Bench assessment of PC-CMVs modes in transport and emergency ventilators under ICU conditions.

Although there has been an increase in bench test evaluation of mechanical ventilators in recent years, a publication gap remains in assessing Pressure Control Continuous Mandatory Ventilation Modes with a set point targeting scheme PC-CMVs. This study evaluates the operational variability in PC-CMVs of eleven transport and emergency ventilators used in ICU units in Brazil during the COVID-19 pandemic. The assessment involved a comprehensive set of test scenarios derived from existing literature and the NBR ISO 80601-2-12:2014 standard. Nine parameters were computed for five consecutive breaths, offering a comprehensive characterization of pressure and flow waveforms. Most ventilators had Inspiratory pressure and PEEP values that fell outside of the tolerance ranges. Notably, three mechanical ventilators failed to reach the target pressures within the specified inspiratory times during test scenarios with a higher time constant (τ). We observed significant differences among emergency and transport ventilators in all assessed parameters, indicating a performance difference in PC-CMVs modes. The current results might help clinicians determine which ventilator models are suitable for specific clinical situations, particularly when unfavorable circumstances compel doctors to use ventilators that may not provide adequate support for patients in intensive care units.

First real-time imaging of bronchoscopic lung volume reduction by electrical impedance tomography.

BACKGROUND: Bronchoscopic lung volume reduction (BLVR) with one-way endobronchial valves (EBV) has better outcomes when the target lobe has poor collateral ventilation, resulting in complete lobe atelectasis. High-inspired oxygen fraction (FIO2) promotes atelectasis through faster gas absorption after airway occlusion, but its application during BLVR with EBV has been poorly understood. We aimed to investigate the real-time effects of FIO2 on regional lung volumes and regional ventilation/perfusion by electrical impedance tomography (EIT) during BLVR with EBV. METHODS: Six piglets were submitted to left lower lobe occlusion by a balloon-catheter and EBV valves with FIO2 0.5 and 1.0. Regional end-expiratory lung impedances (EELI) and regional ventilation/perfusion were monitored. Local pocket pressure measurements were obtained (balloon occlusion method). One animal underwent simultaneous acquisitions of computed tomography (CT) and EIT. Regions-of-interest (ROIs) were right and left hemithoraces. RESULTS: Following balloon occlusion, a steep decrease in left ROI-EELI with FIO2 1.0 occurred, 3-fold greater than with 0.5 (p < 0.001). Higher FIO2 also enhanced the final volume reduction (ROI-EELI) achieved by each valve (p < 0.01). CT analysis confirmed the denser atelectasis and greater volume reduction achieved by higher FIO2 (1.0) during balloon occlusion or during valve placement. CT and pocket pressure data agreed well with EIT findings, indicating greater strain redistribution with higher FIO2. CONCLUSIONS: EIT demonstrated in real-time a faster and more complete volume reduction in the occluded lung regions under high FIO2 (1.0), as compared to 0.5. Immediate changes in the ventilation and perfusion of ipsilateral non-target lung regions were also detected, providing better estimates of the full impact of each valve in place. TRIAL REGISTRATION: Not applicable.

Bendopneia é um sinal semiológico associado a baixa reserva diastólica em pacientes insuficiência cardíaca com fração de ejeção preservada / Bendopnea is a semiological sign associated with low diastolic reserve in heart failure patients with preserved ejection fraction

INTRODUÇÃO: A Insuficiência Cardíaca com Fração de Ejeção Preservada (ICFEP) é uma condição prevalente na população geral, cujo diagnóstico pode ser desafiador. Atualmente, há uma escassez de dados sobre quais aspectos do exame clínico são mais relevantes para o diagnóstico. MÉTODOS: Foram avaliados pacientes com suspeita de ICFEP em um ambulatório de hospital terciário de Cardiologia. A bendopneia foi explorada por um operador experiente através da ântero-flexão do tórax do paciente em posição sentada por tempo>30s. Casos com elevação da frequência respiratória com sensação de dispneia foram considerados positivos. Em caso de dúvida um segundo examinador era consultado. Casos duvidosos foram considerados negativos. A reserva diastólica foi acessada utilizando a ecocardiografia com Doppler tissular para acessar os valores de e' lateral em condições de repouso e durante um teste de pré-carga provocado pela elevação passiva de membros inferiores. Ademais, realizou-se cálculo do escore H2FPEF para diagnóstico de ICFEP. Estes grupos foram comparados através das diferenças das médias do escore H2FPEF estimada pelo teste t não pareado com nível de significância (a) de 95%. Finalmente, realizou-se regressão linear para comparação dos beta-coeficientes (b) da variação do e lateral repouso e durante a elevação de membros inferiores. Desta forma, o valor do b coeficiente será diretamente proporcional à reserva diastólica. RESULTADOS: Obteve-se 305 pacientes, dos quais 149 com bendopneia presente ao exame físico. O grupo sem bendopneia apresentou um H2FPEF de 2.7(±0.16), enquanto com pacientes com dispneia apresentaram um escore de 3.8(±0.16). Essa diferença entre os grupos apresentou significância estatística (p<0.001) (Figura 1). O teste de reserva diastólica foi realizado em 92 pacientes. O grupo sem bendopneia apresentou b=0.77(IC 95%:0.64;0.89), enquanto aqueles com bendopneia apresentaram um valor mais baixo de reserva diastólica com b=0.53 (IC 95%:0.32;0.74) (Figura 2). CONCLUSÕES: A bendopneia é um sinal semiológico útil para diagnóstico de ICFEP e está associado a baixa reserva diastólica.

