Nanoindentation into a bcc high-entropy HfNbTaTiZr alloy-an atomistic study of the effect of short-range order.

The plastic response of the Senkov HfNbTaTiZr high-entropy alloy is explored by means of simulated nanoindentation tests. Both a random alloy and an alloy with chemical short-range order are investigated and compared to the well understood case of an elementary Ta crystal. Strong differences in the dislocation plasticity between the alloys and the elementary Ta crystal are found. The high-entropy alloys show only little relaxation of the indentation dislocation network after indenter retraction and only negligible dislocation emission into the sample interior. Short-range order-besides making the alloy both stiffer and harder-further increases the size of the plastic zone and the dislocation density there. These features are explained by the slow dislocation migration in these alloys. Also, the short-range-ordered alloy features no twinning plasticity in contrast to the random alloy, while elemental Ta exhibits twinning under high stress but detwins considerably under stress relief. The results are in good qualitative agreement with our current knowledge of plasticity in high-entropy alloys.

Postoperative atrial fibrillation (POAF) after cardiac surgery: clinical practice review.

Postoperative atrial fibrillation (POAF) after cardiac surgery is associated with elevated morbidity and mortality. Although current prediction models have limited efficacy, several perioperative interventions can reduce patients' risk of POAF. These begin with preoperative medications, including beta-blockers and amiodarone. Moreover, patients should be screened for preexisting atrial fibrillation (AF) so that concomitant surgical ablation and left atrial appendage occlusion can be performed in appropriate candidates. Intraoperative interventions such as posterior pericardiectomy can reduce mediastinal fluid accumulation, which is a trigger for POAF. Furthermore, many preventive strategies for POAF are implemented in the immediate postoperative period. Initiating beta-blockers, amiodarone, or both is reasonable for most patients. Overdrive atrial pacing, colchicine, and steroids have been used by some, although the evidence base is less robust. For patients with POAF, rate-control and rhythm-control strategies have comparable outcomes. Decision-making regarding anticoagulation should recognize that the stroke risk associated with POAF appears to be lower than that for general nonvalvular AF. The evidence that oral anticoagulation reduces stroke risk is less clear for POAF patients than for patients with general nonvalvular AF. Given that POAF tends to be shorter-lived and is associated with greater bleeding risks in the perioperative period, decisions regarding anticoagulation should be individualized. Finally, wearable technology and machine learning algorithms for better predicting and managing POAF appear to be coming soon. These technologies and a comprehensive clinical program could meaningfully reduce the incidence of this common complication.

Left Atrial Peak Systolic Strain as an Indicator Pathway of Diastolic Dysfunction of the Left Ventricle.

BACKGROUND: Left atrial peak systolic strain (LA-PSS) imaging is an emerging index of left atrial function, and it was shown to be decreased in heart failure with preserved ejection fraction (EF). We aimed to determine whether LA-PSS could be used as an additional diagnostic parameter to current existing guidelines for the presence of left ventricle diastolic dysfunction (LVDD). MATERIALS AND METHODS: A total of 190 consecutive adult patients with cardiovascular risk factors and normal left ventricle EF with no prior history of heart failure were included in the study. Speckle tracking software was used to study ventricular parietal deformity, left ventricle global longitudinal systolic strain, and LA-PSS. RESULTS: The median left ventricle global longitudinal systolic strain was -19%, with a significant difference ( P < 0.001) between patients with normal diastolic function versus those with LVDD. The median LA-PSS was 33% (30% to 38%) ( P < 0.001). Most patients (61%) had grade 1 atrial dysfunction based on PSS (range 24%-35%). The analysis of the area under the receiver operating characteristic curve of the LA-PSS as a potential indicator pathway of LVDD was 67% [95% confidence interval (CI), 62-72], and 75% (95% CI, 70-80), when the indeterminate pattern was included. The decreased LA-PSS made it possible to reclassify patients with an indeterminate pattern of diastolic function in 96% of cases. CONCLUSIONS: These results support the potential role of LA-PSS as an additional parameter for the diagnosis of LVDD in patients with normal EF, and may be integrated into the guidelines for routine evaluation of patients.

Recovery of Lung Function After 149 Days on Extracorporeal Membrane Oxygenation for COVID-19.

This report highlights survival and the patient's perspective after prolonged venovenous extracorporeal membrane oxygenation (ECMO) for COVID-19-related respiratory failure. A 36-year-old man with COVID-19 presented with fever, anosmia, and hypoxia. After respiratory deterioration necessitating intubation and lung-protective ventilation, he was referred for ECMO. After 3 days of conventional venovenous ECMO, he required multiple creative cannulation configurations. Adequate sedation and recurrent bradycardia were persistent challenges. After 149 consecutive days of ECMO, he recovered native lung function and was weaned from mechanical ventilation. This represents the longest-duration ECMO support in a survivor of COVID-19 yet reported. Necessary strategies included unconventional cannulation and flexible anticoagulation.

