bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Motion Analyzing System for Implanted Tilting Disk Valves
Authors: Dohi Takeyoshi , Sakuma Ichiro , Funakubo Hiroyasu , Matsumoto Hiroshi , Ide Hirofumi , Takai TNobuharu
Published: November 2008

Abstract: : A motion‐analyzing system was developed to quantitatively evaluate functions of the implanted tilting disk valve, e.g., an open angle and a duration of valve open and/or shut. In this system a picture of the valve on an x‐ray cinefilm is displayed on the CRT screen by the TV camera for extraction of valve position. Data extracted are stored in the computer and are used to calculate parameters for motion analysis of the valve. The reliability of this system was confirmed within 3d̀ of error using the valve model prior to the evaluation of cinefilms clinically procured. With the aid of this motion analyzing system, complicated motions of the tilting disk valve were easily quantified and the useful information as given for clinical diagnosis and further valve development.
Thoughts and Progress
Authors: Schooneman F. , Streiff F.
Published: November 2008

Abstract: : Donor safety and high‐quality plasma are important assumptions for a successful plasma donation. The manual technique has two major inconveniences: It is time consuming and there are risks in the transfusion because the system is not closed. Among the available technological options, filtration has great future prospects insofar as a hemocompatible and efficient membrane can be made available and at low cost. Hemascience Travenol developed the polycarbonate membrane for the first disposable. Because of a high rate of no or very low plasma flow (5–10%), the company equipped the disposable with a new membrane: the nylon membrane. This membrane was tested according to biological and technical protocols; 39 disposables were used. The anticoagulant was acid citrate dextrose formula A. The results were good: time to collect 600 g of plasma, 34 min (only two occurrences of low flow); no problem with blocking or clotting. The main biological data show no problem with molecule activation (complement factors, coagulation factors), a good recovery of Factor VIII, and no contamination of platelets (5 ± 2times103/ml). No side‐effects in the donor were noted. These results confirm that the Hemascience Travenol system is one of the best automatic plasmapheresis systems and could be used to separate great quantities of plasma from donors.
The Impact of Erythropoietin on Hemodialyzer Design and Performance
Authors: Schmidt Baerbel , Ward Richard A.
Published: November 2008

Abstract: The present study investigated theoretically and experimentally the effects of increases in hematocrit on the clearance of urea by the Baxter ST15 hollow fiber dialyzer. In a theoretical model that incorporates the three component resistances for the overall mass transfer rate, namely, the resistance of the blood (Rb)‐, membrane (Rm)‐, and dialysate side (Rd), it was predicted that a change in hematocrit would alter only the blood side resistance. The overall impact of this alteration is expected to be determined by the relative contribution of Rb to the overall resistance (RO). The modest contribution of Rb to RO implies that a major change in Rb (50%) would have only a minor effect on RO (11%) and consequently on urea clearance (5%). These theoretical conclusions were tested experimentally and the results confirmed the theoretical predictions. Indeed, there was little change in urea clearance in the clinically relevant range of variations in hematocrit (19–39%). Possible ways of compensation by minor changes in the hollow fiber geometry are discussed as well as the more complex relationships with larger solutes (creatinine) or unequally distributed solutes (potassium, phosphate).
Cellulosic versus Synthetic Membranes: A Reasonable Comparison?
Authors: Baurmeister U. , Vienken J. , Luttrell A.
Published: November 2008

Abstract: Of the two main classes of dialysis membranes, cellulosic and synthetic, the former represents the standard membrane used in dialysis therapy. The disputed properties of cellulosic membranes related to biocom‐patibility have inspired a number of authors to compare these two membrane classes from a variety of perspectives. However, such a strict categorization as “synthetic” or “cellulosic” is of doubtful value from the point of view of polymer chemistry. Here, biocompatibil‐ity and performance properties of these two membrane classes are compared with the aim of investigating the validity of this categorization. The biocompatibility parameters studied are complement and leukocyte activation together with activation of the coagulation cascade. Analysis of a variety of both cellulosic and synthetic membranes with different degrees of biocompatibility showed that biocompatibility can be achieved by both classes of membranes and is, therefore, not a particular property of one class only. Furthermore, performance and ß2‐microglobulin removal properties of the two classes of membranes do not particularly favor one of these classes. Therefore, differences between cellulosic and synthetic membranes are not manifested in parameters like biocompatibility, hydraulic permeability, and overall performance.
Bacterial Contamination of Hemodialysis Center Water and Dialysate: Are Current Assays Adequate?
Authors: Harding George B. , Pass Ted , Million Carolyn , Wright Rita , DeJarnette Jan , Klein Elias
Published: November 2008

Abstract: Many dialysis centers depend on clinical laboratories or a commercially available dip culture to determine the contamination levels in water and dialysate. To determine whether these standard clinical culture procedures adequately quantitate bacterial contamination in hemodialysis center water and dialysate, test results of two routine clinical media was compared, trypticase soy agar (TSA) and plate count agar (PCA), with those of nutrient‐poor R2A medium. Dialysate samples demonstrated significant differences in media, the temperature of incubation, and plating techniques (pour plate versus spread plates). Purified water for dialysis demonstrated significant differences only for media; however, temperature was an important variable. Selective growth on R2A agar of some water‐and dialysate‐contaminating species was studied by velvet disk and loop transfer of colonies. A strong selectivity for water‐borne bacteria was demonstrated by R2A agar; the bacteria that did not grow on TSA and PCA have been identified.
Isoelastic Polyurethane Prosthesis for Segmental Trachea Replacement in Beagle Dogs
Authors: Schauwecker H. H. , Gerlach J. , Planck H. , Bücherl E. S.
Published: November 2008

