bluuebunny/crossref_metadata_2025 huggingface dataset:
A Miniaturized Centrifugal Pump for Assist Circulation
Authors: Taguchi Shinichi , Yozu Ryohei , Mori Atsuo , Aizawa Takeshi , Kawada Shiaki
Published: November 2008

Abstract: The newly developed Nikkiso HMS–15 is a miniaturized centrifugal pump. It has an impeller diameter of only 50 mm and a priming volume of only 25 ml. A totally new approach was applied to develop this very small pump. The new pump showed comparable hemolysis with pumps twice as big (e. g., the most widely used coneshaped centrifugal pump [index of hemolysis, 0. 005]). This finding refutes the belief that the pump diameter must be sufficiently large in size. Clinical application for cardiac assist was performed for 48 h without any thrombus formation despite low heparin dosage. Also, the pump showed quite favorable blood trauma when applied as a pump for cardiopulmonary bypass during open heart surgery. The compactness, the high controllability, and the system versatility proved to be very effective for clinical application. This pump is considered very reliable for its highly optimized design.
Less Platelet Damage in the Curved Vane Centrifugal Pump: A Comparative Study with the Roller Pump in Open Heart Surgery
Authors: Nishinaka Tomohiro , Nishida Hiroshi , Endo Masahiro , Koyanagi Hitoshi
Published: November 2008

Abstract: The centrifugal pump with the curved vane (Lifestream Centrifugal Pump [LCP]) was applied to cardiopulmonary bypass (CPB) in 10 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin levels, platelet counts, and serum β–thromboglogulin (β–TG) levels were measured during CPB. The results were compared with those for a comparative roller pump (RP) group (n = 10). There was no difference in CPB time between LCP (112 ± 22 min) and RP (121 ± 22 min) groups. Serum β–TG levels (ng/ml) were lower in the LCP group than in the RP group (34 ± 9 vs. 101 ± 80, 5 min; 81 ± 33 vs. 236 ± 112, 30 min; 120 ± 53 vs. 314 ± 100, 60 min after initiation of CPB; p < 0. 05). There were no significant differences in hemolysis and platelet depletion. The LCP showed excellent hemodynamic performance with less blood trauma in clinical application to open heart surgery.
Vascular Prosthese s for Aortocoronary Bypass Grafting: A Review
Authors: Tomizawa Yasuko
Published: November 2008

Abstract: Alternative conduits must be chosen when autologous grafts are not available for coronary artery bypass grafting (CABG). Viable grafts do not always have perfect characteristics for CABG, and homologous venous conduits have been used with unsatisfactory results. Many small caliber vascular grafts used for coronary bypass conduits have been developed in the past, but most of them have failed except in rare instances. In this paper the current problems in available conduits, new technologies for improvement, animal models, and possibilities for the future for CABG conduits are discussed.
Use of a Phosphorus‐Enriched Dialysis Solution to Hemodialyze a Patient with Lithium Intoxication
Authors: Zabaneh R.I. , Ejaz A.A. , Khan A.A. , Nawab Z.M. , Leehey D.J. , Ing T.S.
Published: November 2008

Abstract: A normophosphatemic patient suffering from lithium intoxication was hemodialyzed with a phosphorus‐enriched, bicarbonate‐based dialysis solution. A post‐dialysis fall in plasma phosphorus level was prevented.
Ultrafiltration and Backfiltration during Hemodialysis
Authors: Ofsthun Norma J. , Leypoldt John K.
Published: November 2008

Abstract: Ultrafiltration is the pressure‐driven process by which hemodialysis removes excess fluid from renal failure patients. Despite substantial improvements in hemodialysis technology, three significant problems related to ultrafiltration remain: ultrafiltration volume control, ultrafiltration rate control, and backfiltration. Ultrafiltration volume control is complicated by the effects of plasma protein adsorption, hematocrit, and coagulation parameters on membrane performance. Furthermore, previously developed equations relating the ultrafiltration rate and the transmembrane pressure are not applicable to high‐flux dialyzers, high blood flow rates, and erythropoietin therapy. Regulation of the ultrafiltration rate to avoid hypotension, cramps and other intradialytic complications is complicated by inaccurate estimates of dry weight and patient‐to‐patient differences in vascular refilling rates. Continuous monitoring of circulating blood volume during hemodialysis may enable a better understanding of the role of blood volume in triggering intradialytic symptoms and allow determination of optimal ultrafiltration rate profiles for hemodialysis. Backfiltration can occur as a direct result of ultrafiltration control and results in transport of bacterial products from dialysate to blood. By examining these problems from an engineering perspective, the authors hope to clarify what can and cannot be prevented by understanding and manipulating the fluid dynamics of ultrafiltration.
The Influence of the Dialysate Flow Rate on Hollow Fiber Hemodialyzer Performance
Authors: Allen Richard , Frost Thomas Herbert , Hoenich Nicholas Andrew
Published: November 2008

