bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Excretion Mechanism of a Perfluorochemical Emulsion
Authors: Tsuda Yoshio , Nakura Kazuaki , Yamanouchi Kouichi , Yokoyama Kazumasa , Watanabe Masahiro , Ohyanagi Harumasa , Saitoh Yoichi
Published: November 2008

Abstract: The excretion mechanism of perfluorochemicals (PFC) via the lung has been studied by physicochemical and histochemical methods. Monocytes that had phagocytized PFC particles were found in the lung capillaries, and alveolar macrophages that had phagocytized PFC particles were found in the alveoli. Vacuolated macrophages were observed microscopically in the alveolar space of rats injected with PFC emulsions. The PFC content in alveolar macrophages reached a maximum level of 1.44mg/1 times 108 cells 72 h after injection. It was confirmed by means of a wavelength dispersive x‐ray analyzer that fluorine atoms were present in the vacuolated alveolar macrophages. The peroxidase activity of the PFC‐phagocytizing macrophages suggest that monocytes phagocytize PFC particles in the circulation and migrate to the alveolar space. This study shows that the monocyte/macrophage system is related to one mechanism for excretion of PFC after intravenous injection of PFC emulsions.
Biocompatibility of Hemoglobin Solutions. I. Reactions of Vascular Endothelial Cells to Pure and Impure Hemoglobins
Authors: Feola Mario , Simoni Jan , Fishman David , Tran Rue , Canizaro Peter C.
Published: November 2008

Abstract:Hemoglobin (Hb) solutions can cause vasoconstriction and activation of intravascular coagulation. Because the endothelium plays a major role in the regulation of vascular tone and hemostasis, a study was conducted of human umbilical vein endothelial cells (EC) incubated with various Hbs. Cell injury was evaluated by electron microscopy and the release of lactic dehydrogenase, H2O2, and procoagulant “tissue factor.“ Cell reaction was assessed by the measurement of 6‐keto‐prostaglandin F (PGF)Iα(metabolite of prostacyclin) and thromboxane B2(metabolite of thromboxane A2). Incubation with unmodified bovine hemoglobin for 24 h caused no cell injury and a reaction characterized by 48.4±8.2% increase in 6‐keto‐PGF1αproduction, accompanied by 40.2±9.4% reduction in thromboxane (Tx)B2(compared with a control group of EC incubated with saline solution). Incubation with a nonpure Hb solution (Hb plus red blood cell membrane aminophospholipids; a‐PLs) caused cell injury with significant release of tissue factor, plus a reaction characterized by 97.5±12.5% increase in TxB2production, accompanied by 25.3±3% reduction in 6‐keto‐PGF1α. A second nonpure Hb [Hb plus bacterial environmental endotoxin (E)] caused cell injury, the release of tissue factor, and increased production of both prostaglandins, with greater release of TxB2(197±17%) than of 6‐keto‐PGF1α(112±8.3%). These data indicate that the endothelium reacts differently to pure and nonpure hemoglobins. The biocompatibility of Hb solutions, with regard to vasoconstriction and activation of intravascular coagulation, depends on the absence of stromal a‐PLs and bacterial E.
The Preparation of a Urokinase‐AT‐III‐PGE1‐Methyldopa Complex, and Its Effects on Platelet Adhesion, Coagulation Times, Protein Adsorption, and Fibrinolysis
Authors: Chandy Thomas , Sharma Chandra P.
Published: November 2008

Abstract:Modifications of urokinase by substances possessing useful therapeutic activity permit combined action preparations to be obtained. Here an attempt was made to develop a complex having combined action for therapeutic activity. The possibility of repeatedly modified urokinase with antithrombin‐III‐methyldopa‐prostaglandin E1had been experimentally demonstrated. The complex was immobilized on albuminated substrate, which showed fibrinolytic, anticoagulant, and antiplatelet effects simultaneously, in addition to the normal antihypertensive action of methyldopa. The complex immobilized substrate also demonstrated an increase in albumin‐surface attachment and a reduction in fibrinogen binding. This may be one of the parameters for a reduced platelet‐surface attachment, which may also improve the blood compatibility of the substrate. The approaches suggested indicate the possible new ways of creating nonthrombo‐genic surfaces with wider applications. A better understanding of the mechanism of these complexes are needed in in vivo conditions to correlate these findings.
Eicosanoid Release as Laboratory Indicator of Biocompatibility
Authors: Mahiout A. , Jörres A. , Schultze G. , Meinhold H. , Kessel M.
Published: November 2008

Abstract:Biocompatibility evaluation of extracorporeal devices requires the establishment of sensitive indicators of blood cells/surface interactions. Among others, arachidonic acid derivatives, such as prostaglandins and thromboxanes, play an important role in the cell control systems. Hence, the release of eicosanoids during blood exposure to dialyzer membranes was investigated. Experiments included in vitro incubation of human blood with flat membranes (FM), as well as ex vivo perfusion of hollow fiber membranes (HFM) with blood from healthy volunteers in single‐pass fashion. In both models, a significant release of prostaglandin E2(PGE2) and thromboxane B2(TXB2) was detected. In addition, the amount of eicosanoid release depended on the type of membrane tested. After a 10‐min FM incubation with fresh blood, plasma concentrations of TXB2and PGE2were pronounced by polycarbonate when compared to Cuprophan and poly aery lonitrile. During 10 min of open loop perfusion of HFM, polymethylmethacrylate was the most active biomaterial, whereas the reactivity of Cuprophan was significantly lower. Among HFM, Hemophan was by far the less active. These results indicate that the release of eicosanoids represents a sensitive parameter of blood cells/membrane reactivity. Thus, the question arises as to whether or not the extracorporeal process of cyclooxy‐genase activity could contribute to the clinical side effects of chronical hemodialysis.
Oxygen Tension Monitoring in Uremic Patients During Hemodialysis Treatment
Authors: Morosetti Massimo , Meloni Carlo , Mattia Consalvo , Meschini Luciano , Corradini Silvia , Rocco Monica , Taccone‐Gallucci Massimo , Casciani Carlo Umberto
Published: November 2008

