Mechanical, Thermal, and Physicochemical Properties of Filaments of Poly (Lactic Acid), Polyhydroxyalkanoates and Their Blend for Additive Manufacturing.

Polymeric blends are employed in the production of filaments for additive manufacturing to balance mechanical and processability properties. The mechanical and thermal properties of polymeric filaments made of poly (lactic acid) (PLA), polyhydroxyalkanoates (PHA), and its blend (PLA-PHA) are investigated herein and correlated to their measured structural and physicochemical properties. PLA exhibits the highest stiffness and tensile strength, but lower toughness. The mechanical properties of the PLA-PHA blend were similar to those of PLA, but with a significantly higher toughness. Despite the lower mechanical properties of neat PHA, incorporating a small amount (12 wt.%) of PHA into PLA significantly enhances toughness (approximately 50%) compared to pure PLA. The synergistic effect is attributed to the spherulitic morphology of blended PHA in PLA, promoting interactions between the amorphous regions of both polymers. Thermal stability is notably improved in the PLA-PHA blend, as determined by thermogravimetric analysis. The blend also exhibits lower cold crystallization and glass transition temperatures as compared to PLA, which is beneficial for additive manufacturing. Following additive manufacturing, X-ray photoelectron spectroscopic showed that the three filaments present an increase in C-C and C=O bonds associated with the loss of C-O bonds. The thermal process induces a slight increase in crystallinity in PHA due to chain reorganization. The study provides insights into the thermal and structural changes occurring during the melting process of additive manufacturing.

Cinética del lactato para el pronóstico en el shock cardiogénico asistido con oxigenador extracorpóreo de membrana venoarterial / Lactate levels as a prognostic predict in cardiogenic shock under venoarterial extracorporeal membrane oxygenation support

Introducción y objetivos: El lactato y su evolución se asocian con el pronóstico de los pacientes en shock, si bien es escasa la evidencia en aquellos asistidos con oxigenador extracorpóreo de membrana venoarterial (ECMO-VA). Nuestro objetivo es evaluar su valor pronóstico en shock cardiogénico asistido con ECMO-VA. Métodos: Estudio de pacientes tratados con ECMO-VA por shock cardiogénico de indicación médica entre julio de 2013 y abril de 2021. Se calculó el aclaramiento de lactato: (lactato inicial − lactato 6 h) / lactato inicial × tiempo exacto entre ambas determinaciones. Resultados: De 121 pacientes, 44 (36,4%) tenían infarto agudo de miocardio; 42 (34,7%), implante intraparada; 14 (11,6%), tromboembolia pulmonar, 14 (11,6%), tormenta arrítmica y 6 (5,0%), miocarditis fulminante. A los 30 días habían fallecido 60 pacientes (49,6%); la mortalidad fue mayor con el implante intraparada que con el implante en circulación espontánea (30 [71,4%] de 42 frente a 30 [38,0%] de 79; p=0,030). Se asociaron de manera independiente con la mortalidad a 30 días la alanina aminotransferasa (ALT) antes del implante y el lactato (tanto basal como a las 6 h y el aclaramiento). Los modelos de regresión que incluían el lactato presentaron mejor capacidad predictiva de la supervivencia que las puntuaciones ENCOURAGE y ECMO-ACCEPTS, con mayor área bajo la curva ROC en el modelo con lactato a las 6 h.Conclusiones: El lactato (basal y a las 6 h y el aclaramiento) es un predictor independiente para el pronóstico de los pacientes en shock cardiogénico asistidos con ECMO-VA que facilita una mejor estratificación del riesgo y tiene una capacidad predictiva superior (AU)

