Use of supplemental oxygen during exercise testing and training for people with chronic obstructive pulmonary disease: a survey of Australian pulmonary rehabilitation programs.

OBJECTIVES: The aims of this study were to determine, in Australian pulmonary rehabilitation programs for people with COPD: (1) whether oxygen saturation (SpO2) was monitored during exercise testing; (2) whether supplemental oxygen was available during exercise testing and/or training; (3) whether oxygen was prescribed during exercise training; and the reason for providing oxygen; (4) whether a protocol was available for supplemental oxygen prescription during exercise training. METHODS: This was a cross-sectional multi-center study using a purposed-designed survey. De-identified survey data were analyzed and the absolute number and percentage of responses were recorded for each question. RESULTS: The survey was sent to 261 pulmonary rehabilitation programs and 142 surveys (54%) were available for analysis. Oxygen saturation was monitored during exercise testing in 92% of programs. Supplemental oxygen was available in the majority of programs during exercise testing (82%) and training (84%). The rationale cited by 87 programs (73%) for prescribing oxygen during exercise training was maintaining SpO2 above a threshold ranging from SpO2 80-88%. Forty-five (32%) programs had a protocol for oxygen prescription during exercise training. CONCLUSION: While monitoring of SpO2 during exercise testing and using supplemental oxygen during testing and training is common in Australian pulmonary rehabilitation programs, few programs had a protocol in place for the prescription of supplemental oxygen for people with COPD who were not on long-term oxygen therapy. This may be due to lack of strong evidence to support the use of supplemental oxygen during exercise training.

The minimal detectable difference for endurance shuttle walk test performance in people with COPD on completion of a program of high-intensity ground-based walking.

BACKGROUND: In people with moderate-to-severe chronic obstructive pulmonary disease (COPD), the minimal detectable difference (MDD) in endurance shuttle walk test (ESWT) performance following exercise training is unclear. We sought to determine the MDD for ESWT performance following supervised ground-based walking training using anchor- and distribution-based approaches and report whether these values exceeded random variation in test performance. METHODS: Participants with COPD trained for 30-45 min, 2-3 times weekly for 8-10 weeks. The ESWT was performed before and after the training period. Immediately after training, participants rated their change in walking ability using a Global Rating of Change scale. Receiver Operating Characteristic curves were used to derive the value that best separated those who perceived their improvement in walking ability to be at least 'a little' better from 'almost the same, hardly any change'. These values were compared with those calculated using a distribution-based method. Random variation in test performance was defined as the minimal detectable change (MDC), calculated using the standard error of measurement. RESULTS: 78 participants (aged 70 ±â€¯8 yr and FEV1 43 ±â€¯15% predicted) completed the ESWT before and after training. The value that best separated those who perceived their walking ability as 'a little' better was 70 s. The 95% confidence intervals around this estimate traversed zero. The distribution-based estimate was 156 s. The MDC was 227 s. CONCLUSIONS: The MDD established using the anchor- and distribution-based approaches differed considerably. Large variation in test performance cautions against using the MDD to interpret changes in an individual. CLINICAL TRIALS REGISTRATION: Australian New Zealand Clinical Trials Registry (ACTRN12609000472279).

Six-minute walk test in pulmonary rehabilitation: do all patients need a practice test?

BACKGROUND AND OBJECTIVE: The six-minute walk test (6MWT) is widely used as an outcome measure in pulmonary rehabilitation programs (PRP). A learning effect for the test has been reported in COPD; however, limited data exist in patients with other respiratory diagnoses. The objectives of this study were to: (i) report the magnitude of change in 6MWD with test repetition in patients referred to an outpatient PRP, and (ii) compare the magnitude of change in 6MWD with test repetition in patients with COPD, interstitial lung disease (ILD), bronchiectasis and asthma. METHODS: Retrospective study of 349 patients with stable COPD (n = 245), ILD (n = 21), bronchiectasis (n = 33) or asthma (n = 50) who performed two 6MWT at enrollment into a PRP. RESULTS: 6MWD increased in all groups on the second test (all P < 0.001). At least 80% of patients in each diagnostic group walked further on their second 6MWT. The magnitude of change (mean, 95% CI) was greater (P < 0.05) in the COPD (37 m, 95% CI: 33-41 m) and ILD (41 m, 95% CI: 27-55 m) cohorts compared with the bronchiectasis (22 m, 95% CI: 14-31 m) and asthma (19 m, 95% CI: 11-27 m) cohorts. CONCLUSIONS: Respiratory diagnosis influences the magnitude of the learning effect for the 6MWT. The findings support the recommendation of a practice 6MWT at baseline assessment in order to provide an accurate measure of the effects of rehabilitation on 6MWD.

