Clinical evaluation of the microporous hollow fiber oxygenator

This report concerns a clinical evaluation for a newly devised hollow fiber oxygenator, Capiox II. It functions on a one-pump system, and is simple to set up and operate. This equipment was used for 118 patients undergoing cardiac surgery at Tokyo University Hospital from February 1982 through February 1983. The gas transfer capacity proved to be satisfactory. The employment of an air-oxygen blender prevented overoxygenation, and reasonable levels of PaO₂ and PaCO₂ were demonstrated with a FiO₂ 0.7, ratio 0.7 at normothermia. The destruction of platelets was much less with the use of this oxygenator, as compared to findings with the BOS-10. Hemolysis by Capiox II appeared to be lower than that by BOS-10, but the difference was not statistically significant. Differences were distinct in the amount of microbubbles; strikingly, no bubble was evidenced in Capiox II by the ultrasound bubble detector, during general procedures. We conclude that Capiox II is of excellent clinical value, and should be used especially for infants as well as adult patients with possible long perfusions. The merits and demerits of this equipment are given attention.     

Oxygenator with Built-in Hemoconcentrator: A New Concept

Abstract: A hemoconcentrator is an instrument essential for open heart surgery without blood transfusion. In order to simplify the extracorporeal blood circuit and to facilitate handling of cardiopulmonary bypass, we have combined a hollow fiber unit for gas exchange and that for hemofiltration into one component and developed a new membrane oxygenator with the function of a hemoconcentrator. The cylindrical device consists of a hollow fiber for hemofiltration with another fiber for gas exchange provided outside. Both of them adopt the blood outside perfusion system. Blood enters and flows through the central hole for hemofiltration and then flows into the oxygenator. By applying the flow mode to the device, blood is allowed to flow from the center of the core toward the hollow fiber around it. Therefore, even distribution of blood flow to the entire fiber is realized, and the performance of the device is improved. The oxygen transfer rate was 317 ml/min at a flow rate of 6 L/min, and the ultrafiltration rate was 7 L/h at a flow rate of 4 L/tnin with a hematocrit of 25%. The combined structure of the two units has not caused any adverse effects. In conclusion, by combining an oxygenator and a hemoconcentrator, excellent and simplified hemoconcentration is made available as the blood outside flow mode is adopted, which is one of the unique aspects of this device.     

Extracorporeal membrane oxygenator compatible with centrifugal blood pumps

Coil-type silicone membrane oxygenators can only be used with roller blood pumps due to the resistance from the high blood flow. Therefore, during extracorporeal membrane oxygenation (ECMO) treatment, the combination of a roller pump and an oxygenator with a high blood flow resistance will induce severe hemolysis, which is a serious problem. A silicone rubber, hollow fiber membrane oxygenator that has a low blood flow resistance was developed and evaluated with centrifugal pumps. During in vitro tests, sufficient gas transfer was demonstrated with a blood flow less than 3 L/min. Blood flow resistance was 18 mm Hg at 1 L/min blood flow. This oxygenator module was combined with the Gyro C1E3 (Kyocera, Japan), and veno-arterial ECMO was established on a Dexter strain calf. An ex vivo experiment was performed for 3 days with stable gas performance and low blood flow resistance. The combination of this oxygenator and centrifugal pump may be advantageous to enhance biocompatibility and have less blood trauma characteristics.     

Development of an Intravascular Pumping Oxygenator Using a New Silicone Membrane

Abstract: A new intravascular pumping oxygenator (IVPO) was developed for intravascular gas exchange and circulatory assistance in critically ill patients with respiratory and circulatory failure. The IVPO utilizes new silicone hollow fibers (diameter. 1 mm: membrane width, 50 μm) and consists of two driving tubes for the oxygenation and pumping of circulating blood. The performance characteristics of the IVPO were studied using an experimental ex vivo model. With a mean hemoglobin concentration of 10.5 ± 2.3 g/dl, total oxygen transfer was 5.6 ± 1.5 ml/min at a blood flow of 200 ml/min and 6.3 ± 2.2 ml/min at a blood flow of 250 ml/min. Total CO₂ transfer was 3.8 ± 1.4 ml/min at a blood flow of 200 ml/min and 4.2 ± 1.6 ml/min at a blood flow of 250 ml/min during IVPO pumping. This preliminary experiment demonstrated that the IVPO has the capacity to function both as a circulatory assist pump and as an intravascular hollow fiber oxygenator.     