Introduction and objectives: Lactate and its evolution are associated with the prognosis of patients in shock, although there is little evidence in those assisted with an extracorporeal venoarterial oxygenation membrane (VA-ECMO). Our objective was to evaluate its prognostic value in cardiogenic shock assisted with VA-ECMO. Methods: Study of patients with cardiogenic shock treated with VA-ECMO for medical indication between July 2013 and April 2021. Lactate clearance was calculated: [(initial lactate − 6 h lactate) / initial lactate × exact time between both determinations]. Results: From 121 patients, 44 had acute myocardial infarction (36.4%), 42 implant during cardiopulmonary resuscitation (34.7%), 14 pulmonary embolism (11.6%), 14 arrhythmic storm (11.6%), and 6 fulminant myocarditis (5.0%). After 30 days, 60 patients (49.6%) died, mortality was higher for implant during cardiopulmonary resuscitation than for implant in spontaneous circulation (30 of 42 [71.4%] vs 30 of 79 [38.0%], P=.030). Preimplantation GPT and lactate (both baseline, at 6hours, and clearance) were independently associated with 30-day mortality. The regression models that included lactate clearance had a better predictive capacity for survival than the ENCOURAGE and ECMO-ACCEPTS scores, with the area under the ROC curve being greater in the model with lactate at 6 h. Conclusions: Lactate (at baseline, 6h, and clearance) is an independent predictor of prognosis in patients in cardiogenic shock supported by VA-ECMO, allowing better risk stratification and predictive capacity (AU)

Co-infections and superinfections complicating COVID-19 in cancer patients: A multicentre, international study.

BACKGROUND: We aimed to describe the epidemiology, risk factors, and clinical outcomes of co-infections and superinfections in onco-hematological patients with COVID-19. METHODS: International, multicentre cohort study of cancer patients with COVID-19. All patients were included in the analysis of co-infections at diagnosis, while only patients admitted at least 48 h were included in the analysis of superinfections. RESULTS: 684 patients were included (384 with solid tumors and 300 with hematological malignancies). Co-infections and superinfections were documented in 7.8% (54/684) and 19.1% (113/590) of patients, respectively. Lower respiratory tract infections were the most frequent infectious complications, most often caused by Streptococcus pneumoniae and Pseudomonas aeruginosa. Only seven patients developed opportunistic infections. Compared to patients without infectious complications, those with infections had worse outcomes, with high rates of acute respiratory distress syndrome, intensive care unit (ICU) admission, and case-fatality rates. Neutropenia, ICU admission and high levels of C-reactive protein (CRP) were independent risk factors for infections. CONCLUSIONS: Infectious complications in cancer patients with COVID-19 were lower than expected, affecting mainly neutropenic patients with high levels of CRP and/or ICU admission. The rate of opportunistic infections was unexpectedly low. The use of empiric antimicrobials in cancer patients with COVID-19 needs to be optimized.

Predictors of multidrug-resistant Pseudomonas aeruginosa in neutropenic patients with bloodstream infection.

OBJECTIVES: To assess risk factors for multidrug-resistant Pseudomonas aeruginosa (MDR-PA) infection in neutropenic patients. METHODS: Single-centre retrospective analysis of consecutive bloodstream infection (BSI) episodes (2004-2017, Barcelona). Two multivariate regression models were used at BSI diagnosis and P. aeruginosa detection. Significant predictors were used to establish rules for stratifying patients according to MDR-PA BSI risk. RESULTS: Of 661 Gram-negative BSI episodes, 190 (28.7%) were caused by P. aeruginosa (70 MDR-PA). Independent factors associated with MDR-PA among Gram-negative organisms were haematological malignancy (OR 3.30; 95% CI 1.15-9.50), pulmonary source of infection (OR 7.85; 95% CI 3.32-18.56), nosocomial-acquired BSI (OR 3.52; 95% CI 1.74-7.09), previous antipseudomonal cephalosporin (OR 13.66; 95% CI 6.64-28.10) and piperacillin/tazobactam (OR 2.42; 95% CI 1.04-5.63), and BSI occurring during ceftriaxone (OR 4.27; 95% CI 1.15-15.83). Once P. aeruginosa was identified as the BSI aetiological pathogen, nosocomial acquisition (OR 7.13; 95% CI 2.87-17.67), haematological malignancy (OR 3.44; 95% CI 1.07-10.98), previous antipseudomonal cephalosporin (OR 3.82; 95% CI 1.42-10.22) and quinolones (OR 3.97; 95% CI 1.37-11.48), corticosteroids (OR 2.92; 95% CI 1.15-7.40), and BSI occurring during quinolone (OR 4.88; 95% CI 1.58-15.05) and ß-lactam other than ertapenem (OR 4.51; 95% CI 1.45-14.04) were independently associated with MDR-PA. Per regression coefficients, 1 point was assigned to each parameter, except for nosocomial-acquired BSI (3 points). In the second analysis, a score >3 points identified 60 (86.3%) out of 70 individuals with MDR-PA BSI and discarded 100 (84.2%) out of 120 with non-MDR-PA BSI. CONCLUSIONS: A simple score based on demographic and clinical factors allows stratification of individuals with bacteraemia according to their risk of MDR-PA BSI, and may help facilitate the use of rapid MDR-detection tools and improve early antibiotic appropriateness.

