bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Compact, Highly Efficient, Totally Implantable Motor–Driven Assist Pump System
Authors: OKAMOTO EIJI , TOMODA KIYOSHI , YAMAMOTO KATSUYUKI , MITAMURA YOSHINORI , MIKAMI TOMOHISA
Published: November 2008

Abstract: We have developed a compact, highly efficient, totally implantable assist pump system, which consists of a motor–driven assist pump and a transcutaneous energy and optical information transmission system. The motor–driven assist pump consists of ad. c. brushless motor and a specially designed miniature ball screw. A magnetic coupling mechanism between the blood pump and an actuator provides active blood filling via mild suction force. The controller consists of a PID follow–up controller using an 8–bit one–chip microcomputer. The volume of the pump is 350 ml, and its controller is 210 ml. Pump outflow of 5. 8 L/min was obtained against a mean afterload of 100 mm Hg. The pump showed a high efficiency rate and good durability. An efficiency rate of 19–21% (pump output/motor input) was obtained during 87 days of continuous pumping. No mechanical trouble occurred for an accumulated period of 6 months.
The Italian Artificial Heart Program
Authors: MAMBRITO B. , Arabia M. , CHIECO S. , FERRAZZI P. , FERRI E. , FIERLI M. , GLAUBER M. , MELI M. , ZAGARA M.
Published: November 2008

Abstract: In Italy, artificial heart development was promoted by virtue of a special program on technological and industrial development in areas related to cardiology and cardiosurgery. A first prototype series of electromechanical total artificial hearts (TAHs) and ventricular assist devices (VADs), with ball–screw–based actuation technology, has been developed, and preliminary bench tests and short–term animal implant experiments were performed. The project started with analysis and development of existing TAH and VAD models, and it included a fill–sensor–free control scheme and anatomical fitting studies using a three–dimensional computer model of the chest cavity. Second–generation prototypes are currently being developed, and they are scheduled for mediumterm bench and in vivo testing by early 1994.
Recirculation Measures with Urea and Mannitol During Hemodialysis
Authors: Kirschbaum Barry
Published: November 2008

Abstract: A simple, accurate, and reproducible method of measuring recirculation in grafts during hemodialysis is essential for improving the efficiency of dialysis. In our studies, plasma samples for plasma urea nitrogen (PUN) were taken from the arterial line of the dialyzer at blood flows (A) of 200, 300, and 400 ml/min, preceded by a 5–min period of equilibration, and at 15 s and 2 min after turning the flow down to 100 ml/min (S), the latter serving as systemic samples. Recirculation was calculated as (S – A)/(S – V). Total blood flow (Qb) through the grafts was measured by color Doppler ultrasound. We found a significant, inverse relationship between recirculation and total flow through the graft at dialyzer Qb of 400 but not 300 or 200 ml/min. The magnitude and prevalence of recirculation was always greater when the 2 min sample was used as S compared to the 15 s sample and as dialyzer Qb increased. As a qualitative, urea–independent measure of recirculation, we assayed the appearance of mannitol in the arterial line in blood drawn 15 s after initiating a mannitol push into the venous line. Blood obtained just prior to the mannitol push was used as the zero blank. Thirteen of 18 patients had a measurable, but low, level of mannitol, 5 did not, and 2 had inconsistent results in studies done on separate days. We conclude that the majority of patients receiving chronic hemodialysis have a low degree of recirculation and that methods relying on urea must be suspected of exaggerating the true degree of recirculation.
A One–Step, Operator–Independent Method for Isolating Islets of Langerhans from the Porcine Pancreas
Authors: Arbet–Engels Christophe , Darquy Sylviane , Capron Frédérique , Pueyo Maria E. , Dimaria Sophie , Poitout Vincent , Reach Gérard
Published: November 2008

Abstract: Large–scale isolation of islets of Langerhans is one of the major obstacles in islet transplantation. Until now, isolation methods relied on enzymatic digestion, the duration of which relies on a decision dictated by the operator's experience. This approach has always hindered development of an automated method. The aim of this study was to develop a one–step method based on complete digestion of the pancreas. The original aspect of the technique (derived from the Ricordi method) is use of the University of Wisconsin (UW) solution in the digestion medium and a continuous flow collagenase processing circuit with local cooling and rewarming to allow tissue digestion to proceed at 37°C while settling of the cell suspension takes place at 4°C. A stopcock system permits the alternate use of two settling chambers so that while one is in the circuit, the other can be removed for cen–trifugation, resuspension of the crude islet preparation in collagenase in free UW solution, and further purification in a density gradient system. Ten experiments were performed, and 545, 750 ± 48, 670 purified pig islets were obtained per totally digested pancreas. Histological studies showed cell integrity. Insulin secretion in response to double glucose stimulation under perfusion conditions demonstrated the functional viability of the isolated islets. In conclusion, this one–step method makes it possible to obtain a high number of viable islets of Langerhans in the absence of any decision by an operator, and it should therefore provide basis for an automated method.
Oversaturation Status of Reticuloendothelial System Following Cardiopulmonary Bypass
Authors: Shimono Takatsugu , Yada Isao , Kusagawa Minoru , Nosé Yukihiko
Published: November 2008