Abstract: The aim of this study was to evaluate the influence on cerebral and cutaneous vascular regions of PaO2 reduction during acetate dialysis, by monitoring conjunctival oxygen tension (PcjO2) and Transcutaneous oxygen tension (PtcO2) during hemodialysis (HD) treatment. The study was performed on 23 patients with end‐stage renal disease in chronic HD. All patients underwent dialytic treatment with cuprophan membranes and acetate containing dialysate. PcjO2 and PtcO2 were recorded and Pao2 and arterial carbon dioxide tension (PaCO2) were also measured. Results of the study show that hypoxemia during acetate dialysis with cuprophan membranes is not accompanied by changes of PcjO2 and therefore by changes in cerebral oxygenation. Moreover, PtcO2 remains constant during dialysis treatment. Furthermore, maintenance of normal oxygen tension at the conjunctival level is not obtained at the expense of the peripheral region of the skin.
Vacuum Generation in Pneumatic Artificial Heart Drives with a Specially Designed Ejector System
Authors: Schima H. , Huber L. , Spitaler F.
Published: November 2008

Abstract: To improve the filling characteristics of pneumatically driven membrane Artificial hearts (AHs), a vacuum is applied during diastole. This paper describes an ejector system for AH‐drivers based on the Venturi effect, which was designed for this purpose. It provides vacuums of more than ‐40 mmHg at flow rates up to 50 1/min requiring a supplying primary gas pressure of less than 150 kPa (1140 mmHg). Under normal working conditions, the necessary supply flow was less than 51/min. The device is small, cheap, quiet and fail‐safe, and has been evaluated successfully in experimental and clinical use.
Errors in Estimates of Peritoneal Fluid Volume
Authors: Daniels Frederick H. , Nedev Nedju D. , Lowe Lisa C. , Leonard E. F. , Cortell T Stanley
Published: November 2008

Abstract: Inherent limitations in the suitability of drainage volumes for monitoring intraperitoneal fluid volume have resulted in the frequent use of indicator dilution techniques, but little attention has been given to confirming the adequacy of the estimates that volume markers provide. In a series of experimental exchanges in rats, volume estimates were compared based on the dilution of blue dextran and hemoglobin with direct collections of surgically exposed intraperitoneal fluid. Significant systematic and random errors in the indicator dilution volume estimates were observed. The systematic errors appeared to be due to the rapid removal of a fixed amount of marker from peritoneal fluid, while the random errors were caused by the rapid appearance of a variable amount of endogenous chromogen. The behavior of the markers observed in this study was not consistent with the assumptions commonly used to analyze volume transport inperitoneal dialysis.
In‐Vitro Assessment of Centrifugal Pumps for Ventricular Assist
Authors: Jakob Heinz , Kutschera Yvonne , Palzer Bodo , Prellwitz Winfried , Oelert Hellmut
Published: November 2008

Abstract: Currently two major types of centrifugal pumps are commercially available for ventricular assist: the Biomedicus‐cone (Group I) and the Centrimed‐impeller pump (now Sarns 3M)(Group II). To compare them for blood trauma and hemolysis, an in‐vitro experiment was designed with a Stöckert roller pump as a standard control (Group III). The in‐vitro circuit was constructed consisting of a pump head, electromagnetic flow probe, polyvinyl chloride tubing and a reservoir, identical for all groups. Human ACD blood was used for priming and was circulated with a flow rate of 2 L/min for 24. h. Blood samples were taken at 0, 1, 3, 6, 12, and 24. h and zero control values were subtracted from the resulting data per time interval. Among the 16 parameters studied, a highly significant difference in favor of Group I was found for glutamate oxalacetate transaminase (GOT) and lactate dehydrogenase (p < 0.0001) and for the free plasma hemoglobin (p < 0.0001) after 12 and 24. h, respectively. The hemolytic index (Allen) again was lowest for group I in contrast to Groups II and III (0.012 versus 0.060 and 1.70) after 24. h. All other parameters studied did not render significant differences between the systems tested. The authors conclude that the Biomedicus pump currently is the least traumatic centrifugal pump for ventricular assist.
Effectiveness of Push/Pull Hemodiafiltration Using Large‐Pore Membrane for Shoulder Joint Pain in Long‐Term Dialysis Patients
Authors: Maeda Kenji , Kobayakawa Hiroyuki , Fujita Yoshiro , Takai Ichiro , Morita Hiroyuki , Emoto Yutaka , Miyazaki Takashi , Shinzato Takahiro
Published: November 2008

Abstract: Long‐term hemodialysis (HD) patients complaining of shoulder joint pain were treated by HD and by push/pull HDF using high‐flux synthetic membranes with large pores (Asahi PAN 20CX2) for 2 weeks. The results showed no significant difference in Kt/Vurea between HD and push/pull HDF. Nevertheless, reduction of the plasma β2‐microglobulin was greater during push/pull HDF than during‐HD. These findings can be explained by far more convective flux in push/pull HDF than in HD: nearly 30 L during push/pull HDF vs. 3 L during HD. In the present study, there was no alleviation of the shoulder joint pain during HD treatment, whereas marked relief of the symptom was found during push/pull HDF treatment. Since the two treatment modalities differ simply in their efficiency in removing larger molecular weight substances, the joint pain alleviation effected by push/pull HDF could well be ascribed to elimination of an unknown larger molecular weight substance causing this symptom. However, a considerable amount of β2‐microglobulin was removed both by HD and push/pull HDF. Therefore, the substance causing the joint pain might be larger than β2‐microglobulin.
A New Multilayered Composite Hollow Fiber Membrane for Artificial Lung
Authors: Kamo Jun , Uchida Makoto , Hirai Takayuki , Yosida Haruhiko , Kamada Kensuke , Takemura Tom
Published: November 2008

