Trayectorias de función pulmonar en asma persistente: del preescolar al escolar / Lung function trajectories in persistent asthma: from preschool to schoolchildren

Introducción: Se han informado patrones de deterioro temprano de la función pulmonar en el asma pediátrica. Nuestro objetivo fue identificar las trayectorias de la función pulmonar en la espirometría, desde la edad preescolar hasta la edad escolar. Materiales: Estudio prospectivo realizado entre el 2016 y el 2021. Se reclutaron pacientes con asma persistente a quienes se les realizó oscilometría de impulso (IOS)-espirometría al inicio y después de 3 años. La espirometría anormal se definió de acuerdo con las guías ATS/ERS. Métodos: se utilizó χ2 y ANOVA para comparar las características clínicas y promedios de parámetros de la espirometría e IOS entre trayectorias. Resultados: 86 pacientes, promedio de edad 5,3 y 8,3 años en su primera y segunda evaluación. El 70,9% de los pacientes mantuvo la espirometría normal en ambas evaluaciones (trayectoria 1), el 9,3% presentó espirometría preescolar anormal que normalizó en la edad escolar (trayectoria 2) y el 19,8% espirometría en anormal en ambas evaluaciones (trayectoria 3). La trayectoria 3 registró menor peso promedio al nacer (2,4 kg vs 3,02 kg p = 0,04), mayor promedio de exacerbaciones (5,3 vs 2,01 p = 0,00002), mayor promedio de hospitalizaciones (0,61 vs 0,16 p = 0,04), parámetros promedio más bajos en espirometría (relación VEF1/CVF %, relación VEF0,75/CVF %, VEF0,75 L, VEF0,5 L), promedios más bajos en X5 kPa/Ls y más altos en AX kPa/Ls, que la trayectoria 1. Conclusiones: La trayectoria 1 fue la más frecuente, con persistencia de función pulmonar normal. La trayectoria 3, la segunda más frecuente, inició seguimiento con función pulmonar disminuida en la espirometría y disfunción de vía aérea pequeña en el IOS que se mantuvo en la edad escolar. Los niños que siguieron la trayectoria 3 tuvieron menor peso al nacer, más exacerbaciones y hospitalizaciones que los niños de la trayectoria 1.

Introduction: Patterns of early decline in lung function have been reported in pediatric asthma. Our objective was to identify pulmonary function trajectories in spirometry, from preschool age to school age. Materials: Prospective study conducted between 2016 and 2021. Patients with persistent asthma who underwent impulse oscillometry (IOS)-spirometry at baseline and after 3 years were recruited. Abnormal spirometry was defined according to ATS/ERS guidelines. Methods: χ2 and ANOVA was used to compare clinics characteristics and means of IOS-spirometry parameters between trajectories. Results: 86 patients, mean age of 5,3 and 8,3 years in their first and second evaluation. 70.9% of the patients maintained normal spirometry in both evaluations (Track 1), 9.3% presented abnormal preschool spirometry that normalized at school age (Track 2) and 19.8% abnormal spirometry in both evaluations (Track 3). Trajectory 3 had a lower average birth weight (2,4 kg vs 3,02 kg p = 0,04), higher average of exacerbations (5,3 vs 2,01 p = 0,00002), higher average of hospitalizations (0,61 vs 0,16 p = 0,04), lowest averages parameters in spirometry (FEV1/FVC % ratio, FEV0,75/FVC % ratio, FEV0,75 L, FEV0,5 L), lower average in X5 kPa/Ls and higher in AX kPa/Ls, than trajectory 1. Conclusions: Trajectory 1 was the most common, with persistent normal lung function. Trajectory 3, the second most frequent, started follow-up with decreased lung function in spirometry and small airway disfunction in the IOS that were maintained at school age. Children who followed trajectory 3 had lower birth weight, more exacerbations, and hospitalizations than children in trajectory 1.

Función pulmonar oscilometría de impulso en pediatría: procedimiento y aplicación clínica / Pulmonary function impulse oscillometry in pediatrics: procedure and clinical application

La Oscilometría de Impulso (IOS) es una técnica no invasiva que evalúa las propiedades mecánicas de todo el sistema respiratorio durante la respiración tranquila. Mide la impedancia total del sistema respiratorio, evaluando la resistencia total de la vía aérea, la resistencia de la vía aérea alta y las propiedades elásticas del pulmón. Detecta el compromiso de la vía aérea periférica en forma muy precoz, antes que la espirometría, y es útil en niños pequeños porque no requiere maniobras de espiración forzada. Permite evaluar la respuesta broncodilatadora y broncoconstrictora a través de pruebas de provocación bronquial para el diagnóstico de hiperreactividad bronquial. La IOS tiene un rol en la evaluación temprana y seguimiento de la función pulmonar en niños con enfermedades respiratorias crónicas, principalmente asma bronquial, displasia broncopulmonar y fibrosis quística. Este artículo revisa los aspectos fisiológicos, técnicos y aplicación clínica de la IOS, considerando las últimas recomendaciones para la estandarización del examen y las limitaciones que dificultan su interpretación .

Impulse Oscillometry (IOS) is a non-invasive technique that assesses the mechanical properties of the entire respiratory system during quiet breathing. It measures the total impedance of the respiratory system by evaluating total airway resistance, upper airway resistance, and elastic properties of the lung. It detects peripheral airway compromise very early, before spirometry, and is useful in young children because it does not require forced expiration maneuvers. It allows evaluating the bronchodilator and bronchoconstrictor response through bronchial provocation tests for the diagnosis of bronchial hyperreactivity. The IOS has a role in the early evaluation and monitoring of lung function in children with chronic respiratory diseases, mainly bronchial asthma, bronchopulmonary dysplasia and cystic fibrosis. This article reviews the physiological, technical, and clinical application aspects, considering the latest recommendations for the standardization of the test and the limitations that hinder its interpretation.

Lung function evaluation through computerized tomography and 3D reconstruction of airways: a body mass index pilot study / Evaluación de la función pulmonar mediante tomografía computarizada y reconstrucción 3D de las vías respiratorias: estudio piloto del índice de masa corporal

SUMMARY: Obesity is a worldwide epidemic that has become a risk factor for the development of respiratory problems, meaning it is necessary to generate models that assess lung function in obese patients for proper treatment. The objective of this study was to evaluate a model for analyzing respiratory function according to body composition, by analyzing the structure and function of the airways by computed tomography (CT). Lung function and body fat percentage (BF%) were measured in three male subjects (25 ± 6 years), with different body mass index (BMI; normal, overweight, obese). A third-dimensional (3D) reconstruction of the airways was performed using CT. Trachea, right and left main bronchi and anterior segmental bronchus of the right and left lung were measured. Three measurement points were established for each structure, and the average value of these three points was used for the analysis. An increase in the thickness of the airways wall of the left and right main bronchi and right segmental bronchus was observed as BMI and BF% increased. The same was observed for the percentage of airway wall area (%AWA) and airway resistance in the main and segmental bronchi. The proposed 3D reconstruction model and the three-point analysis simplified image assessment and allowed to observe the problems caused by obesity in lung function.