Abstract: Porous polyurethane (nonwoven) was used for the development of tracheal prosthesis, which‐in a special testing design‐was adapted to shape and biome‐chanic properties of the natural organ. This prosthesis was implanted into 19 beagle dogs using inverted, everted, and end‐to‐end anastomosis. Insufficiency of the anastomosis or infection was observed in the everted and end‐to‐end anastomosis, whereas the inverted anastomosis showed complete incorporation into surrounding tissue of the porous prosthesis but was complicated by airway obstruction due to anastomosis granuloma.
Changes of the Serum Amikacin (AMK) Level in Patients with Serious Acute Renal Failure Treated by Continuous Arteriovenous Hemofiltration (CAVH)
Authors: Takagi N. , Oda H. , Tokita Y. , Yabana M. , Toya Y. , Abe Y. , Ueda S. , Minamisawa K. , Yamada Y. , Ishigami T. , Gotoh T. , Takeda K. , Ishii M.
Published: November 2008

Abstract: This study clarified changes in the serum amikacin (AMK) levels in the blood of 5 patients (4 men and 1 woman; average age 59.2 ± 5.9 years) with serious acute renal failure treated by continuous arteriovenous hemofiltration (CAVH). The following principal results were obtained. (A) The average remaining rate of AMK in the blood after 6 h was 60.8 ± 5.3% and 50.4 ± 5.3% after 12 h. The average half‐life period (t1/2ß) of AMK in the blood during CAVH was 18.3 ± 3.4 h. (B) The remaining rate of AMK in the blood after 12 h correlated significantly with the blood urea nitrogen (BUN) level (r = 0.71, p < 0.05) and with the volume of urine excreted per day (r =‐0.71, p < 0.05). (C) The average lowest AMK concentration after 24 h for a continuous 17‐day period was 3.3 μ/ml. These results suggest that the administration of 100 mg of AMK once a day is useful and safe for patients with serious acute renal failure treated by CAVH and that it will not accumulate in the body.
Perfusion of Uremic Blood Ultrafiltrate on Uncoated Charcoal
Authors: Politi Laura , Cerulli Nicola , D'Angelo Anna Rita , Scandurra Roberto
Published: November 2008

Abstract: A granular uncoated charcoal removes from uremic blood ultrafiltrates many chemical species that are not removed by dialysis. Charcoal treatment dramatically improves the general condition of the patients and normalizes their blood pressure. To obtain a rapid depuration, the initial treatment should be intensive (at least 16 daily treatments) and the effects prolonged over time by once‐a‐week charcoal treatment between two standard hemodialyses. Biogel P2 chromatography documents well all the events of a depurative treatment that cannot be monitored by hematochemical analyses.
A Large‐Scale Magnetic Separator for Selective Cell Separations with Paramagnetic Microbeads
Authors: Hardwick R. Alan , Prisco Michael R. , Shah Dinesh O.
Published: November 2008

Abstract: An improved magnetic separator has been developed for use in large‐scale cell separations. This separation method uses paramagnetic microbeads coated with antibodies that selectively bind to target cells. The magnetic separator attracts the microbead‐target cell aggregates and holds these aggregates at its surface while the suspending fluid and nontarget cells flow past. The optimum separator design was determined to be two magnetic assemblies in series along with a peristaltic pump. The assemblies consist of neodymium‐iron‐boron magnet bars sandwiched between steel bars (magnetic pole pieces). The size and pole spacing of the two magnetic assemblies are designed to be different, so that the first assembly, which captures <99.99% of the microbeads, has good magnetic reach‐out and a high magnetic holding force at its surface, while the second assembly has an even higher magnetic holding force at its surface. Studies show that the separator can remove 1 times 1010 microbeads from a suspension of red blood cells processed at a flow rate of 9 ml/min, so that no microbeads are detected in the effluent.
Quantification of Perivalvular Thrombus Formation in Blood Pumps by Polar Coordinate Mapping
Authors: Pantalos George M. , Everett Scott D. , Mohammad S. Fazal , Burns Gregory L. , Solen Kenneth A. , Reynolds Larry O. , Olsen Don B.
Published: November 2008

Abstract: A polar coordinate mapping technique (PCMT) to quantitatively describe perivalvular thrombus formation was applied in the examination of prosthetic valves from paracorporeal assist devices. The method begins by photographing the upstream and downstream views of the freshly retrieved valves using Transparency film. The valve images are then projected onto 10 x planforms of the valves, and the boundaries of the observable thrombi are traced. The radial thrombus length is then measured at 5d̀ increments and plotted on Cartesian coordinates as a function of polar coordinate. Mean radial thrombus length and incidence of thrombus are calculated. Statistical analysis can then be used to test for differences in the length, incidence, and pattern of thrombus formation between test groups. The effect of valve selection, anticoagulant regime, and other factors that influence thrombus formation can be quantitatively compared with the PCMT. Consequently, the PCMT could be a valuable assessment tool for efforts being made to reduce thrombosis in prosthetic blood pumps.
Leukotriene B4 in Hemodialysis
Authors: Tridon A. , Albuisson E. , Deteix P. , Verdier A. Marques , Gaillard G. , Bétail G. , Baguet J. C.
Published: November 2008

