Quantitative computed tomography analysis of the airways in patients with cystic fibrosis using automated software: correlation with spirometry in the evaluation of severity / Análise quantitativa por tomografia computadorizada das vias aéreas, usando programa automático, em pacientes com fibrose cística: avaliação da gravidade em correlação com a espirometria

Abstract Objective: To perform a quantitative analysis of the airways using automated software, in computed tomography images of patients with cystic fibrosis, correlating the results with spirometric findings. Materials and Methods: Thirty-four patients with cystic fibrosis were studied-20 males and 14 females; mean age 18 ± 9 years-divided into two groups according to the spirometry findings: group I (n = 21), without severe airflow obstruction (forced expiratory volume in first second [FEV1] > 50% predicted), and group II (n = 13), with severe obstruction (FEV1 ≤ 50% predicted). The following tracheobronchial tree parameters were obtained automatically: bronchial diameter, area, thickness, and wall attenuation. Results: On average, 52 bronchi per patient were studied. The number of bronchi analyzed was higher in group II. The correlation with spirometry findings, especially between the relative wall thickness of third to eighth bronchial generation and predicted FEV1, was better in group I. Conclusion: Quantitative analysis of the airways by computed tomography can be useful for assessing disease severity in cystic fibrosis patients. In patients with severe airflow obstruction, the number of bronchi studied by the method is higher, indicating more bronchiectasis. In patients without severe obstruction, the relative bronchial wall thickness showed a good correlation with the predicted FEV1.

Resumo Objetivo: Realizar a análise quantitativa das vias aéreas utilizando programa automático, em imagens de tomografia computadorizada de pacientes com fibrose cística, correlacionando com a espirometria. Materiais e Métodos: Foram estudados 34 pacientes com fibrose cística - 20 masculinos e 14 femininos; idade de 18 ± 9 anos -, divididos em dois grupos segundo a espirometria: grupo I (n = 21) - sem obstrução grave ao fluxo aéreo (volume expiratório forçado no primeiro segundo [VEF1] > 50% previsto); grupo II (n = 13) - com obstrução grave (VEF1 ≤ 50% previsto). Foram automaticamente obtidos: diâmetro, área, espessura e atenuação da parede da árvore traqueobrônquica. Resultados: Na média, foram estudados 52 brônquios por paciente. O número de brônquios analisados foi maior no grupo II. A correlação com a espirometria foi melhor no grupo I, principalmente entre a espessura relativa da parede da terceira a oitava geração brônquica e o VEF1 previsto. Conclusão: A análise quantitativa das vias aéreas em imagens de tomografia computadorizada pode ser útil na avaliação da gravidade da doença na fibrose cística. Nos pacientes com obstrução grave ao fluxo aéreo, o número de brônquios estudados pelo método é maior, indicando mais bronquiectasias. Nos pacientes sem obstrução grave, a espessura relativa da parede dos brônquios tem boa correlação com o VEF1 previsto.

Quantitative computed tomography analysis of the airways in patients with cystic fibrosis using automated software: correlation with spirometry in the evaluation of severity.

OBJECTIVE: To perform a quantitative analysis of the airways using automated software, in computed tomography images of patients with cystic fibrosis, correlating the results with spirometric findings. MATERIALS AND METHODS: Thirty-four patients with cystic fibrosis were studied-20 males and 14 females; mean age 18 ± 9 years-divided into two groups according to the spirometry findings: group I (n = 21), without severe airflow obstruction (forced expiratory volume in first second [FEV1] > 50% predicted), and group II (n = 13), with severe obstruction (FEV1 ≤ 50% predicted). The following tracheobronchial tree parameters were obtained automatically: bronchial diameter, area, thickness, and wall attenuation. RESULTS: On average, 52 bronchi per patient were studied. The number of bronchi analyzed was higher in group II. The correlation with spirometry findings, especially between the relative wall thickness of third to eighth bronchial generation and predicted FEV1, was better in group I. CONCLUSION: Quantitative analysis of the airways by computed tomography can be useful for assessing disease severity in cystic fibrosis patients. In patients with severe airflow obstruction, the number of bronchi studied by the method is higher, indicating more bronchiectasis. In patients without severe obstruction, the relative bronchial wall thickness showed a good correlation with the predicted FEV1.