RESUMEN: La obesidad es una epidemia mundial, la que se ha transformado en un factor de riesgo en el desarrollo problemas respiratorios. Al respecto, generar modelos de evaluación de la función pulmonar en pacientes obesos es relevante para su adecuado tratamiento. El objetivo de este trabajo fue evaluar un modelo de la estructura y función de las vías aéreas (VA) con tomografía computarizada (TC) que permita analizar su compor- tamiento de acuerdo a la composición corporal. A tres sujetos de sexo masculino (25±6 años), de distinto índice de masa corporal (IMC; normal, sobrepeso, obeso), se les midió función pulmonar y porcentaje de grasa corporal (% GC). A través de TC se realizó una reconstrucción en tercera dimensión (3D) de las VA. Se realizaron mediciones de las VA de la tráquea, bronquios principales derecho e izquierdo y bronquio segmentario anterior del pulmón derecho e izquierdo. Para cada estructura se establecieron tres puntos de medición, el valor utilizado para los análisis fue el promedio de estos tres puntos. En los tres participantes se observó un aumento del grosor de la pared de las vías aéreas de los bronquios principal derecho e izquierdo y bronquio segmentario derecho a medida que aumenta el IMC y el % GC. Por otra parte, el porcentaje de área de la pared de las vías aéreas (% APVA) se comportó de la misma manera para ambos bronquios principales y segmentarios. La resistencia de las vías aéreas (RVA), tanto general como específica, aumentó en paralelo con el % APVA en los bronquios principales y segmentarios. A través de un modelo de reconstrucción 3D de la estructura de la VA por TC, evaluando tres puntos, se pudo observar los problemas que trae la obesidad a la función pulmonar simplificando el análisis de imagen.

Reprodutibilidade das mensurações da mecânica respiratória em pacientes sob ventilação mecânica invasiva / Reproducibility of respiratory mechanics measurements in patients on invasive mechanical ventilation

RESUMO Objetivo: Avaliar a reprodutibilidade intra e interexaminador das mensurações da resistência e das complacências estática e dinâmica do sistema respiratório em pacientes sob ventilação mecânica. Métodos: Trata-se de estudo analítico realizado com indivíduos com idade ≥ 18 anos, em ventilação mecânica invasiva, que não tinham diagnóstico clínico de doença do aparelho respiratório e/ou anormalidade de caixa torácica. Foram realizadas três aferições da mecânica respiratória com intervalo de 1 minuto entre elas. A primeira e a terceira aferições foram realizadas pelo avaliador A e a segunda aferição, pelo avaliador B. A comparação dos valores de resistência e complacências estática e dinâmica do sistema respiratório foi calculada por meio do coeficiente de correlação intraclasse. Resultados: Foram realizadas 198 aferições da mecânica respiratória em 66 pacientes sob ventilação mecânica, com idade média de 52,6 ± 18,6 anos, índice de massa corporal médio de 21,6 ± 2,1kg/m2, predomínio do perfil cirúrgico (61,5%) e sexo feminino (53,8%). Foram obtidos valores médios das três aferições para resistência do sistema respiratório (A1: 15,7 ± 6,8cmH2O/L/s; B1: 15,7 ± 6,4cmH2O/L/s e A2: 15,9 ± 6,2cmH2O/L/s), para complacência estática do sistema respiratório (A1: 42,1 ± 13,7mL/cmH2O; B1: 42,4 ± 14,6mL/cmH2O e A2: 42,2 ± 14,5mL/cmH2O) e para complacência dinâmica do sistema respiratório (A1: 21,3 ± 7,3mL/cmH2O; B1: 21,4 ± 7,5mL/cmH2O e A2: 21,3 ± 6,2mL/cmH2O). Também foram encontrados valores do coeficiente de correlação intraclasse para resistência do sistema respiratório (R = 0,882 e p = 0,001; R = 0,949 e p = 0,001 - interexaminadores A1 versus B e B versus A2, respectivamente; R = 0,932 e p = 0,001 - intraexaminador); complacência estática do sistema respiratório (R = 0,951 e p = 0,001; R = 0,958 e p = 0,001 - interexaminadores A1 versus B e B versus A2, respectivamente; R = 0,965 e p = 0,001 - intraexaminador) e complacência dinâmica do sistema respiratório (R = 0,957 e p = 0,001; R = 0,946 e p = 0,001 - interexaminadores A1 versus B e B versus A2 respectivamente; R = 0,926 e p = 0,001 - intraexaminador). Conclusão: A mensuração de mecânica respiratória apresenta boa reprodutibilidade intra e interexaminador para as aferições de resistência e complacências estática e dinâmica do sistema respiratório em pacientes ventilados.

ABSTRACT Objective: To evaluate the intra- and interexaminer reproducibility of measurements of the resistance and static and dynamic compliance of the respiratory system in patients on mechanical ventilation. Methods: This was an analytical study conducted with individuals aged ≥ 18 years who were on invasive mechanical ventilation and had no clinical diagnosis of respiratory system disease and/or chest abnormality. Three measurements of respiratory mechanics were performed with a 1-minute interval between them. The first and third measurements were performed by examiner A, the second by examiner B. The values for the resistance and static and dynamic compliance of the respiratory system were compared using the intraclass correlation coefficient. Results: A total of 198 measurements of respiratory mechanics were performed for 66 patients on mechanical ventilation. The patients had a mean age of 52.6 ± 18.6 years and a mean body mass index of 21.6 ± 2.1kg/m2; a surgical profile (61.5%) and female sex (53.8%) were predominant. Mean values were obtained for the three measurements of respiratory system resistance (A1: 15.7 ± 6.8cmH2O/L/s; B1: 15.7 ± 6.4cmH2O/L/s and A2: 15.9 ± 6.2cmH2O/L/s), respiratory system static compliance (A1: 42.1 ± 13.7mL/cmH2O; B1: 42.4 ± 14.6mL/cmH2O and A2: 42.2 ± 14.5mL/cmH2O) and respiratory system dynamic compliance (A1: 21.3 ± 7.3mL/cmH2O; B1: 21.4 ± 7.5mL/cmH2O and A2: 21.3 ± 6.2mL/cmH2O). The intraclass correlation coefficient was also calculated for respiratory system resistance (R = 0.882 and p = 0.001; R = 0.949 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.932 and p = 0.001 - intraexaminer); respiratory system static compliance (R = 0.951 and p = 0.001; R = 0.958 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.965 and p = 0.001 - intraexaminer) and respiratory system dynamic compliance (R = 0.957 and p = 0.001; R = 0.946 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.926 and p = 0.001 - intraexaminer). Conclusion: The measurements of resistance and static and dynamic compliance of the respiratory system show good intra- and interexaminer reproducibility for ventilated patients.

