GERMAN RESEARCH, Issue 1 2005
Susanne Eickhoff Dr.
Throughout the world, there are about 45,000 dams interrupting the natural flow of water to the oceans. This significantly affects the silicon cycle, endangering the ecological balance [source]

Building a Compact, Low-Cost, and Portable Peristaltic Sampling Pump

GROUND WATER, Issue 6 2007
William W. Woessner
Hydrogeologic research often involves obtaining water quality samples in field settings without vehicle access. Such conditions often require the use of a sampling pump. Researchers at The University of Montana have been using a handheld peristaltic pump powered by a rechargeable variable-speed drill. This Montana Drill Pump (MDP) is highly portable and can be inexpensively built for about $225 to $295 (US). Over the last two decades, the pump has been used to sample and filter (as appropriate) surface water and ground water for analyses of general inorganic and organic chemistry, stable and radioactive isotopes, pathogens, and trace pharmaceuticals and to develop small-diameter wells and sample suction lysimeters. The MDP provides researchers and educators with an economical tool to pump water in classrooms, laboratories, and field settings. [source]

Automatic Delineation of Capture Zones for Pump and Treat Systems: A Case Study in Piedmont, Italy

GROUND WATER MONITORING & REMEDIATION, Issue 2 2010
Tiziana Tosco
The design of a pump and treat (P&T) system for the hydraulic control of a contaminated plume in a confined aquifer is presented here. Being the system designed for the emergency containment of a nonaqueous phase liquid plume, the evaluation of the system's short-term efficiency was considered an important issue. For this reason, both time-related and ultimate capture zones were defined. They were traced using the automatic protection area (APA) model, a capture-zone delineation tool based on a hybrid forward-backward particle tracking algorithm, that provides an automatic post-processing encirclement of capture zones. Two simple indexes are here proposed for the evaluation of the performance of the hydraulic barrier, that is, the efficacy and efficiency indexes, calculated from the capture areas provided by APA. The discharge rates of the wells were dimensioned applying the APA algorithm, maximizing efficacy and efficiency of the barrier. Results proved both visually (via plotting of capture zones) and numerically (via calculation of the indexes) that the P&T system can provide a complete capture of the contaminated area and minimizes the volume of extracted water. Consequently, the APA algorithm was proved to be a useful tool in capture zone delineation. As a future perspective, it could be coupled with the real-time measurement of pumping rates and water levels and be implemented as a part of a tuning tool for the management of the hydraulic barrier. [source]

Preoperative Intra-Aortic Balloon Pump in Patients Undergoing Coronary Bypass Surgery: A Systematic Review and Meta-Analysis

JOURNAL OF CARDIAC SURGERY, Issue 1 2008
Adel M. Dyub M.D., M.Sc.
The primary outcome was hospital mortality and secondary outcomes were IABP-related complications (bleeding, leg ischemia, aortic dissection). Methods: MEDLINE, EMBASE, Cochrane registry of Controlled Trials, and reference lists of relevant articles were searched. We included randomized controlled trials (RCTs), and cohort studies that fulfilled our a priori inclusion criteria. Eligibility decisions, relevance, study validity, and data extraction were performed in duplicate using pre-specified criteria. Meta-analysis was conducted using a random effects model. Results: Ten publications fulfilled our eligibility criteria, of which four were RCTs and six were cohort studies with controls. There were statistical as well as clinical heterogeneity among included studies. A total of 1034 patients received preoperative IABP and 1329 did not receive preoperative IABP. The pooled odds ratio (OR) for hospital mortality in patients treated with preoperative IABP was 0.41 (95% CI, 0.21,0.82, p = 0.01). The number needed to treat was 17. The pooled OR for hospital mortality from randomized trials was 0.18 (95% CI, 0.06,0.57, p = 0.003) and from cohort studies was 0.54 (95% CI, 0.24,1.2, p = 0.13). Overall, 3.7% (13 of 349) of patients who received preoperative IABP developed either limb ischemia or haematoma at the IABP insertion site, and most of these complications improved after discontinuation of IABP. Conclusion: Evidence from this meta-analysis support the use of preoperative IABP in high-risk patients to reduce hospital mortality. [source]

Predictors of Survival 1 Hour After Implantation of an Intra-aortic Balloon Pump in Cardiac Surgery