Late Pathophysiologic Sequelae after Utilization of an Intravenacaval Oxygenator in Experimental Animals

Abstract: The intravenacaval hollow fiber oxygenator (IVOX) has been shown to be remarkably free from acute adverse effects on the venae cavae, right heart, and lungs when indwelling experimentally in sheep and in human clinical trial patients. However, all pathophysiologic assessments reported to date have been carried out during or immediately after IVOX utilization. It is recognized that IVOX indwelling in the venae cavae for up to 3 weeks could produce minor or unrecognized acute injury that could become more evident or more harmful after several weeks had elapsed following removal of the device. Therefore, this current study was designed and carried out to assess any pathophysiologic sequelae that could be recognized on follow–up examination 4 months after removal of an IVOX device that had been indwelling in the venae cavae for from 7 to 13 days. Extensive clinical and physiologic assessments of the blood, hemody namics, and pulmonary functional status of 8 sheep were carried out 4 months after removal of IVOX devices that had been indwelling for 7 to 13 days. Each animal was then euthanized and complete necropsy examination was conducted looking especially for gross or histologic lesions in the venae cavae, access veins, right heart, and lungs. Findings indicated that all animals were normal, without clinically or pathologically significant pathophysiologic abnormalities or adverse effects from the IVOX utilization. Detailed hematologic, hemodynamic, blood chemistry, pulmonary function, and gross and histopathologic findings, presented in graphic, tabular, and photographic form, document the conclusion that utilization of an IVOX device in normal sheep for from 7 to 13 days produces no significant adverse late pathophysiologic sequelae.     

Polypropylene hollow fiber oxygenators: effect of the sorption of perfluoropolyethers

The introduction of microporous polypropylene hollow fibers in recent years has brought considerable advances to blood oxygenators. However, lifetime and assembly problems are still unresolved. In this work we tried to rate the oxygen permeation velocity by turning the fibers more hydrophobic through the sorption of a perfluorocarbon. Fomblin HC/25, a perfluoropolyether, is well known for its low surface tension and high affinity for oxygen. Celgard X10, X20, and X30 commercial hollow fibers were tested. The hollow fibers showed high affinity for the perfluoropolyether; swelling was clearly shown. A new system for the measurement of oxygen permeation velocity was developed. The oxygen transport velocity was not significantly changed after sorption. The Celgard microporous hollow fibers impregnated with perfluoropolyether showed no water permeation after 2 months of use, reducing one of the most serious problems in the lifetime of these types of fibers.     

Comparing oxygen transfer performance between three membrane oxygenators: effect of temperature changes during cardiopulmonary bypass