Abstract: The gas Transfer performances in a gas/membrane/liquid system were investigated in detail with various membranes. It was found that the oxygen flux in the gas/membrane/liquid system was saturated when the oxygen flux (Fg‐g) in the gas/membrane/gas system became more than 1.0 times 10‐5 cm3 (STP) cm‐2s‐1cm Hg‐1 (Fcg‐g). This was explained as follows: The resistance of a boundary layer at liquid phase is dominant, i.e., the membrane resistance is negligible in the region of Fg‐g which is greater than Fcg‐g. Consequently, Fg‐g of the membrane should be designed to be greater than Fcg‐g, in order to satisfy the gas Transfer performance required for blood oxygenation. On the basis of the results above, we have developed a new three‐layered composite hollow fiber membrane (MHF) consisting of an ultrathin polyure‐thane layer supported between two microporous polyethylene layers to prevent serum leakage. It was shown through the evaluation in vitro that MHF had good gas Transfer performances for long‐term perfusion, and no serum leakage was observed. These characteristics suggest that MHF is quite suitable for long‐term usage such as extracorporeal membrane oxygenation (ECMO).
Transesophageal Echocardiographic Findings of Intracardiac Events During Cardiac Assist
Authors: Nasu Michihiro , Okada Yukikatsu , Fujiwara Hiroshi , Sono Jun , Nishiuchi Sunao , Tatemichi Kiyoshi , Shomura Toyo
Published: November 2008

Abstract: Transesophageal echocardiography (TEE) is an easy, noninvasive and reproducible method for evaluation of left ventricular function, coronary flow patterns, and intracardiac blood flow patterns during cardial assist. TEE facilitated better management of the patients with LVAD and gave us the various information: (a) Observing the drawing catheter tip by TEE, it could be settled just above the mitral orifice to obtain the maximum bypass flow; in addition, dislocation of the catheter tip could be easily diagnosed, (b) The intracardiac thrombus could be clearly detected by TEE; it was removed without complications, weaning from left ventricular assist device (LVAD). (c) The left ventricular wall motion was periodically observed. The end systolic LV diameter (Ds) was decreasing and fractional shortening (%FS) was increasing as the natural heart recovery. Additionally, the pre‐ejection period (PEP) and the ejection time (ET) were measured. The ratio of PEP/ET was decreasing gradually. Ds did not alter with preload change during on‐off testing unlike the other parameters. Ds seems to be the most reliable parameter for the natural heart recovery within certain amounts of bypass flow, (d) The flow velocity in the left anterior descending coronary artery could be measured by Transesophageal Doppler method; it was clinically shown that counterpulsation produced a larger amount of coronary blood flow than copulsation.
Analysis of Clinical Factors for Survival After Left and Biventricular Bypass Using Centrifugal Pump Following Open Heart Surgery in Infants and Adults
Authors: Matsuda Hikaru , Matsuwaka Ryousuke , Kaneko Mitsunori , Kobayashi Tohru , Miyamoto Katsuhiko , Morisaki Hirosi , Kawata Hiroaki , Takami Hirosi , Masai Takahumi , Nakano Susumu , Kawashima Yasunaru
Published: November 2008

Abstract: A total of eight patients, including three infants, received left or biventricular assist using centrifugal pump (CFP) following open heart surgery. Three infants, aged 9–11 months and with complex cardiac lesions, were supported by left heart bypass (LHB) using pediatric type CFP for 63 h, 64 h, and 13 days. All were weaned from LHB, but long‐term survival was not obtained, mainly due to complications. In five adult patients, LHB alone was used in three, and biventricular support in two for 33–240 h with three survivals. The factors related to unsuccessful recovery were delayed start of support and multiorgan failure.
A Method for Constricting Large Veins for Use in Arterial Vascular Reconstruction
Authors: Moritz Anton , Grabenwoger Florian , Windisch Alfred , Horvath Reinhard , Windberger Ursula , Losert Udo , Wolner Ernst
Published: November 2008

Abstract: A satisfactory biologic graft can be created if dilated, but otherwise unusable veins are wrapped with a constrictive mesh tube. The purpose of this study was to determine whether a resorbable constrictive tube creates an appropriately sized vascular graft by induction of neoarterial wall growth. In 8 sheep a 5 cm segment of the carotid artery was resected and the external jugular vein inserted as a tubular graft. The vein was either wrapped with a polydioxanon (PDS) reinforced polyglactin (Vicryl) mesh (n = 4), a Vicryl mesh (n = 4), or a Dacron mesh tube (n = 3) to achieve a diameter reduction to 7 mm. Or the vein was used without reinforcement (n = 3). At angiography after 6 months the unreinforced veins had a diameter of 19 mm (range 15–22). The Vicryl reinforced veins measured 9.4 (8.5–10) mm, but 3 of 4 developed aneurysmatic dilatations at sites of valve sinuses with a mean diameter of 19 (15–21) mm. PDS reinforced veins measured 7.4 mm (7.1–7.9). Two of 4 had minor aneurysms of 13 and 16 mm. The two remaining PDS reinforced grafts were indistinguishable from the native artery. Dacron tubes reduced the vein size reliably to 7.6 (7.5–7.9) mm, but showed narrowing at the proximal anastomoses (PDS 7.2 ± 0.4, Dacron 6.1 ± 0.4, p = 0.016). PDS wrapping reduced maximal graft diameter to 10.9± 4 mm as compared to that of the native vein, 18.7±pL 3.5 (p < 0.05). Resorbable meshes can reduce the diameter of a venous graft by strenghtening the vessel wall. PDS reinforcement needs further technical refinement to prevent local dilatation at the sites of venous valves. Dacron seems to be a safe alternative in this respect but tends to create anastomotic narrowing.
A New Approach for the Filtrate Regeneration System in the Wearable Artificial Kidney
Authors: Tada Yoko , Horiuchi Takashi , Ohta Yuji , Dohi Takeyoshi
Published: November 2008