Abstract: In the past, it was generally believed that the phagocytic function of the reticuloendothelial system (RES) was depressed after cardiopulmonary bypass (CPB), but several investigators reported differing results. Therefore, this study was performed to determine the effect of CPB on RES function, experimentally and clinically. Six dogs undergoing CPB (CPB group) were compared with an identical number of dogs subjected to thoracotomy without CPB (control group). A lipid emulsion test was performed in all dogs before and after the surgical procedure to measure RES phagocytic function. Any ultrastructural changes in Kupffer cells were observed by electron microscopy. In both groups, the RES phagocytic index showed a significant decline after surgery. However, comparison of the 2 groups revealed that there was a significantly greater decrease in the CPB group (p < 0. 05). Electron microscopy of the Kupffer cells showed that the number of phagosomes, especially those containing deformed erythrocytes, increased after CPB. Twenty patients undergoing cardiac surgery requiring CPB (Group A) and 8 patients undergoing pulmonary resection (Group B) were studied. RES phagocytic function was determined 3 days prior to surgery and 3 days postoperatively using the lipid emulsion test. No significant difference was observed in the preoperative phagocytic indices between the 2 groups. The phagocytic function remained almost unchanged in Group A on the third postoperative day, compared with the preoperative value, but it increased significantly in Group B on the third postoperative day, compared with the preoperative value. The intergroup difference was significant on the third postoperative day (p < 0. 01). These findings suggest that phagocytic activities of RES are not depressed but stimulated by CPB and that the phagocytic ability of RES is saturated by formed microparticles after CPB, such as residual of hemolyzed erythrocytes, protein aggregates, and microbubbles, among others. “Depressed RES phagocytic function” after CPB may not be a proper expression of this situation. It should be considered that the status of RES function after CPB is not functionally depressed but functionally oversaturated.
Results of Circulatory Support for Postoperative Cardiogenic Shock
Authors: Murakami Taiji , Kino Koichi , Irie Hiroyuki , Kioka Yukio , Indo Shunjyu , Kawakami Shunji , Yamada Makoto , Shimizu Nobuyoshi
Published: November 2008

Abstract: Over the last 5 years, 15 patients received ventricular assist devices (VADs) (Group 1) and 5 percutaneous cardiopulmonary support (CPS) (Group 2) while in postoperative cardiogenic shock. Group 1 consisted of 8 men and 7 women ranging in age from 22 to 73 years (average age, 55 years). Nine of these patients underwent surgery for valve replacement, 5 for coronary artery bypass grafting, and 1 for closure of a ventricular septal rupture. The duration of VAD support ranged from 6 h to 9 days (mean, 3. 9 days). Group 2 consisted of 4 men and 1 woman ranging in age from 49 to 68 years (average age, 57 years). One of these patients underwent surgery for valve replacement, 1 for coronary artery bypass grafting, 2 for replacement of a thoracic aneurysm, and 1 for left ventricular aneurysmectomy. The duration of CPS ranged from 4 h to 8 days (mean, 2. 8 days). In Group 1, 13 patients were weaned from the VADs and 8 survived. Bleeding occurred in 5 patients, renal failure in 4, infection in 3, cardiac failure in 4, cerebral infarction in 1, perioperative myocardial infarction in 1, arrhythmia in 1, and ileus in 1. In Group 2, 4 patients were weaned from the CPS and 3 survived. Bleeding occurred in 3 patients, renal failure in 2, CNS injury in 2, and cardiopulmonary failure in 1. The 8 survivors in Group 1 have been followed for 2 to 56 months (mean, 28. 7 months). Five patients were in NYHA class I, 2 were in class II, and 1 was in class III. The 3 survivors in Group 2 have been followed for 6 to 18 months (mean, 10. 6 months). Two of these patients were in NYHA class I, and 1 was in class III. The VADs and CPS were both effective in preventing circulatory failure, but serious complications were observed more frequently in patients with CPS.
Clinical Experience with Nikkiso Centrifugal Pumps for Extracorporeal Circulation
Authors: Onoda K. , Kondo C. , Mizumoto T. , Kusagawa H. , Katayama Y. , Hayashi T. , Komada T. , Hirano R. , Miyamura T. , Tanaka J. , Yasuda F. , Tanaka K. , Shimpo H. , Yada I. , Yuasa H. , Aizawa T. , Kusagawa M.
Published: November 2008

Abstract: A comparative study of a newly developed impeller–type centrifugal pump, Nikkiso HMS–15, was made to assess the effects on hemolysis, platelet function, and renal function for extracorporeal circulation (ECC) during open heart surgery. The Bio–pump (cone–type, Medtronic) and the roller pump were used as controls. The increase of serum hemoglobin level in the Nikkdiso pump was significantly lower than that in the other pumps. The decrease of platelet counts was recognized after the initiation of ECC in the three pumps whereas the levels of platelet factor 4 and β–thromboglobulin in the Nikkiso pump group increased by far less than in the other two groups. Moreover, renal function was better maintained in the Nikkiso pump group; in particular, a significantly higher urine output was recorded during ECC and for 1 h after the termination of ECC. The results of our clinical studies suggest that the Nikkiso centrifugal pump is suitable for ECC during open heart surgery.
Nonthrombogenic Polymer Vascular Prosthesis
Authors: Nojiri Chisato , Senshu Kazuhisa , Okano Teruo
Published: November 2008

Abstract: Although many synthetic vascular grafts have been developed and evaluated experimentally or clinically, none of them have met long‐term patency when applied as a small diameter vascular substitute. We have recently developed a small caliber vascular graft (3 mm i.d.) using a nonthrombogenic polymer coating. The graft consists of three layered structures: Dacron for the outer layer, polyurethane in the middle layer, and a HEMA/ styrene block copolymer (HEMA‐st) coating for the inner layer. HEMA‐st is an amphiphilic block copolymer composed of 2‐hydroxyethyl methacrylate and styrene which has demonstrated improved blood compatibility over existing biomedical polymers in both in vitro and ex vivo experiments. Ten grafts were evaluated in a dog bilateral carotid replacement model. The grafts were electively retrieved at 7, 14, 30, 92, and 372 days after implantation.

