The body weight-walking distance product as related to lung function, anaerobic threshold and peak VO2 in COPD patients

The bodyweight walking distance product and its relationship with clinical markers in patients with symptomatic peripheral artery disease

PURPOSE

The six-minute walk test (6MWT) is extensively employed to evaluate gait impairment in patients with symptomatic peripheral artery disease (PAD) and has been associated with different health outcomes. However, various approaches exist for calculating and interpreting the six-minute test in order to address the needs of patients more effectively. Therefore, we investigated how these different approaches correlate with functional capacity and cardiovascular health in patients with symptomatic PAD.

METHODS

In total, 227 PAD patients [65.2% men and 67 (13) y.o.] were included in this cross-sectional study. The 6MWT was performed along a 30-meter corridor and the distance was expressed in three ways: absolute (described as the meters walked during the test), relativized (based on the results of the 6MWT in healthy individuals), and DW (multiplying the body weight in kilograms by the absolute distance in the 6MWT). A functional capacity z-score was calculated using the results of the handgrip strength test, 4-meter walking test, and sit-and-stand test. A cardiovascular parameter z-score was calculated with data on brachial and central blood pressure, the low-frequency component/high-frequency component ratio, and carotid-femoral pulse wave velocity.

RESULTS

The absolute (b = 0.30, 95%CI: 18-0.43, R² = 0.11, p < 0.001) and DW (b = 0.40, 95%CI: 27-0.53, R² = 0.17, p < 0.001) measures were related to functional capacity, independently of sex, age, and the ankle-arm index of the patients. Neither absolute nor DW were related to cardiovascular health. The relativized measure was not associated with either functional capacity or cardiovascular health.

CONCLUSION

In patients with symptomatic PAD, absolute and DW measures are related to functional capacity, but not cardiovascular function.

Pulmonary function test results are correlated with 6-minute walk distance, distance-saturation product, and 6-minute walk work in patients with lymphangioleiomyomatosis

BACKGROUND AND OBJECTIVE

Lymphangioleiomyomatosis (LAM) is a rare multicystic lung disease. Although a correlation between pulmonary function test (PFT) results and exercise capacity appears probable, it has not yet been demonstrated. The aim of this study was to assess whether PFT results correlate with 6-minute walk test (6MWT) results in patients with LAM.

METHODS

We conducted a retrospective study of all patients with a diagnosis of LAM followed in a French reference centre over a 13-year period. PFT and 6MWT data were collected. Distance-saturation product (DSP) and 6-minute walk work (6MWORK) were calculated.

RESULTS

A total of 62 patients were included. Their median forced expiratory volume in 1 s (FEV1) was 82.7 % predicted and their median forced vital capacity (FVC) was 96.7 % predicted. The median diffusing capacity of the lungs for carbon monoxide (DLCO) was 58.5 % predicted and was decreased in 79 % of the patients. The median 6-minute walk distance was 535 m, which was 90.9 % of the 602 m predicted distance. The median DSP was 497.4 m % and the median 6MWORK was 32,910 kg.m. The distance walked during the 6MWT was significantly correlated with FVC%predicted (R = 0.435), FEV1 %predicted (R = 0.303), TLC%predicted (R = 0.345), FRC%predicted (R = 0.262), RV/TLC ratio (R = -0.271), and DLCO%predicted (R = 0.279). DSP and 6MWORK were each significantly correlated with different PFT results.

CONCLUSION

The present study shows that PFT results are potential predictors of the exercise capacity in patients with LAM. Additional studies are required to evaluate the interest of DSP and 6MWORK in LAM.

Impairments of functional exercise capacity, muscle strength, balance and kinesiophobia in patients with chronic kidney disease: a cross-sectional study

BACKGROUND

Muscle weakness, balance, and functional capacity are affected in patients with chronic kidney disease (CKD) in dialysis. However, studies about kinesiophobia, peripheral and respiratory muscle strength, balance, exercise capacity, fatigue, and physical activity level in patients with CKD 3-4 are limited. The study aimed to compare the functional exercise capacity, peripheral and respiratory muscle strength, pulmonary function, balance, kinesiophobia, physical activity, fatigue, and dyspnea between patients with CKD 3-4 and controls.

METHODS

This cross-sectional study included 43 patients and 45 controls. Functional exercise capacity [6-Minute Walking Test (6MWT)], peripheral and respiratory muscle strength, pulmonary function, dyspnea, fatigue, physical activity, balance [Berg Balance Scale (BBS)], and kinesiophobia were evaluated.

RESULTS

Demographic characteristics were similar in patients [53(50-57) y, 26 M/17F] and controls [51(4.506-55) y, 33 M/12F] (p > 0.05). The 6MWT, respiratory and peripheral muscle strength, pulmonary function, physical activity, and BBS were significantly lower, and the level of dyspnea and kinesiophobia were higher in patients compared with controls (p < 0.05).

CONCLUSIONS

Patients had impaired functional exercise capacity, upper and lower extremity muscle strength, respiratory muscle strength, pulmonary function, and balance, increased perception of dyspnea and kinesiophobia, and reduced physical activity level compared with controls. Patients should be directed to cardiopulmonary rehabilitation programs.

Objective assessment of functional capacity in patients with peripheral artery disease: a narrative review

INTRODUCTION

Peripheral artery disease (PAD) patients with claudication symptoms exhibit impaired functional capacity, which has been associated with disease severity, worse quality of life and higher risk of cardiovascular events. Different tests have been used to assess functional capacity in PAD patients. Therefore, understanding the characteristics, strengths and limitations of these tests are important to support the choice of tests to be used in clinical practice.

AREAS COVERED

This review summarizes the main methods to assess functional capacity in PAD patients, discussing their psychometric properties, applications, and limitations.

EXPERT OPINION

Robust evidence supports the use of treadmill and six-minute walk tests in PAD patients, as their results are associated with clinically meaningful outcomes, adequate psychometric properties and are sensitive to effects of interventions. On the other hand, other functional tests (Shuttle-walk test, outdoor walking capacity test, timed-up and go, four-meter walk test, heel-rise test, short physical performance battery and modified physical performance battery) are related to activities of daily living and do not require sophisticated equipment and can be easily used in clinical practice. However, these other tests still need evidence regarding their clinical relevance, reliability, and ability to detect long-term intervention changes, providing further investigation directions.

Tidal volume expandability and ventilatory efficiency as predictors of mortality in Taiwanese male patients with chronic obstructive pulmonary disease: A 10-year follow-up study - Is V̇O2peak or FEV1% the gold standard?

Despite our knowledge of the risk factors for mortality associated with chronic obstructive pulmonary disease (COPD), the mortality rate for this condition continues to increase. This study aimed to investigate the predictive power of physiological variables on all-cause mortality in COPD patients compared to peak oxygen uptake (V ˙ O2peak) and forced expired volume in one second (FEV1). We conducted a retrospective study of 182 COPD patients with complete lung function tests, cardiopulmonary exercise testing (CPET), and survival data. Cox regression analysis was used to estimate the hazard ratios for all-cause mortality. The median follow-up period was 6.8 (IQR 3.9-9.2) years. Out of the 182 patients in our study, sixty-two (34.1%) succumbed to various causes. Of these, 27.4% (n = 17) experienced acute exacerbations, 24.2% (n = 15) had advanced cancer, and 12.9% (n = 8) had cardiovascular disease as the primary cause of death. Another 25.8% (n = 16) passed away due to other underlying conditions, while 6.5% (n = 4) had an unknown cause of death. One patient's demise was attributed to a benign tumor, and another's to a connective tissue disease. The ratio of tidal volume to total lung capacity (VTpeak/TLC) and the ratio of minute ventilation and V ˙ O2 at nadir (V ˙ E/V ˙ O2nadir) (AUR 0.83, 95% CI 0.76-0.91) were superior predictors of all-cause mortality compared to V ˙ O2peak and FEV1%. A mortality prediction formula was derived using these variables. This study highlights the potential of VTpeak/TLC and V ˙ E/V ˙ O2nadir as predictive markers for COPD all-cause mortality in COPD. CPET is an effective tool for evaluating COPD mortality; however, the predictive equation requires further validation.

Hierarchical stratification of the factors related to exertional dyspnoea and exercise intolerance in male COPD patients

BACKGROUND

The order and extent of interactions across the factors affecting exertional dyspnoea (ED) and exercise intolerance (EI) in patients with chronic obstructive pulmonary disease (COPD) are not clear. We hypothesized that lung and non-lung variables were the primary variables, ED was the secondary variable and EI was the tertiary variable.

METHODS

Data on demographics, blood tests, cardiac imaging, lung function tests and invasive dead space fractions (V_D/V_T) during incremental exercise test of 46 male COPD subjects were obtained. These variables were categorized by factor analysis and pair-wise correlation analysis was conducted. The best factor of each category was selected and then multivariate regression was conducted.

RESULTS

Peak tidal inspiratory flow (V_T/T_Ipeak), V_D/V_Tpeak and tidal lung expansion capability, and resting diffusing capacity of the lungs (D_LCO)% predicted were the primary pulmonary factors most related to ED, whereas body mass index (BMI), haemoglobin and cholesterol levels were the primary non-pulmonary factors. In multivariate regression analysis, V_T/T_Ipeak, V_D/V_Tpeak and D_LCO% were the primary factors most related to ED (r² = 0.69); ED was most related to EI (r = -0.74 to -0.83).

