Should the 6-Minute Walk Test Be Compared When Conducted by 2 Different Assessors in Subjects With COPD?

BACKGROUND: The 6-min walk test (6MWT) is an important tool in the assessment of functional capacity and prognosis in patients with COPD. However, especially in long-term follow-up in clinical settings, this test may be executed by a different assessor, and it is not well known whether 6MWT has an acceptable inter-rater reliability. The aim of this study is to analyze the intra- and inter-rater reliability of the performance in 6MWT, its cardiorespiratory changes, and effort perception in subjects with COPD. METHODS: Thirty-two subjects with a diagnosis of COPD participated in the study, but 3 subjects did not appear on the second day of evaluation and therefore were included only in the intra-rater analysis; the first and second tests were executed by the same assessor with a 30-min interval between them, and the last was executed by a different assessor a week later. The intra-rater reliability was verified comparing the first and second 6MWT performance, and the inter-rater reliability was verified comparing the third test with the best performance of the first and second tests. RESULTS: The intraclass correlation coefficient values were >0.75 (P < .001) for the walked distance on the 6MWT; however, the limits of agreement, SE of measurement, and minimal detectable difference were higher than the minimum clinically important differences already mentioned in the literature (∼25, 26, and 54 m), and the coefficient of variation was small in both intra- and inter-rater comparisons. CONCLUSIONS: The 6MWT showed excellent reliability for distance and perceived exertion and moderate to excellent for HR and SD as assessed by intra- and inter-rater analysis. Thus, based on the main study outcomes, we concluded that the 6MWT can be compared when conducted by 2 different evaluators.

Repercussões cardiorrespiratórias agudas no uso correto de inaladores aerossóis de pó seco / Acute cardiopulmonary repercussions in the correct use of the dry-powder inhalers

Modelo do estudo: Trata-se de estudo original, transversal, clínico e comparativo. Objetivo do estudo: Avaliar as repercussões cardiorrespiratórias agudas no uso correto de inaladores aerossóis de pó seco (IPS) em pacientes com asma. Metodologia: Foram avaliados, em dois momentos, 17 pacientes adultos asmáticos em uso de IPS (Formoterol e Budesonida). As variáveis avaliadas, pré e pós-uso do IPS, foram: antropométrica, cognitiva, força muscular, sinais vitais, saturação de oxigênio, pressões respiratórias e pico de fluxo. No primeiro momento (M1) foi avaliada e monitorada a execução rotineira antes e imediatamente após uso do IPS e entregue folheto explicativo sobre o uso correto. No segundo momento (M2), 30 dias após M1, houve a mesma avaliação, entretanto, com execução correta do IPS. Resultados: No M2 ocorreram aumentos significativos da pressão inspiratória de 64,2±2,03 para 74,1±31,7 (cmH2O); pressão expiratória de 71,05±33,8 para 80±31,4 (cmH2O); capacidade vital de 3,3±0,9 para 3,9±0,9 (l) e reduções na frequência de pulso de 80,310,7 para 72,2±9,4 (bpm) e do duplo produto de 10001±1693 para 8846±1416 (teste t-Student pareado, p<0,05). Conclusões: O uso correto de IPS traz ao paciente repercussões cardiorrespiratórias positivas, melhorando as condições respiratórias e reduzindo o trabalho cardíaco.

Study model: It is a cross-over, clinical and comparative study. Objective: To evaluate the acute respiratory and cardiac respercussions in correct use of the dry powder inhalers (DPI) in patients with asthma. Methodology: Seventeen adult patients with asthma using DPI (Formoterol and Budesonide)were evaluated in two moments. The mensuared variables, before and after use of DPI, were: anthropometric, cognitive, muscle strength, vital signs, periferic oxygen saturation, respiratory pressures and peak expiratory flow. In the first moment (M1) was evaluated and monitored the usual performance before and immediately after using DPI and delivered an explicative leaflet about the correct use. In the second moment (M2), 30 days after M1, there was the same evaluation, however, with correct use ofthe DPI. Results: In the M2 there were increases to inspiratory pressure of 64,2±2,03 to 74,1±31,7(cmH2O); expiratory pressure of 71,05±33,8 to 80±31,4 (cmH2O); vital capacity of 3,3±0,9 to 3,9±0,9(l) and reductions in the pulse frequence of 80,3±10,7 to 72,2±9,4 (bm) and double product of 10001±1693 to 8846±1416 (paired t test, p<0,05). Conclusions: The correct use of the DPI promoves the positive respiratory and cardiac repercussions, improving respiratory conditions and reducing cardiac work.