JOURNAL OF CARDIAC SURGERY, Issue 1 2001
Harald Hausmann M.D.
From July 1996 to March 2000, 391 patients with intraoperative cardiac lowoutput syndrome who underwent surgery with heart-lung bypass and had an intre-aortic balloon pump (IABP) Implanted were analyzed in a prospective study. Of these 391 patients, 153 (39%) were operated on in an emergency situation, and 238 (61%) patients had elective surgeries. The perioperative mortality was 34% (133 patients). Clinical parameters were analyzed 1 hour after IABP support began. Statistical multivariate analysis showed that patients with an adrenaline requirement higher than 0.5 ,g/kg/min, a left mrial pressure higher then 15 mmHg, output of less than 100 mL/hour, and mixed venous saturation (SvO2) of less then 60% had poor outcomes. Using this data, we developed an IABP score to predict survival early after IABP implantation in cardiac surgery. We conclude that the success or failure of perioperative IABP support can be predicted early after implantation of the balloon pump. In patients with low-output syndrome despite IABP support, implantation of a vantricular assist system should be considered. [source]

A linear cavity Brillouin fiber laser with multiple wavelengths output

LASER PHYSICS LETTERS, Issue 5 2008
M.R. Shirazi
Abstract A linear cavity Brillouin fiber laser (BFL) is proposed and demonstrated for multi-wavelength operation. The BFL uses a single mode fiber (SMF) as a non-linear gain medium and an optical circulator to generate a linear cavity resonator. Two couplers are used to inject the Brillouin Pump (BP) and tap the BFL output respectively. The effect of the coupler ratio on the BFL performance is studied by keeping constant the ratio of the first coupler and varying the ratio of the second coupler. 11 simultaneous lines with a line spacing of 0.8 nm are obtained at a BP of 11.7 dBm and a coupler ratio of 95:5. The laser output is stable at room temperature with 5 lines obtained at above , 30 dBm, and has the largest signal to noise ratio observed at the remaining lines. The proposed BFL has the advantage of being able to operate at any wavelength and is only dependent on the available BP wavelength. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Safety and Efficacy of Intrathecal Baclofen Infusion by Implantable Pump for the Treatment of Severe Spinal Spasticity: A Spanish Multicenter Study

NEUROMODULATION, Issue 4 2000
J Vidal MD
Objective. To assess long-term efficacy, safety and functional benefit of intrathecal baclofen for severe spinal spasticity. Materials and Methods. This prospective multicenter study was performed in two stages: the first one consisted of an intrathecal bolus injection of baclofen, and the second of a continuous intrathecal baclofen infusion by means of an implantable pump. The sample consisted of 72 adult patients with severe spinal spasticity. Sixty-four were implanted and followed for 36 months. Muscular tone, spasms, and functional scales were evaluated before and periodically after administration of the drug, with a follow-up period of 36 months. Results. A very significant decrease in tone and spasms was observed in all cases (p < 0.001). Tolerance appeared during the first 12 months, increasing doses from a mean initial dose of 83.2 ,g (range 25,200 ,g) to a mean final dose of 270 ,g (range 25,800 ,g). Later on, efficacy remained stable, except in cases of mechanical problems of the infusion system. [source]

Median Arcuate Ligament Syndrome,A Novel Treatment Using an Intrathecal Morphine Pump to Relieve Intractable Visceral Pain

PAIN PRACTICE, Issue 2 2008
Oren T. Guttman MD
,,Abstract Purpose: Median arcuate ligament syndrome, which presents with intractable visceral pain, is difficult to both diagnose and treat. This case report describes the first use of an intrathecal morphine pump as an effective therapeutic intervention. Clinical features: We describe a 39-year-old female who presented with a four-year history of misdiagnosed debilitating abdominal pain. After multiple failed attempts at medical management and surgeries, a trial of intrathecal narcotics provided significant relief. Six months after insertion of an intrathecal morphine pump, the patient was pain-free and had resumed all activities of daily living. Conclusion: The use of an intrathecal narcotic pump should be considered for treatment of patients with intractable visceral pain secondary to median arcuate ligament syndrome.,, [source]