All grafts were patent without detectable thrombi along the graft length including anastomotic sites. Scanning electron micrographs of retrieved graft lumen showed fairly clean surfaces covered with a homogenous protein‐like layer without microthrombi or endothelial cell lining. The thickness of the surface protein layer measured by a transmission electron microscopy was what can be described as monolayer protein adsorption regardless of implantation periods of as much as 372 days. A stable monolayer adsorbed protein layer formed on HEMA‐st surfaces demonstrated nonthrombogenic activities in vivo and secure long‐term patency of small caliber vascular grafts with the absence of an endothelial cell lining.
Hemodialysis with Regenerated Cellulosic Membranes Does Not Reduce Plasma Selenium Levels in Chronic Uremic Patients
Authors: Bonomini Mario , Manfrini Vania , Marini Alvaro , Risio Franco De , Niri Luciano , Klinkmann Horst , Albertazzi Alberto
Published: November 2008

Abstract: Selenium (Se) is considered an essential and very important trace element for humans. Se blood levels are frequently low in end‐stage renal disease (ESRD) patients, but very little has been established concerning the mechanisms that could modify Se status in uremia, including a supposed dialysis‐mediated Se depletion. In order to verify whether hemodialysis (HD) can induce a loss of Se, thereby leading or contributing to a low plasma Se concentration, we investigated the effect of HD procedure with the most commonly used regenerated cellulosic membrane (Cuprophan) on plasma Se levels in 20 uremic patients on HD for 62.5 ± 49.4 months. Plasma Se levels were also determined in 15 chronic renal failure (CRF) nondialyzed patients and in 28 age‐matched healthy controls. Se concentration was determined by atomic absorption spectrophotometry. Plasma Se levels of both HD patients (61.3 ± 8.5 μ/L) and CRF nondialyzed patients (56.4 ± 10.1 μg/L) were significantly lower than in normal subjects (78.3 ± 9.7 μg/L, p < 0.001). In CRF nondia‐lyzed patients, a significant (p < 0.05) negative correlation was found between the plasma Se concentration versus serum creatinine values. Within the HD group, plasma Se levels significantly increased after the HD procedure (72.8 ± 17.2 μg/L, p < 0.02) together with hemat‐ocrit and total plasma protein values (p < 0.05 and p < 0.001, respectively). In the hollow fiber dialyzer during an HD session, the Se concentration increased but not significantly from the blood inflow site (64.6 ± 12.5 μg/L) to the outflow site (72.6 ± 17 μg/L) and decreased, again not significantly, from the dialysate entrance (5 ± 1.9 μg/L) to the outlet (4.8 ± 2.5 μ?.). In HD with low‐flux regenerated cellulosic dialyzer, very likely due to the high molecular weight of Se‐binding proteins, the replacement treatment did not induce a Se loss in chronic uremic patients with a low plasma Se concentration.
Usefulness of Plasma Exchange in Recurrent Nephrotic Syndrome Following Renal Transplant
Authors: Torretta Lorella , Perotti Cesare , Costamagna Laura , Tarantino Antonio , Salvaneschi Laura
Published: November 2008

Abstract: Nephrotic syndrome due to focal segmental glomerulosclerosis (FSGS) frequently recurs even after transplantation and may cause failure of the renal al‐lograft. We report a case in which plasma exchange (PE) was used to treat a 32‐year‐old patient with biopsy‐proven recurrence of FSGS in a second renal transplant after the first allograft had failed. One year after the second renal graft, the patient presented with proteinuria of 5 g/day and a creatinine level of 1.46 mg/dl. A course of 9 PE was performed over a 15‐day period. Proteinuria improved rapidly, and 20 days after the last PE, it was already down to 0.8 g/day. This level continued to decrease progressively (0.5 g/day after 3 months) and reached zero after approximately 6 months. Eleven months after PE treatment, the patient had no proteinuria and his plasma creatinine level was normal. In our opinion PE should be instituted early in recurrent nephrotic syndrome after renal transplantation. The optimum frequency of such treatment still has to be established, especially with regard to its use as long‐term maintenance therapy.
Hemodialyzer Performance: Biological Indices
Authors: Holmes Clifford J.
Published: November 2008

Abstract: In the last decade there has been a rapid increase in the number of biological indices that could potentially be used as measures of hemodialyzer or membrane biocompatibility. Consequently, it has become more challenging for all of those involved in renal replacement therapy to evaluate the relative merits of one membrane versus another when faced with their ever increasing variety of parameters. This review attempts to summarize the current array of biological parameters described in the literature as indices of biocompatibility and provide a critique of their utility. Emphasis is placed on measures of activation of the plasma cascade systems, complement, coagulation, and kinin as primary indices of biocompatibility. Additional information on neutrophil, monocyte, platelet, lymphocyte and natural killer (NK.) cell effects may provide further insight into blood‐membrane mediated interactions although many of these may parallel plasma cascade systems activation. The importance of good statistical design and analysis is emphasized to ensure meaningful interpretation of any study
Convective Mass Transfer in Hemodialysis
Authors: Jaffrin Michel Y.
Published: November 2008