Abstract:The clearance characteristics of two sizes of hemodialyzers (0.9 m2and 1.5 m2) from the same range of products have been studied over the dialysate flow range of 500–3,000 ml/min to establish the device's overall mass transfer resistance characteristics. The results obtained demonstrate a difference in the overall mass transfer resistance which is most marked at the commonly used dialysate flow rate of 500 ml/min. This difference suggests that the increase in size results in the introduction of flow imperfections which reduces the benefit that might be gained by the use of a larger surface area. Results established indicate a reduction in the overall mass transfer resistance with an increasing dialysate flow rate. This reduction is attributed to the presence of turbulence in the dialysate pathway at higher flow rates. The presence of such turbulence was confirmed by visual inspection of the dialyzer after the completion of the study when it was noted that the original well‐ordered configuration present in a new dialyzer had been substantially disturbed. Correlation of the dialysate flow rate with overall mass transfer resistance by the use of a Wilson plots indicates a nonlinear relationship. This nonlinearity is attributed to a nonfully developed turbulent flow profile in the dialysate pathway
Molecular Basis for the Management of Secondary Hyperparathyroidism in Chronic Renal Failure
Authors: Fukagawa Masafumi , Yi Hung , Fukuda Naoko , Kurokawa Kiyoshi
Published: November 2008

Abstract: Recent clinical and experimental data suggest that the resistance of parathyroid cells to the physiological concentration of calcitriol plays an important role in the pathogenesis and the progression of secondary hyperparathyroidism in chronic renal failure. This resistance is due to the decreased density of the calcitriol receptor in parathyroid cells, which may result from impaired up‐regulation of calcitriol receptor. Since patients with larger parathyroid glands were more resistance to calcitriol pulse therapy than those with smaller glands and calcitriol receptor density inversely correlated with gland weight, the size of the parathyroid gland may serve as a marker for the degree of resistance to calcitriol. Furthermore, the possible role of phosphorus in the control of parathyroid function has been suggested recently. Thus, it is most important to prevent the progression of parathyroid hyperplasia in chronic renal failure by the early use of active vitamin D, calcitriol pulse therapy, and dietary phosphorus restriction.
Prevention of Restenosis after Coronary Angioplasty with Low‐Density Lipoprotein Apheresis
Authors: Adachi Hiromasa , Niwa Akihiro , Shinoda Toshio
Published: November 2008

Abstract: A prospective study was performed to determine whether low‐density lipoprotein (LDL) apheresis, when performed only immediately before and after percutaneous transluminal coronary angioplasty (PTCA), is effective in preventing restenosis of coronary artery lesions following PTCA. Thirty‐six patients with coronary heart disease (CHD) and hypercholesterolemia were divided into 2 groups. The 9 patients in the LDL group underwent LDL‐apheresis 1 day before and 5 days after PTCA while the 27 patients of the control group underwent PTCA but did not undergo LDL‐apheresis. Follow‐up coronary angiography (CAG) was performed 4 months after PTCA. The rate of restenosis of coronary artery lesions was significantly lower in the LDL group (0%) than in the control group (30%). These findings suggest that LDL‐apheresis, when performed before and after PTCA, is effective in preventing restenosis of coronary artery lesions in patients with CHD and hypercholesterolemia.
Lack of a Fast‐Acting Effect of Erythropoietin on Arterial Blood Pressure and Endothelin Level
Authors: Hon George , Vaziri N.D. , Kaupke Charles J. , Tehranzadeh A. , Barton Cyril
Published: November 2008

Abstract: Recombinant erythropoietin (EPO) has been shown to induce vascular smooth muscle contraction in vitro suggesting a rapid acting pressor effect. In addition its chronic administration has been shown to raise plasma endothelin. This study was designed to explore the presence, if any, of fast‐acting effects of EPO on the arterial blood pressure and endothelin level in vivo. Nine stable patients with end‐stage renal disease (ESRD) were included in a double‐blind, crossover, placebo‐controlled study using IV bolus injections of either EPO or saline solution administered to patients while they were comfortably seated in reclining chairs and undisturbed in individual climate‐controlled rooms. After a 15‐min resting period, the bolus injection was given, and blood pressure (BP) and heart rate were measured and recorded automatically every 5 min for 60 min using an electronic device to avoid operator bias/error. In addition, blood samples were obtained for plasma endothelin determination at time 0 and at 5, 30, and 60 min after injection. Patients were studied approximately 2 h before their regularly scheduled dialysis session. The EPO dosage given (50–60 U/kg) was equal to the maintenance dose, routinely administered during dialysis. No significant change was observed in arterial BP, heart rate, or plasma endothelin concentration relative to the baseline values after either EPO or placebo administration. Thus, the results have excluded a rapid effect on BP, heart rate, and endothelin concentration of EPO at therapeutic doses which, when chronically administered, can clearly raise arterial blood pressure in ESRD patients.
An Artificial Neural System for Closed Loop Control of Locomotion Produced via Neuromuscular Electrical Stimulation
Authors: Sepulveda Francisco , Cliquet Alberto
Published: November 2008

Abstract: The use of neuromuscular electrical stimulation for restoration of gait in spinal cord injured subjects has been seriously pursued by many investigators for the past 15 years. By and large, however, systems to date require the intervention of a person, be it the patient or an observer, and are restricted to control of stimulation onset and termination. Further, existing systems are not adaptable to environmental and patient variations. This work proposes a system that relies on neural computing to determine proper muscle activation patterns from biome‐chanical signals. The intelligent system is trained to perform gait under supervision, after which it can be used to control muscle stimulation in an unknown environment.