Use of CoZmonitor® in youth with type 1 diabetes,

PEDIATRIC DIABETES, Issue 2 2008
Erin Cobry
Background:, The purpose of this study was to evaluate the effectiveness of directly integrating self-monitoring blood glucose (BG) information with insulin pump therapy on overall glycemic control. Methods:, In this randomized trial, 34 youth with type 1 diabetes using insulin pump therapy were trained on the use of the Deltec Cozmo® Insulin Pump. Seventeen were randomized to use the CoZmonitor® Blood Glucose Module, a device that attaches to the back of the pump using FreeStyle® technology to perform BG tests which read directly on the pump screen. The remaining 17 (control group) used a FreeStyle Flash meter, a stand-alone BG meter, for their BG testing. At baseline, 3 and 6 months, the subjects filled out a questionnaire, had a hemoglobin A1c (HbA1c) test, and had pumps and meters downloaded. Results:, After 3 months of study, there were no changes in mean HbA1c (± SD) values for the experimental (8.7 ± 1.1 to 8.6 ± 1.1) or the control groups (9.1 ± 1.4 to 9.2 ± 1.5). There were also no significant differences in HbA1c values after 6 months. The average number of BG tests per day did not change significantly in either group during the study. After 3 and 6 months, the experimental group rated satisfaction with the use of the CoZmonitor at 4.4 and 3.8 (respectively) on a five-point Likert scale, with 5 being the most satisfied. Conclusions:, Although significant changes in HbA1c values or the number of BG tests were not found, use of the BG module had a positive level of satisfaction. [source]

Pump activated by a foot switch pedal for controlled administration of local anaesthetic drugs

ANAESTHESIA, Issue 8 2002
H. B. J. Fischer
No abstract is available for this article. [source]

Remarkable Site Difference of Vibrational Energy Relaxation in Benzene Dimer: Picosecond Time-Resolved IR,UV Pump,Probe Spectroscopy,

ANGEWANDTE CHEMIE, Issue 39 2010
Ryoji Kusaka
Ganz entspannt: Die Schwingungsenergierelaxation (VER) von Isotopologen des Benzol-Dimers auf dem C-H-Streckschwingungsniveau wurde durch zeitaufgelöste Pikosekunden-IR-UV-Pump-Sonden-Spektroskopie untersucht (siehe Bild, h=C6H6, d=C6D6). Dabei ergab sich ein bemerkenswerter Unterschied in den Relaxationslebensdauern: Die Lebenszeit des ,stehenden" Benzolmoleküls (,Stem", 110,ps) ist 4.5mal kürzer als die des ,liegenden" (,Top", 500,ps). [source]

Observation of Terahertz Vibrations in the Nitrogenase FeMo Cofactor by Femtosecond Pump,Probe Spectroscopy,

ANGEWANDTE CHEMIE, Issue 23 2010
Ines Delfino Dr.
Hochgepumpt: Die Dynamik des durch Resonanz-Raman-Spektroskopie nicht charakterisierbaren FeMo-Cofaktors (siehe Bild) wurde nun mit kohärenter Puls-Schwingungsspektroskopie als Sonde untersucht: Ein Laserpuls mit sichtbarem Licht (15,fs) pumpte die Probe in einen angeregten elektronischen Zustand, und ein zweiter Puls (<10,fs) untersuchte die Änderung in der Transmission als Funktion des Zeitabstands. [source]

The Aachen MiniHLM,A Miniaturized Heart-Lung Machine for Neonates With an Integrated Rotary Blood Pump

ARTIFICIAL ORGANS, Issue 9 2010
Jutta Arens
Abstract The operation of congenital heart defects in neonates often requires the use of heart-lung machines (HLMs) to provide perfusion and oxygenation. This is prevalently followed by serious complications inter alia caused by hemodilution and extrinsic blood contact surfaces. Thus, one goal of developing a HLM for neonates is the reduction of priming volume and contact surface. The currently available systems offer reasonable priming volumes for oxygenators, reservoirs, etc. However, the necessary tubing system contains the highest volumes within the whole system. This is due to the use of roller pumps; hence, the resulting placement of the complete HLM is between 1 and 2 m away from the operating table due to connective tubing between the components. Therefore, we pursued a novel approach for a miniaturized HLM (MiniHLM) by integrating all major system components in one single device. In particular, the MiniHLM is a HLM with the rotary blood pump centrically integrated into the oxygenator and a heat exchanger integrated into the cardiotomy reservoir which is directly connected to the pump inlet. Thus, tubing is only necessary between the patient and MiniHLM. A total priming volume of 102 mL (including arterial filter and a/v line) could be achieved. To validate the overall concept and the specific design we conducted several in vitro and in vivo test series. All tests confirm the novel concept of the MiniHLM. Its low priming volume and blood contact surface may significantly reduce known complications related to cardiopulmonary bypass in neonates (e.g., inflammatory reaction and capillary leak syndrome). [source]