Abstract: Leukotrienes are eicosanoids arising from arachidonic acid via 5 lipooxygenase, an enzyme essentially present in leukocyte cells. Leukotriene B4 might be an indicator of neutropolymorphonuclear leukocyte activation when there is contact with artificial membranes. The level of plasmatic leukotriene B4 was measured at three different times during the hemodialysis treatment in several patients undergoing dialysis on three different membranes (one cellulosic and two synthetics). A moderate increase of leukotriene B4 was observed early (at 15 min), comparable among the three membranes, but levels returned to baseline at 180 min. Leukotriene B4 production proved leukocyte activation and was probably related to a direct interaction with dialysis membrane. Nevertheless, complement intervention could not be excluded. Leukotriene B4 is one molecule more among the group of inflammatory mediators produced during hemodialysis treatment.
Continuous In‐Line Monitoring of Oxygen Delivery to Control Artificial Heart Output
Authors: Takatani S. , Noda H. , Takano H. , Akutsu T.
Published: November 2008

Abstract: In order to evaluate the pump output control based on the oxygen delivery to peripheral tissues, arterial and mixed venous hemoglobin content ([Hb]) and oxygen saturation (SO2) were continuously monitored in three biventricular bypass animals (3‐, 6‐, and 40‐day experiments) with fibrillating ventricles. The specially developed oxygen sensors were mounted in the outflow ports of the artificial hearts to measure [Hb] and SO2. One animal was exercised on the treadmill at 2.0 mile/h for 15 min with pump flows fixed to deliver oxygen of (a) above 13 cc/min/kg, (b) 10, and (c) 9. In (a), the mixed venous saturation (Sv02) dropped to ˜25% with no increase in the blood lactate level. In (b) and (c), the SvO2 decreased to ˜10–15% with increase in blood lactate levels from 4 to 10–30 mg/dl. Also, the recovery of the SvO2 in these groups following the termination of the exercise was slower in comparison to (a). The lower limit of the SvO2 level that would create oxygen debt situation in the peripheral tissues was ˜25–30% for the exercise of 2.0 mile/h. The SvO2 reflects changes in respiratory status, pump output, hemoglobin level, and metabolism, and is thus a useful indicator to diagnose quickly the circulatory status as well as possibly to control the artificial heart output.
Local Blood Residence Times in the Penn State Artificial Heart
Authors: Francischelli David E. , Tarbell John M. , Geselowitz David B.
Published: November 2008

Abstract: Thrombus formation associated with cardiac assist devices is a major concern in their application. Thrombogenesis is thought to be a function of, among other things, fluid shear stress and blood residence time. In the current study, a fiber–optic probe was developed and employed in conjunction with indicator dilution techniques to evaluate the local near–wall fluid residence times at a number of locations inside the Penn State 70 cc parallel port and 100 cc angle port left ventricular assist devices (LVADs). In this in vitro study, both 50% and 30% systolic duration regimes were investigated for each chamber. Using a relatively inexpensive optical arrangement, two decades of dye concentration (10‐6–10‐4M of fluorescein sodium) were easily discernible. The washout process was characterized by an exponential decay with a time constant T. For all positions and operating conditions tested, T values were between 1–2 beats. In all cases tested, values of T in the valve regions were significantly longer (8.9–31.6%; p ≥ 0.0075) than in the chamber proper. At every position T was substantially lower in the 70 cc chamber than in the larger pump (17.8–27.4%). Systolic duration appeared to have no significant effect on T at the majority of investigated sites. The results indicate that the valve regions, which are known to have greater shear stresses, are also in contact with a volume element of blood for a longer time than is the rest of the chamber. This combination may be detrimental to fragile blood components.
Clinical Study of High‐Flux Cuprammonium Rayon Hemodialysis Membranes
Authors: Opatrný Karel , Sylvie Sylvie , Lopot Frantiŝek , Vít Ladislav , Válek Albert , Opatrný Karel
Published: November 2008

Abstract: The aim of this crossover clinical study was to gain basic information on the hemocompatibility and effectiveness of recently developed high‐flux membranes made of cuprammonium rayon with ultrafiltration coefficients of 10, 17, and 19 ml/mm Hg/h (S12W, SU12W, and SS12W dialyzers, respectively), and to identify any possible differences from a conventional membrane made of the same material with an ultrafiltration coefficient of 6 ml/mm Hg/h (C12W dialyzer). All the tested membranes led to an abrupt drop in leukocyte count in the initial phase of hemodialysis. In high‐flux membranes, C5a anaphylatoxin would pass into the dialysate, but mean C5a anaphylatoxin concentrations in the dialysate were lower by orders of magnitude than its plasma concentrations, which behaved, in high‐ and low‐flux membranes alike, typically of those made of nonsubstituted cellulose with no intermembrane differences. As judged by the concentrations of the thrombin‐antithrombin III complex, the coagulation system was activated—again, without differences between membranes. The reduction rates for urea, creatinine, and phosphates were comparable for all the tested membranes. Compared with baseline, the post‐dialysis serum concentrations of β2‐microglobulin in high‐flux membranes, unlike the low‐flux membrane, were significantly lower. We conclude that there are no significant differences between the tested high‐ and low‐flux membranes made of cuprammonium rayon in the monitored hemocompatibility parameters, and that high‐flux membranes are capable of reducing serum β2‐microglobulin concentrations.
Analysis of Heart Morphology and Function Following Erythropoietin Treatment of Anemic Dialysis Patients
Authors: Sikole A. , Polenakovic M. , Spirovska V. , Polenakovic B. , Masin G.
Published: November 2008