Computer simulations suggest that the best neural architecture for control of gait is a neural network including units corresponding to movement history. Separate networks for the stance and swing phases, respectively, were found to work better than a single neural network trained on the entire gait cycle. The artificial neural device proposed here also includes a voice recognition system that will allow for voluntary locomotion. A safety circuit has been designed to preclude acceptance of unwanted vocal commands in the latter system.
Environmental Transmission of Hepatitis B and Hepatitis C Viruses Within the Hemodialysis Unit
Authors: Neto Miguel Cendoroglo , Manzano Sandra Ivelize Rodrigues , Canziani Maria Eugenia , Silva Antonio Eduardo Benedito , Cirenza Maria Lúcia Ferraz , Sesso Ricardo de Cintra , Ajzen Horácio , Draibe Sérgio Antonio
Published: November 2008

Abstract: The hepatitis B virus (HBV) can be transmitted in the dialysis setting through blood transfusions and environmental surfaces. Transfusion related hepatitis C virus (HCV) infection is very well known, but only recently the environmental transmission of this virus was postulated. In order to study the prevalence, mechanisms of transmission, and the ALT patterns of HBV and HCV infections in hemodialysis and CAPD patients before the implementation of HBV vaccination and HCV screening in the blood bank, we conducted a study from January 1987 to January 1990. Sera from 185 hemodialysis and 124 CAPD patients were stored in this period and later analyzed for HBsAg, anti‐HBc, anti‐HBs, and anti‐HCV (second generation ELISA). The prevalence of any HBV marker was 55.7% (103/185) for hemodialysis patients and 31.5% (39/124) for CAPD patients (hemodialysis vs. CAPD, p < 0.001). The prevalence of positive anti‐HCV was 35.1% (65/185) for hemodialysis and 33.9% (42/124) for CAPD patients (not significant). There was a significant association between HBV markers positivity and anti‐HCV positivity. The multivariate analysis of risk factors revealed an association of the positivity of each virus with the duration of renal replacement therapy (RRT), number of previous blood transfusions, and past history of hemodialysis treatment. Thus, besides the transfusion‐related transmission, hemodialysis environmental transmission may also occur for both viruses. The findings of a high prevalence of both viruses and evidence for environmental transmission in the dialysis setting are of major importance for the planning of future preventive measures.
The Effect of Total Blood Exchange with PHP Solution on Cardiac Xenotransplantation
Authors: Liu Hui , Agishi Tetsuzo , Suga Hideiku , Hayasaka Yutaro , Teraoka Satoshi , Ota Kazuo
Published: November 2008

Abstract: Prevention of hyperacute rejection is a difficult and unsolved problem in xenotransplantation. Natural antibodies and complement activation have been known to play an important role in the xenotransplantation between discordant species pairs. In the present study, total blood exchange (TBE) was performed with pyridox‐alated‐hemoglobin‐polyoxyethylene conjugate (PHP) solution (Ajinomoto Co., Inc., Kawasaki, Japan) before cardiac xenotransplantation in order to remove the immunoglobulins and prolong xenograft survival time. Guinea pigs and rats were used as the discordant species combination for donor and recipient. Two groups were established: Group 1, untreated control (n = 8) and Group 2, TBT with PHP solution (n = 8). The exchange blood transfusion was carried out at the rate of 15–20 ml/h utilizing PHP solution using a blood pump. After the blood exchange was processed, hematocrit (Ht) levels dropped to 4 or 5%, and a cardiac xenotransplantation was performed within 24 h. The levels of serum IgA, IgM, and IgG were decreased to less than 25, 25, and 10% of the base line, respectively, after blood exchange. A mean xenograft survival time in Group 2 was prolonged to 472 ± 74 min and to 10.4 ± 1.8 min in Group 1 (p < 0.01). A titer of the anti‐guinea pig lymphocytotoxic antibody in rat serum was decreased to almost nil. The data from this study suggest that total blood exchange with PHP solution may be useful in preoperative removal of xenograft antibodies in xenotransplantation.
In Vivo Studies of Pulsatile Implantable Impeller Assist and Total Hearts
Authors: Qian K.X. , Wang S.S. , Cuh S.H.
Published: November 2008

Abstract: A pulsatile impeller assist heart and a total heart were tested as a chronic left ventricular assist device in 5 calves and an acute biventricular assist device in 4 pigs respectively, to evaluate their blood compatibility. During the left ventricular assist experiments, the indicators for hemolysis, thrombogenesis, renal dysfunction, and hepatic dysfunction were measured preoperatively, at the beginning of the pumping, 6 h postoperatively, and every following day. The results demonstrated that the impeller assist heart causes no severe blood damage nor organ dysfunction in the experiments lasting up to 11 days. In biventricular assist experiments, the number of red blood cells, white blood cells, platelets, and the he‐matocrit, hemoglobin, free hemoglobin, and lactate dehy‐drogenase levels were tested preoperatively at the beginning of the pumping and every 2 h postoperatively. The data remained in acceptable ranges during experiments lasting 6 h. It is confirmed that the authors' impeller assist heart and total heart have the advantages of simplicity, implantability, and pulsatility with good blood compatibility.
Fuzzy Control Concept for a Total Artificial Heart
Authors: Kaufmann Ralf , Becker Kurt , Nix Christoph , Reul Helmut , Rau Günter
Published: November 2008

Abstract: The development of an electromechanically driven total artificial heart (Helmholtz‐TAH) was initiated in 1990. Anatomical fitting, biocompatibility, and automatic physiologic adaptation of pump output are the basic requirements that characterize the overall TAH concept. For evaluation of these features, a TAH labtype was developed. It provides most features of the conceptual artificial heart and supports in vitro testing of energy conversion, pump behavior, structural parts, sensors, and control concepts. A fuzzy controller has been implemented for adaptation of the pump rate to body perfusion demand by left pump chamber filling detection. This controller will be an important element of a future extensive TAH control system. The implementation is supported by a professional fuzzy control development tool that allows on‐line and real time optimization of control strategies for dynamic processes. The first experiments proved the feasibility and the advantages of this fuzzy control concept. The first in vitro test results are presented.
Protein Adsorption by Artificial Membrane Materials Under Filtration Conditions
Authors: Birk Horst‐Walter , Kistner Andrea , Wizemann Volker , Schütterle Georg
Published: November 2008