Abstract: Convective mass transfer in hemodialysis is associated with ultrafiltration (UF). In the absence of diffusion as in hemofiltration, the convective clearance is equal to S QF where S is the apparent solute sieving coefficient and QF the UF flow rate, but the convective contribution significantly decreases when diffusion is present. A rigorous calculation of the combined diffusion–convection mass transfer for partially rejected solutes is very complex. In this paper we review various models of mass fluxes found in the literature. Since all these models express the mass flux through the membrane as a linear function of blood and dialysate concentrations with different coefficients, we present a general expression for the hemodiafiltration clearance combining diffusion and convection which can be adapted to each model of mass flux. A surprising result is that the convective contribution to the clearance is, in the limit of dominant ultrafiltration, independent of the solute sieving coefficient, in contrast to the model of Villaroel et al. This is due to the effect of increased solute concentration at the membrane which compensates exactly for the effect of the sieving coefficient. This effect is overlooked in the Villaroel et al. model which assumes well mixed blood and dialysate compartments. Comparison with in vitro clearance measurements for urea, creatinin, vitamin B12, and myoglobin (16,000 daltons) supports this observation even when diffusion dominates as in the case of clinical conditions for hemodiafiltration. An empirical correlation for the overall clearance valid for all solutes and blood flows between 200 and 500 ml/min is found to be K = KD+ 0.43 QF+ 8.3 times 10‐3Q2Fwhen clearances and QFare in ml/min.
A Thermoconductive and Thermoselective Leukocyte Filter
Authors: Matsuda Yukihiro , Naito Keiko , Tasai Kimitaka , Mizuguchi Kazumi , Nosé Yukihiko
Published: November 2008

Abstract: Previously, it was reported by our group that the superphysiological temperature of over 43°C affected leukocyte properties. It was speculated that heat treatment might alter the immunological properties of leukocytes. In order to take advantages of this phenomenon, attempts were made to develop a thermoconductive and thermoselective leukocyte filter. A stainless steel fiber was selected for the new material of a leukocyte filter due to its good heat conductance, stability during thermal change, and inertness to any chemicals. Preliminary studies were conducted to evaluate the effect of fiber diameter and temperature on the filtration of blood cells. As a result, more than 99% of white blood cells (WBCs) and platelets were removed utilizing a 4 μm diameter fiber filter. The environmental temperatures of the filtration process were varied to 4, 20, 36, and 50°C for 5 min. Almost 95% of WBCs and platelets were removed at 4, 20, and 36°C. However, the reduction of platelets was remarkably suppressed at 50°C (54%). Additionally, the removal of lymphocytes was significantly lower than that of neutrophils at 50°C (69% vs. 83%; p = 0.0002). These data demonstrate that effective heat treatment and removal of leukocytes are possible with an ultrafine stainless steel fiber filter.
Study of Cardiac Structures in Relation to the Pericardial Cavity for Total Artificial Heart Implantation
Authors: Komoda Takeshi , Uyama Chikao , Maeta Hajime , Ozaki Kenichi
Published: November 2008

Abstract: To enhance the design of the completely im‐plantable total artificial heart (TAH), we developed a coordinate system that expresses the geometry of the heart, including that at the interface with the TAH and that of the pericardial cavity. This coordinate system (ventricular coordinate system) was developed using 3D images of the heart which were obtained from magnetic resonance images. The origin is located on the centroid of the mitral annulus at 25 ms delay from the ECG R wave (M0), and the y axis is the axis from M0 to the apex at 25 ms delay (Apex0). The x‐y plane includes M0, Apex0, and the centroid of the tricuspid annulus at 25 ms delay. Since the y axis expresses the apical orientation of the heart, data using this coordinate system are not affected by individual variation in heart orientation. Heart geometry data were obtained in 5 normal subjects. Compared with that using the coordinate system based on the thoracic wall, the expression of the data of interface geometry for the heart and the TAH is simplified when the ventricular coordinate system is used. A method of expressing the geometry of the pericardial cavity using the ventricular coordinate system is also proposed. These methods may be applicable in obtaining data in patients suffering from cardiomyopathy.
Mathematical Model for a New Mode of Artificial Ventilation: Volume Assisted Pressure Supported Ventilation: A Comparative Study
Authors: Bonassa Jorge
Published: November 2008

Abstract: The patient submitted to artificial ventilation generally is connected to a high impedance flow source with controlled respiratory cycles to assure volume requirements or to a low impedance pressure source with spontaneous cycles to allow synchronization between his effort and system flow delivery. These two types of cycles represent the initial and final stages of artificial ventilation. The patient who needs a volume guarantee and at the same time presents unstable or insufficient inspiratory effort is difficult to manage with assisted cycles which are analogous to the controlled presence of a high impedance flow source. This paper presents a new approach where the respiratory cycles are obtained by the combination of flow and pressure sources using mathematical modeling. These cycles, named volume assisted pressure supported (VAPS) cycles, are compared with conventional assisted cycles showing a decrease in the patient work of breathing (WOB) during assisted ventilation. The theoretical results have been confirmed by clinical trials.
Clinical Comparison of Blood Oxygenators: A Retrospective Study
Authors: Turri Fabio , Volpe Alexandre Delia , Leirner Adolfo A.
Published: November 2008