Therapeutic blowing toys: does the overlap of ventilatory stimuli alter the respiratory mechanics of healthy schoolchildren? / Brinquedos terapêuticos de sopro: a sobreposição de estímulos ventilatórios altera a mecânica respiratória de escolares saudáveis?

ABSTRACT Objective: To verify whether the overlapping of ventilatory stimuli, resulting from playing with blowing toys, changes the respiratory mechanics of healthy schoolchildren. Methods: Cross-sectional study with healthy schoolchildren aged seven to 14 years old from Florianópolis, Santa Catarina, Southern Brazil. Spirometric data were obtained, a health questionnaire and the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire were also applied. The procedure consisted of playing with the following blow toys in a random order: soap bubbles, party whistles and balloon. Before and after the intervention, the assessment of respiratory mechanics was carried out by impulse oscillometry - IOS (Erich Jaeger, Germany®). The ANOVA for repeated measures test was applied. Results: 71 students of both genders with mean age of 9.7±2.1 years participated in the study. Results showed a progressive decrease of impedance (Z5), total airway resistance (R5) and resonance frequency (Fres) when the moment before the use of the first toy was compared with the moment after the third toy (Z5/p=0.048; R5/p=0.049; Fres/p=0.004). Fres also differed between the moment before the first and the second toy (p=0.048). After the use of each of the three blowing toys, the oscillometric parameters did not differ. Conclusions: The difference in oscillometric parameters of R5 before the use of each toy indicates that the overlap of ventilatory stimuli produced by them provided a reduction in the R5.

RESUMO Objetivo: Verificar se a sobreposição de estímulos ventilatórios decorrentes da execução de brinquedos de sopro altera a mecânica respiratória de escolares saudáveis. Métodos: Estudo transversal com escolares saudáveis de sete a 14 anos de idade, provenientes de Florianópolis, Santa Catarina, Brasil. Foram obtidos dados espirométricos e realizada aplicação de um recordatório de saúde e do questionário International Study of Asthma and Allergies in Childhood (ISAAC). A coleta de dados consistiu na aplicação dos brinquedos bola de sabão, língua de sogra e balão de forma aleatória. Antes e após a intervenção foi realizada a avaliação da mecânica respiratória por meio da oscilometria de impulso - IOS (Erich Jaeger, Germany®). Aplicou-se o teste de ANOVA para medidas repetidas. Resultados: Participaram do estudo 71 escolares de ambos os sexos, com média de idade de 9,7±2,1 anos. Houve redução progressiva na impedância respiratória a 5 hertz (Z5), na resistência total das vias aéreas (resistência a 5 hertz - R5) e na frequência de ressonância (Fres) ao comparar o momento antes do uso do primeiro e do terceiro brinquedo (Z5/p=0,048; R5/p=0,049; Fres/p=0,004). Fres também diferiu no momento antes do primeiro e do segundo brinquedo (p=0,048). Após o uso de cada um dos três brinquedos, os parâmetros oscilométricos não diferiram. Conclusões: Observando a diferença nos parâmetros oscilométricos da R5 antes do uso de cada um dos brinquedos, notou-se que a sobreposição de estímulos ventilatórios produzidos por eles proporcionou uma redução na R5.

Impulse oscillometry and obesity in children / Oscilometria de impulso e obesidade em crianças

Abstract Objective: To compare impulse oscillometry system parameters of normal-weight children with overweight and obese children. Method: All participants were submitted to the evaluation of lung function (spirometry and impulse oscillometry) following the American Thoracic Society standards. The evaluation of respiratory mechanics was performed using the Jaeger™ MasterScreen™ Impulse Oscillometry System (Erich Jaeger, Germany), three tests were recorded, with acquisition for at least 20 seconds. Results: The study included 81 children (30 in the control group, 21 in the overweight group, and 30 the in obesity group), matched for age and sex. Regarding spirometry data, obesity group showed higher numerical values in relation to the control group; however, there were no significant differences among the three groups. For impulse oscillometry parameters, there was a difference between control group and obesity group for respiratory impedance (p = 0.036), resistance at 5 hertz (p = 0.026), resonant frequency (p = 0.029), and reactance area (p = 0.014). For the parameters expressed in percentage of predicted, there were differences in resistance at 5 hertz, resonant frequency, and reactance area between control group and obesity group. Conclusions: Obese children showed increased oscillometry parameters values representative of airway obstruction, compared to normal-weight children. Changes in some oscillometry parameters can already be observed in overweight school-aged children.

Resumo Objetivo: Comparar parâmetros do Sistema de Oscilometria de Impulso de crianças com peso normal com crianças com sobrepeso e obesas. Método: Todos os participantes foram submetidos à avaliação de mecanismos respiratórios utilizando o Sistema de Oscilometria de Impulso Jaeger™ (MasterScreen™ IOS, Erich Jaeger, Alemanha) seguindo as normas da Sociedade Torácica Americana. Todos os participantes foram submetidos a testes de espirometria e oscilometria (três testes foram registrados, com coleta de dados por pelo menos 20 segundos). Resultados: O estudo incluiu 81 crianças (30 no grupo de controle, 21 no grupo sobrepeso e 30 no grupo obesidade), pareadas por idade e sexo. No que diz respeito a dados de espirometria, o grupo obesidade mostrou valores numéricos mais elevados; contudo, não houve diferenças significativas entre os três grupos. No que diz respeito a parâmetros do Sistema de Oscilometria de Impulso, houve diferença entre o grupo de controle e o grupo obesidade em Z5 (p = 0,036), resistência 5 hertz (p = 0,026), frequência de ressonância (p = 0,029) e área de reatância (p = 0,014). Nos parâmetros expressos em percentual previsto, houve diferenças em resistência 5 hertz, frequência de ressonância e área de reatância entre o grupo de controle e grupo obesidade. Conclusões: Crianças obesas mostraram parâmetros de oscilometria aumentados representativos de obstrução das vias aéreas em comparação a crianças com peso normal. As alterações em alguns parâmetros oscilométricos já podem ser observadas em crianças com sobrepeso em idade escolar.