Abstract: Elevated plasma levels of numerous low molecular weight proteins (LMWP) in renal insufficiency are likely to contribute to the uremic syndrome. Dialysis‐related amyloidosis, caused by the accumulation of β2‐microglobulin (β2M), has highlighted the need for a renal replacement therapy that allows the elimination of LMWP in addition to small solutes. Synthetic membrane materials employed under hemofiltration conditions proved to be most effective in lowering elevated β2M plasma levels. In addition to convection, protein adsorption to artificial membrane materials is an important mechanism for β2M removal. Using an in vitro setup, 12 commercially available hemofilters representing 11 different membrane materials were perfused with human blood containing 125I‐labeled plasma proteins. Under filtration conditions, total protein adsorption ranged from 338–2,098 mg/m2 of membrane surface, and the fraction of adsorbed LMWP varied between 14–70% of total protein adsorption and was negatively correlated to total protein adsorption. β2M adsorption showed up to an 8‐fold difference between membranes, and was negatively correlated with total protein adsorption and positively correlated with the adsorption of LMWPs.
Selenium in Uremia
Authors: Bonomini Mario , Albertazzi Alberto
Published: November 2008

Abstract: The importance of selenium as an essential trace element for man has been increasingly recognized during the last several years. Selenium deficiency has been associated with cases of congestive cardiomyopa‐thy, skeletal myopathy, anemia, enhanced cancer risk, elevated incidence of cardiovascular disease, immune system alterations, hair and nail changes, and abnormalities in thyroid hormone metabolism. These symptoms are frequently present in chronic uremic patients. Nevertheless, the prevalence and significance of selenium deficiency in the uremic syndrome is still not clearly defined. This article reviews the selenium status in chronic uremic patients, the supposed pathogenetic mechanisms of selenium disturbance in uremia, and the possible role of selenium deficiency on some uremic abnormalities.
“Intelligent” Polymers in Medicine and Biotechnology
Authors: Hoffman Allan S.
Published: November 2008

Abstract: One can define “intelligent” polymers as those polymers that respond with large property changes to small physical or chemical stimuli. These polymers may be in various forms, such as in solution, on surfaces, or as solids. One may also combine intelligent aqueous polymer systems with biomolecules to yield a large family of polymers that respond intelligently to physical, chemical, or biological stimuli. This article overviews such interesting and versatile polymer systems.
Extracorporeal Circulation with Autogenous Oxygenation: Hemodynamic and Gasometric Parameters
Authors: Marques Euclydes , Oshiro Milton S. , Cestari Idágene A. , Hayashida Sérgio A. , Leirner Adolfo A.
Published: November 2008

Abstract: Ten experimental perfusions with autogenous oxygenation were performed in mongrel dogs to evaluate the efficacy of the procedure in maintaining normal hemodynamic conditions and adequate blood gases for 1 h. Blood was drained from the right and left atria and pumped to the pulmonary artery and aorta, respectively. Two closed circuits containing compliant chambers and roller pumps were utilized. Artificial ventilation with an Fio2 of 50% were used in 5 animals and with an Fio2 level of 30% in the other 5. EKG, cardiac output, aortic, pulmonary artery, and left atrium pressures were registered. Pulmonary tissue was biopsied after perfusion. The heart was electrically fibrillated after perfusion was established and defibrillated at the end of the bypass. The procedure was able to maintain blood gases and pulmonary, aortic, and left atrial pressures within normal ranges during the perfusion. The mobility of the heart and the access to all coronary arteries was excellent. Clinical central nervous system evaluation, EKG tracings, and pulmonary histo‐logical exams showed no adverse effects of perfusion. We conclude that the technique employed may present a suitable proceeding for extracorporeal circulation in closed heart surgeries, and its clinical application should be evaluated as a safe and economical alternative.
Influence of the Compliance of the Pump Housing and Cannulas of a Paracorporeal Pneumatic Ventricular Assist Device on Transient Pressure Characteristics
Authors: Ogino Hitoshi , Klangsuk Nongchana , Jin Wu , Bowles Christopher T. , Yacoub Magdi H.
Published: November 2008

Abstract: The dependence of transient pressure characteristics of a ventricular assist device (VAD) on the compliance of its housing and cannulas was investigated in a mock circulation. The peak rate of change of pressure (dP/dtmax) values was greater in the cannulas than other compartments and was associated with valve closure‐induced pressure oscillations. When cannula compliance was increased from 0.0057 to 0.0129 cm3/mm Hg, these values decreased by ˜20%, and outflow cannula pressure oscillation frequency decreased from 17.5 Hz by 35%. This trend was also apparent in the inflow. A VAD housing compliance increase from 0.0162 to 0.0483 cm3/mm Hg caused a dP/dtmax decrease of 30% in both the blood chamber and the outflow cannula. The effect of this change on the inflow was weaker implying that housing absorbs the energy associated with outflow deceleration more effectively than the inflow. These findings suggest that increasing VAD housing and cannulas compliance can improve hydrodynamic performance.
System Considerations Favoring Rotary Artificial Hearts with Blood‐Immersed Bearings
Authors: Jarvik Robert K.
Published: November 2008