Validity of the six-minute step test of free cadence in patients with chronic obstructive pulmonary disease.

OBJECTIVES: to evaluate the concurrent validity of the six-minute step test (6MST) in assessing exercise capacity of COPD patients using the six-minute walk test (6MWT) as a gold-standard. The predictive validity of the 6MST was assessed to determine a cut-off point for identification of low exercise capacity. METHOD: thirty-two COPD patients (50-87 years old) with mild to very severe obstruction performed the 6MST and 6MWT twice. RESULTS: Concurrent validity: a strong positive correlation (Pearson) between the number of ascents on the first (T1), second (T2) and the best of both (T1 or T2) tests during the 6MWT was observed. Although a moderate negative correlation with BODE index and FEV1 was found, it was considered insufficient to test the validity, therefore ROC curves were not applied. The predictive validity (ROC) of the 6MST to identify low physical capacity (compared with the 6MWT) using the performance of T1 or T2, or solely T1 was considered accurate, and the area under the curve was 0.8 (IC95% 0.62-0.98) and 0.85 (IC95% 0.70-0.99), respectively. To classify patients, the cut-off points of 86 and 78 steps were chosen, with both values showing 90% of sensitivity and specificity of 64% and 68% for T1 or T2, or solely T1, respectively. CONCLUSION: The number of steps on the 6MST was valid to verify exercise capacity in COPD patients and the cut-off point of 78 steps was able to identify patients with poor exercise tolerance. Values under this cut-off point are considered to identify patients with a poorer prognosis.

Validity of the six-minute step test of free cadence in patients with chronic obstructive pulmonary disease / Validade do teste de degrau de seis minutos de cadência livre em pacientes com doença pulmonar obstrutiva crônica

Objectives: to evaluate the concurrent validity of the six-minute step test (6MST) in assessing exercise capacity of COPD patients using the six-minute walk test (6MWT) as a gold-standard. The predictive validity of the 6MST was assessed to determine a cut-off point for identification of low exercise capacity. Method: thirty-two COPD patients (50-87 years old) with mild to very severe obstruction performed the 6MST and 6MWT twice. Results: Concurrent validity: a strong positive correlation (Pearson) between the number of ascents on the first (T1), second (T2) and the best of both (T1 or T2) tests during the 6MWT was observed. Although a moderate negative correlation with BODE index and FEV1 was found, it was considered insufficient to test the validity, therefore ROC curves were not applied. The predictive validity (ROC) of the 6MST to identify low physical capacity (compared with the 6MWT) using the performance of T1 or T2, or solely T1 was considered accurate, and the area under the curve was 0.8 (IC95% 0.62-0.98) and 0.85 (IC95% 0.70-0.99), respectively. To classify patients, the cut-off points of 86 and 78 steps were chosen, with both values showing 90% of sensitivity and specificity of 64% and 68% for T1 or T2, or solely T1, respectively. Conclusion: The number of steps on the 6MST was valid to verify exercise capacity in COPD patients and the cut-off point of 78 steps was able to identify patients with poor exercise tolerance. Values under this cut-off point are considered to identify patients with a poorer prognosis. .