Abstract: In the filtrate and/or dialysate regeneration system, which is expected to miniaturize the artificial kidney, ammonium decomposed from urea by immobilized urease is removed competitively by ion‐exchangers from coexisting cations. Since divalent cations such as Ca2+ and Mg2+ are more favorably exchanged than ammonium ion, this system needs supplementation of these cations and, thus, additional amount of ion‐exchanger. To minimize these requirements, we utilized positively charged membrane to process cation‐free filtrate in which urea is dialyzed. Positively charged membranes were tested in vitro to evaluate separation efficiency between urea and cations. Equilibrium adsorption of ammonium ion to ion‐exchanger with or without co‐existing cations demonstrates that this filtrate regeneration system can reduce the amount of ion‐exchanger up to one‐half to one‐third of that of the conventional system. In an ex vivo experiment with a mongrel dog, blood urea nitrogen (BUN) concentration was maintained at the same level or up to 23% less than the initial value.
Usefulness of Thrombelastography for Dosage Monitoring of Low Molecular Weight Heparin and Unfractionated Heparin During Hemodialysis
Authors: Shinoda Toshio , Arakura Hideo , Katakura Masafumi , Shirota Toshihide , Nakagawa Seinosuke
Published: November 2008

Abstract: Low molecular weight heparin (LMH) acts as an anticoagulation agent mainly through its anti‐activated coagulation factor X (Xa) activity. Thrombelastography (TEG) is expected to be useful to monitor the dosage of LMH during hemodialysis because reaction time on TEG (TEG‐r) is considered to reflect blood thromboplastin formation time, which depends on the formation of Xa. To test this possibility, we compared the usefulness of TEG, activated coagulation time (ACT), activated partial thromboplastin time (APTT), and anti‐Xa activity in 28 hemodialysis patients using both conventional unfractionated heparin (UFH) and LMH on separate dialysis procedures. Anti‐Xa activity of LMH was comparable to that of UFH when it was measured using both LMH and UFH as standards. Anti‐Xa activity, which theoretically depended on the heparin concentration in blood samples, did not correlate with the degree of dialyzer clotting. The APTT correlated well with anti‐Xa activity in patients using LMH (r = 0.686, p > 0.01) and UFH (r = 0.906, p > 0.01), but not with the degree of dialyzer clotting. The TEG‐r correlated well with the degree of dialyzer clotting both in patients using LMH and those using UFH (measurements of samples obtained from the venous side of the extracorporeal circuit) and weakly correlated with anti‐Xa activity in patients using LMH (r = 0.402, p > 0.05). The ACT did not correlate with the degree of dialyzer clotting or anti‐Xa activity. These results suggest that TEG‐r reflects the efficacy of heparin in the extracorporeal blood circuit, whereas APTT mainly reflects heparin concentration of the blood samples. It appears TEG is useful for dosage monitoring of LMH as well as UFH during hemodialysis.
Estimation of Theophylline Clearance During Continuous Arteriovenous Hemofiltration
Authors: Horton Michael W. , Godley Paul J. , Moore Emory S. , Fineg Jerry , Gillespie William R.
Published: November 2008

Abstract: Pharmacologic agents and other non‐protein‐bound compounds smaller than 5,000 daltons have the potential to be removed by continuous arteriovenous hemofiltration (CAVH). A proposed method for estimating drug clearance by CAVH (ClCAVH) equates ultrafiltrate clearance to the product of the sieving coefficient and the average ultrafiltration rate. This simplified approach for estimating ClCAVH would be a clinically useful method for calculating replacement doses, as it economizes on the sampling and analytical requirements associated with the conventional method. Presented are some theoretical considerations and a brief evaluation of the accuracy of this proposed method. The evaluation was conducted using an animal model whereby CAVH was performed in four male beagles. During the hemofiltration period, an i.v. bolus of theophylline, 6 mg/kg, was administered over 15 s. Samples for analysis of theophylline were collected from the arterial, venous, and ultrafiltrate ports at 0, 5, 15, 30, 45, 60, 90, 120, 180, 240, 360, and 480 min following dosage administration. The volume of ultrafiltrate produced during each collection interval was measured. Theophylline serum concentrations were determined by a high performance liquid chromatography assay. Statistically, the simplified method was found to result in significantly (p < 0.05) larger estimates of ultrafiltrate clearance when compared to the conventional method. However, the average magnitude of difference was only 9% and does not constitute a clinically significant margin between the two methods.
Development of Computer‐Aided Motion Analyzing (CAMA) System for Radiopaque Implanted Tilting Disk Heart Valves
Authors: Ohta Yuji , Horiuchi Takashi , Dohi Takeyoshi , Sugaya Katsuhiko , Matsumoto Hiroshi , Ide Hirofumi
Published: November 2008