OBJETIVO: Realizar a análise quantitativa das vias aéreas utilizando programa automático, em imagens de tomografia computadorizada de pacientes com fibrose cística, correlacionando com a espirometria. MATERIAIS E MÉTODOS: Foram estudados 34 pacientes com fibrose cística - 20 masculinos e 14 femininos; idade de 18 ± 9 anos -, divididos em dois grupos segundo a espirometria: grupo I (n = 21) - sem obstrução grave ao fluxo aéreo (volume expiratório forçado no primeiro segundo [VEF1] > 50% previsto); grupo II (n = 13) - com obstrução grave (VEF1 ≤ 50% previsto). Foram automaticamente obtidos: diâmetro, área, espessura e atenuação da parede da árvore traqueobrônquica. RESULTADOS: Na média, foram estudados 52 brônquios por paciente. O número de brônquios analisados foi maior no grupo II. A correlação com a espirometria foi melhor no grupo I, principalmente entre a espessura relativa da parede da terceira a oitava geração brônquica e o VEF1 previsto. CONCLUSÃO: A análise quantitativa das vias aéreas em imagens de tomografia computadorizada pode ser útil na avaliação da gravidade da doença na fibrose cística. Nos pacientes com obstrução grave ao fluxo aéreo, o número de brônquios estudados pelo método é maior, indicando mais bronquiectasias. Nos pacientes sem obstrução grave, a espessura relativa da parede dos brônquios tem boa correlação com o VEF1 previsto.

The influence of purulence on ciliary and cough transport in bronchiectasis.

BACKGROUND: Individuals with bronchiectasis exhibit colonization and infection of the respiratory system, with a consequent alteration of the macroscopic appearance of secretions, which ranges from mucoid to purulent. Purulence is related to the structural conformation, rheological profile, and transport indexes of mucus. We analyzed and compared the transport properties of respiratory secretions with mucoid appearance versus those with purulent appearance in patients with bronchiectasis and in subjects without lung disease. METHODS: In a simulated cough machine we assessed the mucociliary transport and contact angle of 32 mucoid and 19 purulent samples from subjects with bronchiectasis, and 21 samples from subjects without lung disease. RESULTS: Mucociliary transport was lower in the mucoid samples (0.78 ± 0.22) and in the purulent samples (0.73 ± 0.22) than in the samples from subjects without lung disease (1 ± 0.19). The purulent samples had less displacement in the simulated cough machine (7.57 ± 3 cm) than did the mucoid samples (23 ± 15 cm) or the samples from subjects without lung disease (34 ± 8.4 cm), as did the mucoid samples compared to the samples from subjects without lung disease. The purulent samples had a higher contact angle (25 ± 6.1°) than the mucoid samples (17 ± 7.8°) or the samples from subjects without lung disease (10 ± 2.5°), as did the mucoid samples compared to the samples from subjects without lung disease. CONCLUSIONS: Respiratory secretions in individuals with bronchiectasis have poor transport properties, which manifest as reduced mucociliary transport, reduced mucus transport by cough, and higher contact angle. These features were more accentuated in the purulent samples. This simple classification can be used by therapists to plan treatments, and by researchers to obtain more homogeneity between groups of subjects.

Acute lung injury induced by the intravenous administration of cigarette smoke extract.