Abstract: In a two‐way study, we treated renal anemia in chronic hemodialysis patients with recombinant human erythropoietin (rh‐EPO) and followed heart morphology and function dynamics by echocardiography. Thirty‐eight patients were randomly divided in two equal groups: the therapy group, treated with rh‐EPO for 24 months, and the control group, not treated during the first 12 months and treated with rh‐EPO during the second 12 months. Anemia was corrected, and hematocrit was maintained between 30 and 35 vol% by subcutaneous rh‐EPO administration. Echocardiographic assessment was performed at the end of the untreated control phase and was repeated after 12 months of rh‐EPO treatment in the control group and after 12 and 24 months of treatment in the therapy group. The results revealed significant morphologic, hemodynamic, and eventually functional changes. After 12 months of rh‐EPO treatment, the end‐diastolic volume (EDV) decreased from 135.8 ± 23.7 to 109.8 ± 25.3 ml, p < 0.001; stroke volume (SV) from 91.9 ± 17.6 to 71.3 ± 12.4 ml, p < 0.001; left ventricular mass‐Devereux (LVMD) from 297.2 ± 57.8 to 218.0 ± 50.4 g, p < 0.01; cardiac output (CO) from 7,279 ± 1,932 to 5,711 ± 1,276 ml/min, p < 0.002; total peripheral resistance (TPR) rose from 1,330 ± 390 to 1,707 ± 373 dynes X s/cm5, p > 0.007. After 24 months, LVMD decreased further from 224.6 ± 43.1 to 195.7 ± 46.3 g, p < 0.004. The relaxation time index (RTI) decreased from 64.7 ± 20.4 to 52.4 ± 18.0 ms, p < 0.045, suggesting improved diastolic function. Our results indicate that correction of renal anemia can normalize heart morphology and improve heart function.
Origin of the Rhythmical Fluctuations in the Animal Without a Natural Heartbeat
Authors: Yambe Tomoyuki , Nitta Shin‐ichi , Sonobe Taro , Naganuma Shigeru , Kakinuma Yoshito , Kobayashi Shin‐ichi , Nanka Shunsuke , Ohsawa Noboru , Akiho Hiroshi , Tanaka Motonao , Fukuju Takeo , Miura Makoto , Uchida Naoki , Sato Naoshi , Mohri Hitoshi , Koide Satoshi , Abe Ken‐ichi , Takeda Hiroshi , Yoshizawa Makoto
Published: November 2008

Abstract: In order to analyze the origin of the rhythmical fluctuations in the cardiovascular system, an artificial heart, which does not have rhythmical periodicities such as altering heart rate and cardiac function, was utilized in chronic animal experiments with adult goats. Two pneumatically actuated ventricular assist devices were implanted as a total biventricular bypass under general anesthesia, and then the natural heart was electrically fibrillated to constitute the biventricular bypass type of complete prosthetic circulation model. All hemodynamic data were recorded under awake conditions and were calculated in the computer system by spectral analysis methods. In the power spectrum of the arterial blood pressure of the animal with the artificial heart, the Mayer wave peak and respiratory wave peak were clearly observed, and spectral analysis including the coherence function suggests that the Mayer waves originated from the peripheral vascular resistance and the respiratory waves probably originated from the periodicities of the pulmonary circulation. These fluctuations in the circulatory system influenced the arterial baroreflex system and transfer to the sympathetic outflow through the central baroreflex system, which suggests that rhythmical fluctuations in hemodynamic parameters originate at least in part from these vascular periodicities.
Effects of Unloaded Reperfusion on Mitochondrial Function in the Postischemic Myocardium
Authors: Waldenberger Ferdinand Rudolf , Andres Janusz , Flameng Willem
Published: November 2008

Abstract: The effect of mechanical unloading on recovery of postischemic myocardial performance, high energy phosphate content, and mitochondrial function was tested in an isolated working rabbit heart model. After 30 min of global ischemia, prolonged unloaded reperfusion could prevent complete loss of contractility, deterioration of mitochondrial function, and depletion of the ATP pool as was found when only short‐term unloading was performed. Aortic flow recovered to 21% of preischemic control, and left ventricular dP/dt max to 46% (p < 0.05 vs. short‐term unloading). OPR and ADP/O stabilized at 42 and 72%, respectively (p < 0.05 vs. short‐term unloading), and ATP at 33% of control (p < 0.05 vs. short‐term unloading). These results show the beneficial effect of prolonged unloading in postischemic hearts.
Vascular Access for Hemodialysis
Authors: Vanholder R. , Ringoir S.
Published: November 2008

