bluuebunny/crossref_metadata_2025 huggingface dataset:
Prognostic Indices of Survival in Patients Supported with Temporary Devices (Tah, Vad)
Authors: Pavie A. , Muneretto C. , Aupart M. , Rabago G. , Leger Ph. , Tedy G. , Bors V. , Gandjbakhch I. , Cabrol C.
Published: March 2018

In an attempt to identify current indications and patient selection criteria for the use of mechanical circulatory support, we reviewed our experience in 83 patients who received a total artificial heart (TAH; n = 43), ventricular assist device (VAD) (n = 13), centrifugal pump (n = 17) or extracorporeal membrane oxigenation (ECMO) (n = 8) as a bridge to transplantation (Group I, n = 50) or for recovery from heart failure (Group II, n = 33). Comparing patients successfully transplanted (n = 20) or weaned (n = 9) who survived initial hospitalization, and those who died on mechanical support, there were no differences in preoperative renal, hepatic or pulmonary functions. Postoperative urinary output and bilirubin levels were the earliest variables affecting survival, and urinary output 24 hours after implant was discriminative in patients who survived (p < 0.01). Age (above or below 40 years) and modality of terminal heart failure (acute versus chronic) were the most important factors affecting survival in the bridge to transplant group: 82% of young patients with acute decompensation were transplanted and 63% are long-term survivors while all patients over 40 years with chronic heart failure died on mechanical support (MS). In postcardiotomy patients, duration of cardiopulmonary bypass (CPB) was significantly different comparing survivors with those who died in either bridge or recovery groups and all patients who had a CPB > 4 hours died on MS or after transplantation or weaning. In conclusion, preoperative indices indicating reversibility of multiple organ dysfunction remain to be identified. In the future however MS could be used in all desperately ill candidates for heart transplantation to establish the reversibility of multiple organ dysfunction and avoid a waste of donor organs. Selection of patients remains the most important factor influencing results of mechanical circulatory support procedures.
Computational Fluid Dynamics of Artificial Heart Valves
Authors: Dubini G. , Pietrabissa R. , Fumero R.
Published: March 2018

A large number of in vitro studies during the last thirty years have assessed the fluid dynamic behavior of different artificial heart valves. The present study illustrates the utility of the Finite Element Method for fluid dynamic evaluation of prosthetic heart valves. The valves investigated were the Bjork-Shiley Convex-Concave (curved disc), the Medtronic-Hall (flat disc) and the Carbomedics (bileaflet). These three types were chosen in order to clarify the role of different occluder geometries on global and local fluid dynamics. The Finite Element Method was used to calculate pressure and velocity fields in the fluid domain around each valve. There were significant differences, mainly in local fluid dynamics, between the three valves. The Reynolds number also plays an important role.
Time Delay Compensation for Closed-Loop Insulin Delivery Systems: A Simulation Study
Authors: Reboldi G.P. , Home P.D. , Calabrese G. , Fabietti P.G. , Brunetti P. , Benedetti M. Massi
Published: March 2018

Closed loop insulin therapy certainly represents the best possible approach to insulin replacement. However, present limitations preclude wider application of the so-called artificial pancreas. Therefore, a thorough understanding of these limitations is needed to design better systems for future long-term use. The present simulation study was designe: to obtain better information on the impact of the measurement delay of currently available closed-loop devices both during closed-loop insulin delivery and blood glucose clamp studies, and to design and test a time delay compensator based on the method originally described by O.J. Smith. Simulations were performed on a Compaq Deskpro 486/25™ personal computer under MS-DOS™ operating system using Simnon™ rel. 3.00 software. There was a direct relationship between measurement delay and amount of insulin delivered, i.e., the longer the delay the higher the insulin dose needed to control a rise in blood glucose; the closed-loop response in presence of a time delay was qualitatively impaired both during insulin delivery and blood glucose clamp studies; time delay compensation was effective in reducing the insulin dose and improving controller stability during the early phase of clamp studies. However, the robustness of a Smith's predictor-based controller should be carefully evaluated before implementation in closed-loop systems can be considered. 1)

1) Compaq Deskpro is a trademark of Compaq Computer Corporation; MS-DOS is a trademark of Microsoft Corporation; Simnon is a trademark of SSPA Systems.
Dynamic Filtration of Blood: A New Concept for Enhancing Plasma Filtration
Authors: Ding L. , Laurent J.M. , Jaffrin M.Y.
Published: March 2018

We have shown previously that blood flow pulsations created by intermittent squeezing of the inlet blood line significantly increased the plasma filtration rate in membrane plasmapheresis. However, in order to avoid hemolysis, the filtration increase had to be limited to about 50%. We have now devised a more efficient pulsation generator. By properly matching the tubing compliance and the pulsation amplitude, it is possible to extract 50 ml/min of plasma from 90 ml/min of blood at 36% hematocrit with a 1000 cm2 polypropylene hollow fiber filter without hemolysis. Simultaneous recording of the time course of plasma filtration rate measured by an electromagnetic flow meter and transmembrane pressure showed that the increase in mean plasma flow rate was due to a dynamic filtration process which prevents the establishment of concentration polarization. The transmembrane pressure (Ptm) increases over a 0.5-second interval when the tube is squeezed. The membrane responds with an increase in filtration since the concentration polarization layer takes a few seconds to build up. The Ptm then drops when the tube is released before the polarization layer has time to build up appreciably and a sudden acceleration of the blood flow (velocity spike) helps clean the membrane, reducing the polarization. Tests with bovine blood show that the system is very efficient in reducing membrane plugging with small area filters.
In vivo Comparative Evaluation of Hemodialysis Tubing Plasticized with DEHP and TEHTM
Authors: Christensson A. , Ljunggren L. , Nilsson-Thorell C. , Arge B. , Diehl U. , Hagstam K-E. , Lundberg M.
Published: March 2018