Objetivos: Avaliar a validade concorrente do desempenho no teste de degrau de seis minutos (TD6) em analisar a capacidade física da DPOC, relacionando-o com o teste de caminhada de seis minutos (TC6), bem como verificar a presença de validade de critério preditiva do TD6, determinando um valor de corte para identificar baixa capacidade física. Método: Trinta e dois pacientes com DPOC estágios leve-muito grave, de ambos os sexos, entre 50-87 anos, realizaram dois TD6 e dois TC6. Resultados: Validade concorrente: observou-se correlação forte positiva (Pearson) entre o número de subidas do primeiro (T1), segundo (T2) e do melhor dos dois (T1 ou T2) TD6 com a distância percorrida no TC6. Embora constatamos correlações negativas entre os desempenhos no TD6 com o índice BODE e VEF1, essas não foram suficientes para caracterizar validade, não sendo traçadas as curvas ROC. A validade preditiva (curvas ROC) do TD6 para identificar baixa capacidade física (comparação com o TC6), utilizando o desempenho do T1 ou T2 ou somente do T1, foi considerada acurada para alguns propósitos, sendo a área abaixo da curva de 0,8 (IC95% 0,62-0,98) e 0,85 (IC95% 0,70-0,99), respectivamente. Para classificar os pacientes, escolhemos o ponto de corte de 86 e 78 degraus, apresentando sensibilidade de 90% e 90% e especificidade de 64% e 68%, para T1 ou T2 e somente T1, respectivamente. Conclusão: O desempenho no TD6 apresentou-se válido para verificar capacidade física na DPOC e identificou pacientes com baixa capacidade física, utilizando como ponto de corte 78 degraus, em que valores abaixo disso representaram pior prognóstico. .

Reproducibility of cadence-free 6-minute step test in subjects with COPD.

BACKGROUND: Six-minute step test (6MST) has been used to assess functional capacity in chronic conditions; however, its reproducibility in the COPD population has not been evaluated. Our study objective was to evaluate 6MST reproducibility. METHODS: The test was performed in a single 20-cm height step, and subjects were instructed to step up and down (cadence-free) for 6 min. Subjects underwent three tests. The first and second were controlled by the same assessor with a 30-min interval. The third test was controlled by a different assessor one week later. For intra-rater comparison, the first and second performances of the test were used, and for inter-assessor comparison, the better performance of the first two tests was compared with the third test. RESULTS: Excellent intra-rater and inter-rater relative reproducibility was observed (intraclass correlation coefficient > 0.8), and there was no statistical difference (repeated measures of analysis of variance) among the performances of the three tests. Intra-rater error values were acceptable (mean error of 5.7 steps and limits of agreement between -7 and 18 steps). Inter-rater error values were not acceptable (mean error of 4.4 steps and limits of agreement between -20 and 29 steps. CONCLUSIONS: 6MST proved to be reproducible in the COPD population when performed by the same assessor.

COPD patients' oxygen uptake and heart rate on-kinetics at cycle-ergometer: correlation with their predictors of severity.

OBJECTIVES: To assess whether there is a correlation between oxygen uptake (VO2) and heart rate (HR) on-kinetics in the constant-load cycle-ergometer test (CLT) and the BODE index and its isolated variables in patients with chronic obstructive pulmonary disease (COPD). METHOD: Fourteen male patients between 55 and 78 years of age with moderate to severe COPD were evaluated. Each patient underwent spirometry, the six-minute walk test (6MWT), the cycle-ergometer incremental test (IT) and CLT on alternate days. The exhaled gases were collected, and the VO2 and HR on-kinetics were analyzed. The BODE index was calculated. RESULTS: It was noted that the VO2 tau (τ) and mean response time (MRT) were significantly higher than HR τ and MRT. Moderate and strong correlations between τ and MRT of the VO2 and HR and the BODE index was noted (r=0.75 and r=0.78; r=0.62 and r=0.63, respectively), and there were correlations between the VO2 τ and MRT and the forced expiratory volume in one second (FEV1) (r=-0.60; r=-0.53) and the distance traveled at 6MWT (DT-6MWT) (r=-0.61; r=-0.44) and DT-6MWT % predicted (r=-0.62; r=-0.46). The HR τ and MRT were correlated with DT-6MWT (r=-0.59; r=-0.58) and DT-6MWT % predicted (r=-0.62; r=-0.62). CONCLUSION: The slowing of cycle-ergometer VO2, and especially of HR on-kinetics, may be key markers of disease severity. Furthermore, airflow obstruction and reduced exercise capacity are associated with the slowing of patients' VO2 and HR on-kinetics.