Recently, a new oxygenator (Dideco 903 [D903], Dideco, Mirandola, Italy) has been introduced to the perfusion community, and we set about testing its oxygen transfer performance and then comparing it to two other models. This evaluation was based on the comparison between oxygen transfer slope, gas phase arterial oxygen gradients, degree of blood shunting, maximum oxygen transfer, and diffusing capacity calculated for each membrane. Sixty patients were randomized into three groups of oxygenators (Dideco 703 [D703], Dideco; D903; and Quadrox, Jostra Medizintechnik AG, Hirrlingen, Germany) including 40/20 M/F of 68.6 +/- 11.3 years old, with a body weight of 71.5 +/- 12.1 kg, a body surface area (BSA) of 1.84 +/- 0.3 m(2), and a theoretical blood flow rate (index 2.4 times BSA) of 4.4 +/- 0.7 L/min. The maximum oxygen transfer (VO(2)) values were 313 mL O(2)/min (D703), 579 mL O(2)/min (D903), and 400 mL O(2)/min (Quadrox), with the D903 being the most superior (P < 0.05). Oxygen (O(2)) gradients were 320 mm Hg (D703), 235 mm Hg (D903), and 247 mm Hg (Quadrox), meaning D903 and Quadrox are more efficient versus the D703 (P < 0.05). Shunt fraction (Qs/Qt) and diffusing capacity (DmO(2)) were comparable (P = ns). Diffusing capacity values indexed to BSA (DmO(2)/m(2)) were 0.15 mL O(2)/min/mm Hg/m(2) (D703), 0.2 mL O(2)/min/mm Hg/m(2) (D903), and 0.18 mL O(2)/min/mm Hg/m(2) (Quadrox) with D903 outperforming D703 (P < 0.0005). During hypothermia (32.0 +/- 0.3 degrees C), there was a lower absolute and relative VO(2 )for all three oxygenators (P = ns). The O(2) gradients, DmO(2) and DmO(2)/m(2), were significantly lower for all oxygenators (P < 0.01). Also, Qs/Qt significantly rose for all oxygenators (P < 0.01). The oxygen transfer curve is characteristic to each oxygenator type and represents a tool to quantify oxygenator performance. Using this parameter, we demonstrated significant differences among commercially available oxygenators. However, all three oxygenators are considered to meet the oxygen needs of the patients.     

Experimental use of a compact centrifugal pump and membrane oxygenator as a cardiopulmonary support system

Compactness and high performance are the most important requirements for a cardiopulmonary support system. The Nikkiso (HPM-15) centrifugal pump is the smallest (priming volume; 25 ml, impeller diameter; 50 mm) in clinically available centrifugal pumps. The Kuraray Menox (AL-2000) membrane oxygenator, made of double-layer polyolefin hollow fiber, has a minimum priming volume (80 ml) and a low pressure loss (65 mm Hg at 2.0 L/min of blood flow) compared with other oxygenators. The aim of this study was to evaluate the performance of the most compact cardiopulmonary support system (total priming volume: 125 ml) in animal experiments. The cardiopulmonary bypass was constructed in a canine model with the Nikkiso pump and Menox oxygenator in comparison with a conventional cardiopulmonary support system. The partial cardiopulmonary bypass was performed for 4 h to evaluate the gas exchange ability, blood trauma, serum leakage, hemodynamics, and blood coagulative parameters. The postoperative plasma free hemoglobin level of the compact cardiopulmonary system was 29.5 +/- 10.21 mg/dl (mean +/- SD), which was lower than that of the conventional cardiopulmonary system, 48.75 +/- 27.39 mg/dl (mean +/- SD). This compact cardiopulmonary system provided the advantage in terms of reduction of the priming volume and less blood damage. These results suggested the possibility of miniaturization for the cardiopulmonary bypass support system in open-heart surgery in the near future.     

Effects of Ultrathin Silicone Coating of Porous Membrane on Gas Transfer and Hemolytic Performance

Abstract: To assess the effect of an ultrathin (0.2 μm) silicone-coated microporous membrane oxygenator on gas transfer and hemolytic performance, a silicone-coated capillary membrane oxygenator (Mera HP Excelung-prime, HPO-20H-C, Senko Medical Instrument Mfg. Co., Ltd. Tokyo, Japan) was compared with a noncoated polypropylene microporous membrane oxygenator of the same model and manufacturer using an in vitro test circuit. The 2 oxygenators showed little difference in the oxygen (O₂) transfer rate over a wide range of blood flow rates (1 L/min to 8 L/min). The carbon dioxide (CO₂) transfer rate was almost the same in both devices at low blood flow rates. but the silicone-coated oxygenator showed a decrease of more than 20% in the CO₂ transfer rate at higher blood flow rates. This loss in performance could be partly attenuated by increasing the gas/blood flow ratio from 0.5 or 1.0 to 2.0. In the hemolysis study, the silicone-coated membrane oxygenator showed a smaller increase in plasma free hemoglobin than the noncoated oxygenator. The pressure drop across both oxygenators was the same. These results suggest that the ultrathin silicone-coated porous membrane oxygenator may be a useful tool for long-term extracorporeal lung support while maintaining a sufficient gas transfer rate and causing less blood component damage.     