Mechanical properties of l-lysine based segmented polyurethane vascular grafts and their shape memory potential.

Segmented polyurethanes based on polycaprolactone, 4,4 (metylene-bis-cyclohexyl) isocyanate, and l-lysine were synthesized, manufactured as small vascular grafts and characterized according to ISO 7198 standard for cardiovascular implants-tubular vascular prosthesis. In terms of mechanical properties, the newly synthesized polyurethane films exhibited lower secant modulus than Tecoflex™ SG 80A, a well-known medical grade polyurethane. Similarly, when tested as grafts, the l-lysine-based polyurethane exhibited lower longitudinal failure load (11.5 N vs. 116 N), lower circumferential failure load per unit length (5.67 N/mm vs. 14.0 N/mm) and lower suture forces for both nylon (13.3 N vs. 24.0 N) and silk (14.0 N vs. 19.3 N) when compared to Tecoflex™ SG 80A grafts. l-Lysine-based graft exhibited a burst strength of 3620 mmHg (482.6 kPa) and a compliance of 0.16%/mmHg. The cell adhesion was demonstrated with NIH/3T3 fibroblasts where cell adhesion was observed on both films and grafts, while cell alignment was observed only on the grafts. The mechanical properties of this polyurethane and the possibility of strain-induced PCL crystals as the switching phase for shape memory materials, allowed a strain recovery ratio and a strain fixity ratio with values higher than 95% and 90%, respectively, with a repeatability of the shape-memory properties up to 4 thermo-mechanical cycles. Overall, the properties of lysine-based polyurethanes are suitable for large diameter vascular grafts where cell alignment can be controlled by their shape memory potential.

Design and analysis of a burst strength device for testing vascular grafts.

The design and analysis of a device to measure the burst strength (strength under a state of pure radial internal pressure) and compliance of vascular grafts and flexible pressurized tubes is presented. The device comprises three main sections, viz., a clean air-dry pressure controller, a test specimen holder, and automated software for control and data collection. Air pressure is controlled by means of a valve and a dedicated mechanism allowing reaching up to 120 psi in increments of 1 psi, and recording pressure changes with 0.04 psi resolution. The circumferential strain is determined by measuring the radial displacement of the vascular graft using an optical arrangement capable of determining a maximum radial displacement of 10 mm with 0.02 mm resolution. The instrument provides a low uncertainty in compliance (±0.32%/100 mm Hg-1) and burst strength measurements. Due to its simplicity, the device can easily be reproduced in other laboratories contributing to a dedicated instrument with high resolution at low cost. The reliability of the apparatus is further confirmed by conducting finite element analysis, elasticity solutions for pressurized cylinders, and testing of small diameter vascular grafts made of a commercial aliphatic polyurethane tested under radial internal pressure.

Phase singularity point tracking for the identification of typical and atypical flutter patients: A clinical-computational study.

Atrial Flutter (AFL) termination by ablating the path responsible for the arrhythmia maintenance is an extended practice. However, the difficulty associated with the identification of the circuit in the case of atypical AFL motivates the development of diagnostic techniques. We propose body surface phase map analysis as a noninvasive tool to identify AFL circuits. Sixty seven lead body surface recordings were acquired in 9 patients during AFL (i.e. 3 typical, 6 atypical). Computed body surface phase maps from simulations of 5 reentrant behaviors in a realistic atrial structure were also used. Surface representation of the macro-reentrant activity was analyzed by tracking the singularity points (SPs) in surface phase maps obtained from band-pass filtered body surface potential maps. Spatial distribution of SPs showed significant differences between typical and atypical AFL. Whereas for typical AFL patients 70.78 ±â€¯16.17% of the maps presented two SPs simultaneously in the areas defined around the midaxialliary lines, this condition was only satisfied in 5.15 ±â€¯10.99% (p < 0.05) maps corresponding to atypical AFL patients. Simulations confirmed these results. Surface phase maps highlights the reentrant mechanism maintaining the arrhythmia and appear as a promising tool for the noninvasive characterization of the circuit maintaining AFL. The potential of the technique as a diagnosis tool needs to be evaluated in larger populations and, if it is confirmed, may help in planning ablation procedures.