Abstract: Indwelling central venous catheters were consecutively used as access for acute and chronic hemodialysis, emergency treatment of pulmonary fluid overload, intoxication and electrolyte disturbances, plasmapheresis, and semiacute continuous dialysis strategies, such as continuous arteriovenous hemofiltration (CAVH). Modification in catheter structure also made it possible to use this access for long‐term treatment (e.g., surgically insert‐able catheters [Hickman], soft large‐bore catheters for blind insertion). We discuss the remaining open questions in this field: Which is the insertion site of preference (i.e., subclavian, femoral, or deep jugular)? Should we prefer stiff or soft catheters? Should soft catheters be positioned surgically or is blind insertion by nonsurgeons as adequate? Is it necessary to couple catheter insertion to adjuvant techniques, such as echographic guidance, to reduce complications? Is the currently used polymer structure of the catheters acceptable? Should catheter dialysis be used with single or double vascular access?
Complications in Blood Access for Hemodialysis
Authors: Nakagawa Yoshihiko , Ota Kazuo , Sato Yuichi , Fuchinoue Shohei , Teraoka Satoshi , Agishi Tetsuzo
Published: November 2008

Abstract: We retrospectively analyzed a total of 580 blood access complications that occurred at one institution from January 1991 to December 1992. Dysfunction and thrombosis of arteriovenous fistulas (AVFs) due to insufficient blood flow were the most frequent complications (451, 77.8%). Two hundred sixty‐eight (71.5%) patients were treated by reconstructing the AVF at a proxy‐mal location in the ipsilateral arm. Sixty seven patients had prosthetic material. Their cumulative patency rates for 1 year were 74.6% with expanded polytetrafluoroeth‐ylene and 64.2% with polyurethane grafts. Twenty patients had blood access infections, 15 of whom had artificial grafts. Six patients with infections of artificial grafts were successfully treated by local resection with graft rerouting. Venous hypertension due to deep venous thrombosis developed in 23 patients. Fifteen (65.2%) had no previous trauma, and 18 (78.3%) required closure of AVFs. Aneurysm occurred in 40 patients, which included 13 at an anastomosis site in autogenous AVFs, 13 in repeatedly puncturing shunt veins, 11 in prosthetic grafts, and 3 in superficialized arteries. One patient died from septic shock associated with graft infection, and 1 suffered a fatal pulmonary embolism after replacement with a prosthetic graft. The other patients who received surgical treatment for their complications were successfully treated without life‐ or limb‐threatening consequences. Operations developed to provide adequate blood access for hemodialysis have significant rates of complications. Surgeons performing such procedures need to be well‐versed in techniques for creating blood access and for treating attendant complications.
Double Catheterization of the Internal Jugular Vein for Hemodialysis: Indications, Techniques, and Clinical Results
Authors: Tesio Franco , De Baz Hamurabi , Panarello Giacomo , Calianno Giuseppina , Quaia Piero , Raimondi Antonino , Schinella Domenico
Published: November 2008

Abstract: Central vascular catheters are used to access the central vascular system in both acute and chronic uremic patients undergoing hemodialysis. Among different approaches, the internal jugular vein seems to have less adverse effects. We describe our long‐term experience with a two‐catheter system. Percutaneous jugular vein cannulation was performed using Medcomp silicone rubber catheters. The study included 108 patients undergoing hemodialysis. One‐ and 2‐year survival was 93 and 91%, respectively; 36 died because of unrelated causes. Blood flow rate was 284 mL/min; venous pressure at 1 year was 90 mm Hg. Complications included accidental withdrawal (6), dysfunction (4), catheter clotting (11), mediastinal hematoma (2), pneumothorax (1), and sepsis (7). Good long‐term survival and a low complication rate make this system a safe and reliable method of access for long‐term hemodialysis.
Vascular Access for Therapeutic Plasma Exchange
Authors: Grishaber Judy E. , Whitman Eric D.
Published: November 2008

Abstract: Adequate venous access is an essential component of therapeutic plasma exchange (TPEX). The simplest kind of venous access is venipuncture of antecubital veins, but this technique may be limited by venous size or scarring following the procedure, requiring the placement of a specialized vascular access device (VAD). VADs provide reliable central venous access and may remain in place for several weeks or months, depending on the VAD and the venous site chosen. Their use, however, is potentially limited by the risk of complications. We discuss indications for insertion, choice of catheter and access site, and complications of VAD placement for TPEX.
Fibrin Sheet Covering Subclavian or Femoral Dialysis Catheters
Authors: Hombrouckx R. , D'Halluin F. , Bogaert A.M. , Ieroy F. , De Vos J.Y. , Iarno L.
Published: November 2008

Abstract: The existence of a sheet around a single lumen dialysis catheter tip, which provokes a valve mechanism, is proved by the observation that several times during the replacement procedure of a dialysis catheter, a sheet surrounding the surface of the catheter is removed with the dialysis catheter. This sheet is grey, approximately 1 mm thick and 30 mm long and consists of fibrin and thrombocytes. Bacteriological examinations were always negative. The existence of the sheet in vivo is demonstrated by digitalized angiography during the removal procedure for single lumen dialysis catheters. Rarely, only the sheet is removed with the catheter. In all other instances, the sheet is stripped off and remains in the subcutaneous tunnel or in the vascular bed without causing much clinical discomfort in most patients. Occasionally an episode of cough, dyspnea, hypotension, retrosternal oppression or hemoptae after removing the single lumen dialysis catheter, suggest pulmonary embolism or lung infarction.
Severe Electrolyte Disturbances in Lethal Subclavian Catheter Dialysis
Authors: Hombrouckx R. , De Vos J.Y. , Iarno L.
Published: November 2008