Abstract: The results for platelet count (PC), activated clotting time (ACT), postoperative bleeding, and hemo‐derivatives usage in cardiac surgeries were crossed against the type of oxygenator used. These were two bubble and one membrane type. A sample of the surgery population for each type was selected at random. Thus, the patients in this study were divided into 3 groups: BA: 87 patients, bubble oxygenator; BB: 87 patients, bubble oxygenator; M: 73 patients, membrane oxygenator. The groups were statistically similar (p < 0.05) for age, body surface area, cardiopulmonary bypass (CPB) time, and prevalence of cardiac disease. The rate of PC 15 min after CPB end and before its beginning was BA, 0.48 ± 0.02; BB, 0.49 ± 0.02; M, 0.55 ± 0.03. The rate of ACT after protamine administration and before CPB was BA, 1.22 ± 0.03; BB, 1.16 ± 0.03; M, 1.16 ± 0.03. Volume (ml) of total postoperative bleeding (POB) was BA, 904 ± 72; BB, 963 ± 73; M, 867 ± 83. Patient percentage that used hemoderivatives (HD) was BA, 86.3%; BB, 88.5%; M, 90.0%. No statistical difference was found between groups (p > 0.05). This study indicates that although membrane oxygenators have better theoretic and experimental biocompatibility, no significant difference in PC, ACT, POB, and HD usage was observed in the clinical setting. All values are expressed as the mean ± standard error of the mean.
Design, Manufacturing, and Testing of a Paracorporeal Pulsatile Ventricular Assist Device: S˜o Paulo Heart Institute VAD
Authors: Oshiro Milton S. , Hayashida Sergio A. , Maizato Marina J.S. , Marques Euclydes F. , Stolf Noedir A.G. , Jatene Adib D. , Leirner Adolfo A.
Published: November 2008

Abstract: This paper describes the design of a ventricular assist device (VAD), its manufacturing, and testing. The VAD presented is pulsatile, with a free‐floating membrane, smooth internal surfaces, and pericardial valves. It comprehends also a pneumatic driving unit capable of operating in the “full to empty,” EKG synchronized or asynchronous modes. In vitro tests were performed to assess its mechanical durability, hydrodynamic performance, and hemolysis. To optimize cannulas and implant techniques, we performed in vivo tests in 22 sheep and 8 calves. In these tests, we also evaluated hemolysis and the device's capacity to normalize hemodynamic parameters during induced cardiac failure. The VAD worked for 4,000 h without failure in a mock circulatory loop. In full to empty mode, it displayed a rate‐mediated “Starling‐like” performance. Optimum output was achieved with a systole duration of 40% of the cycle. The in vitro hemolysis index (IH) was 6.7 ±2.1. Hemolysis in animal experiments was clinically nonsignificant. In calves with induced cardiac failure, the VAD was able to normalize hemodynamic parameters within 120 min.
Albumin‐based Solutions for Peritoneal Dialysis: Investigations with a Rat Model
Authors: Park Min Sun , Heimbtirger Olof , Bergström Jonas , Waniewski Jacek , Werynski Andrzej , Lindholm Bengt
Published: November 2008

Abstract: To evaluate albumin, an osmotic agent for peritoneal dialysis, the peritoneal fluid and solute transport were investigated during a 4‐h single cycle peritoneal dialysis with albumin‐based dialysis solutions. Two different albumin solutions were used in 15 normal Sprague‐Dawley rats: isotonic 7.5% albumin solution (ADS 1, n = 7) and a combined 7.5% albumin and 1.36% glucose solution (ADS 2; n = 8). A standard 1.36% Dianeal solution was used to provide control values (n = 6). The rate of the intraperitoneal volume change (Qv) was positive during the initial 90 min with ADS 2 and during the initial 60 min with Dianeal 1.36% solution but negative with ADS 1. The peritoneal bulk flow reabsorption rate, Qa, was similar in all three groups. The estimated rate of transcapillary ultrafiltration (Qu=Qv+Qj was positive with all three solutions throughout the dialysis. With ADS 1, Qu increased gradually during the initial 90 min and then remained stable, but it decreased with ADS 2 and Dianeal 1.36% solution. Qu with ADS 2 did not differ from that with Dianeal 1.36% solution during the initial 60 min, but it was significantly higher during the latter part of dialysis. The value of Qu during the last 2 h of dialysis was 0.026 ± 0.010 and 0.025 ± 0.009 ml/min with ADS 1 and ADS 2, respectively, and it was significantly higher than that with Dianeal 1.36% solution (0.005 ± 0.007 ml/ min; p< 0.017). After 4 h of dialysis, 76.1 ± 10.2 and 78.8 ± 11.1% of the initial amount of albumin remained in the peritoneal cavity with ADS 1 and ADS 2, respectively. Since a positive value of Qu was maintained for at least 4 h during dialysis with the two albumin‐based solutions and was significantly higher after 4 h of dialysis than with the Dianeal 1.36% solution, and since (Qa) was similar with the three solutions, the present findings indicate that the differences in the Qv values are due to the differences in the transcapillary ultrafiltration rate (QU). Furthermore, ADS 2, a solution containing both crystalloid and colloid osmotic agents, resulted in higher and more prolonged ultrafiltration than did the conventional glucose solution. After 4 h of dialysis, about 20–25% of the initial amount of albumin was absorbed, indicating that albumin‐based dialysis solutions may compensate for the protein loss into dialysate in continuous ambulatory peritoneal dialysis (CAPD) patients. The results of the present study may provide useful reference data in the evaluation of alternative osmotic agents.
Hepatitis C Virus Associated Cryoglobulinemic Neuropathy Successfully Treated with Plasma Exchange
Authors: Murai Hiroyuki , Inaba Shoichi , Kira Jun‐ichi , Yamamoto Akifumi , Ohno Masaharu , Goto Ikuo
Published: November 2008