Development of a Disposable Magnetically Levitated Centrifugal Blood Pump (MedTech Dispo) Intended for Bridge-to-Bridge Applications,Two-Week In Vivo Evaluation

ARTIFICIAL ORGANS, Issue 9 2010
Eiki Nagaoka
Abstract Last year, we reported in vitro pump performance, low hemolytic characteristics, and initial in vivo evaluation of a disposable, magnetically levitated centrifugal blood pump, MedTech Dispo. As the first phase of the two-stage in vivo studies, in this study we have carried out a 2-week in vivo evaluation in calves. Male Holstein calves with body weight of 62.4,92.2 kg were used. Under general anesthesia, a left heart bypass with a MedTech Dispo pump was instituted between the left atrium and the descending aorta via left thoracotomy. Blood-contacting surface of the pump was coated with a 2-methacryloyloxyethyl phosphorylcholine polymer. Post-operatively, with activated clotting time controlled at 180,220 s using heparin and bypass flow rate maintained at 50 mL/kg/min, plasma-free hemoglobin (Hb), coagulation, and major organ functions were analyzed for evaluation of biocompatibility. The animals were electively sacrificed at the completion of the 2-week study to evaluate presence of thrombus inside the pump, together with an examination of major organs. To date, we have done 13 MedTech Dispo implantations, of which three went successfully for a 2-week duration. In these three cases, the pump produced a fairly constant flow of 50 mL/Kg/min. Neurological disorders and any symptoms of thromboembolism were not seen. Levels of plasma-free Hb were maintained very low. Major organ functions remained within normal ranges. Autopsy results revealed no thrombus formation inside the pump. In the last six cases, calves suffered from severe pneumonia and they were excluded from the analysis. The MedTech Dispo pump demonstrated sufficient pump performance and biocompatibility to meet requirements for 1-week circulatory support. The second phase (2-month in vivo study) is under way to prove the safety and efficacy of MedTech Dispo for 1-month applications. [source]

Prediction of Leakage Flow in a Shrouded Centrifugal Blood Pump

ARTIFICIAL ORGANS, Issue 9 2010
Ji-Bin Teo
Abstract This article proposes a phenomenological model to predict the leakage flow in the clearance gap of shrouded centrifugal blood pumps. A good washout in the gap clearance between the rotating impeller surfaces and volute casing is essential to avoid thrombosis. However, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Computational fluid dynamics (CFD) analysis was performed to investigate the leakage flow in a miniaturized shrouded centrifugal blood pump operating at a speed of 2000 rpm. Based on an analytical model derived earlier, a phenomenological model is proposed to predict the leakage flow. The leakage flow rate is found to be proportional to h,, where h is the gap size and the exponent , ranges from 2.955 to 3.15 for corresponding gap sizes of 0.2,0.5 mm. In addition, it is observed that , is a linear function of the gap size h. The exponent , compensates for the variation of pressure difference along the circumferential direction as well as inertia effects that are dominant for larger gap clearances. The proposed model displays good agreement with computational results. The CFD analysis also showed that for larger gap sizes, the total leakage flow rate is of the same order of magnitude as the operating flow rate, thus suggesting low volumetric efficiency. [source]

Optimal Moving Angle of Pusher Plate in Occlusive-Type Pulsatile Blood Pump

ARTIFICIAL ORGANS, Issue 7 2010
Hyuk Choi
Abstract Since the occlusive-type pulsatile extracorporeal blood pump (Twin-Pulse Life Support System; Seoul National University, Seoul, Korea) received the CE mark of the European Directives and Korea Food and Drug Administration approval (2004) for short-term applications as an extracorporeal life support system, the pump system has been tested for hemolysis. This pump system was recently upgraded with an ameliorated pusher plate to reduce hemolysis. In this study, numerical analysis and in vitro tests were performed to determine the optimal conditions for increasing the durability of the blood sac and pump output. During the simulation, the minimum sliding interface force (SIF) for the angle of the pusher plate movement (PPM) was calculated (40,70°). In the in vitro durability test, the angle of the PPM was increased gradually from 40 to 70° in 10° increments, and the mean time to failure (MTTF) of the blood sac was calculated. Fifteen tests were conducted for each case: 40, 50, 60, and 70° (n = 15 each). The MTTF of the blood sac was defined as the time when a crack of the blood sac occurred. The longer lifetime of the blood sac at 60° of the PPM (297.0 h) than that at 50° (197.6 h) was attributed to the lower SIF value (,0.13, normalized value) at 60° of the PPM. [source]