State of the art: how to set up a pulmonary rehabilitation program.

Pulmonary rehabilitation plays an essential role in the management of symptomatic patients with COPD. The benefits of rehabilitation include a decrease in dyspnoea and fatigue, and improvements in exercise tolerance and health-related quality of life. Importantly, rehabilitation reduces hospitalization for acute exacerbations and is cost-effective. Although most of the evidence for pulmonary rehabilitation has been obtained in patients with COPD, symptomatic individuals with other respiratory diseases have been shown to benefit. In this review we outline a stepwise approach to establish, deliver and evaluate a pulmonary rehabilitation program (PRP) that would be feasible in most settings. Throughout the review we have specified the minimum requirements for a PRP to facilitate the establishment of programs using limited resources. Recommendations for staffing and other resources required for a PRP are presented in the first section. Exercise training is a focus of the section on program delivery as this is the component of rehabilitation that has the strongest level of evidence for benefit. Program considerations for patients with respiratory conditions other than COPD are described. Different approaches for delivering the education component of a PRP are outlined and recommendations are made regarding topics for group and individual sessions. The problems commonly encountered in pulmonary rehabilitation, together with recommendations to avoid these problems and strategies to assist in their resolution, are discussed. The review concludes with recommendations for evaluating a PRP.

Inspiratory muscle training for patients with chronic obstructive pulmonary disease: a practical guide for clinicians.

Reduced inspiratory muscle strength is common in people with chronic obstructive pulmonary disease (COPD) and is associated with dyspnea and decreased exercise capacity. Most studies of inspiratory muscle training (IMT) in COPD have demonstrated increased inspiratory muscle strength. Many have also shown improvements in dyspnea and exercise capacity. However, a persisting challenge when translating and applying the findings of these studies in clinical practice is the disparity in training loads, modalities, and outcomes measures used in the different studies. This commentary summarizes our clinical and research experience with a threshold IMT device with the aim of providing clinicians interested in prescribing IMT in this population with practical recommendations regarding patient selection, assessment, and implementation of training. We propose using an interval-based high-intensity threshold IMT program for people who are unable to participate fully in whole-body exercise training because of comorbidities such as severe musculoskeletal problems. Initial training loads equivalent to at least 30% of a person's maximum inspiratory pressure (PImax) are required for all people undertaking IMT. Supervision, which includes monitoring of oxygen saturation throughout the first training session, is recommended, and patients are warned to expect transient delayed-onset muscle soreness, a consequence of muscle adaptation to an unaccustomed activity. We recommend training be undertaken 3 times a week for 8 weeks, with loads progressively increased as symptoms permit. It is prudent to exclude people at risk of pneumothorax or spontaneous rib fracture. Evaluation of IMT should include measures of PImax, dyspnea, health-related quality of life, and exercise capacity.

Six-minute walk distance in healthy Singaporean adults cannot be predicted using reference equations derived from Caucasian populations.

OBJECTIVES: The 6-min walk test (6MWT) is commonly used to assess the functional exercise capacity of individuals with cardiopulmonary disease. Recent studies have established regression equations to predict the 6-min walk distance (6MWD) in healthy Caucasian populations; however, regression equations have yet to be established for the Singaporean population. The aim of this study was to determine 6MWD in healthy Singaporeans and identify contributors to 6MWD in this population. We also compared measured 6MWD with predicted 6MWD from two regression equations derived in Caucasian subjects. METHODOLOGY: Thirty-five healthy subjects (32 Chinese, 16 men) aged between 45 and 85 years performed three walking tests using a standardized protocol. 6MWD was defined as the greatest distance achieved from the three tests. Heart rate (HR) was recorded each minute during the 6MWT. Other measurements included age, height, leg length, smoking history and self-reported physical activity. RESULTS: 6MWD was 560 +/- 105 m and was not significantly different between men and women (P = 0.19). 6MWD was related to age (r = -0.36, P = 0.03), height (r = 0.35, P = 0.04), leg length (r = 0.38, P = 0.02) and the maximum HR achieved on the 6MWT when expressed as a percentage of the predicted maximum HR (%predHRmax, r = 0.73, P < 0.001). Stepwise multiple regression analysis showed that age, height, weight and %predHRmax were independent contributors (P < 0.01) to 6MWD, explaining 78% of the variance. Predicted 6MWD using regression equations derived from Caucasian subjects exceeded measured 6MWD by more than 75 m (P < 0.001). CONCLUSIONS: This is the first study to report 6MWD for healthy Singaporeans aged 45-85 years. The regression equation developed in this study explained 78% of the variance in 6MWD. Published equations derived from Caucasian subjects overestimate 6MWD in Singaporean Chinese.