CONCLUSION

Using hierarchical stratification and statistical methods may improve understanding of the pathophysiology of ED and EI in patients with COPD. KEY MESSAGESThe pathophysiology of exertional dyspnoea (ED) and exercise intolerance (EI) in chronic obstructive pulmonary disease (COPD) is complex. The order and extent of interactions across factors are not clear. In multivariate regression analysis, we found that tidal inspiratory flow, dead space fraction and resting diffusing capacity of the lungs % but not the non-pulmonary factors affected ED.Using correlation coefficients, we further found that ED was the secondary variable and EI was the tertiary variable.Hierarchical stratification of the important factors associated with ED and EI in patients with COPD clarifies their relationships and could be incorporated into management programmes and outcome studies for these patients.

Exercise Combined with a Chinese Medicine Herbal Tea for Patients with Type 2 Diabetes Mellitus: A Randomized Controlled Trial

Objectives: Exercise and Traditional Chinese Medicine (TCM) herbal tea may improve glucose metabolism through quite different mechanisms while sharing some common effects. The purpose of this study was to discover whether the intervention of exercise combined with TCM herbal tea intervention could produce advanced improvement in glucose metabolism than exercise alone in community patients with type 2 diabetes mellitus (T2DM). Materials and Methods: This was a 12-week, randomized controlled trial in which 75 community patients with T2DM were randomly assigned to the single group (n = 39) receiving intervention of aerobic and resistance exercise three times per week and the combined group (n = 36) receiving intervention of TCM herbal tea (consisted of six substances) taken once daily besides the exercise. The change of glycated hemoglobin A1 (HbA1c), tested before and after intervention, served as the primary outcome. Other measurements include fasting plasma glucose (FPG), glycated serum protein (GSP), lipid profile, and physical fitness profile. Results: HbA1c and FPG levels and their changes showed no group difference. The level of GSP was lower, and its decrease was also larger after exercise combined with TCM herbal tea than after single exercise intervention (p < 0.05). Lipid profile and physical fitness parameters were similar in the two groups except the larger six-minute walk test (6MWT) power after the combined intervention (p < 0.05). Patients showed good compliance with the intervention and had similar exercise days or amount in the two groups. No patient reported serious adverse events or significant changes in other lifestyles. Conclusions: A 12-week of exercise combined with TCM herbal tea could not enhance the hypoglycemic effects by exercise alone in community patients with type 2 diabetes. However, the lower GSP level and larger 6MWT work brought by combined intervention suggest its potential benefits, and further studies are needed to explore the effects of longer period and larger dosage of intervention. Clinical Trial Registration Number: Chinese Clinical Trial Registry: ChiCTR1800018721.

Tidal volume expandability affected by flow, dynamic hyperinflation, and quasi-fixed inspiratory time in patients with COPD and healthy individuals

Exertional dyspnea (ED) and impaired exercise performance (EP) are mainly caused by dynamic hyperinflation (DH) in chronic obstructive pulmonary disease (COPD) patients by constraining tidal volume expansion at peak exercise (V_Tpeak). As V_Tpeak is the product of inspiratory time (T_Ipeak) and flow (V_T/T_Ipeak), it was hypothesized that V_Tpeak and V_Tpeak/total lung capacity (V_Tpeak/TLC) may be affected by T_Ipeak and V_T/T_Ipeak. Hence, the study investigated the (1) effect of T_Ipeak and V_T/T_Ipeak on V_Tpeak expansion, (2) factors associated with T_Ipeak, expiratory time (T_Epeak), V_T/T_Ipeak, and V_Tpeak/TLC, and (3) relationships between V_T/T_Ipeak and V_Tpeak/TLC with ED and EP in COPD patients and controls. The study enrolled 126 male stable COPD patients and 33 sex-matched controls. At peak exercise, T_Ipeak was similar in all subjects (COPD versus controls, mean ± SD: 0.78 ± 0.17 s versus 0.81 ± 0.20 s, p = NS), whereas the COPD group had lower V_T/T_Ipeak (1.71 ± 0.49 L/s versus 2.58 ± 0.69 L/s, p < .0001) and thus the COPD group had smaller V_Tpeak (1.31 ± 0.34 L versus 2.01 ± 0.45 L,p < .0001) and V_Tpeak/TLC (0.22 ± 0.06 vs 0.33 ± 0.05, p < .0001). T_Ipeak, T_Epeak, and V_T/T_Ipeak were mainly affected by exercise effort, whereas V_Tpeak/TLC was not. T_Epeak, V_T/T_Ipeak, and V_Tpeak/TLC were inversely changed by impaired lung function. T_Ipeak was not affected by lung function. Dynamic hyperinflation did not occur in the controls, however, V_Tpeak/TLC was strongly inversely related to DH (r = −0.79) and moderately to strongly related to lung function, ED, and EP in the COPD group. There was a slightly stronger correlation between V_Tpeak/TLC with ED and EP than V_T/T_Ipeak in the COPD group (|r| = 0.55–0.56 vs 0.38–0.43). In summary, T_Ipeak was similar in both groups and the key to understanding how flow affects lung expansion. However, the DH volume effect was more important than the flow effect on ED and EP in the COPD group.

Impact of cardiorespiratory rehabilitation program on submaximal exercise capacity of Tunisian male patients with post-COVID19: A pilot study

Post-COVID19 patients suffer from persistent respiratory, cardiovascular, neurological, and musculoskeletal health complaints such as dyspnea, chest pain/discomfort, and fatigue. In Tunisia, the potential benefits of a cardiorespiratory rehabilitation program (CRRP) after COVID19 remain unclear. The main aim of this study was to evaluate the impact of a CRRP on submaximal exercise capacity, evaluated through the 6-min walk test (6MWT) data in post-COVID19 Tunisian patients. This was a cross-sectional study including 14 moderate to severe COVID19 patients aged from 50 to 70 years. CRRP was performed after the end of patients’ hospitalization in COVID19 units for extensive or severe extents of COVID19. Dyspnea (modified medical research council), spirometry data, handgrip strength values, 6MWT data, and 6-min walk work (i.e., 6-min walk distance x weight) were evaluated 1-week pre-CRRP, and 1-week post-CRRP. CRRP included 12 sessions [3 sessions (70 min each)/week for 4 weeks]. Exercise-training included aerobic cycle endurance, strength training, and educational sessions. Comparing pre- and post- CRRP results showed significant improvements in the means±standard deviations of dyspnea by 1.79 ± 0.80 points (p < 0.001), forced expiratory volume in one second by 110 ± 180 ml (p = 0.04), 6-min walk distance by 35 ± 42 m (p = 0.01), 6-min walk work by 2,448 ± 3,925 mkg (p = 0.048), resting heart-rate by 7 ± 9 bpm (p = 0.02) and resting diastolic blood pressure by 6 ± 10 mmHg (p = 0.045). In Tunisia, CRRP seems to improve the submaximal exercise capacity of post-COVID19 patients, mainly the 6-min walk distance and work.

Correlation Comparison and Personalized Utility of Field Walking Tests in Assessing the Exercise Capacity of Patients with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

Background: Incremental shuttle walking tests (ISWT) are regarded as valuable alternatives to 6-min walking tests (6MWT) and cardiopulmonary exercise tests (CPET) owing to the maximal and externally paced loading. This study investigated the validity and reliability of ISWT by analyzing the correlation of the distances of two field tests with peak oxygen consumption (VO2) of CPET in patients with COPD. Methods: In this randomized controlled trial, patients with COPD were enrolled from two hospitals. Three assessments were performed for all patients. The ISWT and 6MWT were repeated twice in Hospital 1 to assess reliability. Results: A total of 29 patients were enrolled. The distances of ISWT (0.782, p < 0.001) and 6MWT (0.512, p = 0.005) correlated with peak VO2. The intraclass correlation coefficients of both ISWT (0.988, p < 0.001) and 6MWT (0.959, p < 0.001) was high. Patients with higher peak VO2 walked a longer distance in ISWT than 6MWT (r = 0.590, p < 0.001). Conclusions: The ISWT more highly correlates with peak VO2 than the 6MWT and has excellent reliability in patients with COPD. According to peak VO2, the walking distances of each field test varied, suggesting that the application should be personalized for the exercise capacity.