Estimation of heart inclination angle using posteroanterior chest radiograph and comparison with cardiac axis obtained from synthesized vectorcardiogram

ABSTRACT In medical practice, it is common to perform electrocardiography exams and by mathematical transformations to obtain the vectorcardiogram. The vectorcardiogram provides important information for medical diagnosis, such as the angle of inclination of the heart. This article aims to present a methodology for estimating the QRS vector-related angle of the heart using a posteroanterior chest radiograph image. We used an open source image processing software (Icy software version 2.3.0.0, Institut Pasteur, France, 2021) to perform a manual measurement of the target angle by analyzing relevant morphological structures from the x-ray images and using some functions to help the user to measure it. 18 radiographic images were selected to measure the angle of the heart by two independent individuals. The measured angles were compared using the mean absolute error (MAE). We then computed the QRS peak elevation angles of the vectorcardiogram (VCG) of the 57 patients collected at Dante Pazzanese Institute of Cardiology. In addition, an individual was randomly selected to measure a set of 57 radiographic images of these same patients. We performed the statistical treatments and the results suggested that the proposed manual method may be an alternative, viable and fast approach to estimating the anatomical heart axis for the purpose of aiding in medical diagnosis. However, further comparisons with more data and information are needed to determine its validity and possible method improvements.

Re-estratificação de risco de candidatos à terapia de ressincronização cardíaca guiada pela ecocardiografia com speckle tracking / Risk re-stratification of candidates for cardiac resynchronization therapy guided by speckle tracking echocardiography

INTRODUÇÃO: A fração de ejeção do ventrículo esquerdo (FEVE) é o parâmetro utilizado para a classificação dos diferentes fenótipos de insuficiência cardíaca (IC). Embora pacientes portadores de IC com FEVE reduzida (ICFER) e evidência de bloqueio de ramo esquerdo (BRE) possam ser considerados para a Terapia de Ressincronização Cardíaca (TRC), há uma taxa de aproximadamente 30% de não-respondedores. Nesse contexto, é fundamental a avaliação de novas técnicas capazes de identificar subgrupos com maior risco de desfechos e que devem ser priorizados para a TRC. OBJETIVO: Avaliar a FEVE com o Global Longitudinal Strain (GLS) na predição de eventos maiores em candidatos à TRC. MÉTODOS: Foram incluídos 99 pacientes candidatos à TRC (ICFER com FEVE≤35% e padrão de BRE no ECG), avaliados no período entre fevereiro de 2008 e outubro de 2012 com follow up de 8 anos. As análises foram segmentadas em grupos com eventos combinados: internação por IC, óbito e/ou transplante cardíaco. RESULTADOS: Pacientes com desfecho apresentaram uma FEVE=26,2(±0,05)% e GLS=-13,9(±12,3)%, enquanto pacientes sem desfecho apresentaram FEVE=27,6(±0,05)% e GLS=-16,2(±7,2)%. A diferença entre os grupos foi estatisticamente significante para o GLS (p=0,04), mas sem significância para FEVE (p=0,07) (Figura 1). À análise de Kaplan-Meier utilizando um valor de corte do módulo de GLS<-16%, observou-se uma diferença significante nas curvas de sobrevida com significância pelo teste de log-rank (p=0.005) (Figura 2). CONCLUSÃO: O GLS é uma ferramenta com potencial uso na re-estratificação de pacientes com ICFER candidatos à TRC. Esse recurso além de descrever uma piora da evolução, pode também ajudar na decisão dos grupos que se beneficiariam de uma intervenção mais precoce.