OBJECTIVE: To investigate the acute effects of intravenous administration of cigarette smoke extract (CSE) on histological, inflammatory, and respiratory function parameters in rats, as well as to compare this potential acute lung injury (ALI) model with that with the use of oleic acid (OA). METHODS: We studied 72 Wistar rats, divided into four groups: control (those injected intravenously with saline); CSE (those injected intravenously with CSE and saline); OA (those injected intravenously with saline and OA); and CSE/OA (those injected intravenously with CSE and OA). RESULTS: Mean lung compliance was significantly lower in the OA and CSE/OA groups (2.12 ± 1.13 mL/cmH2O and 1.82 ± 0.77 mL/cmH2O, respectively) than in the control group (3.67 ± 1.38 mL/cmH2O). In bronchoalveolar lavage fluid, the proportion of neutrophils was significantly higher in the OA and CSE/OA groups than in the control group, as was the activity of metalloproteinases 2 and 9. Pulmonary involvement, as assessed by morphometry, was significantly more severe in the OA and CSE/OA groups (72.9 ± 13.8% and 77.6 ± 18.0%, respectively) than in the control and CSE groups (8.7 ± 4.1% and 32.7 ± 13.1%, respectively), and that involvement was significantly more severe in the CSE group than in the control group. CONCLUSIONS: The intravenous administration of CSE, at the doses and timing employed in this study, was associated with minimal ALI. The use of CSE did not potentiate OA-induced ALI. Additional studies are needed in order to clarify the potential role of this model as a method for studying the mechanisms of smoking-induced lung injury.

Lesão pulmonar aguda induzida pela administração endovenosa de extrato da fumaça do cigarro / Acute lung injury induced by the intravenous administration of cigarette smoke extract

OBJETIVO: Investigar os efeitos agudos da administração endovenosa de extrato da fumaça do cigarro (EFC) em parâmetros funcionais respiratórios, inflamatórios e histológicos em ratos e comparar esse potencial modelo de lesão pulmonar aguda (LPA) com aquele com o uso de ácido oleico (AO). MÉTODOS: Foram estudados 72 ratos Wistar machos divididos em quatro grupos: tratados somente com soro fisiológico (SF; grupo controle); tratados com EFC e SF (grupo EFC); tratados com SF e AO (grupo AO); e tratados com EFC e AO (grupo EFC/AO). RESULTADOS: As médias de complacência foram significantemente menores nos grupos AO e EFC/AO (2,12 ± 1,13 mL/cmH2O e 1,82 ± 0,77 mL/cmH2O, respectivamente) do que no controle (3,67 ± 1,38 mL/cmH2O). A proporção de neutrófilos e a atividade das metaloproteinases 2 e 9 em lavado broncoalveolar foram significantemente maiores nos grupos AO e EFC/AO que no controle. O acometimento pulmonar avaliado por morfometria foi significantemente maior nos grupos AO e EFC/AO (72,9 ± 13,8% e 77,6 ± 18,0%, respectivamente) do que nos grupos controle e EFC (8,7 ± 4,1% e 32,7 ± 13,1%, respectivamente), e esse acometimento foi significantemente maior no grupo EFC que no grupo controle. CONCLUSÕES: A administração endovenosa de EFC, nas doses e tempos deste estudo, associou-se à LPA mínima. O EFC não potencializou a LPA induzida por AO. Estudos adicionais são necessários para esclarecer o papel potencial desse modelo como método de estudo dos mecanismos de agressão pulmonar pelo tabaco.

OBJECTIVE: To investigate the acute effects of intravenous administration of cigarette smoke extract (CSE) on histological, inflammatory, and respiratory function parameters in rats, as well as to compare this potential acute lung injury (ALI) model with that with the use of oleic acid (OA). METHODS: We studied 72 Wistar rats, divided into four groups: control (those injected intravenously with saline); CSE (those injected intravenously with CSE and saline); OA (those injected intravenously with saline and OA); and CSE/OA (those injected intravenously with CSE and OA). RESULTS: Mean lung compliance was significantly lower in the OA and CSE/OA groups (2.12 ± 1.13 mL/cmH2O and 1.82 ± 0.77 mL/cmH2O, respectively) than in the control group (3.67 ± 1.38 mL/cmH2O). In bronchoalveolar lavage fluid, the proportion of neutrophils was significantly higher in the OA and CSE/OA groups than in the control group, as was the activity of metalloproteinases 2 and 9. Pulmonary involvement, as assessed by morphometry, was significantly more severe in the OA and CSE/OA groups (72.9 ± 13.8% and 77.6 ± 18.0%, respectively) than in the control and CSE groups (8.7 ± 4.1% and 32.7 ± 13.1%, respectively), and that involvement was significantly more severe in the CSE group than in the control group. CONCLUSIONS: The intravenous administration of CSE, at the doses and timing employed in this study, was associated with minimal ALI. The use of CSE did not potentiate OA-induced ALI. Additional studies are needed in order to clarify the potential role of this model as a method for studying the mechanisms of smoking-induced lung injury.

