent types of ialyzer is the clearance. Clearance values for hollow fier ialyzer is larger than those for Kiil an Coil ialyzers, clearance values are higher for coil than for Kiil as in figure (1a,, c) ut for moifie Kiil it is larger than that for coil as reporte in references [13, 14]. Session time ecreases with increasing area. he ialysis session time for the Kiil ialyzer range 6-8 hour with ifferent areas, for Kolff ialyzer it is aout 8-10 hour in one session, however, the Kiil ialyzer showe almost 1 hour lesser time than Kolff an this is very othersome an teious for the patient while the hollow fier ialyzer showe almost the lowest constant time ( 4 hour) than oth Kiil an Kolff ialyzers. his is consiere a great improvement on the esign of the other two ialyzers as seen in figures (7).Figure (8) showe almost low variations etween the ifferent materials use especially in the working range of the area ( m²).hus the avent of hollow fier ialyzers greatly increase the efficiency of small solute removal an lea to shorten treatment time. he loo samples taken from the patient at loo flow rates 200, 300 ml/min an occasionally at 250, 350 ml/min accoring to the patient health state an elow this not avise ecause the reuction in loo flow rate can preispose to clotting in the extracorporeal circuit.also if the loo flow is slowe, then very little amount of urea will e remove. he loo leaving the ialyzer has a lower concentration of waste proucts than the loo entering the ialyzer. he clearance values of the hollow fier ialyzer for ifferent areas are varie an they increase with increasing area for the same ialyzer as shown in figures (2), (3) an (5). Memranes of Polyamie an polysulfone ialyzer material use in this stuy iffer in their material, ultrafiltration coefficient, clearances of small an large molecules, area of memrane, iocompatiility an suitaility for re-use ut the ifferences in clearance an time etween these two materials is very low as shown in figure (4). Clearance values for polyamie with area 2.1m² are higher than those for polysulfone with area 2.2m² ue to ifferent materials as given in the manufacturer ata sheets. he moern tren is towars the use of ialyzers containing memranes manufacture from synthetic polymers. he use of unmoifie cellulose such as cuprophan is eclining, an its future prouction is uncertain. Another characteristic of ialyzer is the mass transfer area coefficient KₒA (ml/min) which is the maximum theoretical clearance of the ialyzer in ml/min, It iffers from one ialyzer to another accoring to the ialyzer surface area where it increases with increasing the area an ialysate flow rate (increases from 500 to 800 ml/min) with no change at various loo flow rates as given in [15].he value of KₒA etermines the efficiency of the ialyzer whether it is low, moerate or high. In this stuy, the KₒA values for Kolff an Kiil ialyzer have een taken from reference [4] while for capillary ialyzer was taken from the manufacturer ata sheet. It is foun that when the KₒA values increase the clearance values increase with increasing area for loo flow rates 200 or 300 ml/min, with fixe ialysate flow rate (500 ml/min) as shown in figure (6). he performance inex or extraction ratio (E) for Kolff, Kiil an capillary ialyzer were also otaine for the countercurrent flow. It is clear from this stuy that the E values increase as the ratio Q / Q or (Z) ecomes smaller, an increases as the memrane area an mass transfer coefficient ecome larger. For increasing values of N, E will approach unity an this is more pronounce in the hollow fier than in the Kolff an Kiil ialyzer as shown in figures (9), (10) an (11). hese are compare with the countercurrent ehavior shown in figure (12). Another parameter is the permeaility where it is not the maximum permeaility of the memrane ut an integral expression of machine efficiency. In this stuy the permeaility for Kiil an Kolff ialyzer as reporte in reference [8] compare with the permeaility of the hollow ialyzer which has een otaine experimentally an foun that in reference [8]. he range of loo flow rate was very high ut in the present experiment this was not vali ecause it inuce changes in the hyroynamic conitions in the apparatus an clinical ifficulties. It may cause hemolysis in