Modeling flow effects on thrombotic deposition in a membrane oxygenator

The hypothesis that regions of low blood velocity in a membrane oxygenator, as predicted by computational fluid dynamics (CFD), would correspond with regions of clinical thrombotic deposition was investigated. Twenty heparin-coated oxygenators were sectioned following use in adult extracorporeal membrane oxygenation. The activated clotting time (ACT) was maintained at approximately 180 s via heparin infusion throughout the support period. Cross-sections were systematically photographed, and slides made to allow image projection upon a digitizing pad. Thrombotic deposition was traced to allow creation of a device cross-section image with an overlaid color scale representing thrombotic deposition frequency. A two-dimensional CFD model was developed to predict blood velocities throughout the oxygenator cross-section. Direct spatial comparisons were made between maps of CFD modeled blood speed and thrombotic deposition. Theoretical oxygenator design modification was performed within the CFD model to investigate flow paths which might minimize regions of low blood velocity. CFD results demonstrated that low velocity regions qualitatively matched regions with a high incidence of thrombotic deposition. Thrombotic deposition was also correlated to longer perfusion periods. This technique of coupling clinical data and CFD offers the potential to relate flow characteristics to thrombotic deposition and represents a potentially powerful new methodology for the optimization of oxygenator flow-related biocompatibility.     

Development of silicone rubber hollow fiber membrane oxygenator for ECMO

Silicone rubber hollow fiber membrane produces an ideal gas exchange for long-term ECMO due to nonporous characteristics. The extracapillary type silicone rubber ECMO oxygenator having an ultrathin hollow fiber membrane was developed for pediatric application. The test modules were compared to conventional silicone coil-type ECMO modules. In vitro experiments demonstrated a higher O2 and CO2 transfer rate, lower blood flow resistance, and less hemolysis than the conventional silicone coil-type modules. This oxygenator was combined with the Gyro C1E3 centrifugal pump, and three ex vivo experiments were conducted to simulate pediatric V-A ECMO condition. Four day and 6 day experiments were conducted in cases 1 and 2, respectively. Case 3 was a long-term experiment up to 2 weeks. No plasma leakage and stable gas performances were achieved. The plasma free hemoglobin was maintained within a normal range. This compact pump-oxygenator system in conjunction with the Gyro C1E3 centrifugal pump has potential for a hybrid total ECMO system.     

Impact of oxygenator selection on hemodynamic energy indicators under pulsatile and nonpulsatile flow in a neonatal extracorporeal life support model

This study compared the quality of perfusion delivered by two oxygenators--the hollow-fiber membrane Capiox Baby RX05 and silicone membrane Medtronic 0800--using hemodynamic energy indicators. The oxygenators were tested across varying flow rates and perfusion modes in a neonatal extracorporeal life support (ECLS) model. The experimental ECLS circuit included a Jostra HL-20 heart/lung machine with Jostra Roller pump, oxygenators with associated tubing and components, and a neonatal pseudo-patient. We used a 40/60 glycerin/water solution in the circuit as a blood analog. Testing occurred at flow rates of 250, 500, and 750 mL/min at 37°C under both pulsatile and nonpulsatile flow conditions. Hemodynamic data points consisted of recording 20-s intervals of data, and a total of 96 experimental repetitions were conducted. The pressure drop across the Capiox Baby RX05 oxygenator was significantly lower than the pressure drop across the Medtronic 0800 at all flow rates and perfusion modes. Furthermore, the Medtronic 0800 oxygenator showed significantly lower post-oxygenator energy equivalent pressures, total hemodynamic energy values, and surplus hemodynamic energy retention values compared to those of the Capiox Baby RX05. These results indicate the Medtronic 0800 oxygenator significantly dampens the hemodynamic energy compared to the Capiox Baby RX05. Consequently, clinical use of the Medtronic 0800 in a pulsatile ECLS setting is likely to mitigate the benefits provided by pulsatile flow. In contrast, the Capiox Baby RX05 better transmits hemodynamic energy to the patient with much lower pressure drop.     