Competência glótica na doença pulmonar obstrutiva crônica / Glottal competence in chronic obstructive pulmonary disease

OBJETIVO: Correlacionar a medida do tempo máximo de fonação (TMF) com o volume de ar pulmonar expirado no primeiro segundo do sopro (VEF1) e comparar o TMF, emissão do "s", "z" e relação s/z em indivíduos saudáveis e indivíduos com doença pulmonar obstrutiva crônica (DPOC). MÉTODOS: Foram avaliados 14 voluntários saudáveis, com média de idade de 65 anos, e 16 indivíduos com DPOC, com média de idade de 68 anos. O diagnóstico da doença foi clínico e também obtido por exames da função pulmonar. Os participantes foram submetidos à espirometria para apreciação dos parâmetros VEF1, capacidade vital forçada (CVF) e o índice de Tiffeneau (VEF1/CVF). Registrou-se a emissão prolongada das vogais "a", "i", "u" para análise do tempo máximo de fonação na condição normal e forçada e aferiu-se a relação s/z após a sustentação dos fonemas /s/ e /z/. RESULTADOS: Nos dois grupos, o TMF com a fonação normal foi menor do que o tempo máximo de fonação, com a fonação forçada. A mediana do TMF do grupo controle foi maior do que a do grupo com DPOC, com a fonação normal e a fonação forçada. Não houve correlação entre o tempo máximo de fonação e os valores de VEF1 nos grupos. CONCLUSÃO: Pacientes com DPOC tem diminuição do tempo máximo de fonação e a relação s/z sugere falta de coaptação glótica. Não houve correlação do TMF e a medida do VEF1.

PURPOSE: This study correlates the extent of maximum phonation time (MPT) with the volume of air exhaled in the first second pulmonary (FEV1) and compares the MPT emission of /s/, /z/ and s/z ratio in healthy subjects and those with chronic obstructive pulmonary disease (COPD). METHODS: We studied 14 normal volunteers (control group), mean age 65 years, and 16 patients with COPD, mean age 68 years. The diagnosis of COPD was done by clinical and pulmonary function evaluation. Participants underwent spirometry for analysis of the parameters FEV1, forced vital capacity (FVC) and Tiffeneau index (FEV1/FVC). The maximum phonation time, along with phonemes /s/ and /z/, s/z ratio correlation, and maximum phonation time in both normal and forced phonation were collected and recorded. RESULTS: In both groups, the maximum phonation time with normal phonation was lower than the maximum phonation time with forced phonation. The median of the maximum phonation time in the control group was higher than in the COPD group. There was no correlation between the maximum phonation time and FEV1, in normal volunteers and patients with COPD. CONCLUSION: Patients with COPD have decreased maximum phonation time, while the s/z ratio does not suggest changes in the level of the vocal folds, since the values found were within the normal range. There was no correlation of the TMF and the measure of FEV1.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients.

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 + 8.3 years old, FEV1: 49.3+19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Highlights of the Brazilian Thoracic Association guidelines for interstitial lung diseases.

Interstitial lung diseases (ILDs) are heterogeneous disorders, involving a large number of conditions, the approach to which continues to pose an enormous challenge for pulmonologists. The 2012 Brazilian Thoracic Association ILD Guidelines were established in order to provide Brazilian pulmonologists with an instrument that can facilitate the management of patients with ILDs, standardizing the criteria used for the diagnosis of different conditions and offering guidance on the best treatment in various situations. The objective of this article was to briefly describe the highlights of those guidelines.