Abstract: The newly developed semiautomatic data acquisition and processing system allows Progress in quantitative evaluation of functions of implanted tilting disk valves. In the new system, data acquisition could be carried out semiautomatically by utilizing image processing methods, and the data analysis time was shortened. The system consists of a computer‐controlled cinefilm loading device, a CCD camera, a frame memory, a superimposer, and CRT displays. Since series of the open‐ and shut‐mode frames are commonly observed by turns in normal subjects, data acquisition was carried out manually at the first frame of each mode and semiautomatically from the second frame to the last. By processing the image data with the binarization method, the valve contours were detected, and an open angle and other motion properties can be obtained. Analyzing 90 frames of the cinefilm, this system analyzes data in a time period 20 min shorter than the manual procedure. With the implanted Medtronic Hall valve, a 60 to 65d̀ open angle was calculated.
Bacteria‐ and Endotoxin‐Free Dialysis Fluid for Use in Chronic Hemodialysis
Authors: Bambauer R. , Walther J. , Meyer S. , Ost S. , Schauer M. , Jung W.K. , Göhl H. , Vienken J.
Published: November 2008

Abstract: As the quality of water in the dialysis fluid varies considerably, dialysis fluid is contaminated with a high percentage of bacteria and endotoxins. The bacterial populations contained in the dialysis fluid are as heterogeneous as the chemical structure of the endotoxins that result. The latter can pass through the dialysis membrane whereby high‐flux membranes permit a larger number of retransportable molecules than low‐flux membranes. A central aim toward a future, safe dialysis process should, therefore, be the production of a dialysate that is free of bacteria and endotoxins. As we were able to demonstrate in various examinations, this goal is most likely to be achieved with the aid of sterile filtration using hollow fiber modules of polyamid. To avoid disinfection of the polyamid membrane, as this would only reach bacteria but not endotoxins, the filter was changed after at most 10 h. The achieved dialysis fluid was free of bacteria and endotoxins. We were also able to show that the release of interleukin‐1 was reduced. In addition, side‐effects, such as a drop in blood pressure, headaches, muscular cramps, and nausea, were reduced.
Hepatocyte Culture between Woven Capillary Networks: A Microscopy Study
Authors: Gerlach Jörg , Schnoy N. , Smith Mark D. , Neuhaus Peter
Published: November 2008

Abstract: A multi‐compartment capillary membrane culture model with independently perfused three‐dimensionally woven capillaries was developed for immobilization of hepatocytes in bioreactors. This enables spatial restructuring of cells and enhanced mass transfer performance with more efficient oxygenation and metabolite exchange. Seeding density defines cell behaviour in this model. With low densities cells attach to the membranes and flatten. Increasing density leads to spontaneous formation of aggregates which are immobilized between the capillaries.
Scanning Electron Microscopic Investigation of Catheters for Blood Access
Authors: Bambauer R. , Mestres P. , Pirrung K.J. , Sioshansi P.
Published: November 2008

Abstract: Large‐bore catheters for extracorporeal detoxification methods without and with treated surface with silver or silicone were investigated after removal with a scanning electron microscope and for bacterial colonization. In 42 large‐bore catheters of three different materials, small deposits of fibrin and protein on the inner and outer surface were seen. This second layer covered the entire surface after 3 days and increased to a thickness of 3 to 60 μm during the following days. Bacterial colonization was observed in 38.1%. In contrast to these results, the catheters with the treated outer surface showed a very low thrombogenecity and a low contamination rate of 6.7%.
The Incidence of Subclavian Vein Stenosis Using Silicone Catheters for Hemodialysis
Authors: Beenen Lilian , van Ieusen Rob , Deenik Bert , Bosch Frank H.
Published: November 2008

Abstract: Complications related to the use of silicone subclavian catheters for hemodialysis were prospectively studied in 21 consecutive patients with acute and chronic renal failure. Between July 1991 and December 1992, 34 double‐lumen silicone catheters (Medcomp; 12 French; 20 or 24 cm) were inserted in 21 patients. The mean duration of catheterization was 20 days (range, 2–58 days). Venograms were performed in 16 patients (22 subclavian veins) within 6 months following removal of the catheter. Excluded from angiography were patients whose catheters had been in place less than 1 week or who underwent fewer than 3 dialysis sessions because of minor risk of stenosis. Patients who had ipsilateral repeated catheters were also excluded. Two angiographies showed subclavian vein stenosis, both occurring in the same patient. One showed 50% stenosis with collaterals; one showed 50% stenosis without collaterals. One other complication was a pneumothorax. Catheter thrombosis was observed in 3 patients; catheter sepsis did not occur. We conclude that use of silicone catheters for subclavian cannulation is safe and effective to provide temporary vascular access for acute hemodialysis. The incidence of subclavian vein stenosis is lower compared with polytetrafluoroethylene and polyurethane catheters.
Lateral Catheter Insertion Together with Three Purse‐String Sutures Reduces the Risk for Leakage During Peritoneal Dialysis
Authors: Stegmayr Bernd G.
Published: November 2008

Abstract: Insertion of a catheter is needed to perform peritoneal dialysis. Techniques for insertion vary and have different drawbacks with regard to risk for leakage, secondary peritonitis, and catheter dysfunction. This study includes 85 consecutive patients who underwent a total of 114 insertions; peritoneal dialysis catheters (Tenckhoff, double‐cuffed) were inserted under local anesthesia and using a lateral technique—through the rectus muscle—plus 3 purse‐string sutures. Dialysis in all patients was started in the direct course of insertion of the catheter. One early but no late leakage occurred; leakage occurred in a patient in whom the second purse‐string suture failed. The lateral insertion technique enables immediate start of dialysis and considerably reduces the risk for leakage from peritoneal dialysis fluid.
Combination of Plasma Exchange and Continuous Hemofiltration as Temporary Metabolic Support for Patients with Acute Liver Failure
Authors: Matsubara Shuji
Published: November 2008