Evaluation of Capiox FX05 oxygenator with an integrated arterial filter on trapping gaseous microemboli and pressure drop with open and closed purge line

Gaseous microemboli (GME) remain a challenge for cardiopulmonary bypass (CPB) because there is a positive correlation between microemboli exposure during CPB and postoperative neurological injury. Thus, minimizing the number of GME delivered to pediatric patients undergoing CPB procedures would lead to better clinical outcomes. In this study, we used a simulated CPB model to evaluate the effectiveness of capturing GME and the degree of membrane pressure drop for a new membrane oxygenator, Capiox Baby FX05 (Terumo Corporation,Tokyo, Japan), which has an integrated arterial filter with open and closed purge line.We used identical components in this study as our clinical CPB circuit. Three emboli detection and classification quantifier transducers were placed at prepump, preoxygenator, and postoxygenator sites in the circuit.Two flow probes as well as three pressure transducers were placed upstream and downstream of the oxygenator. The system was primed with human blood titrated to 30% hematocrit with Lactated Ringer’s solution.A bolus of air (1 mL) was injected in the prepump site under nonpulsatile perfusion mode at three flow rates (500,750, and 1000 mL/min) and with the purge line either open or closed. Six trials were performed for each unique set-up for a total of 36 trials.All trials were conducted at 35°C. The circuit pressure was kept constant at 100 mm Hg. Both the size and quantity of microemboli detected at postoxygenator site were recorded for 5 min postair injection. It was found that total counts of GME were significantly reduced with the purge line open when compared to keeping the purge line closed (P < 0.0001 at 1000 mL/min). At all flow rates, most of the GME were under 20 microns in size. In terms of microemboli greater than 40 microns, the counts were significantly higher with the purge line closed compared to keeping the purge line open at flow rates of 750 mL/min and 1000 mL/min (P < 0.01). At all flow rates,there is a tiny difference of less than 1 mmHg in membrane pressure drop between keeping the purge line open and closed, which is due to the small arteriovenous (A-V) shunt(P < 0.001). These results suggest that the integrated arterial filter of the Capiox FX05 oxygenator significantly improves the capturing of GME but has little impact on membrane pressure drop.     

A new bubble oxygenator (OCVC oxygenator): Development and clinical application

A new bubble oxygenator, designed for simple operation and clinical efficacy in intracardiac surgery, has been developed and clinically evaluated. This device is characterized by an oxygenating chamber with controllable blood-volume, integral heat exchanger and two-stage microfilter of gravity drainage system, an apparatus for creating and uniformly distributing oxygen bubbles, and construction materials of the device known to be minimally traumatic to the blood. Clinical experience in 132 infantile and pediatric open heart procedures has demonstrated its effectiveness as measured by embolic complications and simplicity in maintaining physiologic blood gas levels.     