Abstract: Hydrodynamic blood pumps provide such advantages as not requiring an air vent or compliance chamber as well as a great reduction in mechanical complexity with the potential for very long durability. The detailed design of their bearings is emerging as the single most important determinant of long‐term success. Three categories of bearings include remote force, such as magnetic suspension; blood‐isolated, which require a shaft seal; and blood‐immersed using either mechanical or hydrodynamic support. Blood‐immersed bearings permit maximum simplification and miniaturization of the entire system, require no flush fluid, and require no electronics as with magnetic suspension. The Jarvik 2000* heart represents an example of their potential. The intraventricular titanium pump (25 mm diameter, 25 cc, 85 g), uses blood flow through the motor air gap with blood‐immersed bearings. The longest in vitro bearing durability test is ongoing at 20,000,000,000 revolutions with minimal wear (3 years at 15,000 rpm). In vivo results include 5‐month calf survival, no thromboembolism, plasma Hb 2–5 mg%, and power under 10 W. Key Words: Artificial hearts— Blood‐immersed bearings—Rotary blood pumps—Axial flow pumps—Left‐ventricular assist devices.
Fluid Mechanics of the Stagnation Point Flow Chamber and Its Platelet Deposition
Authors: Affeld K. , Reininger A.J. , Gadischke J. , Grunert K. , Schmidt S. , Thiele F.
Published: November 2008

Abstract: The interaction of flow and thrombus generation often is a crucial question for the engineer working in the field of artificial organs. However, this interaction is only incompletely known, and quantitative data under well‐defined experimental conditions are especially rare. These can be attained with the stagnation point flow chamber. This flow model applies platelet‐rich plasma (PRP) as fluid. Its flow conditions are assessed with the help of computational fluid mechanics. In addition, the concept of the boundary layer is introduced, which permits assessment of the platelet flow along the wall. The results of the experiment indicate that platelets are deposited at a defined shear rate.
Concept, Realization, and First In Vitro Testing of an Intraarterial Microaxial Blood Pump
Authors: Sieß Thorsten , Reul Helmut , Rau Günter
Published: November 2008

Abstract: Intravascular operating microaxial pumps have been clinically introduced (Hemopump 21; Hemopump 14) and have proven to be useful tools for cardiac assist. Due to device‐related complications that are associated with the drive concept of an extracorporeal motor and a flexible drive shaft cable, a new pump concept is presented and has been refined in the development process. The cable is replaced by a proximally attached drive unit and an extracorporeal power supply. In addition to ongoing hydrodynamic studies of the flow inside the pump and improvements of the overall hydraulic performance, a microelectric motor was realized and integrated. In vitro tests revealed the feasibility of such a concept.
Development of an Axial Flow Ventricular Assist Device: In Vitro and In Vivo Evaluation
Authors: Mizuguchi Kazumi , Damm George , Benkowsky Robert , Aber Greg , Bacak Jim , Svjkovsky Paul , Glueck Julie , Takatani Setsuo , Nosé Yukihiko , Noon George P. , DeBakey Michael E.
Published: November 2008

Abstract: A collaborative effort between Baylor College of Medicine and NASA/Johnson Space Center is underway to develop an axial flow ventricular assist device (VAD). We evaluated inducer/impeller component designs in a series of in vitro hemolysis tests. As a result of computational fluid dynamic analysis, a flow inducer was added to the front of the pump impeller. According to the surface pressure distribution, the flow inducer blades were connected to the impeller long blades. This modification eliminated high negative pressure areas at the leading edge of the impeller. Comparative studies were performed between inducer blade sections that flowed smoothly into the impeller blades (continuous blades) and those that formed discrete separate pumping sections (discontinuous blades). The inducer/impeller with continuous blades showed significantly (p < 0.003) lower hemolysis with a normalized index of hemolysis (NIH) of 0.018 ±< 0.007 g/100 L (n = 3), compared with the discontinuous model, which demonstrated an NIH of 0.050 ± 0.007 g/100 L (n = 3). The continuous blade model was evaluated in vivo for 2 days with no problems. One of the pumps evaluated ran for 5 days in vivo although thrombus formation was recognized on the flow straightener and the inducer/impeller. As a result of this study, the pump material was changed from polyether polyurethane to polycarbonate. The fabrication method was also changed to a computer numerically controlled (CNC) milling process with a final vapor polish. These changes resulted in an NIH of 0.0029 ± 0.0009 g/100 L (n = 4). which is a significant (p < .0001) value 6 times less than that of the previous model. This model was used for in vivo studies and achieved 9 days of operation with a sufficient flow between 3.6 and 4.7 L/min against 80 to 100 mm Hg mean arterial pressure. Plasma free hemoglobin levels remained at 2–3 mg/dl with a hematocrit of 20%.
Experimental Study of Physiological Advantages of Assist Circulation Using Oscillated Blood Flow
Authors: Kobayashi Shin‐ichi , Nitta Shin‐ichi , Yambe Tomoyuki , Naganuma Shigeru , Hashimoto Hiroyuki , Fukuju Takeo , Tabayashi Kouichi
Published: November 2008