The Impact of Oxygen Pulse and Its Curve Patterns on Male Patients with Heart Failure, Chronic Obstructive Pulmonary Disease, and Healthy Controls-Ejection Fractions, Related Factors and Outcomes

Oxygen pulse (O2P) is a function of stroke volume and cellular oxygen extraction and O2P curve pattern (O2PCP) can provide continuous measurements of O2P. However, measurements of these two components are difficult during incremental maximum exercise. As cardiac function is evaluated using ejection fraction (EF) according to the guidelines and EF can be obtained using first-pass radionuclide ventriculography, the aim of this study was to investigate associations of O2P%predicted and O2PCP with EF in patients with heart failure with reduced or mildly reduced ejection fraction (HFrEF/HFmrEF) and chronic obstructive pulmonary disease (COPD), and also in normal controls. This was a prospective observational cross-sectional study. Correlations of resting left ventricular EF, dynamic right and left ventricular EFs and outcomes with O2P% and O2PCP across the three participant groups were analyzed. A total of 237 male subjects were screened and 90 were enrolled (27 with HFrEF/HFmrEF, 30 with COPD and 33 normal controls). O2P% and the proportions of the three types of O2PCP were similar across the three groups. O2P% reflected dynamic right and left ventricular EFs in the control and HFrEF/HFmrEF groups, but did not reflect resting left ventricular EF in all participants. O2PCP did not reflect resting or dynamic ventricular EFs in any of the subjects. A decrease in O2PCP was significantly related to nonfatal cardiac events in the HFrEF/HFmrEF group (log rank test, p = 0.01), whereas O2P% and O2PCP did not predict severe acute exacerbations of COPD. The findings of this study may clarify the utility of O2P and O2PCP, and may contribute to the currently used interpretation algorithm and the strategy for managing patients, especially those with HFrEF/HFmrEF. (Trial registration number NCT05189301.).

Psychosocial Intervention in Chronic Obstructive Pulmonary Disease: Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Many patients with chronic obstructive pulmonary disease (COPD) experience persistent interrelated psychological and physical symptoms despite optimal treatment. Several studies of psychosocial intervention in COPD have been published in recent years. The present study aimed to conduct a quantitative summary of the efficacy of such interventions on psychological and physical outcomes.

METHODS

Two independent raters screened PubMed, PsycINFO, Embase, Web of Science, Cochrane Library, and CINAHL for eligible studies. In all, 35 independent, randomized controlled trials with a total of 3,120 patients with COPD were included, assessed for their methodological quality, and subjected to meta-analytic evaluation.

RESULTS

Meta-analyses revealed small, statistically significant effects of psychosocial intervention on combined psychological (Hedges's g = 0.28; 95%CI: 0.16-0.41) and physical outcomes (g = 0.21; 95%CI: 0.07-0.35) with no indications of publication bias. Supplementary Bayesian meta-analyses provided strong evidence for a non-zero overall effect on psychological outcomes (Bayes factor (BF) = 305) and moderate support for physical outcomes (BF = 6.1). Exploring sources of heterogeneity with meta-regression indicated that older age of patients and longer duration of interventions were associated with smaller effects on psychological outcomes.

CONCLUSIONS

The results support psychosocial intervention as an additional, useful tool in multidisciplinary respiratory care with the potential to improve both psychological and physical outcomes. Future studies are recommended to monitor adverse effects, apply blinding of active control conditions, and determine sample sizes with a priori power calculations.

REGISTRATION

Registered with Prospero (www.crd.york.ac.uk/prospero/) prior to initiation of the literature search (Reg. ID: CRD42020170083).

Stronger correlation of peak oxygen uptake with distance of incremental shuttle walk test than 6-min walk test in patients with COPD: a systematic review and meta-analysis

Background

The 6-min walk test (6MWT) and incremental shuttle walk test (ISWT) are valid and reliable measures to assess exercise capacity of patients with chronic obstructive pulmonary disease (COPD). However, the comparison of correlation between peak oxygen uptake (peak VO₂) and 6MWT or ISWT distance has not been investigated. We aimed to investigate the correlation between peak VO₂ and 6MWT and ISWT distances in COPD patients through a meta-analysis.

Methods

We systematically searched MEDLINE, Scopus, Embase, and the Cochrane Library up to June, 2020 for studies comparing the correlation of peak VO₂ with either 6MWT or ISWT in COPD patients. Meta-analysis was performed with R software using a fixed-effect model. We compared the correlation coefficient and measured the heterogeneity using I² statistics.

Results

We identified 12 studies involving 746 patients. Meta-analysis showed a significant correlation between peak VO₂ and 6MWT and ISWT distances (6MWT: r = 0.65, 95% CI 0.61–0.70; ISWT: r = 0.81, 95% CI 0.74–0.85; p < 0.0001). The heterogeneity was lower in ISWT than in 6MWT (6MWT: I² = 56%, p = 0.02; ISWT: I² = 0%, p = 0.71). Subgroup analysis showed a higher correlation coefficient in the low exercise capacity group than in the high exercise capacity group in both field tests.

Conclusions

6MWT and ISWT significantly correlated with peak VO₂. Our findings suggest that ISWT has a stronger correlation with peak VO₂ than 6MWT. The exercise capacity in COPD patients may affect the strength of the relationship between peak VO₂ and walking distance in both field tests, suggesting the importance of using various exercise tests.

Trial registration CRD 42020200139 at crd.york.ac.uk/prospero/

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01897-0.

Prediction and types of dead-space fraction during exercise in male chronic obstructive pulmonary disease patients

A high dead space (VD) to tidal volume (VT) ratio during peak exercise (VD/VTpeak) is a sensitive and consistent marker of gas exchange abnormalities; therefore, it is important in patients with chronic obstructive pulmonary disease (COPD). However, it is necessary to use invasive methods to obtain VD/VTpeak, as noninvasive methods, such as end-tidal PCO2 (PETCO2peak) and PETCO2 adjusted with Jones' equation (PJCO2peak) at peak exercise, have been reported to be inconsistent with arterial PCO2 at peak exercise (PaCO2peak). Hence, this study aimed to generate prediction equations for VD/VTpeak using statistical techniques, and to use PETCO2peak and PJCO2peak to calculate the corresponding VD/VTpeaks (i.e., VD/VTpeakETVD/VTpeakJ).A total of 46 male subjects diagnosed with COPD who underwent incremental cardiopulmonary exercise tests with PaCO2 measured via arterial catheterization were enrolled. Demographic data, blood laboratory tests, functional daily activities, chest radiography, two-dimensional echocardiography, and lung function tests were assessed.In multivariate analysis, diffusing capacity, vital capacity, mean inspiratory tidal flow, heart rate, and oxygen pulse at peak exercise were selected with a predictive power of 0.74. There were no significant differences in the PCO2peak values and the corresponding VD/VTpeak values across the three types (both p = NS).In subjects with COPD, VD/VTpeak can be estimated using statistical methods and the PETCO2peak and PJCO2peak. These methods may have similar predictive power and thus can be used in clinical practice.

Inflammatory and oxidative biomarkers as determinants of functional capacity in patients with COPD assessed by 6-min walk test-derived outcomes

INTRODUCTION

Reduction in functional capacity is a negative clinical outcome of chronic obstructive pulmonary disease (COPD). Studies have shown association between inflammatory and oxidative stress biomarkers and functional capacity. However, it is unclear whether these biomarkers are associated with outcomes of functional capacity. Therefore, the aim of this study was to evaluate whether plasma biomarkers of inflammation and oxidative stress are predictors of the 6-min walking test (6MWT)-derived outcomes.

METHODS

Twenty COPD patients were assessed on three consecutive days with different clinical measures, including functional capacity, and blood sampling. Plasma concentrations of IL-6, IL-8, TNF-ɑ, IL-10 and soluble TNF-ɑ receptors (sTNFR1 and sTNFR2) were determined by immunoassays. Oxidative stress was evaluated by determining lipid peroxidation products based on the enzymatic activity of superoxide dismutase (SOD) and catalase, and total antioxidant capacity of plasma. Functional capacity was assessed considering the six-minute walking distance (6MWD) and the estimate of six-minute walking work (6MWW). The association between biomarkers (i.e. inflammation and oxidative stress) and functional exercise capacity was investigated through the Pearson's correlation coefficient. To identify the determinants of the 6MWT, multiple linear stepwise regression analyses were performed with adjustment for age, sex and GOLD classification.

RESULTS

Patients were predominantly male (65%), with mean age of 64 years and moderate airflow obstruction and impaired functional capacity. There were positive correlations between SOD activity and 6MWD (r = 0.520; p = 0.02) and 6MWW (r = 0.554; p = 0.01), as well as a negative correlation between sTNF-R1 and 6MWD (r = -0.437; p = 0.05). SOD was an independent determinant of the functional capacity, explaining 23% of the variability of 6MWD (p = 0.019) and 27% of the variability of 6MWW (p = 0.011). sTNF-R1 levels were associated with 6MWD and, together with SOD explained 40% of variability in 6MWD (p = 0.005).

CONCLUSION

SOD activity was an independent determinant of performance in the 6MWT, and together with sTNFR1 explained 40% of the variations in walking distance in COPD patients. SOD activity and sTNFR1 levels might be seen as potential biomarkers of the functional capacity in patients with COPD.

Pulmonary rehabilitation in patients with interstitial lung diseases: Correlates of success

BACKGROUND AND AIM

Benefits of pulmonary rehabilitation in Interstitial Lung Diseases (ILD) have been reported. The aim of this large multicenter study was to identify the success predictors of pulmonary rehabilitation in a real-life setting.

METHODS

Data of 240 in-patients (110 idiopathic pulmonary fibrosis (IPF), 106 ILD other than IPF and 24 undetermined ILD) undergoing pulmonary rehabilitation in a 10-year period were retrospectively evaluated. Six minute walking distance (6MWT), body weight-walking distance product tests, dyspnoea and arterial blood gases were assessed at admission and discharge. Differences in post rehabilitation changes in outcome measures as function of baseline characteristics were evaluated.