Tormenta arrítmica resuelta tras angioplastia y ablación bajo soporte con oxigenación de membrana extracorpórea venoarterial / Arrhythmic storm solved with ExtraCorporeal Membrane Oxygenation and consecutive percutaneous coronary intervention and ventricular tachycardia ablation

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Prevalencia e incidencia de hiperpotasemia en población española con insuficiencia cardiaca con fracción de eyección deprimida: revisión sistemática y relevancia poblacional / Prevalence and incidence of hyperkalaemia in the Spanish population with heart failure with reduced ejection fraction: a systematic review and populational relevance

Antecedentes y objetivo: La hiperpotasemia (K+≥5,5mmol/l) es un desequilibrio iónico grave cuando aparece en pacientes que padecen insuficiencia cardiaca con fracción de eyección deprimida (ICFED), ya que incrementa el riesgo de fibrilación ventricular. No existen estimaciones del número de pacientes que sufren esta complicación. El objetivo de este estudio fue estimar la prevalencia e incidencia de hiperpotasemia en pacientes con ICFED en España. Materiales y métodos: A partir de una búsqueda bibliográfica sistemática se calculó mediante un metaanálisis la prevalencia de ICFED<40% en población europea y norteamericana. A partir de otra búsqueda bibliográfica sistemática se calculó la prevalencia de hiperpotasemia en individuos con insuficiencia cardiaca, así como su incidencia anual. Considerando los anteriores valores y la pirámide de población española en 2016 se estimó el número de individuos con ICFED que presentan actualmente y que desarrollan cada año hiperpotasemia en España. Resultados: Alrededor de 17.100 individuos (10.000 hombres y 7.100 mujeres) de los 508.000 pacientes con ICFED presentan hiperpotasemia en España. Asimismo, unos 14.900 pacientes con ICFED (9.500 hombres y 5.400 mujeres) la desarrollan cada año. Conclusiones: Aproximadamente uno de cada 30 pacientes con ICFED presenta valores plasmáticos de potasio por encima de 5,5mmol/l

Background and objectives: Hyperkalaemia (K+ levels≥5.5mmol/L) is a severe ion imbalance that occurs in patients who have heart failure (HF) with reduced ejection fraction (HFrEF) and increases the risk of ventricular fibrillation. Given that there are no estimates on the number of patients with this complication, the aim of this study was to estimate the prevalence and incidence of hyperkalaemia in patients with HFrEF in Spain. Material and methods: Based on a systematic literature search and through a meta-analysis, we calculated an HFrEF prevalence of ≤40% in the European and U.S. population. Based on another systematic literature search, we calculated the prevalence of hyperkalaemia in patients with HF and its annual incidence rate. Considering the previous values and the Spanish population pyramid in 2016, we estimated the number of individuals with HFrEF who currently have hyperkalaemia and those who develop it each year in Spain. Results: Approximately 17,100 (10,000 men and 7100 women) of the 508,000 patients with HFrEF in Spain have hyperkalaemia. Furthermore, approximately 14,900 patients with HFrEF (9500 men and 5400 women) develop hyperkalaemia each year. Conclusions: Approximately 1 of every 30 patients with HFrEF has plasma potassium values >5.5 mmol/L

Prevalence and incidence of hyperkalaemia in the Spanish population with heart failure with reduced ejection fraction: a systematic review and populational relevance. / Prevalencia e incidencia de hiperpotasemia en población española con insuficiencia cardiaca con fracción de eyección deprimida: revisión sistemática y relevancia poblacional.