Abstract: A 28‐year‐old Japanese woman who suffered from mononeuritis multiplex was admitted to our hospital. Serological study revealed cryoglobulinemia (type III), hypocomplementemia, high titers of rheumatoid factor (RF), and positive antihepatitis C virus (HCV) antibody. Nerve conduction velocities were slower in sensory nerves than in motor nerves. Biopsied sural nerve showed a marked decrease of myelinated fibers but no evidence of angitis. She received plasma exchange and cryoglobulinpheresis over a period of 2 months with approximately 2.0 L (40 ml/kg) of plasma replaced in each procedure. Both plasma exchange and cryoglobulinpheresis alleviated clinical symptoms, and nerve conduction velocities were improved in several nerves. The serum cryoglobulin level was markedly reduced after the treatment together with the recovery of the C4 level. Thus, complements appeared to be consumed in large quantities in the presence of cryoglobulinemia in this patient. Efficacy of cryoglobulinpheresis indicates the possibility that cryoglobulins produced in association with HCV infection played a role in damaging the nerve directly through the activation of the complement system.
Hemolytic Differences among Artificial Cardiac Valves Used in a Ventricular Assist Pump
Authors: Billy Gregory G. , Miller Cynthia A. , Pallone Michael N. , Donachy James H. , Pierce William S.
Published: November 2008

Abstract: Ventricular assist devices (VADs) required for cardiac support may produce clinically significant hemo‐lysis. VAD valves differ in both mechanics and hemody‐namics. Therefore, we examined a ball valve, a modified tilting disc (MTD) valve, a polyurethane trileaflet valve, and a Bjork‐Shiley monostrut valve to determine their degrees of hemolysis. The valves were tested in a Pierce‐Donachy VAD which pumped fresh bovine blood through a mock loop. Blood samples were analyzed for hemato‐crit and plasma hemoglobin, from which the indices of hemolysis were calculated. A one‐way analysis of variance indicated significant differences between certain valves. The MTD was the most hemolytic. No significant hemolytic difference was found between the trileaflet and monostrut valves despite their different designs. The monostrut valve and the MTD valve were hemolytically very different despite their similar design. This study suggests that the valve type significantly affects the hemolysis produced by the VAD.
Comparison of Hemodialysis versus Hemoperfusion in the Clearance of High‐Dose Methotrexate in Pigs
Authors: Giardino Roberto , Fini Milena , Giavaresi Gianluca , Spighi Massimo , Faenza Stefano , Florio Mario Leonardo , Orlandi Maurizio , Stefoni Sergio
Published: November 2008

Abstract: To evaluate the different capabilities of hemoperfusion (HP) and hemodialysis (HD) treatment in resolving the side effects during high‐dose methotrexate (MTX) therapy, an experimental comparative study was done. Under general anesthesia, 12 female Large‐White pigs, 35 ± 5 kg body weight, underwent a bilateral renal vessel ligature to create an acute renal failure and avoid the physiologic elimination of MTX. An MTX i.v. infusion was performed using a dose of 12.5 g/m2 and for a specific time according to its pharmacokinetics. The animals were divided into 2 groups of 6 animals each and connected to the extracorporeal circuit; the first group was submitted to a 1‐h HP with an anion exchange resin (Dow 1X‐2, Dow Chemical) and the second group to 1‐h HD with capillary polysulfone fibers (F6, Fresenius). Blood samples were taken at established intervals for he‐matological and biochemical evaluations. The results demonstrate a higher capability of HP treatment (p < 0.001) related to HD in MTX removal.
Is the Choice of Membrane Important for Patients with Acute Renal Failure Requiring Hemodialysis?
Authors: Kurtal Hanife , von Herrath Dietrich , Schaefer Klaus
Published: November 2008

Abstract: It has recently been reported that patients with acute renal failure requiring hemodialysis have an improved recovery of renal function and a higher survival rate when the dialysis treatments are performed with a biocompatible membrane rather than a bioincompatible membrane. Our data, obtained in 57 patients with acute renal failure, do not support these findings since neither the mortality nor the required number of dialysis sessions could be influenced by using a biocompatible membrane.

The survival rate was similar in both groups (64 versus 72%), and renal function was regained in both groups after 6 dialysis sessions. We conclude that when reviewing the literature as well as other factors, the underlying clinical condition or the skill of the physicians is probably more important than the theoretical superiority of biocompatible membranes.
Facing the Reality: The World Cannot Afford Uremia Therapy at the Start of the 21st Century
Authors: Friedman Eli A.
Published: November 2008

Abstract: Although remarkably successful in prolonging useful life, there is minimal probability that the majority of the world's population will benefit from contemporary therapy for irreversible renal failure because of its inordinately high cost in light of available resources. While affluent nations establish priorities for allocation of slots for maintenance dialysis or recipients of organ transplants, poor and developing countries must await the development of inexpensive, low technology treatments to substitute for absent kidney function. One attractive potential alternative to contemporary uremia therapy is the use of the intestine as a giant substitute and somewhat displaced nephron. Possible means of extracting wastes via the gut include ingestion of a mixed oral sorbent, instillation of bacterial crystallized enzymes to transform nitrogenous wastes to essential amino acids, or administration of high osmolality laxatives to promote diarrhea containing nitrogenous wastes. Any of these approaches may extract sufficient solute and water to sustain anephric life. An optimistic view of evolving uremia therapy is that within the next decade pills and purges for the poor may supplant more effective though expensive high technology approaches now encompassed in so‐called modern nephrology.
Modulation of Idiotypic and Antiidiotypic Immunoglobulin G Responses in an Immune Thrombocytopenic Purpura Patient as a Consequence of Extracorporeal Protein A Immunoadsorption
Authors: Balint Joseph P. , Cochran Sharon K. , Jones Frank R.
Published: November 2008