New-onset microscopic polyangiitis temporally associated with severe COVID-19 infection: A case report.

The coronavirus disease 2019 has been demonstrated to be a trigger for multiple immune-mediated diseases, such as antineutrophil cytoplasmic antibody-associated vasculitis. Associated vasculitis consists of rare autoimmune disorders that predominantly affect small vessels, leading to endothelial injury and tissue damage. We present a case of a newly diagnosed microscopic polyangiitis temporally associated with coronavirus disease 2019 infection in a previously healthy woman and a literature review. A 66-year-old female presented to the Emergency Room with fever, edema on her legs, productive cough, dyspnea, and hemoptysis. A chest computerized tomography scan revealed bilateral diffuse alveolar opacities with the appearance of diffuse alveolar hemorrhage. Blood analysis revealed a moderate normocytic, normochromic anemia with a hemoglobin of 6.6 g/dL, platelet count of 347 k/dL, leucocytes of 12,000/dL, a creatinine of 3.91 mg/dL (basal Cr: 0.9 mg/dL), and a Blood Urine Nnitrogen of 78 mg/dL. A urine sediment demonstrated glomerular hematuria, with mixed shapes of red blood cells. She was admitted to the intensive care unit and a bedside bronchoscopy revealed progressive bleeding with a bronchioalveolar lavage positive for diffuse alveolar hemorrhage. Given the critical involvement of the lungs and kidney function, the diagnostic approach revealed a positive p-anti-neutrophil cytoplasmic antibody on immunofluorescence and an anti-MPO (myeloperoxidase) level of 124.6 IU/mL. A renal biopsy demonstrated pauciimmune focal and segmental glomerulosclerosis. A diagnosis of microscopic polyangiitis triggered by severe acute respiratory syndrome coronavirus 2 infection was made, and immediate treatment with pulse-dose steroids and cyclophosphamide was initiated. The patient needed renal replacement therapy and was discharged for follow-up with nephrology and rheumatology services. The diagnostic approach of associated vasculitis can be more challenging in the coronavirus disease era. Atypical features in the pulmonary imaging and a rapid deterioration of the renal function should arise the clinical suspicion of the presence of an added condition to the coronavirus disease infection. Autoimmune conditions such as associated vasculitis should be evaluated even in the absence of previous autoimmune history. Prompt diagnosis and treatments must be prioritized to avoid end-organ definite damage. Further, larger and more collaborative studies are needed to confirm the potential role of coronavirus disease 2019 as a trigger of associated vasculitis.

Simulated nanoindentation into single-phase fcc Fe[Formula: see text]Ni[Formula: see text] alloys predicts maximum hardness for equiatomic stoichiometry.

We investigate by molecular dynamics simulation the mechanical behavior of concentrated alloys under nanoindentation for the special example of single-phase fcc Fe[Formula: see text]Ni[Formula: see text] alloys. The indentation hardness is maximum for the equiatomic alloy, [Formula: see text]. This finding is in agreement with experimental results on the strength of these alloys under uniaxial strain. We explain this finding with the increase of the unstable stacking fault energy in the alloys towards [Formula: see text]. With increasing Fe content, loop emission from the plastic zone under the indenter becomes less pronounced and the plastic zone features a larger fraction of screw dislocation segments; simultaneously, the length of the dislocation network and the number of atoms in the stacking faults generated in the plastic zone increase. However, the volume of twinned regions in the plastic zone is highest for the elemental solids and decreases for the alloys. This feature is explained by the fact that twinning proceeds by the glide of dislocations on adjacent parallel lattice planes; this concerted motion is less efficient in the alloys. Finally, we find that surface imprints show increasing pile-up heights with increasing Fe content. The present results will be of interest for hardness engineering or generating hardness profiles in concentrated alloys.

Advancing Education in Endoscopic Spinal Navigation: Novel Methods and Technical Note.