Alterações da repolarização ventricular estão associadas às anormalidades da função sistólica longitudinal em pacientes com ICFEP / Changes in ventricular repolarization are associated with abnormalities in longitudinal systolic function in patients with HFPEF

INTRODUÇÃO: A insuficiência cardíaca de fração de ejeção preservada (ICFEP) é uma síndrome clínica decorrente de uma diversa combinação de anormalidades fisiopatológicas que confluem na elevação das pressões de enchimento do coração. Dentre tais alterações, alguns fenótipos de pacientes podem apresentar anormalidades da função sistólica do ventrículo esquerdo, a despeito de valores da fração de ejeção dentro dos limites da normalidade. Atualmente, há uma escassez de estudos que avaliam qual o papel das alterações no eletrocardiograma (ECG) na ICFEP e como estas podem contribuir para melhor identificação dos mecanismos que levam à intolerância ao exercício. OBJETIVOS: Avaliar a associação entre alterações da repolarização ventricular com as anormalidades na função sistólica do ventrículo esquerdo em uma população com diagnóstico de ICFEP. MÉTODOS: Estudo observacional transversal de 50 pacientes com diagnóstico de ICFEP confirmado pelo escore europeu HFA-PEFF. A repolarização ventricular foi avaliada através da medida do ângulo espacial QRS-T pelo vetocardiograma (método de Kors) e pelo índice TpicoTfim no ECG. As alterações da função sistólica do ventrículo esquerdo foram avaliadas através da medida do Global Longitudinal Strain (GLS) na ecocardiografia com Speckle Tracking. RESULTADOS: Obteve-se uma amostra de 48 pacientes com idade média de 50 (±5) anos, sendo 67% (33) do sexo feminino. Houve correlação moderada e estatisticamente significante entre o GLS e os parâmetros de repolarização ventricular: TpicoTfim (r=0.42; p<0.001) e o ângulo QRS-T (r= 0.58; p-value<0.001). À análise de regressão linear, obteve-se um ß coeficiente de 0.040 do ângulo QRS-T, denotando que para cada aumento de 25º no ângulo QRS-T, há a uma queda de 1% na função sistólica longitudinal pelo GLS. CONCLUSÃO: Nossos dados sugerem que as alterações da repolarização ventricular identificam pacientes com ICFEP que possuem anormalidades da função sistólica do ventrículo esquerdo apesar de apresentarem valores da fração de ejeção dentro dos limites da normalidade. Particularmente, o ângulo espacial QRS-T se mostrou um parâmetro promissor, superior ao TpicoTfim, e com potencial para ser incluído no arsenal multiparamétrico da avaliação diagnóstica da ICFEP.

Enhancing predictive accuracy of H2FPEF score in suspected HFpEF by incorporating left atrial reservoir strain

INTRODUCTION: Diagnosing HFpEF can be challenging, but the H2FPEF score is a valuable tool for clinical decision-making. Atrial fibrillation (AF) plays a significant role in this score, creating challenges for diagnosis in patients without AF or with paroxysmal AF. Left atrial reservoir strain (LArS) has emerged as a promising indicator for both AF and HFpEF. This study explores how incorporating LArS can enhance the predictive ability of the H2FPEF score for exercise capacity in outpatients with suspected HFpEF. METHODS: This cross-sectional study has a sample size of 283 patients with suspected HFpEF. We collected clinical and echocardiographic data and compared LArS values across different H2FPEF score categories. Additionally, we analyzed a subgroup of 129 patients who underwent a Cardiopulmonary Exercise Test (CPET) to evaluate the effectiveness of the H2FPEF score and LArS in predicting Peak VO2. To further comprehend the contribution of each feature in the performance of the H2FPEF score, we used Shapley Additive Explanations (SHAP) analysis. RESULTS: Most patients were female (63%), age of 60 (±12) years and LVEF of 60 (±5.2)%. Patients with low scores had a LArS of 32.6 (± 6.8)%, while those with moderate and high scores had probabilities of 26(± 8.2)% and 16 (±8.2)%, respectively (p<0.001). The H2FPEF score demonstrated an AUC of 0.74 (95% CI: 0.64-0.84) in predicting peak VO2, whereas LArS exhibited an AUC of 0.71 (95% CI: 0.62-0.80). Incorporating LArS into the score improved its performance, resulting in an AUC of 0.82 (95% CI: 0.75-0.89). The SHAP analysis revealed that LArS had a significant impact as the most important feature (Figure 1), while the importance of the atrial fibrillation criterion decreased significantly. CONCLUSIONS: Our findings show that integrating LArS improves the diagnostic performance of the H2FPEF score and offers a valuable alternative to the AF criterion within the H2FPEF algorithm.