Destaques das diretrizes de doenças pulmonares intersticiais da Sociedade Brasileira de Pneumologia e Tisiologia / Highlights of the Brazilian Thoracic Association guidelines for interstitial lung diseases

As doenças pulmonares intersticiais (DPIs) são afecções heterogêneas, envolvendo um elevado número de condições, cuja abordagem ainda é um grande desafio para o pneumologista. As Diretrizes de DPIs da Sociedade Brasileira de Pneumologia e Tisiologia, publicadas em 2012, foram estabelecidas com o intuito de fornecer aos pneumologistas brasileiros um instrumento que possa facilitar a abordagem dos pacientes com DPIs, padronizando-se os critérios utilizados para a definição diagnóstica das diferentes condições, além de orientar sobre o melhor tratamento nas diferentes situações. Esse artigo teve como objetivo descrever resumidamente os principais destaques dessas diretrizes.

Interstitial lung diseases (ILDs) are heterogeneous disorders, involving a large number of conditions, the approach to which continues to pose an enormous challenge for pulmonologists. The 2012 Brazilian Thoracic Association ILD Guidelines were established in order to provide Brazilian pulmonologists with an instrument that can facilitate the management of patients with ILDs, standardizing the criteria used for the diagnosis of different conditions and offering guidance on the best treatment in various situations. The objective of this article was to briefly describe the highlights of those guidelines.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 + 8.3 years old, FEV1: 49.3+19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. ClinicalTrials.gov: NCT00500864 RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Dyspnea descriptors developed in Brazil: application in obese patients and in patients with cardiorespiratory diseases.

OBJECTIVE: To develop a set of descriptive terms applied to the sensation of dyspnea (dyspnea descriptors) for use in Brazil and to investigate the usefulness of these descriptors in four distinct clinical conditions that can be accompanied by dyspnea. METHODS: We collected 111 dyspnea descriptors from 67 patients and 10 health professionals. These descriptors were analyzed and reduced to 15 based on their frequency of use, similarity of meaning, and potential pathophysiological value. Those 15 descriptors were applied in 50 asthma patients, 50 COPD patients, 30 patients with heart failure, and 50 patients with class II or III obesity. The three best descriptors, as selected by the patients, were studied by cluster analysis. Potential associations between the identified clusters and the four clinical conditions were also investigated. RESULTS: The use of this set of descriptors led to a solution with seven clusters, designated sufoco (suffocating), aperto (tight), rápido (rapid), fadiga (fatigue), abafado (stuffy), trabalho/inspiração (work/inhalation), and falta de ar (shortness of breath). Overlapping of descriptors was quite common among the patients, regardless of their clinical condition. Asthma was significantly associated with the sufoco and trabalho/inspiração clusters, whereas COPD and heart failure were associated with the sufoco, trabalho/inspiração, and falta de ar clusters. Obesity was associated only with the falta de ar cluster. CONCLUSIONS: In Brazil, patients who are accustomed to perceiving dyspnea employ various descriptors in order to describe the symptom, and these descriptors can be grouped into similar clusters. In our study sample, such clusters showed no usefulness in differentiating among the four clinical conditions evaluated.

Dyspnea descriptors translated from English to Portuguese: application in obese patients and in patients with cardiorespiratory diseases.

OBJECTIVE: To investigate the usefulness of descriptive terms applied to the sensation of dyspnea (dyspnea descriptors) that were developed in English and translated to Brazilian Portuguese in patients with four distinct clinical conditions that can be accompanied by dyspnea. METHODS: We translated, from English to Brazilian Portuguese, a list of 15 dyspnea descriptors reported in a study conducted in the USA. Those 15 descriptors were applied in 50 asthma patients, 50 COPD patients, 30 patients with heart failure, and 50 patients with class II or III obesity. The three best descriptors, as selected by the patients, were studied by cluster analysis. Potential associations between the identified clusters and the four clinical conditions were also investigated. RESULTS: The use of this set of descriptors led to a solution with nine clusters, designated expiração (exhalation), fome de ar (air hunger), sufoco (suffocating), superficial (shallow), rápido (rapid), aperto (tight), falta de ar (shortness of breath), trabalho (work), and inspiração (inhalation). Overlapping of the descriptors was quite common among the patients, regardless of their clinical condition. Asthma, COPD, and heart failure were significantly associated with the inspiração cluster. Heart failure was also associated with the trabalho cluster, whereas obesity was not associated with any of the clusters. CONCLUSIONS: In our study sample, the application of dyspnea descriptors translated from English to Portuguese led to the identification of distinct clusters, some of which were similar to those identified in a study conducted in the USA. The translated descriptors were less useful than were those developed in Brazil regarding their ability to generate significant associations among the clinical conditions investigated here.