Abstract: The combination of plasma exchange and continuous hemofiltration was applied to patients with acute liver failure, and its clinically advantageous effects were evaluated. This procedure was found to be a powerful approach in decreasing patient morbidity; however, the effect was temporary and the patients finally died. Efforts to eliminate the hepatitis virus, which is the main etiology of hepatic necrosis in Japan, are urgent to salvage patients with fulminant liver failure.
The Hepatix Extracorporeal Liver Assist Device: Initial Clinical Experience
Authors: Sussman Norman L. , Gislason Gardar T. , Conlin Carol A. , Kelly James H.
Published: November 2008

Abstract: Eleven patients were treated with the Hepatix extracorporeal liver assist device (ELAD) between June 1991 and August 1993. The first 2 patients were treated according to Food and Drug Administration guidelines (“Emergency Use of Unapproved Medical Devices,” October 22, 1985), and the remaining 9 were treated according to an Investigational Device Exemption (IDE). The goal of the study was to establish the short‐term safety of ELAD therapy, with a focus on acute medical complications such as hemodynamic instability, complement activation, and deterioration of vital organ function. As secondary goals, the metabolic capacity of ELAD cartridges and their clinical impact were assessed. Treatment was considered successful if the patient recovered sufficient liver function to survive weaning from the ELAD or was stabilized until orthotopic liver transplantation was performed. No short‐term safety problems were associated with ELAD use. In addition, metabolic support was documented in 10 of the 11 patients, and 6 patients reached a successful end‐point. The Hepatix ELAD is safe, and it provides measurable metabolic support in patients with late‐stage liver failure. This pilot study provides the impetus to perform controlled trials of ELAD therapy in the treatment of various types of end‐stage liver disease.
Effects of Pyridoxalated Hemoglobin Polyoxyethylene Conjugate and Stroma‐free Hemoglobin on Renal Vascular Responsiveness to Vasoactive Substances in Isolated Perfused Rat Kidney
Authors: Nishi Kazuhiko , Ueda Shoichi , Sato Daisuke , Nishi Katsuhide
Published: November 2008

Abstract:The effects of pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) and stroma‐free hemoglobin (SFH) on vascular responsiveness to various vasoactive substances were examined in isolated perfused rat kidneys. The kidneys isolated from rats were perfused with 6% PHP, 6% SFH, and6%hydroxyethylstarch (HES) solution at a constant flow rate. Vascular responsiveness to acetylcholine (ACh), nitroglycerin (NG), norepinephrine (NE), and angiotensin‐II (ANG‐II) was examined by measuring the perfusion pressure (PP). Effects of inhibition of endothelium‐derived relaxing factor (EDRF) by NG‐monomethyl L‐arginine (L‐NMMA) on NE‐induced and ANG‐II‐induced renal vascular responses were examined. ACh and NG induced a dose‐dependent decrease in perfusion pressure (PP) in all groups. NE and ANG‐II induced an increase in PP in all groups, but NE‐induced and ANG‐II‐induced responses in the PHP‐perfused and SFH‐perfused groups were significantly larger than those in the HES‐perfused group. L‐NMMA did not alter vascular responsiveness to NE and ANG‐II. These results indicate that PHP and SFH do not inhibit EDRF induced by ACh, but hemoglobin moiety per se does augment the vascular responsiveness to NE and ANG‐II in the isolated perfused rat kidney.
Thoughts and Progress: Electromotive Administration of a New Morphine Formulation: Morphine Citrate
Authors: Stephen Robert , Miotti Danilo , Bettaglio Raffaella , Rossi Cino , Bonezzi Cesare
Published: November 2008

Abstract: Two formulations of morphine citrate were synthesized: trimorphine citrate, 3(MH)+(C6H5O7)3– and morphine sodium citrate, 3(MH)+ 3Na+2(C6H5O7)3–. Four healthy individuals volunteered to undergo electromotive administration of the two formulations. Application of electric current (2 mA) to solutions of trimorphine citrate for 1 h resulted in iontophoretic transcutaneous administration of therapeutic quantities of morphine, without deleterious reduction in the pH of the drug solutions. Application of a 2–mA current to solutions of morphine sodium citrate for 2 h resulted in combined iontophoretic and electrophoretic delivery of morphine with increased administration rates and an improved buffering capacity of the drug solutions.
Internal Hydraulic Loss in a Seal‐less Centrifugal Gyro Pump
Authors: Makinouchi Kenzo , Ohara Yasuhisa , Sakuma Ichiro , Damm George , Mizuguchi Kazumi , Jikuya Tomoaki , Takatani Setsuo , Noon George P. , Nosé Yukihiko
Published: November 2008

Abstract: A new index “loss factor Z” defined by Eq. 1 was introduced as the absolute expression of the mock loop resistance for testing a nonpulsatile pump.

Z= 2g/γΔP/Q2 (1)

where γ is specific gravity of the fluid, g is the acceleration of gravity, ΔP is total pressure head, and Q is flow. Z is expected to be constant, regardless of the pumping parameters. Z values obtained in the same mock loop but with different rotary blood pumps were almost identical and were defined as Z0. New methods of analysis of the flow‐restrictive conditions of various rotary blood pumps are proposed in this paper: namely, differential loss factor ΔZ, and loss factor sensitivity ∂Z/∂A. The proposed Z‐Q curves demonstrated better performance mapping than the conventional ΔP‐Q curves. ΔZ is the difference between the Z‐Q curves of two different pumps. A is a design parameter of the pump; therefore ∂Z/∂A is a quantitative expression of the effect of the design change on the hydraulic performance. These various indices were used to analyze the internal hydraulic loss of a centrifugal pump (Gyro pump). The relationship between its gap size (rotor casing) and hydraulic performance was assessed quantitatively by these indices. In this paper, the derivation processes and above‐mentioned indices are described.
Axial Flow Ventricular Assist Device: System Performance Considerations
Authors: Damm G. , Mizuguchi K. , Aber G. , Bacak J. , Akkerman J. , Bozeman R. , Svejkovsky P. , Takatani S. , Nosé Y. , Noon G.P. , DeBakey M.E.
Published: November 2008