Abstract: To estimate the effect of oscillated blood flow on hemodynamics in an awake condition, left ventricular assist circulation using oscillated blood flow was performed on 3 adult goats as chronic animal examination. A vibrating flow pump (VFP) was used for generating high‐frequency oscillated flow. The blood flow rate of assisted circulation was approximately 1.0 L/min, and the driving frequency of VFP was 25 Hz. Systemic vascular resistance and arterial impedance were calculated in this study. Systemic vascular resistance during assist circulation was decreased compared with that without assistance. Oscillated blood flow may be effective in decreasing vascular resistance. Moreover, it was suggested from the study of arterial impedance that motive characteristics of the vascular wall against changing blood pressure may keep their normal reaction. Therefore, oscillated blood flow may be used for left ventricular assist circulation as concluded from the study of the characteristics of blood vessels.
An Artificial Neural Network‐Based Noninvasive Detector for Suction and Left Atrium Pressure in the Control of Rotary Blood Pumps: An In Vitro Study
Authors: Stöcklmayer Christian , Dorffner Georg , Schmidt Christian , Schima Heinrich
Published: November 2008

Abstract: Rotary blood pumps are used in clinical applications to assist circulation via pumping blood from the left atrium to the aorta. Negative inflow pressures at high flow rates can cause suction of the cannula in the left atrium with deleterious effects on the atrial wall, the blood, and the lung. Therefore, stable and reliable detection of suction and the prediction of the left atrium pressure (LAP) would be of major interest for the control of these pumps. This work reports about an in vitro study of such a detector based on artificial neural networks (ANN). In the first project phase, an ANN was used to estimate the LAP based on pump speed, pump flow, and aortic pressure, obtained from a mock circulation. The inputs for the ANN were 11 characteristic values computed from these three parameters. In the second phase, another ANN was trained to classify various system states, such as suction, danger of suction (a state close to actual suction), and no suction. The first ANN was able to estimate the LAP with an accuracy of ±1.8 mm Hg. The discrimination of suction versus the other two states could be performed with a sensitivity and specificity of about 95% while the more interesting task of distinguishing danger of suction from no suction reached a sensitivity and specificity of about 65% (leaving 25% of each class unclassified and 10% of each class incorrectly classified). The results demonstrate the viability of ANN‐based detectors in supporting the control of rotary blood pumps. Improvements, still necessary for in vivo use of such a detector, will most likely come from extending the approach through spatiotemporal ANNs to account for dynamic state changes.
A Right Ventricular Hemopump Restores Right Ventricular Function with Pulmonary Artery Banding
Authors: Cooper G.J. , Abe Y. , Miyama M. , Deleuze P. , Loisance D.Y.
Published: November 2008

Abstract: We investigated the ability of the Hemopump to support the right ventricle during acute, partial, pulmonary artery obstruction. In 6 pigs, a 14 Fr size Hemopump was placed through the pulmonary artery into the right ventricle. Control measurements were made. A band around the pulmonary artery proximal to the outflow port of the Hemopump was tightened, and measurements were repeated with the Hemopump at minimum and then maximum speed. With banding, right ventricular stroke volume and output decreased (43 [SD,7] to 28 [SD,8] ml, p < 0.001; 4.9 [SD,0.8] to 3.7 [SD,1.0] L/min, p < 0.01 respectively), but they were restored with the Hemopump (38 [SD,5] ml and 4.5 [SD,0.6] L/min; both p = NS vs control). Increases in right ventricular peak systolic (28 [SD,10] to 42 [SD,17] mm Hg; p < 0.01) and end‐diastolic pressure (2 [SD,1] to 12 [SD,6] mm Hg; p < 0.02) were reversed by the Hemopump (29 [SD,8] and 4 [SD,2] mm Hg; both p = NS vs control). Right ventricular pressure rate product almost doubled with banding (3,199 [SD,1,252] to 5,962 [SD,2,796] mm Hg; p < 0.01), but it decreased with the Hemopump (3,368 [SD,767] mm Hg; p = NS vs control). With acute partial pulmonary artery banding, a right ventricular Hemopump restores output from and offloads the right ventricle.
BioMedicus Ventricular Assistance for Postcardiotomy Heart Failure: Evaluation of Univentricular Assistance
Authors: Perko Mario J. , Sander‐Jensen Kåre , Dehnke Charlotte , Pettersson Gösta
Published: November 2008

Abstract: Clinical outcome and hemodynamic effects of unilateral mechanical ventricular support (UMVS) were evaluated in 19 patients with postcardiotomy heart failure refractory to conventional treatment. Adequate circulation with UMVS was maintained in about 75% of the patients. UMVS initiated circulatory stabilization in 5 of 6 patients with biventricular failure, in 2 of 3 patients with right ventricular failure, and in 7 of 10 patients with left ventricular failure. Eight (42%) patients were successfully weaned from UMVS and discharged from hospital. Six (32%) patients died despite a prolonged, stabilized circulation by UMVS. In 5 (26%) patients, the UMVS could not secure stable circulation. Application of the left UMVS induced increases in cardiac output and systemic blood pressure and a decrease in left atrial pressure without changes in pre‐ and afterload of the right ventricle. It is concluded that application of UMVS may induce adequate circulation in patients with postcardiotomy heart failure refractory to treatment with inotropes and in‐traaortic counterpulsation. The outcome of UMVS in left, right, and biventricular failure is acceptable. Thus, this treatment may be recommended for patients with postcardiotomy heart failure.
Morbidity and Mortality in Hemodialysis: The Role of Schedules
Authors: Berland Y. , Brunet P.
Published: November 2008