The migration of plasticizers from blood lines was studied in 11 patients with chronic renal failure on hemodialysis for a period of six months. Di-2-ethylhexylphthalate (DEHP), the conventional plasticizer, was compared with tri-2-ethylhexyltrimellitate (TEHTM). A liquid chromatography method for quantitative determination of DEHP and TEHTM in human blood plasma is described. During treatment with tubing containing DEHP, the plasma level of DEHP rose from 0.10 μg/ml (<0.05-0.17 n=11) to 0.70 μg/ml (0.30-1.6 n=11). When the patients were changed to tubing containing TEHTM, the concentration of DEHP was below or close to the detection limit and TEHTM could not be detected. No adverse events of either tubing were found as regards acute toxic effects, performance or applicability.
Effect of Ethanol Perfusion on Creatinine Removal in a Roux-Y Intestinal Segment
Authors: Koszuta J.J. , Carter J.M. , Ash S.R.
Published: March 2018

Five rats and 2 goats had a bypass operation to allow infusion of sorbents through an inlet ostomy. The sorbents passed through one limb of intestine isolated from food contact to join a food limb which included 30-40% of the original length of small intestine. In goats, serum creatinine levels were elevated by infusion of sterile creatinine solutions intravenously. Twenty-four hour urines were collected before, during and after periods of infusion of sorbents into the inlet ostomy. Infusion of charcoal into the ostomy had little effect on the total daily urinary creatinine excretion (TDUC). However infusion of 4.3 g/kg/day ethanol decreased the TDUC significantly, in both species. In rats, 8.6 g/kg/day ethanol infusion had an even greater effect on TDUC. Studies of intraluminal creatinine concentration in the distal part of the sorbent segment indicated that especially when serum concentration of creatinine is over 2 mg%, ethanol greatly increases the intraluminal creatinine concentration in the intestine. It is concluded that ethanol, in combination with intestinal sorbents or alone, could allow intestinal dialysis to remove considerably more creatinine, and possibly aid transport of other organic substances.
Principle of Operation, Design Criteria and Fluid Dynamics of a new Bileaflet Heart Valve Prosthesis
Authors: Pietrabissa R. , Marconi W. , Fumero R.
Published: March 2018

Bileaflet heart valves show the best fluid dynamic behaviour among mechanical valves and, as a consequence, give the best clinical results. A new bileaflet heart valve has been designed whose main characteristics are the kind of leaflet movement, low profile, fluid dynamics and material.

Two flat leaflets move freely inside a very low profile housing ring. The movement is described by the rolling without sliding of the leaflet surface around a cylindrical surface on the inner wall of the housing. The opening angle is 85°. Both the leaflets and the housing are machined from a solid piece of titanium and then covered with carbon by ion beam techniques. The design phase and the first fluid dynamic evaluation were done by numerical methods.
A new Glucose Clamp Algorithm: Clinical Validation
Authors: Campostano A. , Altomonte F. , Bessarione D. , Casu M. , Triolo A. , Lamedica G.
Published: March 2018

A new glucose clamp technique for in vivo studies of insulin sensitivity was validated clinically. Eighteen patients (10 males, 8 females, age 35-80 years, body mass index 34.6-17.04) were connected to a computer-assisted artificial pancreas “Betalike R”, using a new algorithm based on a “minimal model”, to carry out the glucose clamp technique automatically and especially to overcome the well-known problems of its priming phase. We performed the euglycemic hyperinsulinemic clamp in four patients and the hyperglycemic hyperinsulinemic clamp in 14. In one patient both clamps were done. The mean priming time to reach steady-state glycemia was 20 min. Plasma insulin concentrations were measured every 20 min. This new automatic glucose clamp technique enables the priming phase to be run without any significant overshoot, and accidental variations of glycemia in steady state were reduced to a minimum. The system showed satisfactory safety and stability in controlling the patient's glycemia and assured high speed of the priming phase.
Endothelial cell Seeding: Coating Dacron and Expanded Polytetrafluoroethylene Vascular Grafts with a Biological Glue Allows Adhesion and Growth of Human Saphenous Vein Endothelial cells
Authors: Mazzucotelli J-P. , Klein-Soyer C. , Beretz A. , Brisson C. , Archipoff G. , Cazenave J-P.
Published: March 2018

The establishment of an endothelial lining on vascular grafts to obtain a highly thromboresistant surface in a clinical situation requires optimization of cell collection, quality, adhesion and growth. We have studied the conditions for collection, seeding and growth of human saphenous vein endothelial cells (HSVEC), on Dacron or Gore-Tex expanded polytetrafluoroethylene (PTFE) vascular grafts. Carefully handled veins, as opposed to veins obtained using the usual procedures for coronary bypass graft preparation, yielded a higher rate of successful culture (94% vs 43%) and reached confluence in primary culture sooner (9.4 ± 3 days vs 13.4 ± 4.5 days). HSVEC were seeded at a density of 6x103 cells/cm2 on graft fragments coated with fibronectin (FN) or Transglutine (TGL), a biological glue. There was no HSVEC adhesion on Dacron or PTFE without protein pretreatment of the artificial surface. FN improved HSVEC adhesion but there was no cell growth. Adhesion, doubling time and cell density at confluence on PTFE pretreated with TGL were similar to those on conventional tissue culture polystyrene (TCP) pretreated with TGL or FN. HSVEC adhesion on Dacron pretreated with TGL was lower than on TCP pretreated with TGL; the doubling time was similar but the density at confluence was 40% lower. We conclude that pretreatment of vascular grafts with TGL, besides being an alternative to preclotting of the Dacron graft, allows adhesion and growth to confluence of HSVEC on these surfaces.
Pyrolytic Carbon Coating Enhances Teflon and Dacron Fabric Compatibility with Endothelial cell Growth
Authors: Sbarbati R. , Giannessi D. , Cenni M.C. , Lazzerini G. , Verni F. , De Caterina R.
Published: March 2018

