A Centrifugal Pump Fault Diagnosis Framework Based on Supervised Contrastive Learning.

A novel intelligent centrifugal pump (CP) fault diagnosis method is proposed in this paper. The method is based on the contrast in vibration data obtained from a centrifugal pump (CP) under several operating conditions. The vibration signals data obtained from a CP are non-stationary because of the impulses caused by different faults; thus, traditional time domain and frequency domain analyses such as fast Fourier transform and Walsh transform are not the best option to pre-process the non-stationary signals. First, to visualize the fault-related impulses in vibration data, we computed the kurtogram images of time series vibration sequences. To extract the discriminant features related to faults from the kurtogram images, we used a deep learning tool convolutional encoder (CE) with a supervised contrastive loss. The supervised contrastive loss pulls together samples belonging to the same class, while pushing apart samples belonging to a different class. The convolutional encoder was pretrained on the kurtograms with the supervised contrastive loss to infer the contrasting features belonging to different CP data classes. After pretraining with the supervised contrastive loss, the learned representations of the convolutional encoder were kept as obtained, and a linear classifier was trained above the frozen convolutional encoder, which completed the fault identification. The proposed model was validated with data collected from a real industrial testbed, yielding a high classification accuracy of 99.1% and an error of less than 1%. Furthermore, to prove the proposed model robust, it was validated on CP data with 3.0 and 3.5 bar inlet pressure.

Fluid dynamics characterization and thrombogenicity assessment of a levitating centrifugal pump with different impeller designs.

Technical guidelines nowadays recommend and regulate the use Computational Fluid Dynamics (CFD) to assess the performance of medical devices. CFD coupled to blood damage models has emerged as a powerful tool to evaluate the hemocompatibility of blood recirculating devices. The present study is aimed at evaluating the hydrodynamic performance and the thrombogenic potential of two prototypes of magnetically levitating centrifugal pumps. The two devices differ in the impeller configuration - 6-blades vs. 12-blades - and have been designed to be used in Cardiopulmonary Bypass (CPB) circuits during open heart surgery and in Extracorporeal Membrane Oxygenation (ECMO) to support patients with severe cardiac or respiratory failure. The pumps have been modelled using Direct Numerical Simulation coupled to Lagrangian analysis to predict platelet activation due to abnormal shear stress histories. Numerical results have been compared with experimental data in terms of head generation for different working points. Results show that the 6-blades pump has i) smaller stagnation areas, ii) lower stress levels and iii) higher strain rate, resulting in a lower thrombogenic potential, whereas the 12-blade impeller guarantees a more stable performance at high flow rates, suggesting its preferential use for more demanding applications, such as CPB.

Is there a "safe" suction pressure in the venous line of extracorporeal circulation system?

Successes of extracorporeal life support increased the use of centrifugal pumps. However, reports of hemolysis call for caution in using these pumps, especially in neonatology and in pediatric intensive care. Cavitation can be a cause of blood damage. The aim of our study was to obtain information about the cavitation conditions and to provide the safest operating range of centrifugal pumps. A series of tests were undertaken to determine the points at which pump performance decreases 3% and gas bubbles start to appear downstream of the pump. Two pumps were tested; pump R with a closed impeller and pump S with a semiopen impeller. The performance tests demonstrated that pump S has an optimal region narrower than pump R and it is shifted to the higher flows. When the pump performance started to decrease, the inlet pressure varies but close to -150 mmHg in the test with low gas content and higher than -100 mmHg in the tests with increased gas content. The same trend was observed at the points of development of massive gas emboli. Importantly, small packages of bubbles downstream of the pump were registered at relatively high inlet pressures. The gaseous cavitation in centrifugal pumps is a phenomenon that appears with decreasing inlet pump pressures. There are a few ways to increase inlet pump pressures: (1) positioning the pump as low as possible in relation to the patient; (2) selecting appropriate sized venous cannulas and their careful positioning; and (3) controlling patient's volume status.

Development of Active Centrifugal Pump for Microfluidic CD Platforms.