This report aims to demonstrate how to teach anatomy and understanding of spinal endoscopic vision and navigation using mnemonics. The authors present a new surgical technique for teaching endoscopic spinal navigation in a didactic manner with tips such as the "rule of the hand" and decomposition of the endoscopic navigation movement. We demonstrate how the surgery is seen and illustrate how images are projected onto the screen, then divide the navigation into spatial orientation and self-navigation. The article describes the proper puncture technique, how to introduce the working portal, and how to assimilate this new anatomical vision using the "rule of the hand." The surgeon projects their hand on the video screen to guide themselves when starting the navigation and uses the same technique to localize regions of interest during surgery. Finally, the authors break down the navigational movement into three components: forceps positioning, triangulation, and joystick motion. One of the biggest challenges when learning spinal endoscopic surgery is understanding the anatomy seen through the endoscope. By decomposing movements required for navigation, one can understand how to make proper use of the equipment as well as improve their knowledge of this "new anatomy." The learning methods taught in this article have the potential to decrease the learning curve and radiation exposure to those that are still acquainting themselves to spinal endoscopic navigation. We recommend that further studies measure and quantify the impact of these methods on surgical practice.

Simplified acute physiology score II and Mannheim peritonitis index are associated with in-hospital mortality in patients with abdominal sepsis admitted to ICU.

OBJECTIVE: The objective of this study was to assess the association and interaction of laboratory parameters, Simplified Acute Physiology Score II (SAPSII), Modified Shock Index (MSI), and Mannheim Peritonitis Index (MPI) with in-hospital mortality. MATERIAL AND METHODS: We conducted a single-center case-control study. Adult patients with abdominal sepsis were included from May 2015 to May 2020. Baseline characteristics, laboratory parameters, SAPSII, MSI, and MPI scores at admission were collected. A principal component (PC) analysis was applied to evaluate variable interactions. In-hospital mortality risk was determined through logistic regression models. RESULTS: One hundred and twenty-seven patients were identified, 60 of which were included for analyses. Non-survivors (48.4%) had a higher frequency of hypertension, lactate and MPI, and lower BE and alactic BE levels. Eight PCs were obtained, PC1 being a linear combination of pH, AG, cAG, alactic BE, bicarbonate, and BE. MPI (OR = 9.87, 95% CI: 3.07-36.61, p = 0.0002), SAPSII (OR = 1.07, 95% CI: 1.01-1.14, p = 0.01), and PC1 (OR = 2.13, 95% CI: 1.12-4.76, p = 0.04) were significantly associated with mortality in univariate analysis, while MPI (OR = 10.1, 95% CI: 3.03-40.06, p = 0.0003) and SAPSII (OR = 1.07, CI95%: 1.01-1.14, p = 0.02) remained significant after adjusting for age and sex. CONCLUSION: MPI and SAPSII were associated with mortality, although the interaction of laboratory parameters was not.

OBJETIVO: Evaluar la asociación e interacción de los parámetros de laboratorio, SAPSII, MSI y MPI con la mortalidad intrahospitalaria. MATERIALES Y MÉTODOS: Nosotros realizamos un estudio de casos y controles de pacientes adultos con sepsis abdominal desde mayo 2015 a mayo 2020. Recolectamos las características basales, parámetros de laboratorio, SAPSII, MSI y MPI al ingreso. Se aplicó un Análisis de Componentes Principales. El riesgo de mortalidad intrahospitalaria se determinó mediante modelos de regresión logística. RESULTADOS: Identificamos 127 pacientes, 60 de los cuales se incluyeron. Los no supervivientes (48,4%) tuvieron mayor frecuencia de HAS, lactato y MPI, y menores niveles de EB y EB aláctico. Se obtuvieron ocho Componentes Principales (PC), siendo PC1 una combinación lineal de pH, AG, cAG, EB aláctico, bicarbonato y EB. MPI (OR = 9.87, IC95%: 3.07-36.61, p = 0.0002), SAPSII (OR = 1.07, IC95%: 1.01-1.14, p = 0.01) y PC1 (OR = 2.13, IC95%: 1.12-4.76, p = 0.04) se asociaron significativamente con la mortalidad en el análisis univariado, mientras que MPI (OR = 10.1, IC95%: 3.03-40.06, p = 0.0003) y SAPSII (OR = 1.07, IC 95%: 1.01-1.14, p = 0.02) permanecieron significativos después del ajuste por edad y sexo. CONCLUSIONES: MPI y SAPSII se asociaron con mortalidad, aunque la interacción de los parámetros de laboratorio no lo hizo.

Awake prone positioning and oxygen therapy in patients with COVID-19: the APRONOX study.