Compatibility with endothelial cell attachment and growth appears to be an important requisite of vascular prosthetic materials, possibly influencing thrombosis, pseu-dointimal hyperplasia, and accelerated atherosclerosis at the site of blood-material interaction. Since deposition of pyrolytic carbon (PC) on prosthetic surfaces has been associated with enhanced hemocompatibility, in the present study we assessed whether a thin layer (0.5 μm) of PC deposited onto materials such as knitted Teflon® and Dacron® enhanced endothelial cell attachment and growth. Cultured human umbilical vein endothelial cells (HUVEC) were seeded at a density of 4.5 x 104 cells/cm2 on PC-coated and uncoated grafts. In order to quantify endothelial cell attachment on the fabrics, the area of Teflon and Dacron fabrics covered by endothelial cells was estimated on day 2 after seeding using the point counting method in scanning electron micrographs. Subsequently, on days 2 and 4 after seeding, endothelial cell proliferation was measured both as number of endothelial cells and as total proteins of the endothelial cells covering the fabrics. On day 2 endothelial cell growth on PC-coated fabrics was greater (mean ± SE; area 42.3 ± 9.9 mm2, n = 6; cell number 3.9 x 104 ± 3.03 x 103 cells, n = 4; total proteins 14.9 ± 1.2 μg, n = 4) than on uncoated fabrics (area 10.6 ± 4.6 mm2, n = 6; cell number 2.9 x 104 ± 4.3 x 103 cells, n = 4; total proteins 11.3 ± 1.7 μg, n = 4; P < 0.001, < 0.05 and < 0.05, respectively). On day 4 (n = 6) endothelial cells showed marked proliferation and both cell number and total proteins were still significantly higher on PC-coated fabrics (mean ± SE: cell number 1.9 x 106 ± 1.5 x 105 cells, total proteins 754 ± 57 μg) than on the uncoated ones (cell number 1.4 x 106 ± 5.9 x 104 cells; total proteins 567 ± 23 μg, P < 0.05 for both comparisons). LDH activity (a measure of cytotoxicity) and prostacyclin (PGI2) production (a measure of activation of arachidonic acid metabolism, in the culture medium were both less (P < 0.01) in the presence of PC-coating than in its absence.

We conclude that a thin PC film on Teflon and Dacron knitted fabrics enhances in vitro endothelial cell attachment and growth and reduces LDH leakage and activation of arachidonic acid metabolism in endothelial cells.
Aluminum-Citrate Interaction in End-Stage Renal Disease
Authors: Rudy D. , Sica D.A. , Comstock T. , Davis J. , Savory J. , Schoolwerth A.C.
Published: March 2018

The influence of a sodium citrate/citric acid mixture on the gastrointestinal (Gl) absorption of aluminum (Al) from an Al(OH)3 preparation was evaluated in six stable maintenance hemodialysis patients. Plasma Al concentrations were determined serially after each of the following treatment sequences (I) Al(OH)3; (II) Al(OH)3 + sodium citrate/citric acid; (III) sodium citrate/citric acid; (IV) Al(OH)3 + NaHCO3. AUC0-8 for plasma Al from 0 to 8 hours was significantly greater (p < 0.05) for Al(OH)3 + sodium citrate/citric acid (73 ± 23 μg · hr/l; mean ± SEM) than Al(OH)3 (16±30 μg·hr/l); sodium citrate/citric acid (-27±14 μg·hr/l); or Al(OH)3 + NaHCO3 (6±22 μg·hr/l). The 24 hour Al level remained above baseline (p < 0.03) following Al(OH)3 + sodium citrate/citric acid (31±12 (pre) vs 54+14 μg/l (post), in contradistinction to study limb: I (34±14 vs 30±12 μg/l); III (79±40 vs 65±35 μg/l); and IV (71±37 vs 66±42 μg/l). We conclude that the Gl absorption of Al from Al(OH)3 is enhanced by citrate in patients undergoing hemodialysis and that elevations of plasma Al persist longer. The concomitant administration of citrate and Al-containing phosphate (PO4) binders should be avoided in patients with end-stage renal disease (ESRD). NaHCO3 may serve as an alternative therapy for metabolic acidosis with less risk of enhancing Al absorption.
Using Ultrapure Water in Hemodialysis Delays Carpal Tunnel Syndrome
Authors: Baz M. , Durand C. , Ragon A. , Jaber K. , Andrieu D. , Merzouk T. , Purgus R. , Olmer M. , Reynier J.P. , Berland Y.
Published: March 2018

Since 1977, our patients have undergone chronic HD with ultra-pure dialysate (UPD), defined as having endotoxin levels below 0.008 ng/ml and less than 1 bacteria/ml of dialysate. We evaluated the incidence of carpal tunnel syndrome (CTS) in three groups of patients. Group I (GI), 84 patients, dialysed for 6.1 ± 3.2 years (mean ± SD) with UPD only; Group II (GII), 39 patients, first dialysed for 3.7 ± 2.3 years with non-UPD and afterwards for 8.4 ± 2.1 years with UPD; Group III (G III), 103 patients treated for 6 ± 5.9 years exclusively with non-UPD. All patients were dialysed with cuprophan or cellulose acetate membranes.