Abstract: Syncope, irreversible shock, and respiratory and circulatory arrest developed in a 54‐year‐old diabetic man chronically dialyzed with a subclavian catheter (SC) minutes after the end of a dialysis session. Resuscitation attempts remained unsuccessful. During the resuscitation attempt, a blood analysis showed severe hyponatremia, acidosis, and hypochloremia. Respiratory and cardiac arrest developed during dialysis in a 64‐year‐old woman on chronic SC dialysis. Resuscitation was unsuccessful; chloremia levels were 79 mEq/L, and calcemia levels were 20 mg%. Both patients were dialyzed with a standard dialysate solution. The reasons for the electrolyte disturbances could not be explained technically. The autopsy showed myocardial perforation by the SC and accumulation in the pericardium of the fluids administered during the resuscitation attempt (e.g., glucose 5%, bicarbonate, Ca gluconate, human albumines), thus explaining the erroneous electrolyte results. The reason for the perforation was a too‐rigid central femoral vein catheter, erroneously labeled a subclavian catheter by the supplying firm. Because of a syndrome of progressive vena subcla‐via and vena cava sclerosis with insufficient arterial phase flow and venous‐phase bleeding around the puncture site during single‐needle dialysis, the original SC had to be replaced by a longer one with the tip located in the atrium (this SC was actually a femoral catheter). Analysis of the fluid aspirated through the SC can determine the diagnosis in sudden death of SC dialysis patients.
A New Mock Circulatory Loop and Its Application to the Study of Chemical Additive and Aortic Pressure Effects on Hemolysis in the Penn State Electric Ventricular Assist Device
Authors: Garrison Laura A. , Frangos John A. , Geselowitz David B. , Lamson Theodore C. , Tarbell John M.
Published: November 2008

Abstract: A new mock circulatory loop was developed for hemolysis studies associated with the Penn State electric ventricular assist device (EVAD). This flow loop has several advantages over previously designed loops. It is small enough to accommodate experiments in which only single units of blood are available, it is made out of biocompatible materials, it incorporates good geometry, and it provides normal physiological pressures and flows to both the aortic outlet and the venous inlet of the pumping device. Experiments with reduced aortic pressure but normal cardiac output showed that hemolysis in a loop with normal aortic blood pressure was significantly higher than that in a loop with lowered aortic pressure, thereby illustrating the importance of maintaining loop pressures as close as possible to those found in vivo. This data also imply that blood traveling through the left ventricle in an artificial heart may be subject to higher hemolysis rates than that traversing the right ventricle. Another set of experiments to determine the effects of 4 hemolysis or drag‐reducing agents (Pluronic F‐68, Dextran‐40, Polyox WSR‐301, and Praestol 2273TR) on blood trauma due to the EVAD and associated valves was performed. Results indicated that none of the additives significantly reduced hemolysis under the conditions found in the mock loop. Finally, a compilation of data gathered in these experiments showed that the index of hemolysis (IH) is dependent on hematocrit (HCT), which suggests that another parameter, IH/HCT, may be more suited to the quantification of hemolysis.
The Effect of Valve Type and Drive Line dP/dt on Hemolysis in the Pneumatic Ventricular Assist Device
Authors: Ducko Christopher T. , McGregor Mira L. , Rosenberg Gerson , Pierce William S.
Published: November 2008

Abstract: The objective of this experiment was to investigate the relationship between blood damage and drive line dP/dt and valve type in the pneumatic ventricular assist device. Two mock circulatory loops were assembled using 70–ml Penn State pneumatic ventricular assist devices, one fitted with convexoconcave (CC) valves and one fitted with monostrut (MS) valves. Use of a compliance chamber established three ranges of drive line dP/dt values. Using bovine blood and the methods of generalized estimating equations, it was found that drive line dP/dt was significantly associated with the index of hemolysis (p = 0.00): the lower drive line dP/dt values yielded lower indices of hemolysis. In addition, this association differed between MS and CC valves (p = 0.01); the MS valves consistently yielded a higher index of hemolysis than the CC valves across all drive line dP/dt ranges. However, the relative hemolytic potential of each valve type became much closer at low drive line dP/dt values (2,000–3,000 mm Hg).
Use of a Rate‐Limited Ultrafiltration Circuit with Centrifugal Ventricular Assist
Authors: Curtis Jack J. , Deese Lawrence R. , Walls Joseph T. , Boley Theresa M.
Published: November 2008

Abstract: Renal insufficiency and pulmonary edema are frequently observed in patients who require centrifugal ventricular assist for postcardiotomy ventricular failure. We describe a technique of using a rate‐limited ultrafiltration device in parallel with the assist device circuit to remove excess intravascular volume.
Development of the Baylor/NASA Axial Flow Ventricular Assist Device: In Vitro Performance and Systematic Hemolysis Test Results
Authors: Mizuguchi Kazumi , Damm George A. , Bozeman Richard J. , Akkerman Jim W. , Aber Greg S. , Svejkovsky Paul A. , Bacak Jim W. , Orime Yukihiko , Takatani Setsuo , Nosé Yukihiko , Noon George P. , DeBakey Michael E.
Published: November 2008