Abstract: A cooperative effort between Baylor College of Medicine and NASA/Johnson Space Center is under way to develop an implantable left ventricular assist device for either pulmonary or systemic circulatory support for more than 3 months' duration. Using methodical evaluation and testing, an implantable axial pump has been systematically improved. These improvements include the addition of an inducer as a pumping element in front of the impeller and the construction of an efficient brushless direct current motor. To date, less than 10 W of power is required to generate 5 L/min flow against 100 mm Hg. An index of hemolysis of 0.021 g/100 L has been achieved. Two‐day in vivo feasibility studies in calves are under way to evaluate the antithrombogenic nature of the pump. Further improvements in system efficiency, hemolytic performance, and the antithrombogenic nature of the pump are expected with the use of empirical studies, computer flow modeling, and in vivo testing in calves.
Totally Implantable Total Artificial Heart and Ventricular Assist Device with Multipurpose Miniature Electromechanical Energy System
Authors: Takatani Setsuo , Orime Yukihiko , Tasai Kimitaka , Ohara Yasuhisa , Naito Kozo , Mizuguchi Kazumi , Makinouchi Kenzo , Damm George , Glueck Julie , Ling Jian , Noon George , Nosé Yukihiko
Published: November 2008

Abstract: A multipurpose miniature electromechanical energy system has been developed to yield a compact, efficient, durable, and biocompatible total artificial heart (TAH) and ventricular assist device (VAD). Associated controller‐driver electronics were recently miniaturized and converted into hybrid circuits. The hybrid controller consists of a microprocessor and controller, motor driver, Hall sensor, and commutation circuit hybrids. The sizing study demonstrated that all these components can be incorporated in the pumping unit of the TAH and VAD, particularly in the centerpiece of the TAH and the motor housing of the VAD. Both TAH and VAD pumping units will start when their power line is connected to either the internal power pack or the external battery unit. As a redundant driving and diagnostic port, an emergency port was newly added and will be placed in subcutaneous location. In case of system failure, the skin will be cut down, and an external motor drive or a pneumatic driver will be connected to this port to run the TAH. This will minimize the circulatory arrest time. Overall efficiency of the TAH without the transcutaneous energy transmission system was 14–18% to deliver pump outputs of 4–9 L/min against the right and left afterload pressures of 25 and 100 mm Hg. The internal power requirement ranged from 6 to 13 W. The rechargeable batteries such as NiCd or NiMH with 1 AH capacity can run the TAH for 30–45 min. The external power requirement, when TETS efficiency of 75% was assumed, ranged from 8 to 18 W. The accelerated endurance test in the 42°C saline bath demonstrated stable performance over 4 months. Long‐term endurance and chronic animal studies will continue toward a system with 5 years durability by the year 2000.
Intracorporeal Oxygenation
Authors: RICHARDSON PETER D.
Published: November 2008

Abstract: The dominant problem in the design of an intracorporeal oxygenator is achieving gas transfer rates sufficient for physiological needs in the space available with acceptably low flow resistance to blood. Design problems still to be solved, when configurations with sufficient gas transfer effectiveness are well identified, are biological tolerance (including adequate blood compatibility), ease of manufacture, and prolonged function.
Computer‐Assisted Design of an Implantable, Intrathoracic Artificial Lung
Authors: VASLEF STEVEN N. , MOCKROS LYLE F. , COOK KEITH E. , LEONARD RONALD J. , SUNG JEFFREY C. , ANDERSON ROBERT W.
Published: November 2008

Abstract: A semiempirical mathematical model of convective oxygen transport is used to design a new, low pressure loss, implantable artificial lung that could be used as a bridge to lung transplantation in patients with advanced respiratory failure. The mass transfer and flow friction relations pertinent to the design of a cross–flow hollow fiber membrane lung are described. The artificial lung is designed to transfer over 200 ml/min of oxygen at blood flow rates up to 5 L/min. A compact design and a blood‐side pressure loss of <15 mm Hg allows the device to be implanted in the left chest without the need for a prosthetic blood pump. Surgical implantation of the artificial lung would require the creation of inflow and outflow anastomoses. Oxygen would be supplied via an external source. Blood properties, operating conditions, and empirically determined mass transfer and flow properties are all specified and input into a computer program that numerically solves the design equations. Computer–generated values for the device frontal area, blood path length, and fiber surface area are thereby obtained. The use of this computer–assisted design minimizes the need for extensive trial–and–error testing of prototype devices. Results from in vitro tests of a prototype implantable lung indicate that the mathematical model we describe is an accurate and useful tool in the design of hollow fiber artificial lungs.
Filling a Dialysis Circuit with Albumin Does Not Prevent Platelet Activation During Hemodialysis: In Vivo Study
Authors: BUTUROVI'C JADRANKA , Žemva Žarka , PONIKVAR RAFAEL
Published: November 2008