Results, expressed by Kaplan-Meier actuarial survival curves as the percent of patients without CTS, show that CTS occurred significantly less in GI than in GIII. This may be due to less stimulation of monocytes resulting from the absence of bacteria, endotoxins and pyrogens in the dialysate which would reduce the stimulation of cytokines release, interleukin 1 and 6, and tumor necrosis factor, known to stimulate β2 microglobulin synthesis.
Adherence of Blood Cells to Dialyzer Membranes as a Measure of Biocompatibility
Authors: Kjellstrand P. , Okmark P. , Odselius R. , Thysell H. , Riede G. , Holmquist B.
Published: March 2018

Cell adherence to plate dialyzer membranes was analysed at the end of 4 hours of dialysis. Three types of membranes were examined: Cuprophan® Hemophan® and Gambrane®, (a polycarbonate membrane). The membranes were mounted in dialyzers that contained 23 layers of one membrane type and one layer of each of the two other. Less leukocytes adhered to the Pc than to the Cu and He membranes. Transient initial complement activation during dialysis, which was considerably lower with dialysers containing mainly Pc membrane, was not correlated to adherence of cells to the membranes. Instead flow geometry is proposed as the main factor determining the adherence. Contrary to what has been earlier suggested, we think that leukocyte adherence is not a very suitable measure of membrane biocompatibility. The reason is that the influence of membrane surface-chemical factors can not be separated from mechanical factors due to the design of the device.
In Vivo Demonstration of the Haldane Effect during Extracorporeal Gas Exchange
Authors: Hoffmann B.H. , Böhm S.H. , Morris A.H. , Simon B. , Mottaghy K.
Published: March 2018

During the extracorporeal support (LFPPV-ECCO2R) of 11 patients suffering from severe lung failure (ARDS), we consistently noticed a higher arterial than mixed-venous PCO2 in blood samples drawn at the same time. Two explanations are possible: a) the Haldane effect (HE), b) CO2 from lung tissue metabolism. In order to distinguish changes in PCO2 due to the HE from those due to tissue CO2 production, CO2 content (CCO2) was calculated. The results were compared to animal experiments with hyperoxic apnea, after which arterial and mixed-venous samples were drawn simultaneously. All blood gas samples were analyzed for pH, PCO2, PO2, and 02-saturation, from which CCO2 was calculated. In both groups, PaCO2 was 2.15 mmHg (2.7 mmHg respectively) higher at a lower CaCO2 (-2.87 ml/l, -14.9 ml/l). Oxygen saturation increased by 8.1% in the human group and 17.8% in the animal group. A significant relationship was found between changes in PCO2 and changes in 02-saturation. This is a demonstration of the Haldane effect.
Cardiac Output Requirements and Maximum Dimensions for a Neonate Total Artificial Heart
Authors: Koppert E. , Pantalos G.M. , Tieleman R. , Swier P. , Burns G.L.
Published: March 2018

Two equally important issues need to be addressed during the early stages of the design of an implantable total artificial heart (TAH): proper anatomical fit and cardiac output capacity. As part of a first-time feasibility study to develop a neonate-size TAH, two studies were conducted to establish useful anatomical and physiological standards. The first (Study A) was conducted to determine the maximum dimensions of a neonate-size TAH. Twelve preserved hearts from full-term neonates with the hypoplastic left heart syndrome were examined.

A second study (Study B) was designed to determine the acceptable minimum stroke volume compatible with minimum neonate cardiac output requirements. This study was based on a combination of: a) reported cardiac output studies in healthy term neonates, and term neonates with heart failure, b) body weight range, and c) limiting factors of TAH technology, e.g., valvular regurgitation and leveling off of the maximum cardiac output value at a specific heart rate and filling pressure. The proposed neonatal standards for TAH technology are presented.
Heparin-Coated versus Non-Coated Surfaces for Extracorporeal Circulation
Authors: Mottaghy K. , Oedekoven B. , Pöppel K. , Kovacs B. , Kirschfink M. , Bruchmüller K. , Kashefi A. , Geisen C.
Published: March 2018

Studies were made to compare completely heparin-bonded (HBS) and conventional extracorporeal circulation surfaces using capillary membrane oxygenators (CMO) in sheep and dogs for up to five days. The aims were: to investigate the need for systemic heparinization in the case of heparincoated surfaces, to assess blood compatibility and gas exchange performance of both systems and the extent of complement activation, and to find solutions for plasma leakage by the use of CMO. All studies were performed under standardized conditions, such as drugs, surgery, priming, blood flow rate etc. For heparin-coated surface studies all blood interfaces (CMO, catheters, tubes, etc) were coated. It was possible to eliminate systemic heparinization totally when HBS were used. During the five-day non-heparin application period blood coagulation parameters were almost unchanged and in the physiological range, platelets did not drop below 80%, hemolysis was negligible and gas exchange performance was unaffected. Less complement activation occurred with HBS than with non-coated surfaces
Modification of the Influence of Biomaterials on Contact Activation
Authors: Sundaram S. , Irvine L. , Courtney J.M. , Lowe G.D.O.
Published: March 2018