Bendopneia é um sinal semiológico associado a baixa reserva diastólica em pacientes insuficiência cardíaca com fração de ejeção preservada / Bendopnea is a semiological sign associated with low diastolic reserve in heart failure patients with preserved ejection fraction

INTRODUÇÃO: A Insuficiência Cardíaca com Fração de Ejeção Preservada (ICFEP) é uma condição prevalente na população geral, cujo diagnóstico pode ser desafiador. Atualmente, há uma escassez de dados sobre quais aspectos do exame clínico são mais relevantes para o diagnóstico. MÉTODOS: Foram avaliados pacientes com suspeita de ICFEP em um ambulatório de hospital terciário de Cardiologia. A bendopneia foi explorada por um operador experiente através da ântero-flexão do tórax do paciente em posição sentada por tempo>30s. Casos com elevação da frequência respiratória com sensação de dispneia foram considerados positivos. Em caso de dúvida um segundo examinador era consultado. Casos duvidosos foram considerados negativos. A reserva diastólica foi acessada utilizando a ecocardiografia com Doppler tissular para acessar os valores de e' lateral em condições de repouso e durante um teste de pré-carga provocado pela elevação passiva de membros inferiores. Ademais, realizou-se cálculo do escore H2FPEF para diagnóstico de ICFEP. Estes grupos foram comparados através das diferenças das médias do escore H2FPEF estimada pelo teste t não pareado com nível de significância (a) de 95%. Finalmente, realizou-se regressão linear para comparação dos beta-coeficientes (b) da variação do e lateral repouso e durante a elevação de membros inferiores. Desta forma, o valor do b coeficiente será diretamente proporcional à reserva diastólica. RESULTADOS: Obteve-se 305 pacientes, dos quais 149 com bendopneia presente ao exame físico. O grupo sem bendopneia apresentou um H2FPEF de 2.7(±0.16), enquanto com pacientes com dispneia apresentaram um escore de 3.8(±0.16). Essa diferença entre os grupos apresentou significância estatística(p<0,001) (Figura 1). O teste de reserva diastólica foi realizado em 92 pacientes. O grupo sem bendopneia apresentou b=0.77(IC 95%:0.64;0.89), enquanto aqueles com bendopneia apresentaram um valor mais baixo de reserva diastólica com b=0.53 (IC 95%:0.32;0.74) (Figura 2). CONCLUSÕES: A bendopneia é um sinal semiológico útil para diagnóstico de ICFEP e está associado a baixa reserva diastólica.

Machine learning-driven serum metabolomics: insights into the transition to early-stage heart failure with preserved ejection fraction

Introduction: Metabolomics has emerged as a powerful tool in providing readouts of early disease states before clinical manifestation. Here we used the predictive power of Unsupervised Hierarchical Clustering Analysis (UHCA) and Automated Machine Learning (AutoML) algorithms to identify serum metabolic panels in a population at risk of developing HFpEF. Methods: We studied 215 subjects staged as non-HF, pre-HFpEF and early-stage HFpEF(es-HFpEF). We evaluated clinical, laboratory, echocardiographic, and NMR-based metabolomics of blood serum data. UHCA and AutoML were used to explore metabolic fingerprints potentially related to clinical features or HFpEF. We used Metabolite Set Enrichment Analysis to explore biochemical pathways. Results: The UHCA identified three major patients (P) and two metabolites (M) clusters (Figure). The P clusters were associated with HFpEF stages, cardiac remodeling, diastolic dysfunction, and sex (Pearson Chi-square, p < 0.05) and M clusters with glycine and serine metabolism and urea cycle pathways (FDR-adjusted p-value < 0.002). Considering non-HFpEF and es-HFpEF groups, AUROC mean for feature subset combinations was 0.897 and the highest AUROC (0.995) combined metabolites, clinical, laboratory and echo features. Of the 64 models trained that included metabolites as input, serine (25), uridine (17), 2-oxoglutarate (14), citrate (14), 2-aminobutyrate (13) and taurine (13) were observed more frequently with feature importance value greater than zero. The metabolites with higher sum values of feature importance were serine (0.173), uridine (0.131), 2-aminobutyrate (0.123), choline (0.098) and dimethylamine (0.087). Conclusions: This study revealed characteristic metabolite profiles in the sera of patients at risk of developing HFpEF. These metabolite panels can add information for classificatory algorithms development and contribute to the understanding of HFpEF pathophysiology.