The continuous emerging of microfluidic compact disc (CD) platforms for various real-life applications motivates researchers to explore new innovative ideas towards more integrated active functions. However, microfluidic CDs have some drawbacks, including the unidirectional flow that limits the usable space for multi-stepped biological and chemical assays. In this work, a novel active and bidirectional centrifugal pump is developed and integrated on microfluidic CDs. The design of the developed pump partially replicates the designs of the conventional centrifugal pumps with a modification in the connecting channels' positions that allow the developed pump to be reversible. The main advantage of the proposed centrifugal pump is that the pumping speed can be accurately controlled during spinning or while the microfluidic CD is stationary. Performance tests show that the pumping speed can reach up to 164.93 mm3/s at a pump rotational speed (impellers speed) of 4288 rpm. At that speed, 1 mL of water could be pumped in 6.06 s. To present a few of the potential applications of the centrifugal pump, flow reciprocation, bidirectional pumping, and flow switching were performed and evaluated. Results show that the developed centrifugal pump can pump 1096 µL of liquid towards the CD center at 87% pumping efficiency while spinning the microfluidic CD at 250 rpm. This novel centrifugal pump can significantly widen the range of the applicability of microfluidic CDs in advanced chemical processes and biological assays.

The Influence of Impeller Geometries on Hemolysis in Bearingless Centrifugal Pumps.

Goal: The importance of the main impeller design parameters in bearingless centrifugal pumps with respect to hemolysis for cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) applications are studied in this work. Methods: Impeller prototypes were designed based on theoretical principles. They were manufactured and their hydraulic and hemolytic performance were analyzed experimentally. The cell compatibility is benchmarked against commercially available centrifugal blood pumps BPX-80 (Medtronic) and FloPump 32 (International Biophysics Corporation). Results: The developed prototypes outperform the BPX-80 and FloPump 32 with regard to hemocompatibility by more than a factor of 4.5. The implemented pump features reduced overall and priming volumes. A significant improvement of the cell compatibility is achieved by increasing the radial gap between the impeller and the pump head. The blade should be sufficiently high and a blade outlet angle of 90° provides favorable performance. No correlation between the hydraulic and hemolytic performance is observed. Conclusions: This work identified the most important geometrical parameters of the impeller for blood pumps with respect to cell compatibility. This provides valuable design guidelines for improving existing pumps.

Clinical outcomes of neonatal and pediatric extracorporeal life support: A seventeen-year, single institution experience.

The objective of this study was to describe a single-center experience with neonatal and pediatric extracorporeal life support (ECLS) and compare patient-related outcomes with those of the Extracorporeal Life Support Organization (ELSO) Registry. A retrospective review of subject characteristics, outcomes, and complications of patients who received the ECLS at Penn State Health Children's Hospital (PSHCH) from 2000 to 2016 was performed. Fisher's exact test was used to compare the PSHCH outcomes and complications to the ELSO Registry report. Data from 118 patients were included. Survival to discontinuation of the ECLS was 70.3% and 65.2% to discharge/transfer. Following circuitry equipment changes, the survival to discharge/transfer improved for both neonatal (<29 days) and pediatric (29 days to <18 years) patients. The most common complications associated with ECLS were clinical seizures, intracranial hemorrhage, and culture-proven infection. ECLS for pulmonary support appeared to be associated with a higher risk of circuit thrombus and cannula problems. When compared to the ELSO Registry, low volume ECLS centers, like our institution, can have outcomes that are no different or statistically better as noted with neonatal and pediatric cardiac patients. Pediatric patients requiring pulmonary support appeared to experience more mechanical complications during ECLS suggesting the need for ongoing technological improvement.

High Hemoglobin Is an Independent Risk Factor for the Development of Hemolysis During Pediatric Extracorporeal Life Support.