Abstract: Immune thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by the presence of antiplatelet antibody which sensitizes platelets resulting in their clearance by the reticuloendothelial system. Extracorporeal protein A immunoadsorption has been demonstrated to be of benefit in the treatment of this autoimmune disorder. In the present study, a patient with underlying systemic lupus erythematosus (SLE) presented with ITP. The patient received 14 immunoadsorption treatments and responded to therapy. During the course of immunoadsorption treatments, there was a decline in circulating immune complex (CIC) levels, antinu‐clear antibody (ANA) levels, and antiplatelet IgG antibody levels. In addition, elevated levels of antiidiotypic IgG antibody detected before initiation of therapy were significantly reduced during the course of immunoadsorption treatments. This study suggests that specific autoimmune idiotypic IgG antibody and corresponding antiidiotypic IgG antibody responses may be modulated in association with extracorporeal immunoadsorption employing protein A/silica columns.
Mammalian Erythrocytes as Physiological Carriers of Fluorescent Exogenous Agents: A Comparative Study of Bovine and Camel Red Blood Cells
Authors: El‐Alway Mohamed A. , Hamzah Riyad Y. , Abdel‐Kader Mahmoud M.
Published: November 2008

Abstract: Recently attention has been focused on the investigation of new and effective routes for drug administration in order to avoid their side effects in the human body. Red blood cells (RBCs) exhibit many advantages, i.e., they are naturally occurring, biodegradable, and non‐immunogenic. Their use as drug carriers has many potential applications, including slow drug delivery to the body tissue and drug targeting to a specific site. In this work, the fluorescent exogenous agent sodium fluorescein (ura‐nin) was used as the probe for the encapsulation of the RBCs. The encapsulation process was applied in two different mammalian RBCs: camel and bovine. The results indicate that the encapsulation efficiency of bovine RBCs was 34.0 ± 3.0% with an RBC recovery rate of ∼75% whereas that of camel RBCs was only 8.0 ± 2.0% with a cell recovery rate of ∼47%. These differences demonstrate the dependency of the encapsulation process on the type of mammalian source of the RBCs.
A Mathematical Model for Shear‐Induced Hemolysis
Authors: Yeleswarapu Krishna K. , Antaki James F. , Kameneva Marina V. , Rajagopal Kumbakonam R.
Published: November 2008

Abstract: The time‐varying history of stress exposure within a rotary blood pump makes it difficult to arrive at a quantifiable design criterion for predicting cell trauma‐tization. Constant stress experiments have revealed that there is a threshold stress level above which damage to blood cells occurs depending upon the time of exposure. The shear stress history experienced by cells within a rotary blood pump, however, is highly unsteady. In order to better predict cell trauma under these realistic conditions, a mathematical damage model based on a concept of “damage accumulation” has been developed. This model is evaluated within the context of red cell trauma. Experimental results support the hypothesis that the rate of damage accumulation increases nonlinearly with the stress level as well as the age of the cell.
Seal‐less Centrifugal Blood Pump with Magnetically Suspended Rotor: Rot‐a‐Flot
Authors: Mendler Nikolaus , Podechtl Franz , Feil Gerhard , Hiltmann Peter , Sebening Fritz
Published: November 2008

Abstract: Limitations of current centrifugal blood pumps are related to heat generation of bearings and leakage of seals, to dead water zones, and to poor efficiency. A new concept is proposed in this paper to ameliorate these problems based on a miniaturized magnetic drive, and a prototype is introduced. The pump rotor is suspended and driven by a radial permanent magnetic field that stabilizes the impeller in 4 of the 6 spatial degrees of freedom and allows it to be top‐spun on a single blood‐flushed pivot bearing with minimal load and friction. A shrouded impeller with an open center and 4 logarithmically curved channels is run inside a cone‐and‐plate‐type housing with a spiral volute chamber. In vitro testing was performed comparing this design with the BioMedicus, St. Jude, and Sarns pumps. The prototype is demonstrated to have the smallest internal volume (35 ml), surface (190 qcm), and passage time (0.5 s at 4 L/min), as well as the highest hydraulic efficiency (up to 0.4) of all devices studied.
Design of a Centrifugal Blood Pump with Magnetic Suspension
Authors: Yamane Takashi , Ikeda Tadashige , Orita Toyoki , Tsutsui Tatsuo , Jikuya Tomoaki
Published: November 2008

Abstract: A new concept blood pump, whose impeller is suspended by permanent magnets and a mechanical pivot without seals or ball bearings, is presented in this paper. The primary aim of the blood pump is an application to implantable artificial hearts. The prototype model is of a centrifugal type with a four‐vaned semiopen impeller 50 mm in diameter. Since this mechanism has no seals or ball bearings, flow stagnation or heat generation that might cause blood cell denaturation is expected to be small. The results of performance testing for the prototype model 2 were satisfactory regarding pump head and efficiency. The radial‐suspension magnets and the magnetic coupling were stable. As a result, the present mechanism has been verified to be a candidate applicable to implantable artificial hearts.
In Vitro Analysis of the Floating Mode Phenomenon in the Free Impeller Gyro Pump
Authors: Ohara Yasuhisa , Takatani Setsuo , Nosé Yukihiko
Published: November 2008

Abstract: The Free Impeller Gyro Pump was designed based on a new concept of free impeller, in which the rotational shaft and the mechanical bearings were completely eliminated from the impeller. Due to this characteristic design, a phenomenon occurred in which the impeller lifted off the bottom of the pump housing in a certain range of pumping conditions during the initial in vitro studies (floating mode). We studied this floating mode in detail using a Hall effect position sensor to monitor the impeller position. A Hall sensor signal recorded on the strip chart, which represents the distance between the impeller top and the pump ceiling, proved the existence of the floating mode. By analyzing the data in detail, it was also verified that the floating mode was composed of three subdivided phases: latent, transitional, and dominant. Furthermore, stability of the impeller rotation in the floating mode against the change of pump orientation was also exhibited in this study. These results suggests that the Free Impeller Gyro Pump should possess high antithrombogenicity, atraumatic features, no bearing wear, and stable performance when operated within the range of the floating mode.
Totally Implantable Ventricular Assist System Using a Vibrating Flow Pump
Authors: Nitta Shin‐ichi , Yambe Tomoyuki , Sonobe Taro , Naganuma Shigeru , Kakinuma Yoshito , Kobayashi Shin‐ichi , Tanaka Motonao , Matsuki Hidetoshi , Abe Ken‐ichi , Yoshizawa Makoto , Kasai Takeshi , Hashimoto Hiroyuki
Published: November 2008