Lung Mechanics Over the Century: From Bench to Bedside and Back to Bench.

Lung physiology research advanced significantly over the last 100 years. Respiratory mechanics applied to animal models of lung disease extended the knowledge of the workings of respiratory system. In human research, a better understanding of respiratory mechanics has contributed to development of mechanical ventilators. In this review, we explore the use of respiratory mechanics in basic science to investigate asthma and chronic obstructive pulmonary disease (COPD). We also discuss the use of lung mechanics in clinical care and its role on the development of modern mechanical ventilators. Additionally, we analyse some bench-developed technologies that are not in widespread use in the present but can become part of the clinical arsenal in the future. Finally, we explore some of the difficult questions that intensive care doctors still face when managing respiratory failure. Bringing back these questions to bench can help to solve them. Interaction between basic and translational science and human subject investigation can be very rewarding, as in the conceptualization of "Lung Protective Ventilation" principles. We expect this interaction to expand further generating new treatments and managing strategies for patients with respiratory disease.

Carga de comorbidade e qualidade de vida em indivíduos portadores de insuficiência cardíaca com fração de ejeção preservada / Comorbidity burden and quality of life in individuals with heart failure with preserved ejection fraction

INTRODUÇÃO: A Insuficiência cardíaca com fração de ejeção preservada (ICFEP) corresponde a uma síndrome clínica caracterizada por fração de ejeção maior que 50%. Apesar disso, os portadores dessa afecção apresentam diversos sinais e sintomas limitantes, com destaque para a dispneia e a fadiga, contribuindo para um comprometimento da funcionalidade com impacto negativo na qualidade de vida. Adicionalmente, essa condição pode ser agravada com a carga de comorbidade apresentada pelo indivíduo portador dessa doença. OBJETIVO: Avaliar a influência da carga de comorbidade na qualidade de vida de indivíduos com ICFEP. MÉTODOS: Foi realizado um estudo transversal com 67 pacientes de ambos os gêneros, com idade entre 18 e 75 anos, assistidos em um ambulatório de medicina cardiovascular personalizada de um hospital público. Os indivíduos foram divididos em: grupo com duas comorbidades simultâneas (G2), grupo com três comorbidades simultâneas (G3) e grupo com quatro ou mais comorbidades simultâneas (G4+). A qualidade de vida foi estimada por meio da pontuação no questionário de Minnesota. A normalidade dos dados foi avaliada por meio do teste Shapiro Wilk e os dados não paramétricos por meio do teste Kruskal. CAAE: 39592920.3.0000.5462 RESULTADOS: A pontuação no questionário de qualidade de vida variou conforme a carga de comorbidade (G1 = 23,3 ± 21,0; G2 = 24,2 ± 20,0; G3 = 44,1 ± 28,2) com diferença estatística entre os GCM2 e o GCM4. CONCLUSÃO: O presente estudo sugere que a carga de comorbidade influencia negativamente na qualidade de vida, visto que os indivíduos com um número maior de comorbidades simultâneas apresentaram maior comprometimento da qualidade de vida.

Desaturation-Distance Ratio During Submaximal and Maximal Exercise Tests and Its Association With Lung Function Parameters in Patients With Lymphangioleiomyomatosis.