Abstract: The aim of our prospective clinical study was to evaluate whether filling a dialysis circuit with albumin before hemodialysis (HD) can prevent platelet activation during the procedure. Eight patients with chronic HD participated in the study, each dialyzed first with albumin and a week later without it. All other parameters of the HD procedure were unchanged (cellulose acetate hollow fiber dialyzer, blood flow of 300 ml/min, and low dose heparin). Before HD with albumin, 6. 7% human albumin in saline was recirculated in the dialysis circuit for 10 min at a flow rate of 100 ml/min, and infused into the patient. We found a significant increase in the beta–thromboglobu lin levels during both procedures. We found no difference in plasma coagulation system activation measured by fibrinopeptide A concentration. Neither was there any difference in the macroscopic antithrombotic activity assessed at the end of HD by measuring the volume of clots in the arterial and venous bubble trap and by counting the number of clotted fibers in the dialyzer. It seemed that filling the dialysis circuit, which had a cellulose acetate dialyzer, with human albumin did not improve its thrombogenicity.
Biocompatibility of Heparin‐Coated Membrane Oxygenator During Cardiopulmonary Bypass
Authors: HATORI NOBUO , YOSHIZU HIROSHI , HAGA YOSHIYUKI , KUSAMA YOSHIMASA , TAKESHIMA SHIGETO , SEGAWA DAISUKE , TANAKA SUSUMU
Published: November 2008

Abstract:The biocompatibility of the cardiopulmonary bypass (CPB) circuit, in which an oxygenator is solely heparinized, was assessed by systemic inflammatory reactions as an indicator during CPB. Fourteen patients, 11 males and 3 females, underwent coronary artery bypass surgery and were randomly divided into 2 groups of 7 patients each. For the heparin–coated oxygenator group (Group H), a heparin–coated membrane oxygenator was used in the CPB circuit, and in the control (Group C) an uncoated membrane oxygenator was employed. Systemic inflammatory reactions, such as platelet activation, prostaglandin production, complement activation, and activated granulocyte released substance, were measured prior to, during, and 6 h after CPB. The number of platelets decreased after protamine administration in both groups (14. 5 ±4. 7 times 104/μl in Group H and 13. 8 ± 8. 7 times 104/μd in Group C) and returned to baseline levels in Group H while it remained decreased in Group C at 6 h after CPB. The platelet factor 4 level was significantly lower in Group H (181 ± 40 ng/ml) than in Group C (297 ±131 ng/ml) after protamine administration. Thromboxane–B2(TXB2) rose during CPB in both groups; however, there were significantly different levels of TXB2between the 2 groups at 60 min after CPB (293±258 pg/ml in Group H versus 408 ± 120 pg/ml in Group C) and after protamine administration (259 ± 122 pg/ml in Group H versus 709 ± 418 pg/ml in Group C). Plasma concentrations of granulocyte elastase were significantly lower in Group H at 30, 60 and 90 min, immediately after, and post–CPB than those of Group C. Although the oxygenator was solely heparinized in the CPB circuit, it was sufficiently effective to reduce inflammatory reactions during coronary artery bypass operation, and the heparin–coated surface seems to be more endothelium–like.
Design Improvements of the HIA–VAD Based on Animal Experiments
Authors: EILERS R. , HARBOTT P. , REUL H. , RAKHORST G. , RAU G.
Published: November 2008

Abstract: Since 1990, development of the Helmholtz–Institute at Aachen ventricular assist device (HIA–VAD) was mainly based on animal tests performed at the University of Groningen. Although various in vitro tests had been performed previously, animal testing resulted in significant improvements of the HIA–VAD with regard to hemodynamics and pump handling. The most important design improvement was a new trileaflet polyurethane valve, which was designed as a blood–pump valve with an emphasis on opening behavior and flow resistance. Excellent hydrodynamic performance and sufficient durability of this new valve were confirmed by various in vitro tests. Further design and manufacturing improvements resulted in a completely transparent pump, which can be easily deaired and optically controlled. Final pump design was evaluated during subsequent animal tests, and the results are very promising in view of an efficient cardiac support system. Key Words: Ventricular assist devices–Development–Design–In vitro test–FEM analysis.
Development and Clinical Assay of the BCM Ventricular Assist Device
Authors: DEL CAÑIZO JUAN F. , ANTORANZ J. CARLOS , DESCO M. MAR , ALVAREZ‐VALDIVIELSO J. MIGUEL , FERNANDEZ‐CALEYA DIEGO , LÓPEZ MIGUEL , GARCIA‐BARRENO PEDRO , DUARTE JUAN
Published: November 2008

Abstract: The development of a ventricular assist device is depicted. The seven subprograms that make up the project are described briefly. Results obtained during the clinical assay showed that the new design of the input cannula working as a false auricle provides better efficiency, as well as a certain level of autoregulation for the device.
Experimental In Situ Conditioning of the Latissimus Dorsi Muscle for Circulatory Assist by Multichannel Stimulation
Authors: ROLLER R. , GIRSCH W. , HUBER L. , RAB M. , STÖHR H. G. , SCHIMA H. , LOSERT U. M. , WOLNER E. , THOMA H.
Published: November 2008

Abstract: This study was undertaken to survey the changes in force and fatigue of the latissimus dorsi muscle during transformation into a fatigue–resistant muscle by indirect or nervous multichannel stimulation. In sheep, a silicone chamber connected to a pressure–transducing system was implanted under the left latissimus dorsi muscle. Muscle conditioning was performed by multichannel (carousel) stimulation of the thoracodorsal nerve. The program was started with active periods of 10 min/h producing 10 tetanic contractions/min. It was increased until 70 contractions/min could be performed during 24 h. The changes of muscle force and fatigue were monitored by the silicone balloon system. After a mean period of 22 weeks, fatigue resistance was reached. The fatigueresistant muscle was able to produce a pressure of about 100 mm Hg in the balloon. After finishing the conditioning procedure, muscle forces and the fatigue resistance of the conditioned muscle were evaluated. The conditioned muscle showed only a minimal decrease of force during 20 min. Under a preload of 20 N, it exhibited a maximum tetanic tension of 95 N.