Estimation of Maximum Ventricular Elastance Under Assistance With a Rotary Blood Pump

ARTIFICIAL ORGANS, Issue 5 2010
Telma K. Sugai
Abstract The maximum ventricular elastance is a reliable index for assessing the cardiac function from changes in its pressure-volume relationship. The advantage of this index is that it can represent the contractility of either unassisted hearts or native hearts assisted with rotary blood pumps. However, there are situations in which changes in the ventricular load required for the conventional estimation method might be risky. For example, in a bridge-to-recovery the cardiac function should also be continuously observed after the implantation of a rotary blood pump. In this article, we present the results of the estimation of the maximum elastance with in vivo data using the parameter optimization method, which is a single-beat estimation method. The estimated values for the normal cardiac function (6.8 ± 0.6, 4.5 ± 0.9, 4.2 ± 1.8 mm Hg/mL) were significantly different from those for the low cardiac function (3.2 ± 1.5, 1.9 ± 1.0, 1.9 ± 1.2 mm Hg/mL) from the data of the three animals that were analyzed. Besides, the maximum elastance values were independent of the pump rotational speed. These results indicate that this index might be useful for the detection of the myocardial recovery. [source]

Shape Optimization of the Diffuser Blade of an Axial Blood Pump by Computational Fluid Dynamics

ARTIFICIAL ORGANS, Issue 3 2010
Lailai Zhu
Abstract Computational fluid dynamics (CFD) has been a viable and effective way to predict hydraulic performance, flow field, and shear stress distribution within a blood pump. We developed an axial blood pump with CFD and carried out a CFD-based shape optimization of the diffuser blade to enhance pressure output and diminish backflow in the impeller,diffuser connecting region at a fixed design point. Our optimization combined a computer-aided design package, a mesh generator, and a CFD solver in an automation environment with process integration and optimization software. A genetic optimization algorithm was employed to find the pareto-optimal designs from which we could make trade-off decisions. Finally, a set of representative designs was analyzed and compared on the basis of the energy equation. The role of the inlet angle of the diffuser blade was analyzed, accompanied by its relationship with pressure output and backflow in the impeller,diffuser connecting region. [source]

Numerical Study of a Bio-Centrifugal Blood Pump With Straight Impeller Blade Profiles

ARTIFICIAL ORGANS, Issue 2 2010
Guoliang Song
Abstract Computational fluid dynamic simulations of the flow in the Kyoto-NTN (Kyoto University, Kyoto, Japan) magnetically suspended centrifugal blood pump with a 16-straight-bladed impeller were performed in the present study. The flow in the pump was assumed as unsteady and turbulent, and blood was treated as a Newtonian fluid. At the impeller rotating speed of 2000 rpm and flow rate of 5 L/min, the pump produces a pressure head of 113.5 mm Hg according to the simulation. It was found that the double volute of the pump has caused symmetrical pressure distribution in the volute passages and subsequently caused symmetrical flow patterns in the blade channels. Due to the tangentially increasing pressure in the volute passages, the flow through the blade channels initially increases at the low-pressure region and then decreases due to the increased pressure. The reverse flow and vortices have been identified in the impeller blade channels. The high shear stress of the flow in the pump mainly occurred at the inlet and outlet of the blade channels, the beginning of the volute passages and the regions around the tips of the cutwater and splitter plate. Higher shear stress is obtained when the tips of the cutwater and splitter plate are located at the impeller blade trailing edges than when they are located at the middle of the impeller blade channel. It was found that the blood damage index assessed based on the blood corpuscle path tracing of the present pump was about 0.94%, which has the same order of magnitude as those of the clinical centrifugal pumps reported in the literature. [source]

In Vivo Assessment of a New Method of Pulsatile Perfusion Based on a Centrifugal Pump