BACKGROUND: The awake prone positioning strategy for patients with acute respiratory distress syndrome is a safe, simple and cost-effective technique used to improve hypoxaemia. We aimed to evaluate intubation and mortality risk in patients with coronavirus disease 2019 (COVID-19) who underwent awake prone positioning during hospitalisation. METHODS: In this retrospective, multicentre observational study conducted between 1 May 2020 and 12 June 2020 in 27 hospitals in Mexico and Ecuador, nonintubated patients with COVID-19 managed with awake prone or awake supine positioning were included to evaluate intubation and mortality risk through logistic regression models; multivariable and centre adjustment, propensity score analyses, and E-values were calculated to limit confounding. RESULTS: 827 nonintubated patients with COVID-19 in the awake prone (n=505) and awake supine (n=322) groups were included for analysis. Fewer patients in the awake prone group required endotracheal intubation (23.6% versus 40.4%) or died (19.8% versus 37.3%). Awake prone positioning was a protective factor for intubation even after multivariable adjustment (OR 0.35, 95% CI 0.24-0.52; p<0.0001, E=2.12), which prevailed after propensity score analysis (OR 0.41, 95% CI 0.27-0.62; p<0.0001, E=1.86) and mortality (adjusted OR 0.38, 95% CI 0.26-0.55; p<0.0001, E=2.03). The main variables associated with intubation among awake prone patients were increasing age, lower baseline peripheral arterial oxygen saturation/inspiratory oxygen fraction ratio (P aO2 /F IO2 ) and management with a nonrebreather mask. CONCLUSIONS: Awake prone positioning in hospitalised nonintubated patients with COVID-19 is associated with a lower risk of intubation and mortality.

Aplicaciones e implicaciones de la pausa al final de la inspiración en ventilación mecánica / Applications and implications of end-inspiratory pause in mechanical ventilation / Aplicações e implicações da pausa ao final da inspiração na ventilação mecânica

Resumen: El uso de la pausa al final de la inspiración (PFI) en ventilación mecánica data de hace más de 50 años y con mayor impulso en la década de los 70, se le atribuye una mejoría en la presión parcial de oxígeno arterial (PaO2) al incrementar la presión media de la vía aérea (Pma), mayor aclaramiento de la presión parcial de dióxido de carbono arterial (PaCO2) y permite la monitorización de la presión meseta (Pmeseta) en la mecánica ventilatoria; sin embargo, los estudios clínicos sobre su uso son escasos y controversiales. En este artículo se abordan los mecanismos fisiológicos, fisiopatológicos y la evidencia sobre el uso de la PFI en ventilación mecánica (VM).

Abstract: The use of the end inspiratory pause (EIP) in mechanical ventilation has been going on for more than 50 years and with greater momentum in the 1970s, an improvement in the partial pressure of arterial oxygen (PaO2) is attributed to the increase mean airway pressure, greater clearance of partial pressure of arterial carbon dioxide and allows monitoring of plateau pressure in ventilatory mechanics; However, the Clinical studies on its use are few and controversial. This article addresses the physiological and pathophysiological mechanisms and the evidence on the use of EIP in mechanical ventilation.

Resumo: A utilização da pausa ao final da inspiração (PFI) na ventilação mecânica remonta a mais de 50 anos e com maior impulso na década de 70, atribui-se uma melhora na pressão parcial de oxigênio arterial (PaO2) pelo aumento da pressão média das vias aéreas (Pma), uma maior depuração da pressão parcial de dióxido de carbono arterial (PaCO2) e permite a monitorização da pressão de platô (Pplateau) na mecânica ventilatória, porém estudos Os dados clínicos sobre seu uso são escassos e controversos. Este artigo aborda os mecanismos fisiológicos e fisiopatológicos e as evidências sobre o uso do PFI na ventilação mecânica (VM).

Ultrasonido Point-Of-Care (POCUS) durante la reanimación cardiopulmonar para el diagnóstico de causas reversibles de arresto cardiaco / Point-Of-Care ultrasound (POCUS) during cardiopulmonary resuscitation for the diagnosis of reversible causes of cardiac arrest / Ultrassonografia Point-of-Care (POCUS) durante a reanimação cardiopulmonar para o diagnóstico de causas reversíveis de parada cardíaca

Resumen: La ultrasonografía enfocada al paciente crítico o «ultrasonido Point-Of-Care¼ (POCUS) es una herramienta utilizada en la cabecera del paciente en distintas áreas de la medicina crítica y servicios de emergencias debido a su practicidad y a que provee gran información de forma rápida y no invasiva para realizar diagnósticos y abordajes terapéuticos. El arresto cardiaco (AC) es una situación crítica que requiere una adecuada reanimación cardiopulmonar (RCP) y en la que es crucial la identificación de la etiología para realizar una intervención rápida y lograr la resolución de la misma, particularmente en el escenario de una actividad eléctrica sin pulso (AESP) en la que la ecografía cobra vital importancia. La implementación de protocolos de reanimación cardiopulmonar apoyados de un abordaje ultrasonográfico es factible y de gran utilidad para la identificación etiológica del AC y la resolución de causas específicas.