Effects of Pulsatile Flow on Gas Transfer of Membrane Oxygenator: MENOX EL-4000 and Gyro C1-E3 Pulsatile Mode

Abstract: It is acknowledged that pulsatile flow enhances the gas exchange performance of membrane oxygenators. However, the data for currently developed oxygenators are limited. In this study, the effect of pulsatile flow was assessed utilizing the MENOX EL-4000 oxygenator. The in vitro test was performed following the Association for the Advancement of Medical Instrumentation (AAMI) standards. Pulsatile flow was produced by the Gyro C1-E3 centrifugal pump with periodical changing of the impeller speed. In Study 1, the following 3 groups were created and examined: nonpulsatile flow, pulsatile flow of 40 bpm, and pulsatile flow of 60 bpm. The blood flow rate was maintained at 3 LImin, and the VIQ ratio was I. In Study 2, four groups were examined, nonpulsatile flow with V/Q = 1, nonpulsatile with V/Q = 2, pulsatile with VIQ = 1, and pulsatile with V/Q = 2. The blood flow rate was maintained at 4 LImin, and the pulse frequency was set at 40 bpm. In study 1, although 0, transfer was not enhanced. CO₂, transfer was significantly improved (40–50%) by pulsatile flow, regardless of pulse frequency. Study 2 demonstrated that pulsatile flow resulted in improved CO₂ transfer as did higher ventilation (VIQ = 2). Furthermore, even after applying higher ventilation, the pulsatile mode enhanced CO₂ transfer more than the nonpulsatile mode. It was considered that the pulsatile mode induced an active secondary flow and enhanced mixing effects, and consequently CO₂ transfer was improved. In conclusion, the pulsatile flow significantly enhanced the CO₂ transfer of the MENOX oxygenator. It is indicated that applying the pulsatile mode is a unique and effective method to improve the gas exchange performance for a current membrane oxygenator.     

Gas Exchange Efficiency of a Membrane Oxygenator with Use of a Vibrating Flow Pump

Abstract: We have developed a newly designed blood pump, named the vibrating flow pump (VFP), which can generate high frequency oscillated flow. The driving frequency is 10–50 Hz, and flow volume is linearly controlled electric power (current and voltage). The VFP was applied as the pump for extracorporeal circulation (ECC) in acute animal experiments. The gas exchange efficiency of the membrane oxygenator with the VFP and a roller pump (RP) was evaluated. Under general anesthesia with halothane, 7 adult goats underwent ECC; an inflow can-nula was inserted into the right atrium, an outflow cannula was sutured to the descending thoratic aorta, and total ECC was performed with a flow of about 80 ml/min/ kg. The ECC system with the VFP showed excellent gas exchange efficiency compared with that of the RP. The hemodynamics of ECC using the VFP were easily maintained within normal limits. These results suggest that the VFP is very useful as a pump for ECC; thus, a compact-sized ECC system may be achieved.     

Fabrication,Characterization, and Hemocompatibility Investigation of Polysulfone Grafted With Polyethylene Glycol and Heparin Used in Membrane Oxygenators

Polysulfone (PSF) was grafted chemically with polyethylene glycol (PEG) of different molecular weights (400, 2000, 10 000, and 20 000) and heparin to prepare PSF–PEG–Hep membranes (labeled as PSF–PEG400–Hep, PSF–PEG2000–Hep, PSF–PEG10 000–Hep, and PSF–PEG20 000–Hep). These membranes were synthesized via the following steps: (i) PSF chloromethylation; (ii) PEGylation; and (iii) heparin immobilization process. Water contact angle, critical water permeation pressure, ATR–FTIR, ¹H NMR, UV–visible spectrophotometry, and X‐ray photoelectron spectroscopy were conducted to prove grafting success and to fix the optimal reaction parameters during chemical modification processes. To further evaluate the application potential of the PSF–PEG–Hep membrane in a membrane oxygenator, we conducted pure CO₂ and O₂ gas permeation tests and measured the gas exchange rates of CO₂ and O₂ through a membrane oxygenator using fresh porcine blood. Meanwhile, the hemocompatibility of the membrane was analyzed and compared by protein adsorption, platelet adhesion, and blood coagulation tests. Results of pure gas permeation experiments indicated that the excellent gas transmission properties through PSF membrane were preserved after modification. Blood oxygenation experiments through the PSF–PEG10 000–Hep membrane showed that when the flow rate of porcine blood was 1.5 L/min, CO₂ and O₂ exchange rates reached 102 and 110 mL/min, respectively, which could basically satisfy the gas exchange potential of commercial membrane oxygenators. Besides, the PSF–PEG–Hep membrane has demonstrated more prominent blood compatibility than PSF.     