RESULTS

After rehabilitation, patients showed improvements in all outcome measures (p < 0.05), regardless of the underlying diagnosis or disease severity. Patients needing oxygen therapy at rest showed reduced benefits. Baseline 6MWD inversely correlated with its changes at discharge. Non-significant greater benefits after rehabilitation were found in IPF patients under antifibrotic therapy. In a subset of 50 patients assessed on average 10.3 ± 3.5 months after discharge, the benefits in 6MWD were not maintained (312.9 ± 139.4, 369.7 ± 122.5 and 310.8 ± 139.6 m at admission, discharge and follow up respectively: p < 0.0001).

CONCLUSION

Pulmonary rehabilitation may improve dyspnoea, exercise capacity and fatigue in patients with ILD of different aethiologies and level of severity. The long-term effects need to be established.

Resting Dead Space Fraction as Related to Clinical Characteristics, Lung Function, and Gas Exchange in Male Patients with Chronic Obstructive Pulmonary Disease

Background

Measures of forced expired volume in one second % predicted (FEV₁%), residual volume to total lung capacity ratio (RV/TLC) and diffusing capacity for carbon monoxide measurements (D_LCO) are the standard lung function test for evaluating patients with chronic obstructive pulmonary disease (COPD). The dead space fraction (V_D/V_T) has been shown to be a robust marker of gas exchange abnormality. However, the use of V_D/V_T has gradually become less common. As V_D/V_T measured at rest (V_D/V_TR) has been successfully used in non-COPD conditions, it was hypothesized that in COPD the V_D/V_TR was more sensitive than the standard lung function test in correlation with clinical characteristics and gas exchange. This study aimed to test the hypothesis and to identify the variables relevant to V_D/V_TR.

Methods

A total of 46 male subjects with COPD were enrolled. Clinical characteristics included demographic data, oxygen-cost diagram (OCD), and image studies for pulmonary hypertension. The standard lung function was obtained. To calculate V_D/V_T, invasive arterial blood gas and pulmonary gas exchange (PGX) were measured. The variables relevant to V_D/V_TR were analyzed by multiple linear regression.

Results

Compared to lung function, V_D/V_TR was more frequently and significantly related to smoking, carboxyhemoglobin level, pulmonary hypertension and P_aCO₂ (all p <0.05) whereas FEV₁% was more related to lung function test, P_aO₂ and OCD score. V_D/V_TR and FEV₁% were highly related to resting gas exchange but RV/TLC and D_LCO% were not. Cigarette consumption, the equivalent for CO₂ output, arterial oxyhemoglobin saturation, and the product of tidal volume and inspiratory duty cycle were identified as the parameters relevant to V_D/V_TR with a power of 0.72.

Conclusion

Compared to lung function test, V_D/V_TR is more related to clinical characteristics and is a comprehensive marker of resting gas exchange. Further studies are warranted to provide a noninvasive measurement of V_D/V_TR.

Registration Number

MOST 106-2314-B-040-025 and CSH-2019-C-30.

Expanding the Use of Six-Minute Walking Test in Patients with Intermittent Claudication

BACKGROUND

Six-min walking test (6MWT) has been widely in patients with symptomatic peripheral artery disease (PAD) to quantify the walking impairment and the efficacy of different therapeutic interventions. Despite the aforementioned usefulness of 6MWT for PAD, the information provided by this test goes beyond the meters walked. The aim of this study was to describe the relative values of 6MWT and body weight-walking distance product (DW) in patients with symptomatic PAD.

METHODS

Two hundred twenty-seven patients with symptomatic PAD participated in the study. The 6MWT was performed and absolute and claudication distances were obtained. The results of 6MWT were then relativized and expressed as a percentage of a healthy subject. DW was obtained by the product of 6MWT distance by weight. In both sexes, the relative 6MWT ranged from 57% to 64%.

RESULTS

Absolute 6MWT total distance (P < 0.001) was lower in women than in men, whereas the relative 6MWT total distance was similar between sexes (P = 0.398). The absolute and relative 6MWT total distance were similar among age categories (P > 0.072). The DW was higher in men than in women (P < 0.05). In addition, in women, DW was higher in younger group than in other age groups (P < 0.05).

CONCLUSIONS

Patients with symptomatic PAD achieve less than 70% of the distance achieved by an age-matched healthy subject. In patients with symptomatic PAD, the relative values of 6MWT total distance are similar between sexes and among different age groups, whereas DW are influenced by age and sex.

Mechanisms affecting exercise ventilatory inefficiency-airflow obstruction relationship in male patients with chronic obstructive pulmonary disease

Background

Exercise ventilatory inefficiency is usually defined as high ventilation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E) versus low CO₂ output (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{CO}2 $$\end{document}V˙CO2). The inefficiency may be lowered when airflow obstruction is severe because \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E cannot be adequately increased in response to exercise. However, the ventilatory inefficiency-airflow obstruction relationship differs to a varying degree. This has been hypothesized to be affected by increased dead space fraction of tidal volume (V_D/V_T), acidity, hypoxemia, and hypercapnia.

Methods

A total of 120 male patients with chronic obstructive pulmonary disease were enrolled. Lung function and incremental exercise tests were conducted, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E} $$\end{document}V˙E versus \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{CO}2 $$\end{document}V˙CO2 slope (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S) and intercept (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I) were obtained by linear regression. Arterial blood gas analysis was also performed in 47 of the participants during exercise tests. V_D/V_T and lactate level were measured.

Results

V_D/V_Tpeak was moderately positively related to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S (r = 0.41) and negatively related to forced expired volume in 1 sec % predicted (FEV₁%) (r = − 0.27), and hence the FEV₁%- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S relationship was paradoxical. The higher the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S, the higher the pH and P_aO₂, and the lower the P_aCO₂ and exercise capacity. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I was marginally related to V_D/V_Trest. The higher the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I, the higher the inspiratory airflow, work rate, and end-tidal PCO_2peak.

Conclusion

1) Dead space ventilation perturbs the airflow- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S relationship, 2) increasing ventilation thereby increases \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S to maintain biological homeostasis, and 3) the physiology- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{S} $$\end{document}V˙E/V˙CO2S- \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{\mathrm{V}}\mathrm{E}/\dot{\mathrm{V}}\mathrm{CO}2\mathrm{I} $$\end{document}V˙E/V˙CO2I relationships are inconsistent in the current and previous studies.

Trial Registration

MOST 106–2314-B-040-025.

6-Minute Push Test in Youth Who Have Spina Bifida and Who Self-Propel a Wheelchair: Reliability and Physiologic Response

OBJECTIVE

Despite the common occurrence of lower levels of physical activity and physical fitness in youth with spina bifida (SB) who use a wheelchair, there are very few tests available to measure and assess these levels. The purpose of this study was to determine reliability and the physiologic response of the 6-minute push test (6MPT) in youth with SB who self-propel a wheelchair.

METHODS

In this reliability and observational study, a sample of 53 youth with SB (5-19 years old; mean age = 13 years 7 months; 32 boys and 21 girls) who used a wheelchair performed 2 exercise tests: the 6MPT and shuttle ride test. Heart rate, minute ventilation, respiratory exchange ratio, and oxygen consumption were measured using a calibrated mobile gas analysis system and a heart rate monitor. For reliability, intraclass correlation coefficients (ICCs), SE of measurement, smallest detectable change for total covered distance, minute work, and heart rate were calculated. Physiologic response during the 6MPT was expressed as percentage of maximal values achieved during the shuttle ride test.

RESULTS

The ICCs for total distance and minute work were excellent (0.95 and 0.97, respectively), and the ICC for heart rate was good (0.81). The physiologic response during the 6MPT was 85% to 89% of maximal values, except for minute ventilation (70.6%).

CONCLUSIONS

For most youth with SB who use a wheelchair for mobility or sports participation, the 6MPT is a reliable, functional performance test on a vigorous level of exercise.

IMPACT

This is the first study to investigate physiologic response during the 6MPT in youth (with SB) who are wheelchair using. Clinicians can use the 6MPT to evaluate functional performance and help design effective exercise programs for youth with SB who are wheelchair using.