8 15 Alert E. Yousif et al.: A Comparative Stuy of the Physiological Parameters an Efficiency of the Various ypes of Hemoialyzers aition to that the iffusion of molecules across the memrane ecreases at high flow rates, the interaction etween them ecreases where the molecules on't have enough time to pass through the memrane. Permeaility is irectly proportional to the surface area an inversely proportional to the memrane thickness, whereas the value of permeaility for area 1.8m² is larger than that for 1.6m² for the hollow fier ialyzer. For area 2.1m²; the permeaility value is 756.2ml/min for Q =350 ml/min an thickness 50µm for hollow fier ialyzer while for Kiil ialyzer it is 310 ml/min for Q =400ml/min an thickness mm, whereas the permeaility value is 143ml/min for Q =250 ml/min, A=0.9m² an thickness 0.025mm for the Kolff ialyzer. hus, the hollow fier ialyzer is the largest in permeaility as presente in figures (13) an (14).he overall mass transfer resistance for any type of ialyzer is preferale to e low. It is unpreictale an high for coil ialyzer (113 min/cm at Q =200ml/min) an lesser for parallel ialyzer (74 min/cm at Q =200ml/min) while for the hollow fier ialyzer it is very low (e.g min/cm with 1m²) so it is the est as shown in figures (15). he expression of elivere ose using variants of Kt/V inclue (spkt/v, URR, ekt/v). he spkt/v value shoul e greater than 1.2. his value increase with increasing area for (1, 1.3, 1.7, 2.1 m²) have average spkt/v value (0.796, 1.308, 1.618, 1.636) respectively at loo flow rate 300ml/min. Another popular stanar is to keep a minimum URR of 65%. he average URR value at area (1, 1.3, 1.7, 2.1 m²) are (37.496, , , 66.87) respectively at loo low rate 300ml/min. However, the relation etween the URR an spkt/v is meiate y the relative weight change uring a ialysis session. ekt/v generally is aout 0.2 Kt/V unit lower than spkt/v. he average ekt/v value at area (1, 1.3, 1.7, 2.1 m²) are (0.698, 1.07, 1.402, 1.384) respectively at loo low rate 300ml/min. But these values are lower at loo low rate Appenix 200ml/min. he Kt/V values also affecte y ialyzer specification especially its area, as the area, loo an ialysate flow rate increase these values (spkt/v, URR, ekt/v) also increase, as shown in figures (16), (17) an (18), increasing (spkt/v, URR, ekt/v) with increase area an loo flow rate for a ifferent ialyzer type. 5. Conclusions 1. Kiil, Kolff an hollow fier ialyzer iffer from each other in some features an parameters such as the area of the ialyzer, time of treatment, clearance, flow geometry, cost, multiple use an evice age. hese parameters will affect the evice efficiency. he Kiil evice is somewhat less efficient than Kolff evice; an the hollow fier ialyzer is more efficient an effective than these two types an it is wiely use nowaays. 2. he clearance epens on the removal rate an ialyzer area, where it increases with increasing area. he area of the ialyzer affects the treatment time; the time ecreases with increasing area. he reusaility an isposaility of the evice together with the aove factors will affect the aequacy of the hemoialysis. 3. High efficiency ialyzer requires high mass transfer- area coefficient (KoA), high loo, an ialysate flow rates. 4. Increasing memrane surface area leas to increase the efficiency, permeaility an ialysis aequacy (spkt/v, ekt/v an URR). 