ARTIFICIAL ORGANS, Issue 2 2010
Jesús Herreros
Abstract The aim of this study was to assess platelet dysfunction and damage to organs after extracorporeal circulation using a pump based on a new method that adds a pulsatile flow to the continuous flow provided by a centrifugal pump. The continuous component of the total flow (2,3 L/min) is created by a Bio-Pump centrifugal pump, while the pulsatile component is created by the pulsating of an inner membrane pneumatically controlled by an intra-aortic counterpulsation balloon console (systolic volume of 37.5 mL in an asynchronous way with a frequency of 60 bpm). Six pigs were subjected to a partial cardiopulmonary bypass lasting 180 min and were sacrificed 60 min after extracorporeal circulation was suspended. The hematological study included the measurement of hematocrit, hemoglobin, leukocytes, and platelet function. The new pump did not significantly alter either platelet count or platelet function. In contrast, hematocrit and hemoglobin were significantly reduced during extracorporeal circulation (approximately 5% P = 0.011, and 2 g/dL P = 0.01, respectively). The leukocyte count during extracorporeal circulation showed a tendency to decrease, but this was not significant. In general, the short-term use of the new pump (4 h) did not cause any serious morphological damage to the heart, lung, kidney, or liver. The results suggest that the hemodynamic performance of the new pump is similar to a conventional centrifugal pump and could therefore be appropriate for use in extracorporeal circulation. [source]

Continuous Delivery of Biomaterials to the Skin,Percutaneous Device Interface Using a Fluid Pump

ARTIFICIAL ORGANS, Issue 2 2010
Antonio Peramo
Abstract We have developed an in vitro culture system composed of organotypic human skin explants interfaced with titanium rods attached to a fluid pump. This device was designed to mimic the process of natural mucosa delivery at the point where a rigid, permanent object penetrates living skin. Full thickness human breast skin explants discarded from surgeries were cultured at different time points at the air-liquid interface. The skin specimens were punctured to fit at the bottom of hollow cylindrical titanium rods. Sodium lauryl sulfate (SLS) was delivered continuously to the specimens through the rods by using an attached fluid pump. Histological analysis of the skin explants as well as no-pump controls was then performed. Our results show substantial differences between controls, where no material was pumped at the interface of rod,skin, and specimens treated with SLS, indicating that the technique of pumping the material is effective in producing observable epithelial changes. These results suggest that an adaptation of this type of device may be useful for the treatment of complications arising from the contact between tissues and percutaneous devices in vivo. [source]

Noninvasive Activity-based Control of an Implantable Rotary Blood Pump: Comparative Software Simulation Study

ARTIFICIAL ORGANS, Issue 2 2010
Dean M. Karantonis
Abstract A control algorithm for an implantable centrifugal rotary blood pump (RBP) based on a noninvasive indicator of the implant recipient's activity level has been proposed and evaluated in a software simulation environment. An activity level index (ALI),derived from a noninvasive estimate of heart rate and the output of a triaxial accelerometer,forms the noninvasive indicator of metabolic energy expenditure. Pump speed is then varied linearly according to the ALI within a defined range. This ALI-based control module operates within a hierarchical multiobjective framework, which imposes several constraints on the operating region, such as minimum flow and minimum speed amplitude thresholds. Three class IV heart failure (HF) cases of varying severity were simulated under rest and exercise conditions, and a comparison with other popular RBP control strategies was performed. Pump flow increases of 2.54, 1.94, and 1.15 L/min were achieved for the three HF cases, from rest to exercise. Compared with constant speed control, this represents a relative flow change of 30.3, 19.8, and ,15.4%, respectively. Simulations of the proposed control algorithm exhibited the effective intervention of each constraint, resulting in an improved flow response and the maintenance of a safe operating condition, compared with other control modes. [source]

Aortic Arch Surgery With a Single Centrifugal Pump for Selective Cerebral Perfusion and Systemic Circulation

ARTIFICIAL ORGANS, Issue 1 2010
Keiji Iwata
Abstract In aortic arch surgery, two pumps are required for systemic perfusion and selective cerebral perfusion (SCP). A new technique with a single centrifugal pump for systemic perfusion and SCP was developed and its efficacy and safety evaluated. This technique was adopted for total arch replacement in 22 consecutive patients with true aneurysms (13) and aortic dissection (nine) from January 2005 to January 2008. Cerebral perfusion lines branched from the main perfusion line. During SCP, right radial arterial pressure was maintained at 50 mm Hg and left common carotid arterial pressure at 60 mm Hg, and the regional cerebral oxygen saturation (rSO2) values were maintained at approximately >80% of the baseline value. Two operative deaths (9%) occurred due to pneumonia and hemorrhage in the left lung, respectively. Stroke occurred in one patient (5%). This simple circuit system can thus be easily and safely applied for aortic arch surgery. [source]