COPD patients' oxygen uptake and heart rate on-kinetics at cycle-ergometer: correlation with their predictors of severity / COPD patients' oxygen uptake and heart rate on-kinetics at cycle-ergometer: correlation with their predictors of severity

OBJECTIVES: To assess whether there is a correlation between oxygen uptake (VO2) and heart rate (HR) on-kinetics in the constant-load cycle-ergometer test (CLT) and the BODE index and its isolated variables in patients with chronic obstructive pulmonary disease (COPD). METHOD: Fourteen male patients between 55 and 78 years of age with moderate to severe COPD were evaluated. Each patient underwent spirometry, the six-minute walk test (6MWT), the cycle-ergometer incremental test (IT) and CLT on alternate days. The exhaled gases were collected, and the VO2 and HR on-kinetics were analyzed. The BODE index was calculated. RESULTS: It was noted that the VO2 tau (τ) and mean response time (MRT) were significantly higher than HR τ and MRT. Moderate and strong correlations between τ and MRT of the VO2 and HR and the BODE index was noted (r=0.75 and r=0.78; r=0.62 and r=0.63, respectively), and there were correlations between the VO2 τ and MRT and the forced expiratory volume in one second (FEV1) (r=-0.60; r=-0.53) and the distance traveled at 6MWT (DT-6MWT) (r=-0.61; r=-0.44) and DT-6MWT % predicted (r=-0.62; r=-0.46). The HR τ and MRT were correlated with DT-6MWT (r=-0.59; r=-0.58) and DT-6MWT % predicted (r=-0.62; r=-0.62). CONCLUSION: The slowing of cycle-ergometer VO2, and especially of HR on-kinetics, may be key markers of disease severity. Furthermore, airflow obstruction and reduced exercise capacity are associated with the slowing of patients' VO2 and HR on-kinetics. .

OBJETIVOS: Verificar se há correlação entre a cinética-on do consumo de oxigênio (VO2) e da frequência cardíaca (FC) no teste de carga constante em cicloergômetro (TCC) com o índice BODE e suas variáveis isoladas em pacientes com doença pulmonar obstrutiva crônica (DPOC). MÉTODO: Foram avaliados 14 homens com DPOC de obstrução moderada a muito grave, entre 55 e 78 anos, submetidos em dias alternados à espirometria, teste de caminhada de seis minutos (TC6), teste incremental em cicloergômetro (TI) e TCC. Foram coletados os gases expirados, e a cinética-on do VO2 e da FC foi analisada. O índice BODE foi calculado. RESULTADOS: Observou-se que a tau (τ) e o tempo de resposta média (TRM) do VO2 foram significativamente maiores que a τ e o TRM da FC. Observou-se correlações moderadas e fortes entre a τ e o TRM do VO2 e da FC com o índice BODE (r=0,75 e r=0,78; r=0,62 e r=0,63, respectivamente) e correlações entre a τ e o TRM do VO2 com o volume expiratório forçado no primeiro segundo (VEF1) (r=-0,60; r=-0,53), a distância percorrida no TC6 (DP-TC6) (r=-0,61; r=-0,44) e a DP-TC6 %prevista (r=-0,62; r=-0,46). A τ e o TRM da FC correlacionaram-se com a DP-TC6 (r=-0,59; r=-0,58) e a DP-TC6 %prevista (r=-0,62; r=-0,62). CONCLUSÃO: A lentificação da cinética-on do VO2 e principalmente da FC em cicloergômetro pode ser um marcador importante de gravidade da doença. Adicionalmente, a limitação ao fluxo aéreo e a reduzida capacidade ao exercício estão associadas à lentificação da cinética-on do VO2 e da FC nesses pacientes. .

Assessment of exercise capacity among asthmatic and healthy adolescents.