OBJECTIVE: To evaluate risk factors for hemolysis in pediatric extracorporeal life support. DESIGN: Retrospective, single-center study. SETTING: Pediatric intensive care unit. PATIENTS: Two hundred thirty-six children who received extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Risk factors for hemolysis were retrospectively analyzed from a single center in a total of 236 neonatal and pediatric patients who received extracorporeal membrane oxygenation support (ECMO). There was no difference in the incidence of hemolysis between centrifugal (127 patients) and roller head (109 patients) pump type or between venoarterial and venovenous ECMO. High hemoglobin (Hb) was found to be an independent risk factor for hemolysis in both pump types. The Hb level >12 g/dL was significant in the roller group and the Hb level >13 g/dL was significant in the centrifugal group for the development of hemolysis for the cumulative ECMO run. The presence of high Hb levels on any given day increased the risk of hemolysis for that day of the ECMO run regardless of ECMO pump type. Higher revolutions per minute (RPMs) and higher inlet pressures on any given day increased the risk for the development of hemolysis in the centrifugal pump. Lower inlet venous pressures and RPMs were not associated with hemolysis in the roller group. CONCLUSIONS: An Hb level greater than 13 g/dL was associated with an increased risk of hemolysis, and a high Hb on a given day was associated with a significantly higher risk of hemolysis on the same day. Higher RPMs and lower inlet venous pressures were associated with an increased risk of hemolysis in the centrifugal pump only.

A narrative review of the technical standards for extracorporeal life support devices (pumps and oxygenators) in Europe.

This review summarizes the European rules to control the market when introducing new products. In particular, it shows all the steps to achieve the European Conformity (CE Mark), a certification that all new medical products must achieve before being used in Europe. Extracorporeal membrane oxygenation (ECMO) devices are exposed to the same procedures. Hereby, we present some regulatory issues regarding pumps and oxygenators, providing technical details as released by the manufacturers on their websites and information charts.

Improved Outcome of Cardiac Extracorporeal Membrane Oxygenation in Infants and Children Using Magnetic Levitation Centrifugal Pumps.

Extracorporeal membrane oxygenation (ECMO) has traditionally been and, for the most part, still is being performed using roller pumps. Use of first-generation centrifugal pumps has yielded controversial outcomes, perhaps due to mechanical properties of the same and the ensuing risk of hemolysis and renal morbidity. Latest-generation centrifugal pumps, using magnetic levitation (ML), exhibit mechanical properties which may have overcome limitations of first-generation devices. This retrospective study aimed to assess the safety and efficacy of veno-arterial (V-A) ECMO for cardiac indications in neonates, infants, and children, using standard (SP) and latest-generation ML centrifugal pumps. Between 2002 and 2014, 33 consecutive neonates, infants, and young children were supported using V-A ECMO for cardiac indications. There were 21 males and 12 females, with median age of 29 days (4 days-5 years) and a median body weight of 3.2 kg (1.9-18 kg). Indication for V-A ECMO were acute circulatory collapse in ICU or ward after cardiac repair in 16 (49%) patients, failure to wean after repair of complex congenital heart disease in 9 (27%), fulminant myocarditis in 4 (12%), preoperative sepsis in 2 (6%), and refractory tachy-arrhythmias in 2 (6%). Central cannulation was used in 27 (81%) patients and peripheral in 6. Seven (21%) patients were supported with SP and 26 (79%) with ML centrifugal pumps. Median duration of support was 82 h (range 24-672 h), with 26 (79%) patients weaned from support. Three patients required a second ECMO run but died on support. Seventeen (51%) patients required peritoneal dialysis for acute renal failure. Overall survival to discharge was 39% (13/33 patients). All patients with fulminant myocarditis and with refractory arrhythmias were weaned, and five (83%) survived, whereas no patient supported for sepsis survived. Risk factors for hospital mortality included lower (<2.5 kg) body weight (P = 0.02) and rescue ECMO after cardiac repair (P = 0.03). During a median follow-up of 34 months (range 4-62 months), there were three (23%) late deaths and two late survivors with neurological sequelae. Weaning rate (5/7 vs. 21/26, P = NS) and prevalence of renal failure requiring dialysis (4/7 vs. 13/26, P = NS) were comparable between SP and ML ECMO groups. Patients supported with ML had a trend toward higher hospital survival (1/7 vs. 12/26, P = 0.07) and significantly higher late survival (0/7 vs. 10/26, P = 0.05). The present experience shows that V-A ECMO for cardiac indications using centrifugal pumps in infants and children yields outcomes absolutely comparable to international registry (ELSO) data using mostly roller pumps. Although changes in practice may have contributed to these results, use of ML centrifugal pumps appears to further improve end-organ recovery and hospital and late survival.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass / Avaliação clínica da bomba espiral (Spiral Pump®) após aperfeiçoamentos introduzidos ao projeto original em pacientes submetidos a cirurgias cardíacas com circulação extracorpórea

Objective: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods: This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). Results: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application. .