Abstract: Ultrasound focused on the critical patient or «Point-Of-Care ultrasound¼ (POCUS) is a tool used at the patient's bedside in different areas of critical medicine and emergency services due to its practicality as it provides great information quickly and non-invasive for diagnostic and therapeutic approaches. Cardiac arrest (CA) is a critical situation that requires adequate cardiopulmonary resuscitation (CPR), and in which the identification of the etiology is crucial to carry out a rapid intervention and achieve its resolution, particularly in the setting of a pulseless electrical activity (AESP) in which ultrasound is of vital importance. The implementation of cardiopulmonary resuscitation protocols supported by an ultrasound approach is feasible and of great utility for the etiological identification of CA and the resolution of specific causes.

Resumo: A ultrassonografia focada em pacientes críticos ou «Point-Of-Care ultra-som¼ (POCUS) é uma ferramenta utilizada à beira do leito do paciente em diferentes áreas da medicina crítica e serviços de emergência devido à sua praticidade e ao fato de fornecer uma grande quantidade de informações rapidamente e não invasivo para abordagens diagnósticas e terapêuticas. A parada cardíaca (PC) é uma situação crítica que requer uma adequada ressuscitação cardiopulmonar (RCP) e na qual a identificação da etiologia é crucial para a rápida intervenção e resolução, particularmente no cenário de uma atividade elétrica sem pulso (AESP) em qual o ultra-som é de vital importância. A implementação de protocolos de ressuscitação cardiopulmonar apoiados por uma abordagem ultrassonográfica é viável e muito útil para a identificação etiológica do RAC e resolução de causas específicas.

Rol de la morfología y dispersión de la onda P en la predicción de fibrilación auricular

RESUMEN Las características anisotrópicas ocasionadas por un miocardio auricular patológico pueden jugar un papel importante en la creación de circuitos de reentrada al causar propagación no homogénea y discontinua del impulso en el miocardio auricular. Este miocardio auricular alterado puede generar bloqueo unidireccional, retraso de la conducción y ritmos auriculares reentrantes. En estas condiciones la onda P del electrocardiograma (ECG) puede mostrar alteraciones que pueden asociarse con arritmias auriculares y fibrilación auricular (FA). La dispersión de la onda P (DP) se considera un marcador no invasivo del ECG para el remodelado auricular y es predictor sensible y específico del desarrollo de FA. Se ha demostrado que el aumento de la duración de la onda P y la DP reflejan la prolongación del tiempo de conducción auricular dentro de la aurícula derecha y entre ambas aurículas, y una propagación auricular no homogénea y discontinua de los impulsos sinusales. Un valor de corte de 40 ms de la DP demostró tener una sensibilidad del 83%, una especificidad del 85% y un valor predictivo positivo del 89% para la identificación de pacientes con antecedentes de FA paroxística aislada. Los pacientes con alteración de la morfología de la onda P y dispersión de la onda P en el ECG tienen una gran susceptibilidad a desarrollar FA porque poseen electrogramas endocárdicos auriculares anormalmente prolongados y fraccionados, una duración de onda P significativamente mayor, un tiempo de conducción intraauricular e interauricular significativamente más largo, y una mayor incidencia de inducción de fibrilación auricular sostenida.

ABSTRACT The anisotropic characteristics caused by a pathological atrial myocardium can play an important role in the creation of reentry circuits by causing discontinuous and inhomogeneous impulse propagation in the atrial myocardium. This altered atrial myocardium can lead to unidirectional block, conduction delay, and reentrant atrial rhythms. Under these conditions, the P wave of the electrocardiogram (ECG) can demonstrate alterations that can be associated with atrial arrhythmias and atrial fibrillation (AF). The P-wave dispersion (PD) is considered a non-invasive ECG marker for atrial remodeling and is a sensitive and specific predictor of the development of AF. Increased P wave duration and PD have been shown to reflect prolonged atrial conduction time within the right atrium and between both atria, and discontinuous, inhomogeneous atrial propagation of sinus impulses. A cutoff value of 40 ms for PD was shown to have a sensitivity of 83%, a specificity of 85%, and a positive predictive value of 89% for the identification of patients with a history of isolated paroxysmal AF. Patients with abnormal P wave morphology and P wave dispersion on the ECG are highly susceptible to developing AF because they have abnormally prolonged and fractionated atrial endocardial electrograms, significantly longer P wave duration, and significantly longer intra-atrial and inter-atrial conduction time, and a higher incidence of sustained atrial fibrillation induction.