Knowledge of the influence of biomaterials on the contact phase activation of blood is important. Consequently, it is important to examine if the biomaterial influence is modified by the action of anticoagulants. Contact activation was determined by measuring FXII activity (FXIIA) by a chromogenic substrate assay. Cuprophan in the absence of anticoagulants and in the presence of heparin, low molecular weight heparin (LMWH) and hirudin was compared with controls. The controls were a polystyrene incubation test cell (PS) and two polyamide membranes, NR (zeta potential -28.6 mv and NRZ (zeta potential - 18.0 mv). The investigation has confirmed that measurement of FXIIA is material dependent and demonstrated that contact activation can be mediated by antithrombotic agent.
Characterization of Hemophan Hemodialysis Membranes by Thermoporometry
Authors: Broek A.P. , Bargeman D. , Sprengers E.D. , Smolders C.A.
Published: March 2018

A new wet-state membrane characterization method, thermoporometry, was used to study the effect on membrane structure of commonly used sterilization methods for artificial kidney membranes. The porosity and pore size distribution of differently sterilized hollow fiber Hemophan hemodialysis membranes were determined. Also the effect of a glycerol treatment (before sterilization) on porosity and pore size distribution after sterilization was studied. Hemophan was found to have a pore size distribution of pores with radii between 1.5 and 12 nm. Most of the samples had a maximum pore volume at a pore radius of 2.5 nm, only the steam sterilized and non glycerol treated sample had a maximum pore volume at 1.5 nm. The porosity was found to vary between 14 and 31% and was dependent on the applied treatment
Biochemical Assessment and Clinical Evaluation of a Bilirubin Adsorbent Column (Br-350) in Critically ILL Patients with Intractable Jaundice
Authors: Geiger H. , Klepper J. , Lux P. , Heidland A.
Published: March 2018

We investigated the efficacy of an anion-exchange adsorbent column (ASAHI BR-350, DIAMED) for removal of bilirubin and bile acids in five patients with intractable jaundice of various origin. Four litres of plasma were separated by membrane plasma separation (Plasmaflow OP-05) at a rate of 22.5 ml/min. The plasma was then perfused through an anion exchange adsorbent and returned to the venous blood line of the plasma separator. In some of the patients this procedure was combined with regular hemodialysis treatment. The concentration of total bilirubin was cut by 31 to 60%; total bile acids were reduced by 20 to 74%. Three patients recovered and had a favourable outcome. Two patients died despite the bilirubin adsorption treatment. The effects of the adsorbent column on specific blood parameters, including the coagulation system, were measured. Our data suggest that bilirubin adsorption should be examined further as a treatment for critically ill patients with intractable jaundice.
Phagocyte Metabolic Activity during Hemodialysis with Different Dialyzers Not Affecting the Number of Circulating Phagocytes
Authors: Vanholder R. , Van Landschoot N. , Waterloos M.A. , Delanghe J. , Van Maele G. , Ringoir S.
Published: March 2018

Overall leukocyte counts decrease during certain forms of hemodialysis, but little information is available on the intradialytic evolution of phagocytic metabolic function, especially during dialysis with dialyzers not affecting the number of circulating phagocytes. This study evaluated the phagocytic capacity of granulocytes and monocytes to generate CO2 out of glucose under basic unchallenged conditions and after stimulation with latex or zymosan, before and after 15, 60 and 240 minutes of dialysis with reused cuprophan, AN69S, polysulphone, polymethylmethacrylate and hemophan hemodialyzers. Phagocytic metabolic function was assessed in whole blood on the basis of 14CO2-production from labelled glucose during the phagocytic process. There were no changes in basic unchallenged CO2-production with any of the dialyzers. Reactivity to latex and zymosan, expressed per number of phagocytes, showed no decrease, irrespective of the membrane type. For polymethylmethacrylate and reused cuprophan, a slight but significant increase in metabolic reactivity was observed in response to latex and zymosan. The test employed may give a screening picture of the phagocytic reaction to contact with dialyzers and membranes and thus of their degree of biocompatibility towards the phagocyte system.
Errors in Fluid Balance with Pump Control of Continuous Hemodialysis
Authors: Roberts M. , Winney R.J.
Published: March 2018

The use of pumps both proximal and distal to the dialyzer during continuous hemodialysis provides control of dialysate and ultrafiltration flow rates, thereby reducing nursing time. However, we had noted unexpected severe extracellular fluid depletion suggesting that errors in pump delivery may be responsible. We measured in vitro the operation of various pumps under conditions similar to continuous hemodialysis. Fluid delivery of peristaltic and roller pumps varied with how the tubing set was inserted in the pump. Piston and peristaltic pumps with dedicated pump segments were more accurate. Pumps should be calibrated and tested under conditions simulating continuous hemodialysis prior to in vivo use.
Clinical Evaluation Gf Right Ventricular Function in Patients with Left Ventricular Assist Device (Lvad)
Authors: Bennink G.B.W.E. , Noda H. , Duncan J.M. , Frazier O.H.
Published: March 2018