Abstract: Our newly developed axial flow pump consists of a flow tube, an internal rotating impeller, and a fixed flow stator (we call the stator) behind the impeller. This pump produces a flow of 3 to 8 L/min against 50 to 150 mm Hg pressure difference, respectively, in the range of 10,000 to 16,000 rpm. An axial flow pump that will be used as a ventricular assist device (VAD) has to have low hemolytic and good antithrombogenic characteristics. This paper will show how to decrease the hemolytic properties of this axial flow pump systematically using a test matrix. The test variables evaluated were impeller blade tip geometry, impeller flow tube clearance (radial clearance), impeller stator clearance (axial clearance), impeller blade number, stator blade number, and impeller length. All in vitro hemolysis tests were performed at 5.0 L/min against 100 mm Hg pressure difference using a total of 83 bags of fresh bovine blood. The results were as follows: the impeller blade tip geometry did not significantly effect hemolysis, a 0.005‐inch and a 0.009‐inch radial clearance were significantly (p < 0.01 or 0.001) less hemolytic than the other clearances, a 0.075‐inch axial clearance was significantly (p < 0.05) more hemolytic than the other clearances, two‐and six‐bladed impellers were significantly (p < 0.01 and 0.02, respectively) less hemolytic than a four‐bladed impeller, a five‐bladed stator was significantly (p < 0.05 or 0.01) less hemolytic than the other stators, and the impeller length did not make a significant difference. Currently, the best index of hemolysis is 0.031 ± 0.018 g/100 L, and using parameters from these results, implantable devices are being fabricated.
In Vitro and In Vivo Validation Tests for Total Artificial Heart
Authors: Orime Yukihiko , Takatani Setsuo , Tasai Kimitaka , Ohara Yasuhisa , Naito Kozo , Mizuguchi Kazumi , Makinouchi Kenzo , Matsuda Yukihiro , Shimono Takatsugu , Glueck Julie , Noon George P. , Nosé Yukihiko
Published: November 2008

Abstract: Properly planned in vitro and in vivo studies are mandatory to validate blood pump performance. However, standard procedures for in vitro and in vivo tests of total artificial heart (TAH) performance still do not exist. At Baylor College of Medicine, standard tests procedures for performance validation of the totally implantable TAH have been established. In this paper, these in vitro tests protocols (performance mapping tests, accelerated endurance test, hemolysis test, flow visualization tests, etc.) are described as well as in vivo test procedures (TAH implantation procedure, including surgical technique, postoperative management and tests, etc.). In addition, pathological protocols are presented. In our experience, these procedures are very simple, easy to perform, and inexpensive. These protocols are proposed as standard in vitro and in vivo tests for a TAH.
Assessment of Currently Available Low‐Density Lipoprotein Apheresis Systems
Authors: Matsuda Yukihiro , Malchesky Paul S. , Nosé Yukihiko
Published: November 2008

Abstract: It has already been 10 years since the introduction of low‐density lipoprotein (LDL) apheresis technologies. They have been established as technically and medically feasible for long‐term treatment and economically acceptable, and their long‐term treatment effects have been determined. Currently, there are efforts to develop more selective LDL removal systems. However, after 10 years of research, it is time to carefully review this strategy. The approach may have become too specific in light of the multiple macromolecules involved in the pathogenesis of atherosclerosis. In this paper, the six currently available LDL apheresis systems (plasma exchange, double filtration plasmapheresis, thermofiltration, LDL chemical adsorption (Kaneka system), LDL immunoadsorption, and the heparin‐induced extracorporeal LDL precipitation [HELP] system) were reviewed and scored from various points of view such as effectiveness, simplicity, safety, and cost performance. Finally, each system was assessed from the global point of view in relation to the pathogenesis of lipid‐related diseases.
The Decline in Serum Albumin after Conversion to High Flux, High Efficiency Dialysis
Authors: Kirschbaum Barry
Published: November 2008

Abstract: Hypoalbuminemia among chronic hemodialysis patients is recognized as a poor prognostic sign. We observed that many of our chronic patients had a progressive decrease in their plasma albumin concentrations after they were converted to high flux, high efficiency dialysis from conventional dialysis mode. This change occurred in the absence of changes in the KTIV and protein catabolic rate (per) normalized to body mass. When nitrogen losses were measured, we found no difference in the dialysate concentrations of urea, alpha amino nitrogen, uric acid, or total nitrogen when high flux polysulfone was compared with high efficiency Cuprophan. While urea was the predominant nitrogen solute in all dialysate samples, there were some with a large gap between total and urea nitrogen. Alpha amino nitrogen losses, expressed as leucine equivalents, were substantial, ranging from 8. 4 to 9. 8 g/3. 5 h dialysis treatment. We believe that the increased losses of nitrogen experienced by patients after their conversion to a more efficient method of dialysis and not compensated for by a spontaneous increased intake of protein led to the observed fall in plasma albumin. Both urea and amino acid nitrogen losses need to be accounted for when achievement of higher KTIV dialysis is pursued.
Cavitation Dynamics of Mechanical Heart Valve Prostheses
Authors: Lee C. S. , Chandran K. B. , Chen L. D.
Published: November 2008