OBJECTIVES: To compare the physical performance and responses obtained in the six-minute walking test (6MWT) and the six-minute step test (6MST) between asthmatic and healthy adolescents; and to investigate the relationship between the responses obtained in the tests and the body mass index (BMI), physical activity level and spirometric variables. METHODS: Nineteen asthmatic adolescents (AG) and 19 healthy adolescents (HG) of both sexes, aged between 11 and 15 years, were assessed by means of spirometry, the 6MWT and the 6MST, and their physical activity levels were quantified using the International Physical Activity Questionnaire (IPAQ). RESULTS: The AG had poorer physical performance, lower heart rate (HR) and greater lower-limb (LL) fatigue in the 6MST. In the 6MWT, the AG had positive correlations between walked distance (WD) and duration of intense activity, and between HR and BMI, whereas the HG had positive correlations between WD and HR and between WD and respiratory rate (RR). In the 6MST, the AG showed positive correlations between RR and maximum voluntary ventilation (MVV) and between duration of moderate activity and physical performance. The AG also showed negative correlations between physical performance in the 6MST and BMI, and between sensation of dyspnea and duration of walking. Also in the 6MST, the HG showed positive correlations between RR and MVV, and between BMI and LL fatigue (p < or = 0.05). CONCLUSION: The 6MST demonstrated differences in exercise capacity between the asthmatic and healthy individuals. Furthermore, the physical performance and responses obtained in the tests were correlated with the MVV, BMI and physical activity level.

Avaliação da capacidade de exercício em adolescentes asmáticos e saudáveis / Assessment of exercise capacity among asthmatic and healthy adolescents

OBJETIVOS: Comparar o desempenho físico e as respostas obtidas nos testes de caminhada de seis minutos (TC6) e do degrau de seis minutos (TD6) entre adolescentes asmáticos e saudáveis e correlacionar o índice de massa corpórea (IMC), o nível de atividade física e as variáveis espirométricas com as variáveis obtidas nos testes. MÉTODOS: Foram avaliados 19 adolescentes asmáticos (GA) e 19 saudáveis (GS), com idades entre 11 e 15 anos, de ambos os sexos, por meio da espirometria, do TC6 e do TD6 e foi quantificado o nível de atividade física pelo Questionário Internacional de Atividade Física (IPAQ). RESULTADOS: No TD6, observaram-se menores valores de desempenho físico (TD6-T) e frequência cardíaca (FC) e maiores valores de fadiga de membros inferiores (MMII) no GA. No TC6, houve correlação positiva no GA da distância percorrida (DP) com o tempo de atividade intensa e da FC com o IMC e, no GS, da DP com a FC e com a frequência respiratória (FR). No TD6, houve correlação positiva no GA da ventilação voluntária máxima (VVM) com a FR; do tempo de atividade moderada com o TD6-T; além de correlação negativa do TD6-T com o IMC e da dispneia com o tempo de caminhada; no GS, correlações positivas da VVM com a FR e da fadiga de MMII com IMC (p<0,05). CONCLUSÃO: O TD6 demonstrou diferença na capacidade para o exercício entre asmáticos e saudáveis. Além disso, o desempenho físico e as respostas obtidas nos testes correlacionaram-se com os valores de VVM, IMC e nível de atividade física.

OBJECTIVES: To compare the physical performance and responses obtained in the six-minute walking test (6MWT) and the six-minute step test (6MST) between asthmatic and healthy adolescents; and to investigate the relationship between the responses obtained in the tests and the body mass index (BMI), physical activity level and spirometric variables. METHODS: Nineteen asthmatic adolescents (AG) and 19 healthy adolescents (HG) of both sexes, aged between 11 and 15 years, were assessed by means of spirometry, the 6MWT and the 6MST, and their physical activity levels were quantified using the International Physical Activity Questionnaire (IPAQ). RESULTS: The AG had poorer physical performance, lower heart rate (HR) and greater lower-limb (LL) fatigue in the 6MST. In the 6MWT, the AG had positive correlations between walked distance (WD) and duration of intense activity, and between HR and BMI, whereas the HG had positive correlations between WD and HR and between WD and respiratory rate (RR). In the 6MST, the AG showed positive correlations between RR and maximum voluntary ventilation (MVV) and between duration of moderate activity and physical performance. The AG also showed negative correlations between physical performance in the 6MST and BMI, and between sensation of dyspnea and duration of walking. Also in the 6MST, the HG showed positive correlations between RR and MVV, and between BMI and LL fatigue (p<0.05). CONCLUSION: The 6MST demonstrated differences in exercise capacity between the asthmatic and healthy individuals. Furthermore, the physical performance and responses obtained in the tests were correlated with the MVV, BMI and physical activity level.