Right ventricular function (RVF) during LVAD support can be a threat for patient survival. Despite extensive research, RVF and its interference with left heart function is unclear. This study examines RVF in a retrospective analysis of 14 patients. Hemodynamic data were collected, including heart rate (HR), central venous pressure (CVP), mean pulmonary artery pressure (mPAP), total cardiac output (CO), calculated stroke volume index (SVI) and right ventricular stroke work index (RVSWI). In all patients, CO increased gradually throughout the study period; CVP showed no significant decrease; mPAP and PCWP decreased significantly over the time period; SVI improved and RVSWI increased from the starting level prior to implantation of the LVAD. We conclude that the CO improved with a lowering of the right ventricular afterload combined with a decrease in total circulating volume. The improvement of RVF with LV assist makes this device an option as a bridge to transplant.
Mechanical Support of the Left Ventricle in Ischemia Induced Left Ventricular Failure: An Experimental Study
Authors: Zobel G. , Dacar D. , Kuttnig M. , Rödl S. , Rigler B.
Published: March 2018

Objective

this study compares the hemodynamic effects of intraaortic balloon pumping (IABP), left ventricular assist device (LVAD), and extracorporeal membrane oxygenation (ECMO) in left ventricular failure in pigs.

Methods

In 29 pigs weighing 12 + 0.7 kg left ventricular failure was induced by ligating the left anterior descending coronary artery. Eight animals served as controls. Eight pigs were treated by IABP, seven by LVAD, and six by ECMO. The study period lasted four hours. Hemodynamic and oxygen transport/ uptake parameters were measured continuously or intermittently.

Results

Six animals of the ECMO and LVAD groups survived the 4 hour period, but only 3 and 4 animals of the IABP and control groups survived (p<0.05). Cardiac index decreased about 48% and 22% in the control and IABP groups (p<0.05), whereas there was only a slight decrease in the ECMO (9%) and LVAD (14%) groups. Oxygen delivery fell significantly in the control and IABP groups (p<0.05), compared with only a slight change in the LVAD and ECMO groups.

Conclusion

ECMO is the most effective system for temporary circulatory support in severe ventricular failure. LVAD maintains cardiac output when pulmonary blood flow is provided. IABP is less efficient in supporting the failing heart, especially in the presence of severe ventricular arrhythmias.
Sodium Pump Activity in Uremic Erythrocytes: A Microcalorimetric Study
Authors: Gallice P. , Kovacic H. , Baz M. , Berland Y. , Elsen R. , Sari J-C. , Crevat A.
Published: March 2018

Erythrocyte thermogenesis was studied by flow microcalorimetry in 25 healthy subjects and 27 uremic patients. The heat production (HP) from cells in plasma, decrease in HP induced by ouabain (a specific sodium pump inhibitor) and index of rate response to ouabain action were measured. HP was higher in uremic patients than controls. Sodium pump inhibition with ouabain induced the same decrease in HP in the two groups. The index of rate response to ouabain action was lower in uremic patients than in controls. The difference in total HP may be due to a different age distribution of erythrocytes. Mean sodium pump activity was identical in the two groups, but some patients had lower activity than controls. Ouabain seems to act more slowly in many patients than in controls, perhaps because of hindered binding of the inhibitor.
Effect of Dialyser Composition and Reuse on Neutrophil Count and Elastase α-1 Proteinase Inhibitor Complex Formation
Authors: Donovan K.L. , Pacholok S. , Phillips A. , Humes J.L. , Coles G.A. , Williams J.D.
Published: March 2018

To assess the inter-relationship of leucopenia and PMN elastase release we undertook a prospective crossover study of 6 patients dialysed with new and reused cuprophane, cellulose acetate and polysulfone membranes. Serial blood samples were analysed for PMN count, and elastase-α 1-proteinase inhibitor complex (Eα1PI) concentrations.

After 15 min dialysis with new membranes median PMN counts fell by 72.2%, 25.3% and 22.1% with cuprophane, cellulose and polysulfone, respectively. With reuse the decreases were reduced to 6.4%, 8% and 13.6%. All membranes produced a gradual increase of Eα1PI. Median Eα1PI accumulation rates (ng ml−1min−1) with new membranes were 175, 169 and 187 for cuprophane, cellulose acetate and polysulfone, respectively. With reuse of cuphro-phane and cellulose acetate these rates fell to 99 and 109 (p<0.05 and p<0.05, respectively), however, with polysulfone it remained unchanged at 180 ng ml−1 min−1. This study highlights differences between two aspects of the neutrophil response to haemodialysis, and demonstrates that extrapolation from individual parameters to conclusions concerning biocompatibility may be inappropriate.
Plasma Exchange Treatment in Rapidly Progressive Glomerulonephritis Associated with Antineutrophil Cytoplasmic Autoantibodies
Authors: Frascà G.M. , Zoumparidis N.G. , Borgnino L.C. , Neri L. , Vangelista A. , Bonomini V.
Published: March 2018

This study reports on 12 patients with acute renal failure due to biopsy-proven rapidly progressive glomerulonephritis and signs of systemic disease in whom antineutrophil cytoplasmic autoantibodies (ANCA) were detected by indirect immunofluorescence (IIF) on alcohol-fixed neutrophils and assessed in serial determinations by ELISA. The diagnosis was: Wegener's granulomatosis in nine patients who showed a diffuse cytoplasmic pattern at IIF (c-ANCA), and microscopic polyarteritis in three where a perinuclear pattern (pANCA) was seen.

All patients underwent a course of plasma exchange - PE - (3-10 sessions per patient) associated with steroids and cyclophosphamide. The ANCA titer dropped steeply during PE in all cases and was followed by disappearance of systemic symptoms and renal function improvement within four weeks. After a follow-up period of 50 ± 31.2 months all patients were alive without signs of disease activity; ten had stable renal function, with serum creatinine 1.8 ± 0.7 mg/dl; two had entered regular dialysis treatment after 44 and 82 months.