Abstract: Nine different mechanical mitral heart valves were chosen in order to study cavitation dynamics in detail in an in vitro flow system simulating a single event of mitral valve closure. The transvalvular pressure (ventricular minus atrial pressure) rise rate averaged during the valve closing period was used as an index of the loading rate. A series of photographs in the vicinity of the inflow surface of the valve were attempted during the bubble appearance period using a stroboscopic visualization technique. The in vitro study revealed three sources of cavitation initiation in the design of the mechanical heart valves tested: stop (seat stop or seating lip), inflow strut, and clearance (gap formed between the occluder and the housing or between the two occluders in the closed position). Among these, the occluder stop design was the most critical to cavitation since all valves having the stop at the edge of the major orifice area showed a higher intensity of cavitation and threshold loading rates below the estimated normal physiological value. The analysis of bubble locations and dynamics led us to propose that the fluid squeezing effect between the occluder and the stop in the housing and the streamline contraction effect along the clearance are factors responsible for cavitation incipience.
Fluctuations of the Sympathetic Nerve Discharges in Animals Without Natural Heartbeat
Authors: Yambe Tomoyuki , Nitta Shin–ichi , Naganuma Shigeru , Kakinuma Yoshito , Izutsu Kenji , Akiho Hiroshi , Naganuma Tohru , Kikuchi Yuhichi , Kobayashi Shin–ichi , Ohsawa Noboru , Nanka Shunsuke , Tanaka Motonao , Fukuju Takeo , Miura Makoto , Uchida Naoki , Sato Naoshi , Mohri Hitoshi , Koide Satoshi , Abe Ken–ichi , Takeda Hiroshi , Yoshizawa Makoto
Published: November 2008

Abstract: To assess the effect of artificial circulation on the circulatory regulatory system, rhythmical fluctuations in the cardiovascular system and autonomic nerve discharges were analyzed in animal experiments using adult mongrel dogs. Two pneumatically actuated ventricular assist devices were implanted as total biventricular bypass (BVB) under general anesthesia; then, the natural heart was electrically fibrillated to constitute the BVB part of the complete prosthetic circulation model. All hemodynamic data and sympathetic nerve discharges were recorded and calculated in the computer system by the use of spectral analyzing methods. In the power spectrum of the arterial blood pressure waveform during prosthetic circulation, the Mayer wave peak was significantly decreased though the respiratory wave peak was not signif icantly changed. However, the Mayer wave peak in sympathetic nerve discharges was significantly increased though the respiratory wave peak was not significantly changed. These results suggest that rhythmical fluctuations are a necessary response of the circulatory regulatory system including the autonomic nervous system. However, sympathetic nerve discharges respond to the artificial heart without rhythmical fluctuations.
Gas Transport in the Intracorporeal Oxygenator with Woven Tubes
Authors: TANISHITA KAZUO , PANOL GEORGE , RICHARDSON PETER D. , GALLETTI PIERRE M.
Published: November 2008

Abstract: The woven tubes membrane oxygenator is a suitable configuration for the intracorporeal membrane oxygenator because of a high gas exchange performance and a compact packing of tubing. In this study the oxygen transfer performance of woven tubes was evaluated by an in vitro experiment with an external perfusion mode; the blood flow is outside of the tubes in order to reveal the feasibility of designing the intravascular oxygenator (IVOX) by the woven tubes. The oxygen transfer efficiency of the external perfusion mode is superior to that with the internal perfusion mode because of the larger convective mixing effect on the external surface of the tubes. Thus the use of the external perfusion mode results in the shorter necessary tube length for the rated condition, which enables making the oxygenator unit more compact. All of these features encourage the adoption of the woven tubes for use in the intravascular oxygenator.
Rate of Thrombus Accumulation on Intravenacaval IVOX Devices Explanted from Human Clinical Trial Patients with Acute Respiratory Failure
Authors: IMAI HIROSHI , SCHAAP R. N. , MORTENSEN JD
Published: November 2008

Abstract: The weight gain of IVOX devices removed from the first 49 human clinical trials patients after from 1 to 29 days of implantation into the venae caval blood stream has been assessed. Each patient had received sufficient systemic heparin to maintain activated clotting times between 150 and 200 s while the IVOX device was indwelling. The nature of the material accumulating on the IVOX device was documented histologically as being thrombus in various stages of development. The weight gain findings indicate that an average of 2. 0 g of thrombus accumulates per 24 h on IVOX devices indwelling in the venous blood stream of moderately anticoagulated human acute respiratory failure patients. The rate of weight gain per 24 h of the IVOX device was more rapid during the first 96 h after its implantation than during its second, third, or fourth week of implantation. The accumulated thrombus on the IVOX hollow fibers was associated with a small but measurable decrease (˜ 1%/day) in gas transfer efficiency of the implanted device. The data support the conclusion that IVOX can function effectively and safely without major thrombus formation for up to 29 days in moderately anticoagulated human acute respiratory failure patients.
Late Pathophysiologic Sequelae after Utilization of an Intravenacaval Oxygenator in Experimental Animals
Authors: HENRIE JOHN , IMAI HIROSHI , BAGLEY BARRY , BEZZANT TAMRA , MORTENSEN JD
Published: November 2008

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