Combining Dynamic Hyperinflation with Dead Space Volume during Maximal Exercise in Patients with Chronic Obstructive Pulmonary Disease

Physiological dead space volume (VD) and dynamic hyperinflation (DH) are two different types of abnormal pulmonary physiology. Although they both involve lung volume, their combination has never been advocated, and thus their effect and implication are unclear. This study aimed (1) to combine VD and DH, and (2) investigate their relationship and clinical significance during exercise, as well as (3) identify a noninvasive variable to represent the VD fraction of tidal volume (VD/VT). Forty-six male subjects with chronic obstructive pulmonary disease (COPD) and 34 healthy male subjects matched for age and height were enrolled. Demographic data, lung function, and maximal exercise were investigated. End-expiratory lung volume (EELV) was measured for the control group and estimated for the study group using the formulae reported in our previous study. The VD/VT ratio was measured for the study group, and reference values of VD/VT were used for the control group. In the COPD group, the DHpeak/total lung capacity (TLC, DHpeak%) was 7% and the EELVpeak% was 70%. After adding the VDpeak% (8%), the VDDHpeak% was 15% and the VDEELVpeak% was 78%. Both were higher than those of the healthy controls. In the COPD group, the VDDHpeak% and VDEELVpeak% were more correlated with dyspnea score and exercise capacity than that of the DHpeak% and EELV%, and had a similar strength of correlation with minute ventilation. The VTpeak/TLC (VTpeak%), an inverse marker of DH, was inversely correlated with VD/VT (R2 ≈ 0.50). Therefore, we recommend that VD should be added to DH and EELV, as they are physiologically meaningful and VTpeak% represents not only DH but also dead space ventilation. To obtain VD, the VD/VT must be measured. Because obtaining VD/VT requires invasive arterial blood gases, further studies on noninvasive predicting VD/VT is warranted.

Determinants of Work in the Six-Minute Walk Test in School-Age Children

Abstract Introduction: The Six-Minute Walk Test (6MWT) is widely used to assess functional capacity in children. The measure of work during 6MWT can add important information to the 6MWT assessment in this population as it relates to walking efficiency. Objective: To verify the determinants of work during the Six-Minute Walk Test (6MWTwork) in school-aged children. Method: This is a cross-sectional and exploratory study that included healthy children recruited from the public and private schools of the cities of Belo Horizonte and Uberlândia, Brazil. The inclusion criteria were: children aged 7 to 12 years without diagnosis of chronic cardiorespiratory disease, cognitive, behavioral disorder or physical function impairment (information obtained through self-report of those responsible for children). Exclusion criteria were children who refused to perform the 6MWT; who did not understand the 6MWT or who did not answer the test commands. Three hundred and nineteen school-aged children were included in the study. Correlation analyses and multiple linear regression analysis were used to identify the variables associated with the 6MWTwork. Results: Age, height, nutritional status, physical activity and heart rate showed significant correlation with 6MWTwork (p <0.001) and explained 87% of its variation (p = 0.0001). Conclusion: Age, height, nutritional status and heart rate variation are determinants of 6MWTwork that is able to evaluate functional capacity of school-aged children.

Six-Minute Walk Test: Clinical Role, Technique, Coding, and Reimbursement

The 6-min walk test (6MWT) is a commonly used test for the objective assessment of functional exercise capacity for the management of patients with moderate-to-severe pulmonary disease. Unlike pulmonary function testing, the 6MWT captures the often coexisting extrapulmonary manifestations of chronic respiratory disease, including cardiovascular disease, frailty, sarcopenia, and cancer. In contrast with cardiopulmonary exercise stress testing, this test does not require complex equipment or technical expertise. In this low complexity, safe test, the patient is asked to walk as far as possible along a 30-m minimally trafficked corridor for a period of 6 min with the primary outcome measure being the 6-min walk distance (6MWD) measured in meters. There has been interest in other derived indexes, such as distance-desaturation product (the product of nadir oxygen saturation and walk distance), which in small studies has been predictive of morbidity and mortality in certain chronic respiratory conditions. Special attention to methodology is required to produce reliable and reproducible results. Factors that can affect walk distance include track layout (continuous vs straight), track length, oxygen amount and portability, learning effect, and verbal encouragement. The absolute 6MWD and change in 6MWD are predictive of morbidity and mortality in patients with COPD, pulmonary arterial hypertension, and idiopathic pulmonary fibrosis and patients awaiting lung transplant, highlighting its use in management decisions and clinical trials. As of January 2018, Current Procedural Terminology code 94620 (simple pulmonary stress test) has been deleted and replaced by two new codes, 94617 and 94618. Code 94617 includes exercise test for bronchospasm including pre- and postspirometry, ECG recordings, and pulse oximetry. Code 94618, pulmonary stress testing (eg, 6MWT), includes the measurement of heart rate, oximetry, and oxygen titration when performed. If 94620 is billed after January 2018 it will not be reimbursed.

Investigating the relationships among lung function variables in chronic obstructive pulmonary disease in men

Background

In patients with chronic obstructive pulmonary disease (COPD), the independent contributions of individual lung function variables to outcomes may be lower when they are modelled together if they are collinear. In addition, lung volume measurements may not be necessary after spirometry data have been obtained. However, these hypotheses depend on whether forced vital capacity (FVC) can predict total lung capacity (TLC). Moreover, the definitions of hyperinflation and air trapping according to lung function variables overlap and need be clarified. Therefore, the aim of this study was to evaluate the relationships among various lung function parameters to elucidate these issues.

Methods

Demographic data and 26 parameters of full lung function were measured in 94 men with COPD and analyzed using factor and correlation analyses.

Results

Factor analysis revealed five latent factors. Inspiratory capacity (IC)/TLC and residual volume (RV)/TLC were most strongly correlated with all other lung volumes. IC/TLC, RV/TLC, and functional residual capacity (FRC)/TLC were collinear and were potential markers of air trapping, whereas TLC%, FRC%, and RV% were collinear and were potential markers of hyperinflation. RV/TLC >0.4 (or IC/TLC <0.4) was comparable with the ratio of forced expiratory volume in one second (FEV₁) and FVC <0.7. FVC% and FEV₁% were poorly correlated with TLC%. The correlation study showed that TLC%, RV/TLC, and FEV₁% could be used to represent individual latent factors for hyperinflation, air trapping, inspiration, expiration, and obstruction. Combined with diffusion capacity%, these four factors could be used to represent comprehensive lung function.

Conclusions

This study identified collinear relationships among individual lung function variables and thus selecting variables with close relationships for correlation studies should be performed with caution. This study also differentiated variables for air trapping and lung hyperinflation. Lung volume measurements are still required even when spirometry data are available. Four out of 26 lung function variables from individual latent factors could be used to concisely represent lung function.

Minimal detectable change in six-minute walk test in children and adolescents with cystic fibrosis

PURPOSE

To provide test-retest reliability for the 6-min walk test and the physiological variables obtained during the test, and to establish the minimal detectable change for the distance walked in children and adolescents with cystic fibrosis.

METHODS

40 patients performed two 6-min walk tests on the same day (separated by 30-min of rest). The perceived breathlessness and fatigue in the legs were assessed with the modified Borg scale. The peripheral muscle strength was assessed using a hand dynamometer device, the medicine ball throw test and the horizontal jump test.

RESULTS

The test-retest reliability of the distance walked, dyspnea and fatigue in the legs were good for children (minimal detectable change_90-95: 59.39-70.55 m) and for adolescents (minimal detectable change_90-95: 47.81-56.8 m) with cystic fibrosis. Exercise tolerance is more related to 6-min walk work (distance walked x body weight) than to the distance walked alone and showed a positive association with peripheral muscle strength and forced vital capacity.

CONCLUSIONS

The 6-min walk test is a reproducible and reliable tool to measure exercise tolerance for children and adolescents with cystic fibrosis. The minimal detectable changes reported for the distances achieved by these patients will be useful to identify the effectiveness of therapies aimed at alleviating or improving impaired physical capacity.IMPLICATIONS FOR REHABILITATIONThe 6-min walk test could be used to measure exercise tolerance for children and adolescents with cystic fibrosis, as it is a reliable test over time.An increase in the distance covered in the 6-min walk test that exceeds the minimum detectable change is recommended to determine improved exercise tolerance for children and adolescents with cystic fibrosis.The use of the 6-min walk work (distance walked x body weight) is recommended because it correlates better with exercise tolerance than the distance alone in children and adolescents with cystic fibrosis.

Factors associated with physical function capacity in an urban cohort of people living with the human immunodeficiency virus in South Africa

Background

Effective disease management for people living with human immunodeficiency virus (PLWH) includes the encouragement of physical activity. Physical function capacity in PLWH may be influenced by a variety of factors.

Objectives

This study describes the physical function capacity as assessed with the 6-minute walk test (6MWT) of an urban cohort of PLWH and determined whether a history of pulmonary tuberculosis (PTB), anthropometric measures, age and gender predicted distance walked.

Method

Secondary data collected from 84 PLWH on antiretroviral therapy were analysed. Information included 6MWT distance, anthropometric measurements and demographic profiles. Descriptive and inferential statistics were undertaken on the data. A regression analysis determined predictive factors for 6MWT distance achieved. Significance was set at a p-value of ≤ 0.05.

Results

The study consisted of 66 (78.6%) women and 18 (21.4%) men with a mean age of 39.1 (± 9.2) years. The 6MWT distance of the cohort was 544.3 (± 64.4) m with men walking further (602.8 [± 58.6] m) than women (528.3 [± 56.4] m); however, women experienced greater effort. The majority of the sample did not report a history of PTB (n = 67; 79.8%). Age, gender and anthropometric measures were associated with 6MWT distance, but of low to moderate strength. The regression equation generated included age and gender. This model was statistically significant (p < 0.00) and accounted for 34% of the total variance observed.

Conclusion

Age and gender were predictive factors of physical function capacity and women experienced greater effort.

Clinical implications

This study provides information on the physical function capacity of PLWH and a suggested 6MWT reference equation for PLWH in South Africa.