Background: The desaturation-distance ratio (DDR), the ratio of the desaturation area to the distance walked, is a promising, reliable, and simple physiologic tool for functional evaluation in subjects with interstitial lung diseases. Lymphangioleiomyomatosis (LAM) is a rare neoplastic condition frequently associated with exercise impairment. However, DDR has rarely been evaluated in patients with LAM. Objectives: To assess DDR during maximal and submaximal exercises and evaluate whether DDR can be predicted using lung function parameters. Methods: A cross-sectional study was conducted in a cohort of women with LAM. The 6-min walking test (6MWT) and the incremental shuttle walking test (ISWT) were performed, and DDR was obtained from both tests. The functional parameters were assessed at rest using spirometry and body plethysmography. The pulmonary function variables predictive of DDR were also assessed. Results: Forty patients were included in this study. The mean age was 46 ± 10 years. Airway obstruction, reduced DLCO, and air trapping were found in 60, 57, and 15% of patients, respectively. The distance walked and the DDR for the 6MWT and ISWT were, respectively, 517 ± 65 and 443 ± 127 m; and 6.6 (3.8-10.9) and 8.3 (6.2-12.7). FEV1 (airway obstruction) and reduced DLCO and RV/TLC (air trapping) were independent variables predictive of DDR during exercises field tests [DDR6MWT = 18.66-(0.06 × FEV1%pred)-(0.10 × DLCO%pred) + (1.54 × air trapping), R adjust 2 = 0.43] and maximal [DDRISWT = 18.84-(0.09 × FEV1%pred)-(0.05 × DLCO%pred) + (3.10 × air trapping), R adjust 2 = 0.33]. Conclusion: Our results demonstrated that DDR is a useful tool for functional evaluation during maximal and submaximal exercises in patients with LAM, and it can be predicted using airway obstruction, reduced DLCO, and air trapping.

Respiratory mechanics during methacholine bolus and continuous infusion protocols in asthma model.

Balb/c mice respiratory mechanics was studied in two intravenous methacholine (MCh) protocols: bolus and continuous infusion. The Constant Phase Model (CPM) was used in this study. The harmonic distortion index (kd) was used to assess the respiratory system nonlinearity. The analysis of variance showed difference between groups (OVA vs control) and among doses for both protocols. Bolus protocol posttest: there was a difference between OVA and control at 0.3 and 1 mg/kg doses (p<0.0001 and p<0.001) for Rn. Infusion: there was a difference between OVA and control at 192 µg.kg-1.min-1 dose for Rn, G and H, (p<0.01; p<0.001; p<0.001). An increment was found in kd values near to the observed peak values in bolus protocol. The bolus protocol could better differentiate inflamed and non-inflamed airway resistance, whereas the differences between OVA and control in continuous infusion protocol were associated to airway- and, mainly, parenchyma-related parameters. Moreover, the bolus protocol presented a higher nonlinear degree compared to the infusion protocol.

Assessment of Regional Ventilation During Recruitment Maneuver by Electrical Impedance Tomography in Dogs.

BACKGROUND: During protective mechanical ventilation, electrical impedance tomography (EIT) is used to monitor alveolar recruitment maneuvers as well as the distribution of regional ventilation. This technique can infer atelectasis and lung overdistention during mechanical ventilation in anesthetized patients or in the ICU. Changes in lung tissue stretching are evaluated by monitoring the electrical impedance of lung tissue with each respiratory cycle. OBJECTIVE: This study aimed to evaluate the distribution of regional ventilation during recruitment maneuvers based on the variables obtained in pulmonary electrical impedance tomography during protective mechanical ventilation, focusing on better lung recruitment associated with less or no overdistention. METHODS: Prospective clinical study using seven adult client-owned healthy dogs, weighing 25 ± 6 kg, undergoing elective ovariohysterectomy or orchiectomy. The animals were anesthetized and ventilated in volume-controlled mode (7 ml.kg-1) with stepwise PEEP increases from 0 to 20 cmH2O in steps of 5 cmH2O every 5 min and then a stepwise decrease. EIT, respiratory mechanics, oxygenation, and hemodynamic variables were recorded for each PEEP step. RESULTS: The results show that the regional compliance of the dependent lung significantly increased in the PEEP 10 cmH2O decrease step when compared with baseline (p < 0.027), and for the nondependent lung, there was a decrease in compliance at PEEP 20 cmH2O (p = 0.039) compared with baseline. A higher level of PEEP was associated with a significant increase in silent space of the nondependent regions from the PEEP 10 cmH2O increase step (p = 0.048) until the PEEP 15 cmH2O (0.019) decrease step with the highest values at PEEP 20 cmH20 (p = 0.016), returning to baseline values thereafter. Silent space of the dependent regions did not show any significant changes. Drive pressure decreased significantly in the PEEP 10 and 5 cmH2O decrease steps (p = 0.032) accompanied by increased respiratory static compliance in the same PEEP step (p = 0.035 and 0.018, respectively). CONCLUSIONS: The regional ventilation distribution assessed by EIT showed that the best PEEP value for recruitment maintenance, capable of decreasing areas of pulmonary atelectasis in dependent regions promoting less overinflation in nondependent areas, was from 10 to 5 cmH2O decreased steps.

Challenges for the development of alternative low-cost ventilators during COVID-19 pandemic in Brazil. / Desafios para o desenvolvimento de ventiladores alternativos de baixo custo durante a pandemia de COVID-19 no Brasil.