Left Ventricular Assist for Pediatric Patients With Dilated Cardiomyopathy Using the Medos Vad Cannula and a Centrifugal Pump

ARTIFICIAL ORGANS, Issue 11 2009
Shu-Chien Huang
Abstract Ventricular assist devices for small pediatric patients are expensive and commercially unavailable in Taiwan. We used the Medos ventricular assist device cannula (Medos, Aachen, Germany) and a centrifugal pump to support pediatric patients with dilated cardiomyopathy and decompensated heart failure. From January 2007 to December 2008, three pediatric patients with dilated cardiomyopathy were supported using a centrifugal pump as the left ventricular assist device. The Medos arterial cannula was sutured to the ascending aorta, and the Apex cannula was fixed into the left ventricular apex. When the patient was weaned off of cardiopulmonary bypass, the left ventricular assist device pump was started. The pump flow was gradually titrated according to the filling status of the left ventricle. All the left ventricular assist devices were successfully implanted and functioned well. Two patients on extracorporeal membrane oxygenation had severe lung edema before left ventricular assist device implantation. Both patients required extracorporeal membrane oxygenation for the postoperative period until the pulmonary edema was resolved. Among the three patients, two successfully bridged to heart transplantation after support for 6 and 11 days, respectively. The first patient (10 kg) expired due to systemic emboli 30 days after left ventricular assist device support. In summary, these results suggest that the Medos ventricular assist device cannula and a centrifugal pump is an option for temporary left ventricular assist device support in patients with intractable heart failure and as a bridge to heart transplantation. [source]

Improvement of Hemocompatibility in Centrifugal Blood Pump With Hydrodynamic Bearings and Semi-open Impeller: In Vitro Evaluation

ARTIFICIAL ORGANS, Issue 10 2009
Ryo Kosaka
Abstract We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 µm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces. [source]

Development of a Disposable Maglev Centrifugal Blood Pump Intended for One-Month Support in Bridge-to-Bridge Applications: In Vitro and Initial In Vivo Evaluation

ARTIFICIAL ORGANS, Issue 9 2009
Takeshi Someya
Abstract MedTech Dispo, a disposable maglev centrifugal blood pump with two degrees of freedom magnetic suspension and radial magnetic coupling rotation, has been developed for 1-month extracorporeal circulatory support. As the first stage of a two-stage in vivo evaluation, 2-week evaluation of a prototype MedTech Dispo was conducted. In in vitro study, the pump could produce 5 L/min against 800 mm Hg and the normalized index of hemolysis was 0.0054 ± 0.0008 g/100 L. In in vivo study, the pump, with its blood-contacting surface coated with biocompatible 2-methacryloyloxyethyl phosphorylcholine polymer, was implanted in seven calves in left heart bypass. Pump performance was stable with a mean flow of 4.49 ± 0.38 L/min at a mean speed of 2072.1 ± 64.5 rpm. The maglev control revealed its stability in rotor position during normal activity by the calves. During 2 weeks of operation in two calves which survived the intended study period, no thrombus formation was seen inside the pump and levels of plasma free hemoglobin were maintained below 4 mg/dL. Although further experiments are required, the pump demonstrated the potential for sufficient and reliable performance and biocompatibility in meeting the requirements for cardiopulmonary bypass and 1-week circulatory support. [source]

Design of a Small Centrifugal Blood Pump With Magnetic Bearings

ARTIFICIAL ORGANS, Issue 9 2009
Said Jahanmir
Abstract Design of a blood pump with a magnetically levitated rotor requires rigorous evaluation of the magnetic bearing and motor requirements and analysis of rotor dynamics and hydraulic performance with attention to hemolysis and thrombosis potential. Given the desired geometric dimensions, the required operating speed, flow in both the main and wash flow regions, and magnetic bearing performance, one of several design approaches was selected for a new prototype. Based on the estimated operating speed and clearance between the rotor and stator, the motor characteristics and dimensions were estimated. The motor stiffness values were calculated and used along with the hydraulic loading due to the fluid motion to determine the best design for the axial and radial magnetic bearings. Radial and axial stability of the left ventricular assist device prototype was verified using finite element rotor dynamic analysis. The analysis indicated that the rotor could be completely levitated and spun to the desired operating speed with low power loss and no mechanical contact. In vitro experiments with a mock loop test setup were performed to evaluate the performance of the new blood pump prototype. [source]