Abstract: A totally implantable ventricular assist system (VAS), including a drive system and a percutaneous electric energy transmission system, was developed and evaluated in acute animal experiments using adult goats. This newly designed VAS mainly consists of a vibrating tube, coils, magnets, and a jelly‐fish valve as the outlet valve. For energy transmission, a new implantable transmitter with a plain weave structure was proposed as a noncon‐tacting transform by using the spinal amorphous magnetic fibers. The fluid mechanical and hemodynamic properties and the efficiency of the energy transmission system were evaluated in acute animal experiments using healthy adult goats. This vibrating electromagnetic artificial heart (AH) could generate more than 10 L/min as output volume, with 10 Hz vibration using 20 volts as supplied voltage. The total efficiency of the percutaneous energy transmission system was 76%, and temperature increases were within the acceptable range, suggesting the usefulness of our newly developed implantable VAS.
In Vitro Evaluation of a Pulsatile Assist Device for a Centrifugal Pump Using a New Principle
Authors: Iwaya Fumio , Igari Tsuguo , Hoshino Schunichi , Hikichi Hitoshi
Published: November 2008

Abstract: To induce a pulsatile flow in a centrifugal pump, we developed a new device (pulsatile assist device for centrifugal pump: PADCP) using a new concept. This device consists of a flexible polyurethane tube with an air chamber which is connected to the arterial side of the centrifugal pump circuit directly. A mock circulation system was used for evaluation of this PADCP. Thirty to 40 mm Hg of pulse pressure was obtained under 3–6 L/min of flow rate. By increasing the driving pressure of the PADCP from 200 to 600 mm Hg in a mock system, 4–48 mm Hg of pulse pressure was gained accompanied by a decrease in pump flow and increased left atrial pressure. The decreased pump flow and increased left atrial pressure were recovered easily by increasing the flow rate of the centrifugal pump. Pressures at the proximal site of the PADCP were less than 500 mm Hg. The PADCP was useful to induce a pulsatile flow in a centrifugal pump.
A Clinical Monitoring System for Centrifugal Blood Pumps
Authors: Holzer Stefan , Scherer Reinhard , Schmidt Christian , Schwendenwein Ilse , Wieselthaler Georg , Noisser Robert , Schima Heinrich
Published: November 2008

Abstract: In clinical application of rotary blood pumps, flow obstruction as a result of suction of the inflow can‐nula, kinking of tubing, or thrombus formation occurs quite frequently. Early detection of such problems is essential to avoid hemolysis, tissue degradation, or release of thrombi to the patient. A program was developed for automatic observation of pump performance, tubing resistance, and suction effects, which requires only the measurement of already available parameters (i.e., pump speed, pump flow, aortic pressure). The software is based on Visual‐C and provides a user surface formatted in Windows. Pump flow, its time derivate, and the relationship between the pulsatile component and the mean graft flow are observed to detect suction in the left atrium.

Furthermore, the generated pressure head is predicted from pump speed, graft flow, and the resistance of tubing/ cannula and compared with the actually measured aortic pressure. An alarm sounds if a given limit between prediction and measurement is exceeded. In a mock circulation, suction events were detected in more than 95% with a mean deviation of actual aortic pressure from its predicted value of less than 5%. For in vivo application, even incomplete suction could be detected reliably in more than 90% of events. This system improves and standardizes monitoring of pump performance; it should therefore lead to greater safety during application of such devices.
Fractal Dimension Analysis of the Oscillated Blood Flow with a Vibrating Flow Pump
Authors: Yambe Tomoyuki , Sonobe Taro , Naganuma Shigeru , Kobayashi Shin‐ichi , Nanka Shunsuke , Akiho Hiroshi , Kakinuma Yoshito , Mitsuoka Mikio , Chiba Shigeki , Ohsawa Noboru , Haga Youichi , Idutsu Kenji , Nitta Shin‐ichi , Fukuju Takeo , Miura Makoto , Uchida Naoki , Sato Naoshi , Tabayashi Kouichi , Tanaka Akira , Yoshizumi Naohiko , Abe Kenichi , Takayasu Misako , Takayasu Hideki , Yoshizawa Makoto , Maekawa Toshihiro , Hashimoto Hiroyuki
Published: November 2008

Abstract: To analyze the hemodynamic parameters during circulation with oscillated blood flow, nonlinear mathematical analyzing techniques, including fractal theory, were utilized. Vibrating flow pumps (VFP) were implanted as a left heart bypass, and the ascending aorta was clamped to constitute the total left heart circulation with oscillated blood flow in acute animal experiments using 7 adult goats. Using nonlinear mathematical analyzing techniques, reconstructed attractors of the arterial blood pressure waveform in the phase space during natural circulation and oscillated circulation were analyzed.

Using the Grassberger‐Procaccia correlation dimension analyzing technique, fractal dimension analysis of the reconstructed attractor was performed. During VFP bypass, lower fractal dimensions of the reconstructed attractor were shown compared with those during natural heart circulation. The results suggest that lower dimensional chaotic dynamics contributed to the circulation with oscillated blood flow.