An evaluation of a polyethersulfone hollow fiber plasma separator by animal experiment

Membrane plasma separators are being used routinely for therapy in various diseases. In this study, a newly developed plasma separator made of polyethersulfone (PES) hollow fibers was evaluated for its plasma filtration efficiency and blood compatibility by animal experiment. Hemolysis did not occur under the usual conditions of plasma separation. The sieving coefficients of total protein and albumin were over 95%, and the total cholesterol was over 90% throughout the perfusions. Decreases in white blood cells, platelets, fibrinogen, and coagulation factors were observed during the early stage of plasma separation, but appear to be within acceptable ranges for clinical use.     

Development of an Intravenous Membrane Oxygenator: Enhanced Intravenous Gas Exchange Through Convective Mixing of Blood around Hollow Fiber Membranes

Abstract: In vitro testing of a new prototype intravenous membrane oxygenator (IMO) is reported. The new IMO design consists of matted hollow fiber membranes arranged around a centrally positioned tripartite balloon. Short gas flow paths and consistent, reproducible fiber geometry after insertion of the device result in an augmented oxygen flux of up to 800% with balloon activation compared with the static mode (balloon off). Operation of the new IMO device with the balloon on versus the balloon off results in a 400% increase in carbon dioxide flux. Gas flow rates of up to 9. 5 L/min through the 14–cm–long hollow fibers have been achieved with vacuum pressures of 250 mm Hg. Gas exchange efficiency for intravenous membrane oxygenators can be increased by emphasizing the following design features: short gas flow paths, consistent and reproducible fiber geometry, and most importantly, an active means of enhancing convective mixing of blood around the hollow fiber membranes     

Influence of Hemodialysis Membranes on Gene Expression and Plasma Levels of Interleukin-iβ

Abstract: Plasma levels of interleukin-iβ (IL-iβ) were measured in 10 normal subjects, in 11 nondialyzed end-stage renal failure (ESRD) patients, and in 22 hemodialysis (HD) patients. Of the HD patients, 7 were dialyzed with Cuprophan (CU), 7 with polymethylmethacrylate (PMMA), and 8 with polysulphone (PS) dialyzers. In normal controls, nondialyzed ESRD patients, and HD equipped with CU, PAMM, and PS dialyzers, plasma levels of IL-iβ were 10.73 ± 5.24 pg/ml, 9.97 ± 3.61 pg/ml, 13.17 ± 4.04 pg/ml, 15.16 ± 6.16 pg/ml, and 13.96 ± 5.47 pg/ml, respectively. There were no statistically significant differences among the groups (p ≥ 0.05). In contrast, the gene expression of IL-iβ for peripheral blood mononu-clear cells (PBMC) by in situ hybridization showed differences among the groups. The gene for IL-iβ for PBMC appears in HD equipped with different membranes, but not in cases of nondialyzed uremic patients and normal subjects. With computer imaging analysis, we carried out quantitative analysis of cells in in situ hybridization with an area of positive spots to an area of total cells. In HD with CU, PMMA, and PS, the results were 10.64 ± 1.07, 3.34 ± 0.74, and 3.27 ± 0.64%, respectively. The levels of IL-iβ gene expression in CU were higher than that in PMMA or PS. There were statistically significant differences (p ≤ 0.001) between CU and PMMA or PS and no significant difference between the PMMA and PS (p ≥ 0.05). We suggest measuring the gene expression of cy-tokines for PBMC and which may be better than measuring cytokine levels only for investigating the blood compatibility of dialyzers, which may help in understanding chronic complications of the dialysis procedure.