Objetivos: Apresentar resultados da aplicação da bomba espiral que emprega efeitos hidráulicos centrífugo e axial de bombeamento como elemento propulsor do circuito de circulação extracorpórea em pacientes submetidos a cirurgias cardíacas após modificações introduzidas no design do projeto original. Métodos: O estudo foi realizado em 52 pacientes (51% masculinos), com idade entre 20 a 80 (67±14,4) anos, peso 53 a 102 (71,7±12,6) kg, submetidos na maioria a cirurgia de revascularização miocárdica (34,6%) e Orovalvar (32,8%). Além das avaliações rotineiras, foram registrados rotação, tempo de CEC e para análise do impacto traumático à crase sanguínea, hemoglobina livre na urina (+ a 4+), desidrogenase láctica, fibrinogênio (mg/dL) e contagem de plaquetas (nº/mm3). Resultados: Observou-se a manutenção de parâmetros pressóricos e metabólicos adequados. Quanto aos marcadores de danos à crase sanguínea, as alterações estiveram proporcionais ao tempo maior de circulação extracorpórea. Os níveis de Hemoglobina Livre permaneceram com valores normais, com ligeiro aumento a partir dos 90 minutos de circulação extracorpórea. A Desidrogenase Láctica mostrou aumento, variando as medianas entre 550 a 770 UI/L enquanto o Fibrinogênio mostrou queda das medianas de 130 a 100 mg/dl. O número de plaquetas mostrou ligeira queda das medianas variando entre 240.000 a 200.000/mm3. Não ocorreram dificuldades de saída de perfusão, não se observou óbito imediato e todos os pacientes, exceto 1, obtiveram alta hospitalar. Conclusão: A bomba espiral aplicada como bomba propulsora de sangue durante cirurgia cardíaca se mostrou confiável e segura, não causou impacto traumático ...

Comparison of hemolysis between CentriMag and RotaFlow rotary blood pumps during extracorporeal membrane oxygenation.

The purpose of this investigation was to compare the hemolysis levels for patients on extracorporeal membrane oxygenation (ECMO) incorporating two different rotary blood pumps (CentriMag [CMAG] and RotaFlow [RF]) in identical circuits otherwise. The difference between the two pumps is the cost. One is 20-30 times less expensive than the other. A retrospective analysis of all patients placed on ECMO from June 2008 through May 2012 was done to evaluate hemolysis. Daily plasma hemoglobin (pHb), lactate dehydrogenase (LDH), and lactate levels were collected on all patients. Values were compared between those patients who received a CMAG and those who received an RF. Patients had to be on ECMO for more than 2 days to be included in the study. Linear mixed effects models were fit to the data to assess differences over time for each continuous outcome. Forty patients were placed on ECMO incorporating CMAG, whereas 40 patients received an RF. There were no significant statistical differences between CMAG and RF groups when comparing days on support (8.7 ± 5.0; 8.4 ± 5.7), age (44.8 ± 18.3; 46.1 ± 16.0), body surface area (2.03 ± 0.36; 1.96 ± 0.31), gender (male: 58%, female: 42%; male: 55%, female: 45%), etiology, type of support (veno-arterial [VA)]: 78%, veno-venous [VV)]: 22%; VA: 82%, VV: 18%) and pre-ECMO LDH levels (4004.0 ± 3583.2; 3603.7 ± 3354.1). There were also no significant differences between the CMAG and RF groups when comparing the mean values for daily pHb levels (5.7 ± 3.6; 5.7 ± 4.2), lactate levels (2.8 ± 1.9; 3.0 ± 2.1), and LDH levels (2656.3 ± 1606.8; 2688.6 ± 1726.1) or daily lactate, LDH, and pHb levels for the first 10 days of support. From our investigation, there is no difference between the CMAG and the RF blood pumps in regard to the creation of hemolysis during ECMO. The difference in cost of the devices does not correlate with the performance and outcomes.