Lung volumes and airway resistance in patients with a possible restrictive pattern on spirometry / Volumes pulmonares e resistência das vias aéreas em pacientes com possível padrão restritivo à espirometria

ABSTRACT Objective: Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung volumes and airway resistance plays in the correct classification of patients with a possible restrictive pattern on spirometry. Methods: This was a prospective study involving adults with reduced FVC and FEV1, as well as an FEV1/FV(C) ratio within the predicted range. Restrictive lung disease (RLD) was characterized by TLC below the 5th percentile, as determined by plethysmography. Obstructive lung disease (OLD) was characterized by high specific airway resistance, significant changes in post-bronchodilator FEV1, or an FEF25-75% < 50% of predicted, together with a high RV/TLC ratio. Nonspecific lung disease (NLD) was characterized by TLC within the predicted range and no obstruction. Combined lung disease (CLD) was characterized by reduced TLC and findings indicative of airflow obstruction. Clinical diagnoses were based on clinical suspicion, a respiratory questionnaire, and the review of tests of interest. Results: We included 300 patients in the study, of whom 108 (36%) were diagnosed with RLD. In addition, 120 (40%) and 72 (24%) were diagnosed with OLD/CLD and NLD, respectively. Among the latter, 24 (33%) were clinically diagnosed with OLD. In this sample, 151 patients (50.3%) were obese, and obesity was associated with all patterns of lung disease. Conclusions: Measuring lung volumes and airway resistance is often necessary in order to provide an appropriate characterization of the pattern of lung disease in patients presenting with a spirometry pattern suggestive of restriction. Airflow obstruction is common in such cases.

RESUMO Objetivo: Muitos pacientes com redução proporcional de CVF e VEF1 na espirometria não têm CPT reduzida. O objetivo deste estudo foi avaliar o papel da medida dos volumes pulmonares e da resistência das vias aéreas para a classificação correta de pacientes com possível restrição à espirometria. Métodos: Estudo prospectivo de adultos com CVF e VEF1 reduzidos e relação VEF1/CV(F) na faixa prevista. Distúrbio ventilatório restritivo (DVR) foi definido por CPT < 5º percentil por pletismografia. Distúrbio ventilatório obstrutivo (DVO) foi caracterizado por resistência específica de vias aéreas elevada, resposta significativa do VEF1 pós-broncodilatador e/ou um FEF25-75% < 50% do previsto associado a uma relação VR/CPT elevada. Distúrbio ventilatório inespecífico (DVI) foi caracterizado por CPT na faixa prevista e ausência de obstrução. Distúrbio ventilatório combinado (DVC) foi caracterizado por CPT reduzida e achados indicativos de obstrução ao fluxo aéreo. Os diagnósticos clínicos foram baseados em suspeita clínica, um questionário respiratório e revisão de exames de interesse. Resultados: Foram incluídos 300 pacientes no estudo, dos quais 108 (36%) tiveram diagnóstico de DVR, enquanto 120 (40%) foram diagnosticados com DVO ou DVC e 72 (24%) com DVI. Destes últimos, 24 (33%) tinham diagnóstico clínico de DVO. Nesta amostra, 151 pacientes (50,3%) eram obesos, e isso se associou com todos os padrões de distúrbios funcionais. Conclusões: Medidas dos volumes pulmonares e da resistência das vias aéreas são frequentemente necessárias para a caracterização adequada do tipo de distúrbio funcional em casos com possível restrição à espirometria. A obstrução ao fluxo aéreo é comum nesses casos.

Aplicación del test course navette en escolares / Course navette test aplicaction in school

El desarrollo de la resistencia cardiorrespiratoria en niños, adolescentes y jóvenes se asocia a la disminución de la prevalencia de enfermedades cardiovasculares en niños y adolescentes. La prueba de “course navette” o carrera de 20 metros es una prueba de aptitud cardiorrespiratoria máxima y progresiva, que mide indirectamente el consumo máximo de oxigeno. Niveles altos de capacidad aeróbica durante la niñez y la adolescencia están asociados con una salud cardiovascular actual y futura más saludable. Según la encuesta nacional de salud en Chile (2009-2010) el 17,7 por ciento de la población chilena mayor de 15 años y más, presenta un riesgo cardiovascular alto o muy alto. La población chilena presenta: un elevado nivel de morbilidad por enfermedades crónicas no transmisibles y de sus factores de riesgo. Utilizar una prueba máxima y progresiva en adolescentes, como es la “prueba de course naveta”, puede genera un aumento del riesgo de presentar un evento cardiovascular al evaluar el consumo máximo de oxigeno en nuestra población.

The development of cardiorespiratory endurance in children and young people is associated with decreased prevalence of cardiovascular disease in children and adolescents. The test of "course navette" or 20 meter race is a test of high cardiorespiratory fitness and progressive, which indirectly measures the maximum oxygen consumption. High levels of aerobic fitness during childhood and adolescence are associated with a current cardiovascular health and healthier future. According to the health survey in Chile, 17.7 percent of the Chilean population 15 years and over, has a high or very high cardiovascular risk. The Chilean population has: a high level of morbidity from chronic diseases and their risk factors of disease. Use a high and progressive test in adolescents, such as "proof of course navetta" can generate an increased risk of cardiovascular events in assessing the maximum oxygen consumption in our population.

Within-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary disease

OBJECTIVE: Recent work has suggested that within-breath respiratory impedance measurements performed using the forced oscillation technique may help to noninvasively evaluate respiratory mechanics. We investigated the influence of airway obstruction on the within-breath forced oscillation technique in smokers and chronic obstructive pulmonary disease patients and evaluated the contribution of this analysis to the diagnosis of chronic obstructive pulmonary disease. METHODS: Twenty healthy individuals and 20 smokers were assessed. The study also included 74 patients with stable chronic obstructive pulmonary disease. We evaluated the mean respiratory impedance (Zm) as well as values for the inspiration (Zi) and expiration cycles (Ze) at the beginning of inspiration (Zbi) and expiration (Zbe), respectively. The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed. The diagnostic utility was evaluated by investigating the sensitivity, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01888705. RESULTS: Airway obstruction increased the within-breath respiratory impedance parameters that were significantly correlated with the spirometric indices of airway obstruction (R=−0.65, p<0.0001). In contrast to the control subjects and the smokers, the chronic obstructive pulmonary disease patients presented significant expiratory-inspiratory differences (p<0.002). The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%. Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%). CONCLUSIONS: We conclude the following: (1) chronic obstructive pulmonary disease introduces higher respiratory cycle dependence, (2) this increase is proportional to airway obstruction, and (3) ...