BACKGROUND AND OBJECTIVES: Hyperkalaemia (K+ levels≥5.5mmol/L) is a severe ion imbalance that occurs in patients who have heart failure (HF) with reduced ejection fraction (HFrEF) and increases the risk of ventricular fibrillation. Given that there are no estimates on the number of patients with this complication, the aim of this study was to estimate the prevalence and incidence of hyperkalaemia in patients with HFrEF in Spain. MATERIAL AND METHODS: Based on a systematic literature search and through a meta-analysis, we calculated an HFrEF prevalence of ≤40% in the European and U.S. POPULATION: Based on another systematic literature search, we calculated the prevalence of hyperkalaemia in patients with HF and its annual incidence rate. Considering the previous values and the Spanish population pyramid in 2016, we estimated the number of individuals with HFrEF who currently have hyperkalaemia and those who develop it each year in Spain. RESULTS: Approximately 17,100 (10,000 men and 7100 women) of the 508,000 patients with HFrEF in Spain have hyperkalaemia. Furthermore, approximately 14,900 patients with HFrEF (9500 men and 5400 women) develop hyperkalaemia each year. CONCLUSIONS: Approximately 1 of every 30 patients with HFrEF has plasma potassium values >5.5 mmol/L.

Prediction of circumferential compliance and burst strength of polymeric vascular grafts.

The circumferential compliance and burst strength of vascular grafts are predicted through the conically modified von Mises and elasticity theories, providing an analytical closed form solution for both parameters. Besides the graft's radii, the model for circumferential compliance depends solely on the elastic modulus and Poisson's ratio of the polymer material, and its accuracy was verified by finite element analysis and measurements. The analytical expression of the burst strength requires accurate determination of the material's tensile and compressive yield stress, which were carefully obtained by using digital image correlation measurements in uniaxial tensile and compressive tests of the constitutive material. The average measured circumferential compliance and burst strength of an 8mm graft made of a commonly used biomaterial, Tecoflex® SG-80A, are 1.05%/100mmHg-1 and 34.1psi (1763mmHg) and the proposed analytical predictions fall within the experimental scattering. Thus, it is shown that the circumferential compliance and burst strength of vascular grafts can be analytically predicted by knowing the elastic and yield material properties accurately, without needing to actually test the graft under radial pressure. This is a major advantage which can aid in the design and tailoring of vascular grafts.

Minimal configuration of body surface potential mapping for discrimination of left versus right dominant frequencies during atrial fibrillation.

BACKGROUND: Ablation of drivers maintaining atrial fibrillation (AF) has been demonstrated as an effective therapy. Drivers in the form of rapidly activated atrial regions can be noninvasively localized to either left or right atria (LA, RA) with body surface potential mapping (BSPM) systems. This study quantifies the accuracy of dominant frequency (DF) measurements from reduced-leads BSPM systems and assesses the minimal configuration required for ablation guidance. METHODS: Nine uniformly distributed lead sets of eight to 66 electrodes were evaluated. BSPM signals were registered simultaneously with intracardiac electrocardiograms (EGMs) in 16 AF patients. DF activity was analyzed on the surface potentials for the nine leads configurations, and the noninvasive measures were compared with the EGM recordings. RESULTS: Surface DF measurements presented similar values than panoramic invasive EGM recordings, showing the highest DF regions in corresponding locations. The noninvasive DFs measures had a high correlation with the invasive discrete recordings; they presented a deviation of <0.5 Hz for the highest DF and a correlation coefficient of >0.8 for leads configurations with 12 or more electrodes. CONCLUSIONS: Reduced-leads BSPM systems enable noninvasive discrimination between LA versus RA DFs with similar results as higher-resolution 66-leads system. Our findings demonstrate the possible incorporation of simplified BSPM systems into clinical planning procedures for AF ablation.

Tratamiento del infarto agudo de miocardio con ECMO: más allá del balón de contrapulsación / Treatment of acute myocardial infarction with ECMO: Beyond the intraaortic balloon pump

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Fibroelastosis endomiocárdica como causa de insuficiencia cardiaca avanzada / Advanced heart failure due to endomyocardial fibroelastosis

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