Abstract: Hemodialysis is an efficient therapy for end‐stage renal failure. This treatment, however, must be used in an optimal fashion, i.e., with the best technology and the most adequate schedules. Unfortunately and especially for economic reasons, these basic therapeutic principles are often not respected. As a consequence, morbidity and mortality in maintenance hemodialysis patients have increased. This article underlines four points that could influence mortality in maintenance hemodialysis patients: nutrition, adequacy of hemodialysis, blood pressure control and treatment time.
Analysis of the Urea Generation Rate and the Protein Catabolic Rate in Hemodialyzed Patients
Authors: Lopot F. , Kotyk P. , Bláha J. , Válek A.
Published: November 2008

Abstract: The urea generation rate (G) and the protein catabolic rate (PCR) have been investigated in two groups of hemodialyzed patients over a whole week cycle, one with zero residual renal function (Kr= 0) dialyzed thrice weekly and the other dialyzed twice weekly with nonzero residual renal function. The two‐pool model of urea kinetics was used. No relationship between patients' age and the PCR was found, and also no difference in the PCR between males and females was seen. All patients with a PCR < 0.8 g/kg/day had a midweek predialysis plasma urea level well below 25 mmol/L, which clearly documents the value of a kinetic approach in early detection of patients at risk for malnutrition. In the thrice weekly dialyzed group, a statistically significant relationship was found between PCR and KT/V: PCR = 0.582 + 0.253 ×KT/V, r = 0.374 with p < 0.05. In the twice weekly dialyzed group with nonzero Kr, contribution of the residual renal function had to be included into KT/V to reach a level of statistical significance of PCR = 0.697 + 0.18 ×KT/V, r = 0.481 with p < 0.05. With regard to values of Kr encountered in the investigated group (0–3.5 ml/min), its influence upon PCR is higher than a volumetrically equal increase in excretorial efficacy of the artificial kidney. The G in the thrice weekly dialyzed group was found to be dependent on the length of the interdialytic interval over which it was evaluated. Over the intervals Friday‐Monday, Monday‐Wednesday, and Wednesday‐Friday the following mean values of G were obtained: 0.155, 0.180, and 0.188 mmol/min, respectively. This finding suggests a physiological link between urea generation and its excretion, possibly mediated via its concentration in body fluids. The time constant of this link is apparently quite short, on the order of hours or a few tens of hours. It also indicates that the metabolic status of a dialyzed patient may be influenced not only by the dialysis dose as defined by the KT/V value but also by the overall time schedule of treatment.
Nutritional Treatment of Hemodialysis and Peritoneal Dialysis Patients
Authors: Schmicker Richard
Published: November 2008

Abstract: The success of hemodialysis and peritoneal dialysis therapy is essentially dependent on adequate nutrition. Malnutrition represents one of the main factors in morbidity and mortality of dialysis patients. The main causes of malnutrition are insufficient energy intake, insufficient protein supply, loss of amino acids by dialysis, the uremic state of metabolism, catabolic stress of underlying diseases, and endocrinological disorders. For successful long‐term chronic dialysis therapy, it is very important that patients be in an anabolic nutritional state when entering the dialysis program. In this paper, the nutritional needs of dialysis and peritoneal dialysis patients (fluid restriction, protein intake, energy supply, electrolyte balance, vitamin intake) are discussed to prevent the catabolic state.
Blood‐Contacting Biomaterials: Bioengineering Viewpoints
Authors: Courtney James M. , Lamba Nina M.K. , Gaylor John D.S. , Ryan Calvin J. , Lowe Gordon D.O.
Published: November 2008

Abstract: The investigation of blood‐contacting biomaterials is an important challenge and is relevant for an improvement in the clinical application of biomaterials. With the purpose of improved clinical treatment, bioengineering viewpoints of blood‐contacting biomaterials cover the material options and selection, the utilization of materials, the development of materials with better properties and processing characteristics, and the design of relevant evaluation procedures. The bioengineering objective remains that of achieving an enhanced understanding of the relationship between a biomaterial and the biological response.
The Effects of Endotoxin–Contaminated Dialysate and Polysulfone or Cellulosic Membranes on the Release of TNFα during Simulated Dialysis
Authors: Arduino Matthew J. , Bland Lee A. , McAllister Sigrid K. , Favero Martin S.
Published: November 2008

Abstract: Simulated dialysis of whole blood was used to determine whether membrane factors (biocompatibility), endotoxin (ET) membrane diffusion, or transmembrane monocyte–ET interactions would stimulate tumor necrosis factor (TNFα) release. Whole blood containing EDTA and aprotinin was recirculated in the blood compartment of hollow fiber dialyzers containing either regenerated cellulose or polysulfone membranes. ET–free and ET–spiked dialysate were recirculated consecutively in the dialysate compartment for 30 min each. Blood and dialysate samples were collected at to and after each 30 min of simulated dialysis for determination of TNFa and ET concentrations. TNFa was not detected in any blood samples collected after simulated dialysis with regenerated cellulose (RC) membranes and ET–free or ET–spiked dialysate. However, blood ET concentrations, as determined by the Limulus amebocyte lysate (LAL) assay, increased in RC dialyzers after each 30 min of simulated dialysis even with ET–free dialysate. Since TNFa was not detected in these blood samples, the material detected by the LAL assay probably was not ET but an LAL–reactive material. After simulated dialysis with polysulfone dialyzers and ET–free dialysate, TNFa and ET were not detected in blood samples. ET also was not detected in blood samples after dialysis with ET–spiked dialysate. However, TNFa was detected in 7 of 13 (54%) of the blood samples following the 500 ng/ml of ET dialysate spike. TNFα release during simulated dialysis with polysulfone membranes and ET–contaminated dialysate may be due to transmembrane stimulation of circulating mononuclear cells and not diffusion of ET across the membrane.
Evaluation of Tilting Disc Valves after Fatigue Life Testing: Preliminary Results within a Comparison Program
Authors: Barbaro Vincenzo , Boccanera Giovanni , Daniele Carla , Grigioni Mauro , Palombo Alessandro
Published: November 2008