Effects of home-based respiratory muscle training in children and adolescents with chronic lung disease / Efeitos do treinamento muscular respiratório domiciliar em crianças e adolescentes com doença pulmonar crônica

OBJECTIVE: Respiratory muscle weakness is a functional repercussion of chronic lung disease (CLD). The objective of this study was to assess the effects of home-based respiratory muscle training (RMT) in children and adolescents with CLD or neuromuscular disease (NMD). METHODS: This was a quasi-experimental study involving children and adolescents with CLD or NMD. Before and after 6 months of home-based RMT, we measured respiratory muscle strength (MIP and MEP), PEF, and peak cough flow (PCF). We made statistical comparisons between the pre-RMT and post-RMT values, as well as evaluating the correlation between the duration and effect of RMT. RESULTS: The study included 29 patients, with a mean age of 12 years (range, 5-17 years), of whom 18 (62.1%) were male. The CLD group comprised 11 patients (37.9%), and the NMD group comprised 18 (62.1%). The mean duration of the RMT was 60 weeks (range, 46-90 weeks) in the CLD group and 39 weeks (range, 24-89 weeks) in the NMD group. In comparison with the pre-RMT values, the post-RMT values for MIP and MEP were significantly higher in both groups, whereas those for PEF and PCF were significantly higher only in the NMD group. We found no correlation between the duration and the effect of RMT. CONCLUSIONS: Home-based RMT appears to be an effective strategy for increasing respiratory muscle strength in children and adolescents with CLD or NMD, although it increased the ability to cough effectively only in those with NMD. .

OBJETIVO: A fraqueza muscular respiratória é uma repercussão funcional da doença pulmonar crônica (DPC). O objetivo deste estudo foi avaliar os efeitos do treinamento muscular respiratório (TMR) domiciliar em crianças e adolescentes com DPC ou doença neuromuscular (DNM). MÉTODOS: Estudo quasi-experimental com crianças e adolescentes com DPC ou DNM. Foram medidos a força muscular respiratória (PEmáx e PImáx) e o pico de fluxo da tosse (PFT) antes e depois de 6 meses de TMR domiciliar. Foram realizadas comparações estatísticas entre valores pré- e pós-TMR e foram avaliadas as correlações entre a duração e o efeito do TMR. RESULTADOS: Foram incluídos no estudo 29 pacientes, com média de idade de 12 anos (variação, 5-17 anos), dos quais 18 (62,1%) eram meninos. O grupo DPC consistiu em 11 pacientes (37,9%) e o grupo DNM, em 18 (62,1%). A média da duração do TMR foi de 60 semanas (variação, 46-90 semanas) no grupo DPC e de 39 semanas (variação, 24-89 semanas) no grupo DNM. Em comparação com os valores pré-TMR, os valores pós-TMR para PImáx e PEmáx foram significativamente maiores nos dois grupos, enquanto aqueles para PFE e PFT foram significativamente maiores apenas no grupo DNM. Não houve correlações entre a duração e o efeito do TMR. CONCLUSÕES: O TMR domiciliar parece ser uma estratégia eficaz para o aumento da força muscular respiratória em crianças e adolescentes com DPC ou DNM, embora aumente efetivamente a capacidade de tosse somente naqueles com DNM. .

An overlooked cause of resistant hypertension: upper airway resistance syndrome - preliminary results

OBJECTIVE: Upper airway resistance syndrome is a sleep-disordered breathing syndrome that is characterized by repetitive arousals resulting in sympathetic overactivity. We aimed to determine whether upper airway resistance syndrome was associated with poorly controlled hypertension. METHODS: A total of 40 patients with resistant hypertension were enrolled in the study. All of the patients underwent polysomnographic examinations and 24-hour ambulatory blood pressure monitoring to exclude white coat syndrome and to monitor treatment efficiency. Among 14 upper airway resistance syndrome patients, 2 patients had surgically correctable upper airway pathologies, while 12 patients were given positive airway pressure therapy. RESULTS: All patients underwent polysomnographic examinations; 22 patients (55%) were diagnosed with obstructive sleep apnea and 14 patients (35%) were diagnosed with upper airway resistance syndrome, according to American Sleep Disorders Association criteria. The patients with upper airway resistance syndrome were younger and had a lower body mass index compared with other patients, while there were no difference between the blood pressure levels and the number of antihypertensive drugs. The arousal index was positively correlated with systolic blood pressure level (p = 0.034; rs = 0.746), while the Epworth score and AHI were independent of disease severity (p = 0.435, rs = 0.323 and p = 0.819, rs = -0.097, respectively). Eight patients were treated with positive airway pressure treatment and blood pressure control was achieved in all of them, whereas no pressure reduction was observed in four untreated patients. CONCLUSIONS: We conclude that upper airway resistance syndrome is a possible secondary cause of resistant hypertension and that its proper treatment could result in dramatic blood pressure control. .

Análise comparativa entre a manobra de recrutamento alveolar e a técnica de breath stacking em pacientes com lesão pulmonar aguda / Comparative analysis between the alveolar recruitment maneuver and breath stacking technique in patients with acute lung injury

Objetivo: Comparar a eficácia da manobra de recrutamento alveolar e a técnica de breath stacking, na mecânica pulmonar e na troca gasosa, em pacientes com lesão pulmonar aguda. Métodos: Trinta pacientes foram distribuídos em dois grupos: Grupo 1 - breath stacking e Grupo 2 - manobra de recrutamento alveolar. Após receberem atendimento de fisioterapia convencional, todos os pacientes receberam ambos os tratamentos, com intervalo de 1 dia entre eles. No primeiro grupo foi aplicada primeiramente a técnica de breath stacking e, posteriormente, a manobra de recrutamento alveolar. Já os pacientes do segundo Grupo 2 foram submetidos inicialmente ao recrutamento alveolar e, após, a técnica de breath stacking. Foram avaliadas as medidas de complacência pulmonar e de resistência de vias aéreas antes e após a aplicação de ambas as técnicas. Foram coletadas gasometrias arteriais pré e pós-técnicas para avaliar a oxigenação e a troca gasosa. Resultados: Ambos os grupos apresentaram aumento significativo da complacência estática após breath stacking (p=0,021) e recrutamento alveolar (p=0,03), mas não houve diferença entre eles (p=0,95). A complacência dinâmica não aumentou para os grupos breath stacking (p=0,22) e recrutamento alveolar (p=0,074), sem diferença entre os grupos (p=0,11). A resistência de vias aéreas não diminuiu para ambos os grupos: breath stacking (p=0,91) e recrutamento alveolar (0,82), sem diferença entre os grupos p=0,39. A pressão parcial de oxigênio aumentou significantemente após breath stacking (p=0,013) e recrutamento alveolar (p=0,04); mas entre os grupos não houve diferença (p=0,073). A diferença alvéolo arterial de O2 diminuiu para ambos os grupos após intervenções breath stacking (p=0,025) ...