The COVID-19 pandemic has brought concerns to managers, healthcare professionals, and the general population related to the potential mechanical ventilators' shortage for severely ill patients. In Brazil, there are several initiatives aimed at producing alternative ventilators to cover this gap. To assist the teams that work in these initiatives, we provide a discussion of some basic concepts on physiology and respiratory mechanics, commonly used mechanical ventilation terms, the differences between triggering and cycling, the basic ventilation modes and other relevant aspects, such as mechanisms of ventilator-induced lung injury, respiratory drive, airway heating and humidification, cross-contamination risks, and aerosol dissemination. After the prototype development phase, preclinical bench-tests and animal model trials are needed to determine the safety and performance of the ventilator, following the minimum technical requirements. Next, it is mandatory going through the regulatory procedures as required by the Brazilian Health Regulatory Agency (Agência Nacional de Vigilância Sanitária - ANVISA). The manufacturing company should be appropriately registered by ANVISA, which also must be notified about the conduction of clinical trials, following the research protocol approval by the Research Ethics Committee. The registration requisition of the ventilator with ANVISA should include a dossier containing the information described in this paper, which is not intended to cover all related matters but to provide guidance on the required procedures.

A pandemia por COVID-19 tem deixado os gestores, os profissionais de saúde e a população preocupados com a potencial escassez de ventiladores pulmonares para suporte de pacientes graves. No Brasil, há diversas iniciativas com o intuito de produzir ventiladores alternativos para ajudar a suprir essa demanda. Para auxiliar as equipes que atuam nessas iniciativas, são expostos alguns conceitos básicos sobre fisiologia e mecânica respiratória, os termos comumente utilizados no contexto da ventilação mecânica, as fases do ciclo ventilatório, as diferenças entre disparo e ciclagem, os modos ventilatórios básicos e outros aspectos relevantes, como mecanismos de lesão pulmonar induzida pela ventilação mecânica, pacientes com drive respiratório, necessidade de umidificação de vias aéreas, risco de contaminação cruzada e disseminação de aerossóis. Após a fase de desenvolvimento de protótipo, são necessários testes pré-clínicos de bancada e em modelos animais, a fim de determinar a segurança e o desempenho dos equipamentos, seguindo requisitos técnicos mínimos exigidos. Então, é imprescindível passar pelo processo regulatório exigido pela Agência Nacional de Vigilância Sanitária (ANVISA). A empresa responsável pela fabricação do equipamento deve estar regularizada junto à ANVISA, que também deve ser notificada da condução dos testes clínicos em humanos, seguindo protocolo de pesquisa aprovado pelo Comitê de Ética em Pesquisa. O registro do ventilador junto à ANVISA deve ser acompanhado de um dossiê, composto por documentos e informações detalhadas neste artigo, que não tem o propósito de esgotar o assunto, mas de nortear os procedimentos necessários.

Effects of elastic tape on thoracoabdominal mechanics, dyspnea, exercise capacity, and physical activity level in nonobese male subjects with COPD.

Subjects with severe and very severe chronic obstructive pulmonary disease (COPD) present thoracoabdominal asynchrony (TAA) that reduces ventilatory efficiency and exercise capacity. However, no therapeutic intervention has focused on reducing TAA. The purpose of this study was to evaluate the effects of elastic tape (ET) on thoracoabdominal mechanics, dyspnea symptoms, exercise capacity, and physical activity level in nonobese male subjects with severe-to-very severe COPD. This crossover, randomized trial included nonobese males with severe to very severe COPD. ET was placed on the chest wall and abdomen to reduce TAA. Subjects were evaluated at three hospital visits, each 7 days apart. At visit 1, thoracoabdominal kinematic and pulmonary ventilation were evaluated by optoelectronic plethysmography and electrical impedance tomography, respectively, both at rest and during isoload exercise testing. At visit 2, a cardiopulmonary exercise test (CPET; 10 W/min) was performed until exhaustion. Between the visits, subjects used a physical activity monitor (PAM) (at least 5 days of measurement; 10 h/day). At visit 3, all the tests were repeated in the opposite order of the previous randomization. During the isoload exercise, subjects with ET presented lower tidal and minute volumes (P = 0.01) and reduced TAA (P = 0.02) and dyspnea (P = 0.04). During the CPET, subjects with ET presented an increase in peak oxygen consumption (V̇o2peak; L/min and mL·kg-1·min-1; P = 0.01), test duration (P = 0.009), and maximal load (P = 0.03). Moderate and vigorous physical activity (MVPA), which was evaluated by the PAM, was also increased in subjects with ET (P = 0.01). ET reduced TAA and dyspnea and increased exercise capacity and the duration of MVPA in nonobese male subjects with severe-to-very severe COPDNEW & NOTEWORTHY Elastic tape can be used as a new and low-cost intervention to reduce thoracoabdominal asynchrony and sedentary behavior as well as improve exercise capacity and physical activity level in nonobese male subjects with severe-to-very severe chronic obstructive pulmonary disease.