Design of a Protective Cage for an Intravascular Axial Flow Blood Pump to Mechanically Assist the Failing Fontan

ARTIFICIAL ORGANS, Issue 8 2009
Amy L. Throckmorton
Abstract Currently, no long-term mechanical bridge-to-transplant or bridge-to-recovery therapeutic alternative exists for failing single ventricles. A blood pump that would augment pressure in the cavopulmonary circulation is needed, and would lead to a reduction in elevated systemic venous pressure, and improve cardiac output. Thus, we are developing a collapsible, percutaneously inserted, axial flow blood pump to support the cavopulmonary circulation in adult patients with a failing single ventricle physiology. This collapsible axial flow pump is designed for percutaneous positioning. The outer protective cage will be designed with radially arranged filaments as touchdown surfaces to protect the vessel wall from the rotating components. This study examined the geometric characteristics of the protective cage of filaments and the impeller through the development and numerical analysis of 13 models. A blood damage analysis was also performed on selected geometric models to assess the probability of blood trauma. All models demonstrated an acceptable hydraulic performance by delivering 2,6 L/min at a rotational speed of 6000,10 000 rpm and generating pressure rise of 5,20 mm Hg. Expected trends in the hydraulic performance of the pump models were found. This study represents the initial first design phase of the impeller and protective cage of filaments. Validation of these flow and performance predictions will be completed in the next round of experimental testing with blood bag evaluation. [source]

Development of a Closed Air Loop Electropneumatic Actuator for Driving a Pneumatic Blood Pump

ARTIFICIAL ORGANS, Issue 8 2009
Gi Seok Jeong
Abstract In this study, we developed a small pneumatic actuator that can be used as an extracorporeal biventricular assist device. It incorporated a bellows-transforming mechanism to generate blood-pumping pressure. The cylindrical unit is 88 ± 0.1 mm high, has a diameter of 150 ± 0.1 mm, and weighs 2.4 ± 0.01 kg. In vitro, maximal outflow at the highest pumping rate (PR) exceeded 8 L/min when two 55 mL blood sacs were used under an afterload pressure of 100 mm Hg. At a pumping rate of 100 beats per minute (bpm), maximal hydraulic efficiency was 9.34% when the unit supported a single ventricle and 13.8% when it supported both ventricles. Moreover, pneumatic efficiencies of the actuator were 17.3% and 33.1% for LVAD and BVAD applications, respectively. The energy equivalent pressure was 62.78,208.10 mm Hg at a PR of 60,100 bpm, and the maximal value of dP/dt during systole was 1269 mm Hg/s at a PR of 60 bpm and 979 mm Hg/s at a PR of 100 bpm. When the unit was applied to 15 calves, it stably pumped 3,4 L/min of blood at 60 bpm, and no mechanical malfunction was experienced over 125 days of operation. We conclude that the presently developed pneumatic actuator can be utilized as an extracorporeal biventricular assist device. [source]

Parametric Study of Blade Tip Clearance, Flow Rate, and Impeller Speed on Blood Damage in Rotary Blood Pump

ARTIFICIAL ORGANS, Issue 6 2009
Nahn Ju Kim
Abstract Phenomenological studies on mechanical hemolysis in rotary blood pumps have provided empirical relationships that predict hemoglobin release as an exponential function of shear rate and time. However, these relations are not universally valid in all flow circumstances, particularly in small gap clearances. The experiments in this study were conducted at multiple operating points based on flow rate, impeller speed, and tip gap clearance. Fresh bovine red blood cells were resuspended in phosphate-buffered saline at about 30% hematocrit, and circulated for 30 min in a centrifugal blood pump with a variable tip gap, designed specifically for these studies. Blood damage indices were found to increase with increased impeller speed or decreased flow rate. The hemolysis index for 50-µm tip gap was found to be less than 200-µm gap, despite increased shear rate. This is explained by a cell screening effect that prevents cells from entering the smaller gap. It is suggested that these parameters should be reflected in the hemolysis model not only for the design, but for the practical use of rotary blood pumps, and that further investigation is needed to explore other possible factors contributing to hemolysis. [source]