Objective: To compare the effectiveness of the alveolar recruitment maneuver and the breath stacking technique with respect to lung mechanics and gas exchange in patients with acute lung injury. Methods: Thirty patients were distributed into two groups: Group 1 - breath stacking; and Group 2 - alveolar recruitment maneuver. After undergoing conventional physical therapy, all patients received both treatments with an interval of 1 day between them. In the first group, the breath stacking technique was used initially, and subsequently, the alveolar recruitment maneuver was applied. Group 2 patients were initially subjected to alveolar recruitment, followed by the breath stacking technique. Measurements of lung compliance and airway resistance were evaluated before and after the use of both techniques. Gas analyses were collected before and after the techniques were used to evaluate oxygenation and gas exchange. Results: Both groups had a significant increase in static compliance after breath stacking (p=0.021) and alveolar recruitment (p=0.03), but with no significant differences between the groups (p=0.95). The dynamic compliance did not increase for the breath stacking (p=0.22) and alveolar recruitment (p=0.074) groups, with no significant difference between the groups (p=0.11). The airway resistance did not decrease for either groups, i.e., breath stacking (p=0.91) and alveolar recruitment (p=0.82), with no significant difference between the groups (p=0.39). The partial pressure of oxygen increased significantly after breath stacking (p=0.013) and alveolar recruitment (p=0.04), but there was no significant difference between the groups (p=0.073). The alveolar-arterial O2 difference decreased for both groups after the breath stacking (p=0.025) and alveolar recruitment (p=0.03) interventions, and there was no significant difference between the groups (p=0.81). Conclusion: Our data suggest that the breath stacking and alveolar ...

Evaluación de la medición de las resistencias pulmonares por técnica de interrupción / Assessing the measurement of airway resistance by the interrupter technique

Introducción. Las pruebas de función pulmonar permiten objetivar el grado de obstrucción bronquial en sujetos colaboradores. La medición de las resistencias pulmonares por métodos pasivos es muy útil en sujetos no colaboradores. El objetivo de este estudio fue evaluar la aplicabilidad de la medición de resistencias por interrupción (Rint) en la edad pediátrica, valorando su reproducibilidad, fabilidad y exactitud en relación con otras técnicas de medición de resistencias. Material y métodos. Estudio transversal en niños de entre 2 y 18 años, sanos y con patología obstructiva. Se midió la Rint con un aparato portátil y se comparó con las resistencias medidas por oscilometría y pletismografía. Se valoró la reproducibilidad de las mediciones y la infuencia de diferentes variables (uso de mascarilla o boquilla, sujeción de mejillas o uso de pinza nasal). Resultados. De 460 niños (47,6% menores de 7 años) se obtuvieron medidas válidas en el 82,6%. La reproducibilidad fue muy buena (CCI= 0,9412; p < 0,00001), sin encontrar diferencias entre las medidas obtenidas separadas en el tiempo (0,75 ± 0,3 contra 0,74 ± 0,28; p= 0,435). Ninguno de los factores antes mencionados afectó la reproducibilidad de las medidas. Los valores de resistencia obtenidos por pletismografía y oscilometría fueron superiores a los obtenidos por Rint, con una correlación positiva entre ambos. La correlación con la pletismografía disminuía cuanto mayor era el grado de obstrucción. Conclusiones. La medición de Rint es factible y reproducible, y se correlaciona bien con las resistencias medidas por oscilometría o pletismografía, por lo que sería de utilidad en los pacientes poco colaboradores. En los pacientes obstruidos, podría infraestimar la resistencia, difcultando su uso para el seguimiento de una patología obstructiva moderada-grave o en las pruebas de provocación bronquial.

Introduction. Pulmonary function tests allow an objective assessment of the degree of bronchial obstruction in collaborative subjects. The measurement of airway resistance using passive methods is very helpful in non-collaborative subjects. The objective of this study was to assess the applicability of measuring airway resistance by the interrupter technique (Rint) in pediatric subjects, determining its reproducibility, reliability and accuracy versus other techniques to measure airway resistance. Material and Methods. Cross-sectional study in healthy children and in children with an obstructive airway disease, all aged 2-18 years old. The Rint was measured using a portable device and results were compared to airway resistance measured by oscillometry and plethysmography. The reproducibility of measurements and the infuence of the different outcome measures (use of mask or mouthpiece, cheek support, or nose clip) were assessed. Results. Valid measurements were obtained in 82.6% of 460 children (47.6% younger than 7 years old). Reproducibility was very good (ICC= 0.9412; p <0.00001), and no differences were found among the measurements obtained at separate time intervals (0.75 ± 0.3 versus 0.74 ± 0.28; p= 0.435). None of the factors indicated before had an effect on the reproducibility of measurements. Resistance values obtained by plethysmography and oscillometry were higher than those obtained using the Rint, with a positive correlation between them. The higher the degree of airway obstruction, the worse the correlation with plethysmography. Conclusions. The Rint measurement is a plausible and reproducible technique, and has an adequate correlation with the resistance measurements obtained using oscillometry or plethysmography, thus making it useful for non-collaborative patients. In patients with airway obstruction, this technique could underestimate resistance, so it would be a hurdle to use it to follow-up subjects with a moderate to severe obstructive disease or in bronchial challenge tests.

Effects of different PEEP levels on respiratory mechanics and oxygenation after coronary artery bypass grafting / Efeitos de diferentes níveis de PEEP na mecânica respiratória e oxigenação após revascularização do miocárdio

OBJECTIVE: To compare the effects of different levels of positive end-expiratory pressure on respiratory mechanics and oxygenation indexes in the immediate postoperative period of coronary artery bypass grafting. METHODS: Randomized clinical trial in which 136 patients underwent coronary artery bypass grafting between January 2011 and March 2012 were divided into three groups and admitted to mechanical ventilation with different positive end-expiratory pressure levels: Group A, 5 cmH2O (n=44), Group B, 8 cmH2O (n=47) and Group C, 10 cmH2O (n=45). Data about respiratory mechanics were obtained from mechanical ventilator monitor and oxygenation indexes from arterial blood gas samples, collected twenty minutes after intensive care unit admission. Patients with chronic obstructive pulmonary disease and patients submitted to off-pump, emergency or combined operations were not included. For statistical analysis, we used Kruskal-Wallis, G and Chi-square tests, considering results significant when P<0.05. RESULTS: Groups were homogeneous in terms of demographic, clinical and surgical variables. Patients ventilated with positive end-expiratory pressure of 10 cmH2O (Group C) had best compliance (P=0.04) and airway resistance values, this, however, without statistical significance. They also had best oxygenation indexes, with statistical difference in all analyzed variables, and lower frequency of hypoxemia (P=0.03). CONCLUSION: Higher levels of positive end-expiratory pressure in immediate postoperative period of coronary artery bypass grafting improved pulmonary compliance values and increased oxygenation indexes, resulting in lower frequency of hypoxemia.