5. he extraction ratio E approaches unity for increasing values of N an ecreasing values of Z. his is more pronounce for the hollow fier ialyzer than in Kiil an Kolff ialyzers. 6. ime of treatment is very important; an it is high for Kiil an Kolff ialyzers aout twice that for the hollow fier ialyzer. he ifference of time etween the polysulfone an polyflux is always insignificant. ale (A-1). Comparison of maximum effective permeaility in iniviual types of artificial kineys [8]. ype of ialyzer Numer Reference hickness mm A 2 m Q ml / min D ml / min P ml / min P Kiil 1 Kiil Freeman Skeggs- Leonars 3 Jorgensen Jorgensen Smith Smith Smith Smith Maher Soviet Rotating rum 11 Merrill Wolf Antoine Alwall 13 Alwall Alwall- Prague Coil Kiney 15 Elliot Kolff Kolff Kolff Chronic-A-Coil 19 Freeman ml / min 2 m

9 American Journal of Bioscience an Bioengineering 2015; 3(4): List of symols Symol Meaning Unit " D D " BM.. D K R Diffusivity Diffusivity in loo, memrane, ialysate he overall mass transfer coefficient he overall mass transfer resistance 2 A Area cm Q. Q Bloo an ialysate flow rate C. C Concentration in loo an ialysate mmol l i, o Inlet an Outlet - D Dialysance ml min N he numer of mass transfer units - E he extraction ratio - Z Ratio of loo on ialysate flow rate - t Session time hr. C, C he start an en session urea concentration mmol l t o UF he weight loss Kg W he en session oy weight Kg V oy Boy volume l 2 cm s 2 cm s cm min min cm ml min References [1] Lai1 M. H., Nieh H. M., eng. P., Chen J. J., Huang Y. Y., Lu Y. C., ''Development of an Hemoialysis Simulator for Interisciplinary Learning'', IEEE, pp ,2010. [2] Clauio Ronco, Bernar Canau, Pero Aljama,''Solute Removal y Hollow-Fier Dialyzers'', Hemoiafiltration, Vol. 158, pp , karger, [3] Christopher Kirwan an Anrew Frankel,'' he Artificial Kiney'', Artificial Organs, Springer, [4] Davi O. Cooney, ''Artificial Kiney Devices'', Biomeical Engineering Principles, Marcel Dekker, [5] Vaner et al,'' he Kineys an Regulation of Water an Inorganic Ions'', Human Physiology: he Mechanism of Boy Function, 8 eitions, McGraw Hill Companies, [6] William Drukker, John A. Sargent an Frank A. Gotch, ''History of Hemoialysis, Principles an Biophysics of Dialysis'', Replacement of Renal Function y Dialysis: A ext Book of Dialysis, Kluwer Acaemic Pulishers, thir eition, [7] Narener P. Rey, ''Moeling an Simulation of Biomeical Systems'', Stanar Hanook of Biomeical Engineering an Design, McGraw-Hill, [9] homas A. Depner, ''Hemoialysis aequacy: Basic essentials an practical points for the nephrologist in training'', Hemoialysis International, 9, pp , [10] John. Daugiras an John C. Van Stone, an James. Boag''Physiologic Principles an Urea Kinetic moeling, Hemoialysis Apparatus'', Hanook of Dialysis, 2n an 3r eition, Lippincott Williams & Wilkins Pulishers, [11] homas A. Depner,''Assessing aequacy of hemoialysis: Urea moeling'', Kiney International, Vol. 45, pp , [12] Saiq Jafer Aass, Zaina Ismail Al-Salihi,'' he Effect Of Increasing Dialysate Flow Rate In Hemoialysis'', College of Engineering Journal (NUCEJ) Vol.10, No.1, pp.72-79, [13] Benjamin A. Halpren, Stanton G. Axline, Norman S. Coplon, an Deera M. Brown,'' Clearance of Gentamicin uring Hemoialysis: Comparison of Four Artificial Kineys'', Vol. 133, No. 6, Oxfor journals, pp , [14] Kaye M. an Posen G. A., ''Aaptation of a travenol kiney for chronic ialysis using a Kiil ialyzer an a sterile ialysate circuit'', Vol.10, American Society for Artificial Internal Organs, [15] Ahma aher Azar,''Increasing Dialysate flow Rate Increases Dialyzer Urea Clearance an Dialysis Efficiency: an in Vivo stuy'', Saui Journal of Kiney Diseases an transplantation, 20(6): , [8] Alert Valek an Rene omasek,''comparison of efficacies of various types of artificial kiney'', pp , 1966.