Our results suggest that the rapid removal of ANCA by means of PE can help control disease activity and reduce the risk of death or end-stage renal disease.
Simulation Analysis of the Influence of Hemodialysis Control Parameters on Exchange Processes during Therapy
Authors: Thews O.
Published: March 2018

The effect of dialysis control parameters (dialysate composition, ultrafiltration rate, blood flow rate) on the patient's internal milieu were studied using a mathematical model for the description of the dynamic exchange processes during hemodialysis. This model simulates the electrolyte and water distribution, the acid-base and the oxygenation state as well as the ventilation. The dialysate sodium concentration affects mainly the intra-/ extracellular water and the potassium distribution. The dialysate bicarbonate and acetate concentrations control the acid-base state and the electrolyte distribution (sodium and potassium). In addition, the dialysate acetate concentration has a strong effect on arterial oxygenation and on ventilation. The ultrafiltration rate controls the water distribution between plasma and the interstitial space but also the sodium distribution and the arterial acid-base state. The blood flow rate through the dialyser influences the acid-base state and, by this, it affects the potassium and sodium distribution. The acid-base state is affected in opposite directions when acetate or bicarbonate is used as a buffer.
Tubing Spallation in Extracorporeal Circuits. An in Vitro Study Using an Electronic Particle Counter
Authors: Briceño T. J.C. , Runge T. M.
Published: March 2018

The roller pump is the most common pumping device used in extracorporeal circulation (ECC). The interaction between the roller and tubing causes tubing spallation. Spallation has been associated with complications in ECC. Previous spallation studies present mixed results, including a decrease in the number of circulating particles. The objective of this work is to perform an in vitro study of tubing spallation which elucidates the causes of the particle sequestration, and the effect of tubing material, blood flow rate and duration of the procedure upon spallation. A sampling method minimizing background counts was devised. Silicone and PVC tubing were tested under normal and tight occlusion pressure at typical cardiopulmonary bypass and hemodialysis flow rates, for circulating times up to 4 h. Occlusion pressure and flow rate highly influenced the amount of spallation produced. Particle sequestration was noted and aggregation of the plastic particles was demonstrated. We conclude that, at least in vitro, aggregation causes the decrease in the particle counts and the misleading results obtained in most spallation studies using a Coulter counter.
Coronary Hemodynamics during Hemopump Left-Intraventricular Assistance
Authors: Dubois-Randé J.L. , Deleuze P. , Zelinsky R. , Shiiya N. , Saal J.P. , Geschwind H. , Loisance D.
Published: March 2018

Hemopump left intraventricular pumping (HP) can permit percutaneous transluminal angioplasty (PTCA) in high-risk patients. Benefits may be related to left ventricular unloading or myocardial perfusion improvement, or both. Direct ultrasonic measurements of coronary blood flow were made in the dilated vessel after a successful PTCA in five patients. A 3 Fr intracoronary Doppler catheter was placed in the coronary artery to measure flow velocities (maximal or diastolic velocity; minimum or systolic velocity and mean velocity). A SwanGanz catheter was used to measure the cardiac index and pulmonary capillary wedge pressure. Mean aortic pressures were monitored through an 8 Fr guiding catheter. Measurements were made after a 5-min period of minimal speed (TO) of the HP to avoid retrograde regurgitation through the turbine; during the increase from minimum to maximal speed (T1); after a 5-min period of maximal HP flow (3l/min) (T2) and after HP was pulled back (T3). From TO to T2, cardiac index rose from 1.93 ± 0.38 to 3.26 ± 0.35 l/min/m2 and capillary wedge pressure decreased from 18 ± 6 to 13 ± 5 mmHg (p < 0.05); from T2 to T3, cardiac index decreased to 2.4 ± 0.4 while capillary wedge pressure increased to 17 ± 5 (p < 0.05). Mean arterial pressure and heart rate did not change significantly throughout the study. When the hemopump flow was raised to high speed, coronary blood flow increased immediately but returned shortly to baseline values. At steady state, coronary blood flow was stable at values similar to baseline with a tendency for minimum velocity to be higher, suggesting an improvement in systolic myocardial perfusion. When the HP was removed, coronary blood flow dropped immediately. The coronary resistance index changed inversely to coronary blood flow. At high speed, resistance immediately decreased, returning in steady state to baseline values. When the HP was off, resistance increased immediately. Thus, this preliminary study suggests an improvement of myocardial perfusion during HP support. Further studies are needed to evaluate the effect of HP support on myocardial protection in humans.
Patterns of Blood Response during Cardiopulmonary Bypass
Authors: Sundaram S. , Irvine L. , Courtney J.M. , Taggart D.P. , Wheatley D.J. , Lowe G.D.O.
Published: March 2018

Monitoring of cardiopulmonary bypass (CPB) in terms of alterations to the concentrations of selected blood constituents leads to contrasting patterns of response. This has been verified by determining the influence of CPB on the activation of fibrinolysis, complement, leucocytes and the contact phase of coagulation.