OBJETIVO: Comparar os efeitos de diferentes níveis de pressão expiratória positiva final na mecânica respiratória e nos índices de oxigenação no pós-operatório imediato de revascularização do miocárdio. MÉTODOS: Ensaio clínico randomizado no qual 136 pacientes submetidos à revascularização do miocárdio, entre janeiro de 2011 e março de 2012, foram distribuídos em três grupos e admitidos na ventilação mecânica com diferentes níveis de pressão expiratória positiva final: Grupo A, 5 cmH2O (n=44), Grupo B, 8 cmH2O (n=47) e Grupo C, 10 cmH2O (n=45), sendo os dados da mecânica respiratória obtidos do monitor do ventilador mecânico e os índices de oxigenação por meio de gasometria arterial coletada vinte minutos após a admissão na unidade de terapia intensiva. Não foram incluídos pacientes com doença pulmonar obstrutiva crônica, cirurgias associadas, de emergência ou sem circulação extracorpórea. Para análise estatística, empregaram-se os testes de Kruskal-Wallis, Teste G e Qui-quadrado, considerando os resultados significantes quando P<0,05. RESULTADOS: Os grupos apresentaram-se homogêneos em relação às variáveis demográficas, clínicas e cirúrgicas. Os pacientes ventilados com pressão expiratória positiva final de 10 cmH2O (Grupo C) apresentaram os melhores valores de complacência (P=0,04) e de resistência das vias aéreas, esta, porém sem significância estatística. Apresentaram, ainda, os melhores índices de oxigenação, com diferença estatística em todas as variáveis estudadas, além de menor frequência de hipoxemia (P=0,03). CONCLUSÃO: Níveis mais elevados de pressão expiratória positiva final no pós-operatório imediato de revascularização do miocárdio incrementaram os valores de complacência pulmonar e melhoraram os índices de oxigenação, resultando acarretando em menor frequência de hipoxemia.

Correlação de três variáveis na descrição da permeabilidade nasal (HD, MCA, escala NOSE) de pacientes saudáveis / Correlation of three variables describing nasal patency (HD, MCA, NOSE score) in healthy subjects

Rinoresistometria e rinometria acústica são dois métodos utilizados na avaliação da função respiratória nasal. Ambos utilizam variáveis diferentes para descrever a permeabilidade nasal: o diâmetro hidráulico, HD, na rinoresistometria; e as áreas mínimas da seção transversal, MCA1 (istmo nasal) e MCA2 (cabeça do corneto inferior e corpo cavernoso do septo nasal), na rinometria acústica. OBJETIVO: Analisar a relação entre HD e MCA em pacientes sem afecções nasais e identificar se tais variáveis objetivas apresentam correlação com a escala NOSE, uma ferramenta validada para avaliar a percepção subjetiva de permeabilidade nasal. MÉTODO: Coleta estruturada dos dados de 24 indivíduos saudáveis sem afecções nasais. RESULTADOS: Correlações estatisticamente significativas de fracas a moderadas foram identificadas entre HD e MCA2 antes do descongestionamento. Foi identificada correlação moderada entre HD, MCA2 e escala NOSE no lado mais estreito. CONCLUSÃO: Na avaliação de permeabilidade nasal, parece ser recomendável determinar HD, MCA1 e MCA2, bem como uma variável subjetiva como a escala NOSE, que não aparentam ser variáveis completamente redundantes. Estudos futuros devem avaliar a correlação destas variáveis em pacientes com afecções nasais.

Rhinoresistometry and acoustic rhinometry are two established apparative methods to objectify the respiratory function of the nose. Both methods use different variables to describe nasal patency: "hydraulic diameter", HD, in rhinoresistometry, and "minimal cross-sectional area", MCA1 (nasal isthmus) and MCA2 (head of the inferior turbinate and cavernous body of the nasal septum), in acoustic rhinometry. OBJECTIVE: This study analyzes the mutual correlation of HD and MCA as a pilot study in patients without nasal pathologies. Additionally, we investigated if these objective variables correlate with the NOSE score, a validated tool to measure subjective perception of nasal patency. METHOD: Planned data collection in a collective of 24 healthy subjects without nasal pathologies. RESULTS: Statistically significant, weak to moderate correlations were found between HD and MCA2 before decongestion. A moderate correlation was found between both HD and MCA2 and the NOSE score on the narrower side. CONCLUSION: In the assessment of nasal patency, it seems advisable to determine HD, MCA1 and MCA2, but also a subjective variable such as the NOSE score, which all seem to be not fully redundant variables. In further studies, the correlation of the variables should be assessed in patients with nasal pathologies.

Correlação entre a resistência nasal e diferentes parâmetros da rinometria acústica em crianças e adolescentes com e sem rinite alérgica / Correlation between nasal resistance and different acoustic rhinometry parameters in children and adolescents with and without allergic rhinitis

Rinometria acústica e rinomanometria são importantes técnicas de avaliação da função nasal. Ainda não está definido em que extensão suas variáveis se correlacionam. OBJETIVO: Avaliar as relações entre a resistência nasal (RN) e parâmetros da rinometria acústica em crianças e adolescentes com rinite alérgica e controles. MÉTODO: Vinte pacientes com rinite alérgica e 20 controles foram avaliados. RN, volumes (V4, V5, V2-5) e menores áreas transversais (MC1, MC2) foram mensurados em três momentos: basal, após indução de obstrução nasal e após descongestionante tópico. RESULTADOS: No grupo rinite, a RN se correlacionou significantemente com todos os volumes (V5: r = -0,60) e com MC2. Nos controles, MC1 foi o parâmetro com melhor correlação com a RN no momento basal (r = -0,53) e após descongestionante. Na análise conjunta dos dados, V5 foi o que apresentou as melhores correlações, no momento basal (r = -0,53), quando obstruído (r = -0,58) e após descongestionante (r = -0,46). CONCLUSÕES: Nossos dados demonstram haver correlação negativa e significante entre os valores de rinometria acústica e RN. Em geral, os volumes apresentaram melhor correlação com a RN do que as menores áreas transversais. V5 foi a variável com melhor correlação no grupo com rinite alérgica e na análise conjunta.

Acoustic rhinometry and rhinomanometry are important tests used to assess nasal function. The degree to which the parameters of these tests are correlated is yet to be established. OBJECTIVE: This paper aimed to study the correlations between nasal resistance (NR) and acoustic rhinometry parameters in children and adolescents with allergic rhinitis and controls. METHOD: Twenty patients with allergic rhinitis and 20 controls were enrolled. NR, volumes (V4, V5, V2-5), and minimal cross-sectional areas (MC1, MC2) were measured in three moments: baseline, after induction of nasal obstruction and after topical decongestant administration. RESULTS: Patients with allergic rhinitis had significant correlation between NR and all volumes (V5: r = -0.60) and with MC2. Among controls, MC1 was the parameter with the strongest correlation with NR at baseline (r = -0.53) and after decongestant administration. In the combined analysis, V5 had the highest correlation coefficients at baseline (r = -0.53), after obstruction (r = -0.58) and after decongestant (r = -0.46). CONCLUSIONS: Our data showed that NR and acoustic rhinometry parameters have negative and significant correlations. Nasal volumes are, in general, better correlated than minimal cross-sectional areas. V5 was the parameter with the highest correlation in the rhinitis group and in the combined analysis.