Uso de descritores de dispneia desenvolvidos no Brasil em pacientes com doenças cardiorrespiratórias ou obesidade / Dyspnea descriptors developed in Brazil: application in obese patients and in patients with cardiorespiratory diseases

OBJETIVO: Desenvolver um conjunto de termos descritores de dispneia para uso no Brasil. Investigar a utilidade desses descritores em quatro condições distintas que cursam com dispneia. MÉTODOS: Um conjunto de 111 frases descritivas da sensação de falta de ar foi coletado a partir das informações de 67 pacientes e de 10 profissionais da saúde. Tais frases foram analisadas e reduzidas a 15 expressões, em função de sua frequência de citação, similaridade de significados e potencial importância fisiopatológica. O conjunto de expressões foi aplicado a 50 pacientes com asma, 50 com DPOC, 30 com insuficiência cardíaca e 50 com obesidade graus II ou III. Os três melhores termos selecionados pelos pacientes foram estudados por análise de agrupamentos. Também foram investigadas as possíveis associações entre os agrupamentos encontrados e as quatro condições clínicas incluídas. RESULTADOS: O emprego dessa lista de descritores levou a uma solução com sete agrupamentos, denominados sufoco, aperto, rápido, fadiga, abafado, trabalho/inspiração e falta de ar. Houve grande superposição no uso de descritores pelos pacientes com as quatro condições clínicas. A asma mostrou associações expressivas com sufoco e trabalho/inspiração, enquanto DPOC e insuficiência cardíaca, com sufoco, trabalho/inspiração e falta de ar; e obesidade, com falta de ar apenas. CONCLUSÕES: Pacientes no Brasil habituados a sentir dispneia utilizam diferentes termos para descrever seu sintoma, e tais descrições podem ser agrupadas em conjuntos por similaridade. Tais agrupamentos não mostraram utilidade na distinção diagnóstica entre os grupos avaliados neste estudo.

OBJECTIVE: To develop a set of descriptive terms applied to the sensation of dyspnea (dyspnea descriptors) for use in Brazil and to investigate the usefulness of these descriptors in four distinct clinical conditions that can be accompanied by dyspnea. METHODS: We collected 111 dyspnea descriptors from 67 patients and 10 health professionals. These descriptors were analyzed and reduced to 15 based on their frequency of use, similarity of meaning, and potential pathophysiological value. Those 15 descriptors were applied in 50 asthma patients, 50 COPD patients, 30 patients with heart failure, and 50 patients with class II or III obesity. The three best descriptors, as selected by the patients, were studied by cluster analysis. Potential associations between the identified clusters and the four clinical conditions were also investigated. RESULTS: The use of this set of descriptors led to a solution with seven clusters, designated sufoco (suffocating), aperto (tight), rápido (rapid), fadiga (fatigue), abafado (stuffy), trabalho/inspiração (work/inhalation), and falta de ar (shortness of breath). Overlapping of descriptors was quite common among the patients, regardless of their clinical condition. Asthma was significantly associated with the sufoco and trabalho/inspiração clusters, whereas COPD and heart failure were associated with the sufoco, trabalho/inspiração, and falta de ar clusters. Obesity was associated only with the falta de ar cluster. CONCLUSIONS: In Brazil, patients who are accustomed to perceiving dyspnea employ various descriptors in order to describe the symptom, and these descriptors can be grouped into similar clusters. In our study sample, such clusters showed no usefulness in differentiating among the four clinical conditions evaluated.