Abstract: A fatigue life test, by accelerating the beat rate, simulates several years of virtual life of a prosthetic heart valve in a short period of time. The correlation between the in vivo life of a valve and in vitro testing expectations is as yet not well established, but reproducible test conditions yield precious information about wear and failure. The paper reports a qualitative analysis of mechanical valve wear as part of a comparison program designed to investigate the significance of fatigue testing with the ultimate aim of defining standard guidelines for these type of tests. Two tilting disc valves (29 mm) were subjected to 16 years of fatigue life simulated by means of a Rowan Ash fatigue tester (accelerated rate of 1, 200 bpm). Fatigue–induced effects on valve disc and ring surfaces were observed under a monitor microscope to identify wear sites and patterns. A high speed cinematographic system was used to investigate the mechanisms responsible for the wear (wear modes). Valve closure was inspected at a 6, 000 frame/s rate. Because of disc rotation during the tilting movement, the points of contact between disc and ring are distributed all around the disc edge but focally on the ring. On both sides of the disc, the surfaces present ring–like concentric grooves. After 16 years of fatigue life the valves showed neither severe wear nor alteration of their fluidodynamic behavior in the pulsatile flow test.
Pulsed Doppler Sonography for the Guidance of Vein Puncture: A Prospective Study
Authors: Branger Bernard , Dauzat Michel , Zabadani Bachir , Vécina Frédérique , Lefranc Jean‐Yves
Published: November 2008

Abstract: Blind deep venous puncture is an invasive procedure with risks of serious complications compromising the availability of veins for future punctures or endangering the patient's life. We designed a new hand–held pulsed Doppler probe for coaxial guidance of the puncture needle and a dedicated pulsed Doppler device displaying the depth of the measurement volume. We used this technique prospectively in two independent centers (the nephrology department and the intensive care unit) involving senior as well as junior staff members. Either the non–Doppler or the Doppler method were randomly selected for subclavian vein catheterization in 100 patients and for internal jugular vein catheterization in 30 patients. The success rate on the first attempt was 86. 2% for the non–Doppler method versus 96. 8% for the Doppler method (p = 0. 03). The failure rate of the non–Doppler method used by junior staff members was 9. 2%, reduced to 1. 5% (p = 0. 05) by secondary use of the Doppler method and/or help from a senior staff member (rescue procedure). Pulsed Doppler guidance reduced significantly the failure rate of venous punctures especially when used by seniors or by juniors after a training period.
Different Apheresis Methods in the Treatment of Hypercholesterolemia in Primary Biliary Cirrhosis: A Case Report
Authors: Kojima Shunichi , Toyota Yasushi , Shiba Mariko , Tsushima Motoo , Matsuoka Hiroaki , Yamamoto Akira
Published: November 2008

Abstract: The two different modes of low–density lipoprotein (LDL) apheresis, cascade filtration (CF) and dextransulfate cellulose (DSC) adsorption, were compared for efficiency of cholesterol removal in a patient with severe hypercholesterolemia due to primary biliary cirrhosis (PBC). Decrement in the total cholesterol level by the DSC method was less than that by the CF method. Apolipoprotein B was decreased to almost null by both modules whereas the decrease in albumin was much greater in the second filter of the CF method than in the DSC column. Lipoprotein X which constituted the major portion of serum cholesterol in PBC became negative by passing plasma through the second filter. The CF method was preferred to the DSC method for removal of lipoprotein X, but albumin substitution was mandatory to prevent the decrease of serum albumin in the CF method.
Regenerated Cellulose‐Based Hemodialyzers with Immobilized Proteins as Potential Devices for Extracorporeal Immunoadsorption Procedures: An Assessment of Protein Coupling Capacity and In Vitro Dialysis Performances
Authors: Vallar Laurent , Rivat Claude
Published: November 2008

Abstract:The development of immunoadsorbents usable with whole blood should offer the potential for making significant improvements in extracorporeal immunoadsorption procedures. In contrast to traditional chromatographic media, these hemocompatible matrices could be used without requiring the previous step of the separation of blood cells and plasma. Conventional hemodialyzers seem to be particularly appropriate for such a purpose. This paper describes a feasibility study of the preparation of immunoaffinity supports, from regenerated cellulose (Cuprophan)‐based dialyzers by cyanogen bromide activation and coupling of bovine serum albumin or human immunoglobin G, used as models for immunochemical ligands. Several parameters of the activation and coupling steps were studied in order to define the optimum preparation conditions. In addition, the preservation of the transport properties (clearance and ultrafiltration) of the modified hemodialyzers was evaluated in vitro to ensure that the device potentially could be used in future human therapeutic applications with no risk of massive removal of solutes and fluid from the blood. Results indicate that 150–300 mg of immunoglobulins can be immobilized per square meter of Cuprophan. Modified hemodialyzers show a slight decrease of their clearance values and a slight increase of their ultrafiltration coefficients, and thus they can be proposed as reliable carrier material for extracorporeal cleansing systems.