Comparative Assessment of CPET Versus Typical Work-related Activities in Women With and Without Mild COPD

BACKGROUND

Prevalence of chronic obstructive pulmonary disease (COPD) is increasing in Germany. This study examined the work performance of healthy women compared to those with mild COPD.

PATIENTS AND METHODS

Nineteen women suffering from COPD Global Initiative for Chronic Obstructive Lung Diseases stage I and 41 healthy women underwent standardised cardiopulmonary exercise test (CPET) in comparison to 5 typical work-related tasks. Oxygen uptake, carbon dioxide output, ventilation volume, breathing frequency, heart rate and respiratory exchange ratio (RER) were measured. The activities were quantified. Wilcoxon test and ANOVA were calculated using the SPSS software.

RESULTS

Patients with COPD had a lower exercise capacity compared to healthy women and also showed lower performance during work-related activities. Patients with COPD had a lower oxygen uptake (p<0.001), a higher breathing frequency was accompanied by a higher Borg scale. The heart rate and the ventilation volume as a percentage of maximum CPET were significantly higher in patients with COPD. Women suffering from progressive symptoms had lower oxygen uptakes and RER, whilst breathing frequency and Borg scale were elevated.

CONCLUSION

Even at an early stage of the disease, patients with COPD exhibited limitations in work-related tasks.

Systematic review of the association between exercise tests and patient-reported outcomes in patients with chronic obstructive pulmonary disease

Introduction

Chronic obstructive pulmonary disease (COPD) is an increasingly common cause of death worldwide. Its cardinal symptoms include breathlessness and severely reduced exercise capacity. Several patient-reported outcome (PRO) measures are used to assess health-related quality of life (HRQoL), functional performance, and breathlessness in patients with COPD. Exercise testing is employed to measure functional performance objectively, which is generally believed to impact on overall HRQoL. However, the extent to which commonly used laboratory- and field-based exercise test results correlate with PROs has not been systematically assessed.

Materials and methods

A search of Embase, MedLine, and the Cochrane Library identified primary publications in English that reported data on the correlations (Pearson’s r or Spearman’s ρ) between the outcomes of exercise tests and HRQoL and breathlessness PROs. Studies reporting on the following tests were included: 6-minute walk test (6MWT), 12MWT, incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests.

Results

Of 3,205 articles screened, 28 were deemed eligible for inclusion. The most commonly reported HRQoL PRO measure was the St George’s Respiratory Questionnaire (13 studies), and the most commonly reported breathlessness PRO measure was the Baseline Dyspnea Index (six studies). The St George’s Respiratory Questionnaire appears to correlate very weakly to moderately with the 6MWT, and breathlessness PROs appear to be moderately to strongly associated with 6MWT outcomes. Across all studies, the 6MWT was the most commonly reported exercise test. Very few publications reporting associations between other exercise tests and PRO measures were found.

Conclusion

This review found evidence to support the association of 6MWT outcomes with HRQoL and breathlessness PROs. There were limited data showing correlations with the outcomes of other exercise tests. Further work is required to examine the associations between these PROs and exercise test outcomes.

Self-reported physical activity versus physical function capacity: alternatives for energy expenditure estimation

The extent to which self-report activity measured by the International Physical Activity Questionnaire (IPAQ) can substitute performance-based functional capacity measured by the Six-Minute Walk Test (6MWT) remains inconclusive. This study assessed Physical Activity (PA) and Functional Exercise Capacity (FEC); and also determined the relationship between PA and FEC in apparently healthy young adults. A total of 342 (145 males and 197 females) undergraduates of Obafemi Awolowo University, Ile-Ile, Nigeria participated in the study. The IPAQ was used to assess PA, while FEC was assessed using the 6MWT, and expressed in terms of the Six-Minute Walk Distance (6MWD), Six-Minute Walk Work (6MWW), Maximum Oxygen Uptake (VO2max) and Metabolic Equivalent (METS). Anthropometric and cardiovascular parameters were measured following standardized procedures. Data was analyzed using descriptive and inferential statistics. The alpha level was set at 0.05. The mean age of the participants was 22.0±2.87 years. The mean IPAQ score of all participants was 1471.4±1086.93. The percentage for low, moderate and high PA was 19% (65), 41.2% (141) and 39.8% (136), respectively. The mean 6MWD, 6MWW, VO2max and METS were 639.47 ±66.6 m, 41805.0 ±8520.6 kg·m, 28.9 ±1.92 mlO2k-1min-1, 4.05 ±0.32 mL/kg, respectively. There were signifi cant positive correlations between PA and each of the 6MWD (r=0.268; p=0.001), 6MWW (r=0.219; p=0.001), VO2max (r=0.268; p=0.001), METS (r=0.268; p=0.001). Measures of exercise capacity were not signifi cantly correlated with the anthropometric variables (p>0.05). Self-report of physical activity in healthy young adults does not adequately substitute the results of the Six-Minute Walk Test. Mbada Ch.E., Osifeso T.A., Johnson O.E., Okonji A.M., Odeyemi E.A. Self-reported physical activity versus physical function capacity: alternatives for energy expenditure estimation. Med Rehabil 2016; 20(4): 4-12. DOI: 10.5604/01.3001.0009.5479 null

Relationship between functional capacity and health-related quality of life of patients with type-2 diabetes

AIMS

Physical function is a determinant of survival in chronic diseases, however, little is known about functional capacity (FC) and self-reported health status of patients with type-2 diabetes (T2D). This study investigated the relationship between FC and health related quality of life (HRQoL) of patients with T2D.

MATERIALS AND METHODS

This cross-sectional survey recruited 150 patients with T2D from a Nigerian university teaching hospital using purposive sampling technique. Socio-demographic and physical characteristics were assessed. FC and HRQoL including physical and mental health component summary (PCS and MCS) were assessed using the six minute walk test (6MWT) and Short-Form (SF-12) questionnaire respectively. Maximum oxygen consumption (VO₂ max) was estimated, pre and post 6MWT cardiovascular parameters and fasting blood glucose (FBG) were assessed. Data were analyzed using descriptive and inferential statistics. Alpha level was set at p<0.05.

RESULTS

There were 83(55.3%) women, means of age and FBG of participants were 64.2±8.7years and 7.4±2.4mmol/L respectively. The means of 6-min walk distance (6-MWD) and estimated VO₂ max were 341.55±41.82m and 9.2±0.7mL/kg/min respectively. Significant differences were found between pre and post HR (t=-44.71; p=0.001), SBP (t=-38.38; p=0.001) and DBP (t=-38.58; p=0.001) following 6MWT. The means of PCS and MCS of HRQoL were 48.67±5.51 and 58.39±2.86 respectively. There were significant correlations between FC and each of PCS (r=0.678; p=0.001) and MCS (r=0.211; p=0.009).

CONCLUSION

Patients with T2D demonstrated low functional capacity and reduced HRQoL. Significant relationship exists between FC and physical and mental component summary of HRQoL. Exercise intervention to improve FC and HRQoL were recommended.

Clinical assessment tests in evaluating patients with chronic obstructive pulmonary disease: A cross-sectional study

Exertional dyspnea scales (EDS) and health-related quality-of-life questionnaires (HRQoLQs) are used to assess chronic obstructive pulmonary disease (COPD). The GOLD guidelines categorize patients according to either 1 of these 2 domains, the lung function and the frequency of acute exacerbations in the preceding year, however with inconsistent results. Combining EDS and HRQoLQs may yield better results; however, the best combination is unclear. Whether the EDS quantifies the exercise capacity or the dyspnea perception is also unclear. The study was designed to correlate the EDS with exercise capacity and dyspnea perception and to evaluate the best combination of the EDS and HRQoLQ.Three EDS were compared by exercise capacity and Borg scores at rest and during exercise in 57 patients with COPD. Three HRQoLQs were compared by 4 domains of clinical assessments, and 2 types of exercise. The strength of correlation |r| was categorized by quartiles from <0.3 to ≥0.6.The EDS was better correlated with exercise capacities (|r| = 0.29-0.65, P < 0.05-<0.0001) than with the resting and exertional Borg scores (|r| = 0.08-0.55, P = NS- <0.0001). The EDS were moderately to strongly interrelated, but this correlation was weaker when including Oxygen-cost Diagram (OCD) (with the modified Medical Research Council, mMRC r = -0.56, with the baseline dyspnea index, BDI r = 0.49 vs. mMRC with BDI r = -0.73); however, the OCD had the strongest correlation with walking distance (r = 0.65, vs mMRC r = -0.59, BDI r = 0.5) and peak oxygen uptake (r = 0.39 vs mMRC r = -0.29, BDI r = 0.36). Among the HRQoLQs, the COPD assessment test (CAT) was most strongly correlated with the St. George Respiratory Questionnaire (SGRQ) (r = 0.77) and similar to the SGRQ regarding significant correlations with the other instruments (|r| = 0.29-0.67 vs. 0.36-0.77) but poorly with walking distance (r = -0.02). The OCD was mildly correlated with the CAT (r = -0.4).The EDS was more related to the exercise capacity than to the dyspnea perception and the CAT was most closely related to the other instruments but poorly with walking distance. The OCD can be used to compensate for this weak correlation. The study suggests using the CAT and the OCD simultaneously when undertaking clinical evaluation of patients with COPD.