An in vivo image acquisition system for the evaluation of tracheal mechanics in rats.

Mechanical evaluation of tracheal grafts is of great relevance for transplant research. Although there are some publications demonstrating different techniques of tracheal mechanical evaluation, there is still no definitive or preferred protocol available. Here, we present a simple image processing acquisition system that can be used for in vivo experiments. Six male Wistar rats were submitted to orotracheal intubation and a longitudinal incision was made to expose the trachea. Images of tracheae were acquired from a video camera in different scenarios of bronchoconstriction using methacholine (MCh) (Basal, PBS, MCh 30 µg/kg, MCh 300 µg/kg, and postmetabolized) during imposed-inspiration and imposed-expiration. The area variation ratio (the ratio between areas during expiration vs. inspiration) was 1.1× for the Basal group, while the ratio for MCh 300 µg/kg was 6.5×. The area variation of imaged tracheae was statistically significant at the dose of MCh 300 µg/kg for imposed-inspiration versus imposed-expiration (P = .002). Likewise, elastance data of respiratory mechanics indicated a statistically significant difference at the dose of MCh 300 µg/kg for imposed-inspiration versus imposed-expiration (P = .026). Our image processing analysis protocol presented corresponding behavior when compared to mechanical parameters of the respiratory system. In addition, our image acquisition system was able to highlight the differences between imposed-inspiration and imposed-expiration. Image analysis of the tracheal area variation seems to be in agreement with the elastance of the respiratory system. Taken together, these observations may help future studies of tracheal transplantation for in situ assessment of graft patency.

Author Correction: Low dose of chlorine exposure exacerbates nasal and pulmonary allergic inflammation in mice.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Low dose of chlorine exposure exacerbates nasal and pulmonary allergic inflammation in mice.

Work-exacerbated asthma (WEA) is defined as preexisting asthma that worsens with exposure to irritants [e.g., chlorine (Cl2) derivatives] in the workplace. The maximum allowable concentration in the workplace of Cl2 exposure is 3 mg/ m3 (described in OSHA). We investigated in an experimental asthma model in mice the effects of a single exposure to a sodium hypochlorite dose with this allowed chlorine concentration and a tenfold higher dose. Acute chlorine exposure at 3.3 mg/m3 in the OVA-sensitized group increased eosinophils in the peribronquial infiltrate, cytokine production, nasal mucus production and the number of iNOS positive cells in the distal lung compared to only sensitized mice. The exposure to a higher dose of 33.3 mg/m3 in the OVA-sensitized group resulted in an increase in respiratory system elastance, in the total and differential numbers of inflammatory cells in bronchoalveolar lavage fluid, IL-4, IL-5, and IL-17 in the lungs, eosinophils in peribronquial infiltrate and mucus content in nasal compared to non-exposed and sensitized animals. In this asthma model, chorine exposures at an allowable dose, contributed to the potentiation of Th2 responses. The functional alterations were associated with increased iNOS and ROCK-2 activation in the distal lung.

Mechanical Evaluation of Tracheal Grafts on Different Scales.

Tissue engineered (or bioengineered) tracheas are alternative options under investigation when the resection with end-to-end anastomosis cannot be performed. One approach to develop bioengineered tracheas is a complex process that involves the use of decellularized tissue scaffolds, followed by recellularization in custom-made tracheal bioreactors. Tracheas withstand pressure variations and their biomechanics are of great importance so that they do not collapse during respiration, although there has been no preferred method of mechanical assay of tracheas among several laboratories over the years. These methods have been performed in segments or whole tracheas and in different species of mammals. This article aims to present some methods used by different research laboratories to evaluate the mechanics of tracheal grafts and presents the importance of the tracheal biomechanics in both macro and micro scales. If bioengineered tracheas become a reality in hospitals in the next few years, the standardization of biomechanical parameters will be necessary for greater consistency of results before transplantations.