Fibrinolytic activity was determined by fibrin degradation products (X-FDP's), complement activation by C3a and C5a, leucocyte activation by granulocyte elastase and contact activation by factor XII-like activity (FXIIA). Five patients undergoing elective coronary artery surgery using a bubble oxygenator and pulsatile perfusion were studied. X-FDP's rose gradually during CPB and remained elevated. Similar patterns were observed for elastase and FXIIA. In contrast, C3a rose sharply with peak values at 1½-2h of bypass while C5a did not show significant changes during bypass. The data obtained have enabled the establishment of response patterns for parameters in CPB which will provide information relevant to the clinical application of biomaterials.
Effect of Subcutaneous Administration of Recombinant Human Erythropoietin on Plasma Protein C, Protein S, and Antithrombin III Levels in Patients on Continuous Ambulatory Peritoneal Dialysis
Authors: Lai K.N , Yin J.A. , Li P.K.T. , Yuen P.M.P. , Lui S.F.
Published: March 2018

The effect of subcutaneous administration of recombinant human erythropoietin (rHuEPO) on plasma natural coagulation inhibitors (protein C, protein S, and antithrombin III) was evaluated in 10 uremic patients on continuous ambulatory peritoneal dialysis (CAPD). These patients were commenced on a 16 week-course of twice weekly rHuEPO by the subcutaneous route. The hemoglobin increased significantly from 6.9 ± 1.3 g/dl to 9.6 ± 1.9 g/dl after subcutaneous rHuEPO treatment (p<0.01) at an average dose of 84 ± 9 U/kg body wt/week. With rHuEPO therapy, a significant increase in platelet counts was observed, albeit within the normal range. A significant increase in the prothrombin time was demonstrated at 6 weeks after treatment and increased activated partial thromboplastin time was observed at 6 weeks and 16 weeks after rHuEPO administration although these measurements still remained in normal range. CAPD patients have comparable or even higher plasma levels of natural coagulation inhibitors compared with healthy controls supporting our previous findings that patients on CAPD have normal plasma levels due to an effective compensatory production despite peritoneal losses of these proteins with CAPD. No change in either the immunological or the functional activity of these natural coagulation inhibitors was demonstrated with rHuEPO therapy and clinical thrombosis was not observed during and after rHuEPO therapy. We conclude that there is no laboratory evidence of increased risk of thrombogenesis due to reduction of natural coagulation inhibitors with rHuEPO therapy.
Hemostatic Disturbances Induced by Two Hollow-Fiber Hemodialysis Membranes
Authors: Reber G. , Stoermann C. , de Moerloose P. , Ruedin P. , Leski M.
Published: March 2018

The effects on hemostasis of two high-flux membranes in hollow-fiber configuration, polyamide (PAM) and polyacrylonitrile (AN69), were analyzed in a cross-over study involving ten chronic hemodialyzed patients. Blood samples were obtained at arterial and venous sites of the extracorporeal circuit before dialysis and at 15, 30 and 180 min. Primary hemostasis: PAM induced an early significant drop in platelet counts, but at 180 min there was no longer any difference between membranes. Beta-thromboglobulin release by PAM was significantly higher at all time points. Coagulation: thrombin-antihrombin III complexes (TAT) and fibrinopeptide A increased significantly, the highest values being found with AN69. With both membranes the arteriovenous differences in TAT levels were negative throughout the sessions. Fibrinolysis: no significant differences were observed.

In conclusion, both membranes induced hemostatic changes. Although these two hollow-fiber dialyzers look relatively similar, the changes observed were different, polyamide acting mainly on primary hemostasis and polyacrylonitrile on coagulation.
Unusual Case of Anuria Due to African Bee Stings
Authors: Beccari M. , Castiglione A. , Cavaliere G. , D'Aloya G. , Fabbri C. , Losi B. , Ranzini C. , Romagnoni G. , Sorgato G.
Published: March 2018

We describe a case of multiple African bee stings in which the exceptionally high dose suggests a direct effect of hymenoptera venom on the renal tubules. The case does not follow the previously reported pattern of hypovolemic or anaphylactic shock, hemolysis and/or rhabdomyolysis, despite the potentially lethal amount of venom injected
Calcification Modelling in Artificial Heart Valves
Authors: Fisher A.C. , Bernacca G.M. , Mackay T.G. , Dimitri W.R. , Wilkinson R. , Wheatley D.J.
Published: March 2018

This study has examined a range of methods of studying the calcification process in bovine pericardial and polyurethane biomaterials. The calcification methods include static and dynamic, in vitro and in vivo tests. The analytical methods include measurement of depletion rates of calcium and phosphate from in vitro calcifying solutions, analysis of tissue contents of calcium, histological staining of tissue sections for calcium, X-ray elemental analysis, by scanning electron microscopy, of calcium and phosphorus distributions over valve leaflets calcified in vitro under dynamic conditions. Bovine pericardium, in all test settings, calcified to a much greater degree than polyurethane biomaterials. Polyurethane extracts calcified to a greater degree than bulk polyurethanes. The test protocol used allows progress through increasily demanding calcification tests, with the possibility of eliminating unsuitable materials with tests of limited complexity and expense.
Near Velocity Field Downstream Prosthetic Valves in Aortic Position
Authors: Tonietto G. , Cassot F. , Rieu R. , Garitey V. , Pelissier R.
Published: March 2018

Using a cardiovascular simulator to duplicate in vitro the flow conditions through valves in aortic position, bidimensional velocity maps very near the valve are reconstructed, from an ultrasonic 8 Mhz doppler system, in an elastic model of the ascending aortic arch. Three mechanical heart valves representative of the different types of commercial models (a tilting disc, a ball in cage and a two-leaflet valve) and a new bileaflet prototype were investigated. From examination of the velocity field, it is possible to define the main characteristics of the valve wake and to observe the development of negative velocities associated with regurgitant flows. From a comparison with tests in rigid tubes, the role played by the arch elasticity is analysed.