Relationship between the sensation of activity limitation and the results of functional assessment in asthma patients

OBJECTIVE

In asthma patients, the assessment of activity limitation is based on questions evaluating how limited the patient feels in their activities. However, the lack of functional data complicates the interpretation of the answers. We aimed to evaluate the intensity of relationships between the patient's perception of activity limitation and the results of several functional tests.

METHODS

Twenty patients complaining of asthma exacerbation were invited to complete three scores (Chronic Respiratory Disease questionnaire, Asthma Control Questionnaire, Hospital Anxiety and Depression scale). They also underwent lung function measurements, a 6-minute walk test and a cardio-pulmonary exercise test. In addition, physical activity was studied by actigraphy. Spearman's rank correlation coefficients between the patient's perception of activity limitation and each of the other parameters were analysed.

RESULTS

Five parameters were significantly correlated with the perception of activity limitation: ACQ question 4, related to dyspnea (rs 0.74, p < 0.001); Emotion domain of the Chronic Respiratory Disease questionnaire (rs -0.57, p = 0.02); HAD anxiety (rs 0.48, p = 0.032); HAD depression (rs 0.46, p = 0.041); ACQ question 6, related to reliever use (rs 0.46, p = 0.046). No parameters from the lung function test, 6MWT, CPET or actigraphy, were significantly correlated with the perception of activity limitation.

CONCLUSIONS

In response to questions about limitation of activity, patients do not specifically answer mentioning physical limitation but rather the psychological burden associated with this constraint.

Changes in derived measures from six-minute walk distance following home-based exercise training in congestive heart failure: A preliminary report

The response of derived parameters from six-minute walk distance (6MWD), like 6MW work (6MWW), to exercise training and its correlation with quality of life (QoL) in congestive heart failure (CHF) is not known. A secondary analysis from a randomized controlled trial on 30 patients (23 males; mean age 57.7 ± 10.4 years; mean ejection fraction 31 ± 10%) with CHF in NYHA class I–IV who completed an eight-week home-based exercise training program found a significant improvement in 6MWW (p < 0.05), with similar correlations between 6MWD and 6MWW with QoL. 6MWW does not appear to provide additional benefit to 6MWD in cardiac rehabilitation for CHF.

Comparison of the six-minute walk test with a cycle-based cardiopulmonary exercise test in people following curative intent treatment for non-small cell lung cancer

This study is aimed to (i) compare both the magnitude of impairment in exercise capacity and exercise responses measured during the six-minute walk test (6MWT) and the cardiopulmonary exercise test (CPET) and (ii) investigate the effect of test repetition on six-minute walk distance (6MWD) in people following curative intent treatment for non-small cell lung cancer (NSCLC). Twenty participants (67 ± 10 years; 14 females), 6-10 weeks following lobectomy, underwent a CPET and two 6MWTs. Peak exercise responses, dyspnoea and leg fatigue, as well as heart rate (HR) and oxygen saturation (SpO2) during the 6MWT, were compared to those during the CPET. Compared with exercise capacity when expressed as peak rate of oxygen consumption (%pred) measured during the CPET, exercise capacity when expressed as 6MWD (%pred) was less impaired (81 ± 10 vs. 63 ± 15 %pred; p < 0.001). Compared with the CPET, the 6MWT elicited lower peak HR (119 ± 15 vs. 128 ± 18 beats minute(-1); p = 0.02), lower SpO2 (93 ± 2 vs. 95 ± 3%; p < 0.05), less dyspnoea (3.1 ± 1.6 vs. 6.9 ± 2.6; p < 0.01) and less leg fatigue (2.0 ± 1.9 vs. 6.8 ± 2.4; p < 0.01). The 6MWD increased 19 ± 19 metre (4 ± 4%) with test repetition (p < 0.001). In people following curative intent treatment for NSCLC, the 6MWT appears to elicit sub-maximal exercise responses when compared with the CPET. There is a significant effect of test repetition on 6MWD.

Identification of five chronic obstructive pulmonary disease subgroups with different prognoses in the ECLIPSE cohort using cluster analysis

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease that likely includes clinically relevant subgroups.

OBJECTIVES

To identify subgroups of COPD in ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) subjects using cluster analysis and to assess clinically meaningful outcomes of the clusters during 3 years of longitudinal follow-up.

METHODS

Factor analysis was used to reduce 41 variables determined at recruitment in 2,164 patients with COPD to 13 main factors, and the variables with the highest loading were used for cluster analysis. Clusters were evaluated for their relationship with clinically meaningful outcomes during 3 years of follow-up. The relationships among clinical parameters were evaluated within clusters.

MEASUREMENTS AND MAIN RESULTS

Five subgroups were distinguished using cross-sectional clinical features. These groups differed regarding outcomes. Cluster A included patients with milder disease and had fewer deaths and hospitalizations. Cluster B had less systemic inflammation at baseline but had notable changes in health status and emphysema extent. Cluster C had many comorbidities, evidence of systemic inflammation, and the highest mortality. Cluster D had low FEV1, severe emphysema, and the highest exacerbation and COPD hospitalization rate. Cluster E was intermediate for most variables and may represent a mixed group that includes further clusters. The relationships among clinical variables within clusters differed from that in the entire COPD population.

CONCLUSIONS

Cluster analysis using baseline data in ECLIPSE identified five COPD subgroups that differ in outcomes and inflammatory biomarkers and show different relationships between clinical parameters, suggesting the clusters represent clinically and biologically different subtypes of COPD.

Systematic Review of the Association Between Laboratory- and Field-Based Exercise Tests and Lung Function in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Typical symptoms of chronic obstructive pulmonary disease (COPD) include breathlessness and reduced exercise capacity. Several laboratory- and field-based exercise tests are used to assess the exercise capacity of patients with COPD. It is unclear whether these exercise tests reflect the spirometric measures recommended for diagnosis of COPD. We therefore aimed to systematically assess the correlation between these exercise tests and common measures of lung function. Methods: A search of Embase™, MEDLINE^® and The Cochrane Library identified primary publications in English that reported data on the correlations (Pearson's r or Spearman's rho) between the outcomes of exercise tests and the physiological measures of interest: forced expiratory volume in 1 second (FEV₁), forced vital capacity, inspiratory capacity and arterial oxygen saturation. We included studies reporting on the following exercise tests: 6- and 12-minute walk tests (6MWT and 12 MWT), incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests. Results: Of 1781 articles screened, 45 were ultimately deemed eligible for inclusion in this review. The most commonly reported lung function variable was FEV₁ (reported by 39 studies); the most commonly reported exercise test was the 6-minute walk test (reported by 24 studies). FEV₁ appears to correlate moderately-to-strongly with 6MWT and 12MWT; and moderately-to-very strongly with incremental cycle ergometer tests (ICET); evidence for other exercise tests was limited. Conclusion: There is evidence that 6MWT, 12MWT and ICET correlate with FEV₁ to some degree; - evidence for associations of other exercise tests with measures of lung function in patients with COPD is limited. Clinicians must consider this when deciding to use these tests. Further comparisons of these tests must be made in order to assess which physiological and hemodynamic characteristics they reflect in patients with COPD.

Prognostic value of variables derived from the six-minute walk test in patients with COPD: Results from the ECLIPSE study

In addition to the six-min walk distance (6 MWD), other six-min walk test (6 MWT) derived variables, such as mean walk-speed (6MWSpeed), 6-min walk-work (6 MWW), distance-saturation product (DSP), exercise-induced oxygen desaturation (EID), and unintended stops may be useful for the prediction of mortality and hospitalization in patients with chronic obstructive pulmonary disease (COPD). We studied the association between 6 MWT-derived variables and mortality as well as hospitalization in COPD patients and compared it with the BODE index. A three-year prospective study (ECLIPSE) to evaluate the prognostic value of 6 MWT-derived variables in 2010 COPD patients. Cox's proportional-hazard regressions were performed to estimate 3-year mortality and hospitalization. During the follow-up, 193 subjects died and 622 were hospitalized. An adjusted Cox's regression model of hazard ratio [HR] for impaired 6 MWT-derived variables was significant referring to: mortality (6 MWD ≤334 m [2.30], 6MWSpeed ≤0.9 m/sec [2.15], 6 MWW ≤20000 m kg [2.17], DSP ≤290 m% [2.70], EID ≤88% [1.75], unintended stops [1.99]; and hospitalization (6 MWW ≤27000 m kg [1.23], EID ≤88% [1.25], BODE index ≥3 points [1.40]; all p ≤ 0.05). The 6 MWT-derived variables have an additional predictive value of mortality in patients with COPD. The 6 MWW, EID and the BODE index refine the prognosis of hospitalization.