Contrasting diagnosis performance of forced oscillation and spirometry in patients with rheumatoid arthritis and respiratory symptoms

OBJECTIVES: Pulmonary involvement in rheumatoid arthritis is directly responsible for 10% to 20% of all mortality. The best way to improve the prognosis is early detection and treatment. The forced oscillation technique is easy to perform and offers a detailed exam, which may be helpful in the early detection of respiratory changes. This study was undertaken to (1) evaluate the clinical potential of the forced oscillation technique in the detection of early respiratory alterations in rheumatoid arthritis patients with respiratory complaints and (2) to compare the sensitivity of forced oscillation technique and spirometric parameters. METHODS: A total of 40 individuals were analyzed: 20 healthy and 20 with rheumatoid arthritis (90% with respiratory complaints). The clinical usefulness of the parameters was evaluated by investigating the sensibility, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01641705. RESULTS: The early adverse respiratory effects of rheumatoid arthritis were adequately detected by the forced oscillation technique parameters, and a high accuracy for clinical use was obtained (AUC.0.9, Se = 80%, Sp = 95%). The use of spirometric parameters did not obtain an appropriate accuracy for clinical use. The diagnostic performance of the forced oscillation technique parameters was significantly higher than that of spirometry. CONCLUSIONS: The results of the present study provide substantial evidence that the forced oscillation technique can contribute to the easy identification of initial respiratory abnormalities in rheumatoid arthritis patients that are not detectable by spirometric exams. Therefore, we believe that the forced oscillation technique can be used as a complementary exam that may help to improve the treatment of breathing disorders in rheumatoid arthritis patients.

Utilização da técnica de resistência do interruptor na avaliação da resistência das vias aéreas em pacientes com fibrose cística / Using the interrupter technique to evaluate airway resistance in cystic fibrosis patients

OBJETIVO: Medir a resistência de vias aéreas utilizando a técnica de resistência do interruptor (Rint) em pacientes com fibrose cística (FC) e correlacioná-la com parâmetros espirométricos, assim como avaliar a acurácia de Rint para determinar a resposta das vias aéreas a um broncodilatador. MÉTODOS: Estudo transversal com 38 crianças e adolescentes com FC acompanhados no Ambulatório de FC do Hospital São Lucas, em Porto Alegre (RS). Após a determinação de Rint, os pacientes foram submetidos à espirometria. Para a avaliação da resposta ao broncodilatador, as medições foram repetidas após o uso de salbutamol inalatório. RESULTADOS: Houve uma forte correlação entre o inverso de Rint e VEF1 (r = 0,8; p < 0,001) e moderadas correlações entre o inverso de Rint e FEF25-75% (r = 0,74; p < 0,001) e entre o inverso de Rint e índice de massa corpórea (r = 0,62; p < 0,001). A curva ROC foi utilizada na comparação da resposta ao broncodilatador determinada por Rint com aquela determinada por valores espirométricos. Para um ponto de corte de -28% para Rint, a área sob a curva foi de 0,75, com uma sensibilidade de 66% e uma especificidade de 82%. CONCLUSÕES: Nossos achados indicam que Rint apresenta uma boa correlação com parâmetros espirométricos, embora a técnica Rint não tenha sido suficientemente acurada para substituir a espirometria na avaliação da resposta ao broncodilatador.

OBJECTIVE: To measure airway resistance with the interrupter resistance (Rint) technique in patients with cystic fibrosis (CF) and to determine whether Rint values correlate with spirometric parameters, as well as to evaluate the accuracy of the Rint technique in determining the airway response to a bronchodilator. METHODS: This was a cross-sectional study involving 38 children and adolescents with CF followed at the Cystic Fibrosis Outpatient Clinic of the São Lucas Hospital, located in the city of Porto Alegre, Brazil. After Rint had been measured, the subjects underwent spirometry. To evaluate bronchodilator response, we repeated the measurements after the use of inhaled albuterol. RESULTS: There was a strong correlation between inverse Rint and FEV1 (r = 0.8; p < 0.001), and there was a moderate correlation between inverse Rint and FEF25-75% (r = 0.74; p < 0.001), as well as between inverse Rint and body mass index (r = 0.62; p < 0.001). We used a ROC curve to compare the bronchodilator response, as determined by Rint, with spirometric values. For a Rint cut-off point of -28%, the area under the curve was 0.75, with a sensitivity of 66% and a specificity of 82%. CONCLUSIONS: Our findings suggest that Rint correlates well with spirometric parameters, although the Rint technique was not sufficiently accurate to replace spirometry in the evaluation of bronchodilator responses.

Ventilación mecánica en paciente con enfermedad pulmonar obstructiva crónica / Mechanical ventilation in patient with chronic obstructive pulmonary disease

La enfermedad pulmonar obstructiva crónica (EPOC) es un problema sanitario y económico mundial. En los pacientes que presentan exacerbación aguda y son hospitalizados, alrededor del 8 por ciento requieren soporte ventilatorio. La ventilación no invasiva es el tratamiento de primera línea en la falla respiratoria, no obstante, la ventilación mecánica invasiva también es requerida. Un buen entendimiento de la fisiopatología de la vía aérea y de la mecánica respiratoria es necesario para un mejor manejo de las exacerbaciones y la falla respiratoria. La hiperinsuflación dinámica a nivel pulmonar derivado de una limitación de los flujos espiratorios es un hecho cardinal. Por ello, es necesario una óptima programación del ventilador mecánico que privilegie el vaciamiento espiratorio de los pulmones, mejorar el intercambio gaseoso y minimizar el trabajo respiratorio del paciente. Esta revisión discute las alteraciones fisiopatológicas y mecánicas respiratorias en el paciente con EPOC exacerbado y las técnicas ventilatorias para optimizar el manejo de la falla respiratoria hipercápnica.

Chronic obstructive pulmonary disease (COPD) is a major global healthcare problem. The patients that present acute exacerbation and are hospitalized, about 8 percent needs support ventilator. The noninvasive ventilation is the treatment of the first line in the respiratory failure, nevertheless, the mechanical invasive ventilation also is needed. A good understanding of the airway pathophysiology and lung mechanics in COPD is necessary for a better manage of the acute exacerbations and respiratory failure. The dynamic hyperinflation derived from an expiratory airflow limitation is a cardinal fact. For management, is necessary an appropriate programming of the mechanical ventilator that favors the reducing the amount of air trapping of the lungs, to improve the gas exchange and to minimize the respiratory work of the patient. This review discusses the alterations pathophysiology and lung mechanics in the patient with acute exacerbation of COPD and ventilatory strategies.