Adjunctive Treatment with Rhodiola Crenulata in Patients with Chronic Obstructive Pulmonary Disease--A Randomized Placebo Controlled Double Blind Clinical Trial

Chronic obstructive pulmonary disease (COPD) is a low grade systemic inflammatory disease characterized by dyspnea and exercise intolerance even under standard therapy. Rhodiola crenulata (RC) has been shown to exert anti-inflammatory effects and to enhance exercise endurance, thereby having the potential to treat COPD. In this 12-week, randomized, double-blind, placebo-controlled clinical trial, 57 patients with stable moderate-to-severe COPD aged 70±8.8 years were given RC (250 mg twice/day) (n=38) or a placebo (250 mg twice/day) (n=19) in addition to their standard regimen. There were no significant differences in anthropometrics, quality of life, lung function, six-minute walk and incremental exercise tests between the two groups at enrollment. Over the 12 weeks, RC was well tolerated, significantly reduced triceps skin thickness (Δ=-1 mm, p=.04), change of FEV1 (4.5%, p=.03), and improved workload (Δ=10%, p=.01); although there were no significant differences in these factors between the two groups. However, there were significant between-group differences in tidal volume and ventilation-CO2-output ratio at peak exercise (both p=.05), which were significantly related to peak work rate (both p<.0001). RC tended to protect against acute exacerbation of COPD (p=.1) but not other measurements. RC did not improve the six-minute walk test distance but significantly improved tidal breathing and ventilation efficiency, most likely through improvements in work rate. Further studies with a larger patient population are needed in order to confirm these findings.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT02242461.

The Impact of a Multidimensional Exercise Intervention on Physical and Functional Capacity, Anxiety, and Depression in Patients With Advanced-Stage Lung Cancer Undergoing Chemotherapy

Introduction. Patients with advanced-stage lung cancer face poor survival and experience co-occurring chronic physical and psychosocial symptoms. Despite several years of research in exercise oncology, few exercise studies have targeted advanced lung cancer patients undergoing chemotherapy. The aim of the present study was to investigate the benefits of a 6-week supervised group exercise intervention and to outline the effect on aerobic capacity, strength, health-related quality of life (HRQoL), anxiety, and depression. Methods. VO2peak was assessed using an incremental exercise test. Muscle strength was measured with one repetition maximum test (1RM). HRQoL, anxiety, and depression were assessed using Functional Assessment of Cancer Therapy–Lung (FACT-L) scale and the Hospital Anxiety and Depression Scale (HADS). Results. One hundred and forthteen patients with advanced stage lung cancer were recruited. Forty-three patients dropped out. No serious adverse events were reported. Exercise adherence in the group training was 68%. Improvements in VO2peak ( P < .001) and 6-minute walk distance ( P < .001) and muscle strength measurements ( P < .05) were seen. There was a reduction in anxiety level ( P = .0007) and improvement in the emotional well-being parameter (FACT-L) but no statistically significant changes in HRQoL were observed. Conclusion. The results of the present study show that during a 6-week hospital-based supervised, structured, and group-based exercise program, patients with advanced-stage lung cancer (NSCLC IIIb-IV, ED-SCLC) improve their physical capacity (VO2peak, 1RM), functional capacity, anxiety level, and emotional well-being, but not their overall HRQoL. A randomized controlled trial testing the intervention including 216 patients is currently being carried out.

Early decline in six-minute walk distance from the time of diagnosis predicts clinical worsening in pulmonary arterial hypertension

BACKGROUND

The six-minute walk distance (6MWD) is commonly used to assess pulmonary arterial hypertension (PAH). However, the role of 6MWD in predicting outcomes in PAH is controversial. Clinical worsening is being increasingly considered as a clinically meaningful end point in PAH.

OBJECTIVES

We aimed to investigate whether early longitudinal changes in 6MWD (Δ6MWD) in meters and percent predicted (%pred) from the time of diagnosis predict clinical worsening of PAH.

METHODS

One hundred patients with group I PAH were retrospectively assessed. 6MWD was calculated using American (%pred US) or Canadian (%pred CAN) reference equations. Δ6MWD at 6 months were recorded. Clinical worsening was defined as either: development of right heart failure, hospital admission for PAH, referral for lung transplantation or initiation of prostanoids after oral therapy failed. Optimal 6-month differences in 6MWD to detect worsening were defined with receiver operating characteristics (ROC) analysis.

RESULTS

Progressors, i.e. patients with clinical worsening, and nonprogressors showed significant differences in Δ6MWD. The most clinically significant declines in 6MWD at 6 months were ≥35 m, ≥8%pred US and ≥6%pred CAN. ROC and Cox proportional hazard analyses showed equivalent results for 6MWD %pred and meters. Six-month declines in 6MWD predicted worsening with a high specificity (94%) but a low sensitivity (33%).

CONCLUSIONS

Early declines in 6MWD (within the first 6 months) predict future clinical worsening of PAH with high specificity. Δ6MWD may still be part of a comprehensive assessment of a patient's clinical status. However, given the poor sensitivity, a decline in 6MWD should be used with other clinical tools to make an appropriate assessment of the progression of PAH.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Functional capacity after pediatric liver transplantation: a pilot study

The prospective cross-sectional study investigated the 6MWT performance in pediatric group of liver transplant recipients (6-17 yr, median post-transplantation time of 22 months) and compared to the normal values obtained in healthy children as well as evaluated the reproducibility of the 6MWT. We analyzed the relationship between walked distance and the 6MWw, distance walked × body weight) with the anthropometric, clinical, and pulmonary functions. In post-transplanted group, the average walked distance was significantly shorter compared with control (687 ± 80 m vs. 511 ± 72 m, p < 0.001). The calculated ICC coefficient confirmed the reproducibility among tests. The Pearson correlation revealed that only walked distance in the 6MWT was moderately correlated with tidal volume. Conversely, the 6MWw was significantly correlated with age, weight, height, BMI, FVC, PEF rate, and volume expiratory. According to multiple regression analysis, age, VE and FVC factors explained 80% of the variance in the 6MWw. In conclusion, the pediatric liver transplant recipients' performance in the 6MWT is significantly lower than the values for healthy children of the same age. Notably, the 6MWw may provide relevant information, constituting an additional parameter in the determination of functional capacity.

Alternatives to the six-minute walk test in pulmonary arterial hypertension

INTRODUCTION

The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH. We tested the hypothesis that endurance tests induce a near-maximal physiological demand comparable to incremental tests. We also hypothesized that differences in respiratory response during exercise would be related to the characteristics of the exercise tests.

METHODS

Within two weeks, twenty-one PAH patients (mean age: 54(15) years; mean pulmonary arterial pressure: 42(12) mmHg) completed two cycling exercise tests (incremental cardiopulmonary cycling exercise test (CPET) and CET) and three field tests (ISWT, ESWT and six-minute walk test (6MWT)). Physiological parameters were continuously monitored using the same portable telemetric device.

RESULTS

Peak oxygen consumption (VO(2peak)) was similar amongst the five exercise tests (p = 0.90 by ANOVA). Walking distance correlated markedly with the VO(2peak) reached during field tests, especially when weight was taken into account. At 100% exercise, most physiological parameters were similar between incremental and endurance tests. However, the trends overtime differed. In the incremental tests, slopes for these parameters rose steadily over the entire duration of the tests, whereas in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end. Moreover, cycling exercise tests induced higher respiratory exchange ratio, ventilatory demand and enhanced leg fatigue measured subjectively and objectively.

CONCLUSION

Endurance tests induce a maximal physiological demand in PAH. Differences in peak respiratory response during exercise are related to the modality (cycling vs. walking) rather than the progression (endurance vs. incremental) of the exercise tests.

Perioperative rehabilitation in operation for lung cancer (PROLUCA) - rationale and design

BACKGROUND

The purpose of the PROLUCA study is to investigate the efficacy of preoperative and early postoperative rehabilitation in a non-hospital setting in patients with operable lung cancer with special focus on exercise.

METHODS

Using a 2 x 2 factorial design with continuous effect endpoint (Maximal Oxygen Uptake (VO2peak)), 380 patients with non-small cell lung cancer (NSCLC) stage I-IIIa referred for surgical resection will be randomly assigned to one of four groups: (1) preoperative and early postoperative rehabilitation (starting two weeks after surgery); (2) preoperative and late postoperative rehabilitation (starting six weeks after surgery); (3) early postoperative rehabilitation alone; (4) today's standard care which is postoperative rehabilitation initiated six weeks after surgery. The preoperative rehabilitation program consists of an individually designed, 30-minute home-based exercise program performed daily. The postoperative rehabilitation program consists of a supervised group exercise program comprising cardiovascular and resistance training two-hour weekly for 12 weeks combined with individual counseling. The primary study endpoint is VO2peak and secondary endpoints include: Six-minute walk distance (6MWD), one-repetition-maximum (1RM), pulmonary function, patient-reported outcomes (PROs) on health-related quality of life (HRQoL), symptoms and side effects of the cancer disease and the treatment of the disease, anxiety, depression, wellbeing, lifestyle, hospitalization time, sick leave, work status, postoperative complications (up to 30 days after surgery) and survival. Endpoints will be assessed at baseline, the day before surgery, pre-intervention, post-intervention, six months after surgery and one year after surgery.

DISCUSSION

The results of the PROLUCA study may potentially contribute to the identification of the optimal perioperative rehabilitation for operable lung cancer patients focusing on exercise initiated immediately after diagnosis and rehabilitation shortly after surgery.

TRIAL REGISTRATION

NCT01893580.