Six minute walk distance in healthy subjects aged 55-75 years.

BACKGROUND: The six minute walk test (6MWT) is the most commonly used exercise test in pulmonary rehabilitation; however, the paucity of six minute walk distance (6MWD) reference values from population-based samples limits data interpretation in patients. This study was undertaken to determine 6MWD in a population-based sample of healthy subjects and to identify predictors of 6MWD in this group. METHODS: Seventy Caucasian subjects (33 males) aged 55-75 years performed three tests using a standardised protocol. 6MWD was defined as the greatest distance achieved from the three tests. Other measurements included height, leg length, weight, forced expiratory volume in 1s (FEV(1)), exhaled carbon monoxide and self-reported physical activity including habitual walking. RESULTS: The average 6MWD was 659+/-62 m (range 484-820 m). Males walked 59+/-13 m further than females (P<0.001). Height (r=0.54, P<0.01), weight (r=0.25, P<0.05) and FEV(1) (r=0.48, P<0.001) were significantly correlated with 6MWD. Forwards stepwise multiple regression showed height (R(2)=0.294) and FEV(1) (R(2) change=0.045) to be independent predictors of 6MWD (P<0.05), explaining 33.9% of the variance. CONCLUSIONS: 6MWD in this healthy population-based sample of males and females exceeds values previously reported. Height and FEV(1) were identified as significant independent predictors of 6MWD in this group.

Physiologic responses to incremental and self-paced exercise in COPD: a comparison of three tests.

OBJECTIVES: To investigate cardiorespiratory and dyspnea responses to incremental and self-paced exercise tests in patients with COPD. DESIGN: A prospective within-subject design was used. PATIENTS: Twenty stable subjects (15 men), with a mean (+/- SD) age of 64.0 +/- 7.5 years and moderate-to-severe COPD (ie, mean FEV(1), 0.8 +/- 0.3 L and 28.9 +/- 7.9% predicted) were studied. METHODS: Each subject completed a 6-min walk test (6MWT), an incremental shuttle walking test (ISWT), and a cycle ergometer test (CET), within a 2-week period. The tests were performed at least 24 h apart. Standardized encouragement was utilized in each test with the aim of maximizing performance. Heart rate (HR) and dyspnea were measured each minute throughout the tests, and pulse oximetric saturation (Spo(2)) was measured before and immediately after each test. The distances walked in the 6MWT and ISWT were compared to peak oxygen uptake (Vo(2)) values from the CET. RESULTS: HR increased linearly with increasing workload during the CET and ISWT, but increased alinearly with a disproportionate increase early in the 6MWT. In contrast, dyspnea scores increased linearly during the 6MWT, but increased alinearly with a disproportionate increase late during the CET and ISWT. Peak HR and dyspnea were not significantly different between tests. Spo(2) was significantly lower at the end of both walking tests compared to that at the end of the CET (p < 0.001). The distance walked in both the ISWT and 6MWT were related to peak Vo(2) values on the CET (for both tests, r = 0.73; p < 0.001). CONCLUSIONS: The patterns of response in HR and dyspnea seen during the 6MWT suggest that patients with COPD titrate exertion against dyspnea to achieve a peak tolerable intensity. This strategy is not possible in an externally paced ISWT or CET. However, it is a limited strategy, with performance converging at higher workloads. Similar peak exercise responses were achieved in the 6MWT, ISWT, and CET. Greater oxygen desaturation was observed during the field walking tests, suggesting that both the ISWT and 6MWT are more sensitive than the CET in detecting exercise-induced hypoxemia and in assessing ambulatory oxygen therapy needs.

The effect of learning on ventilatory responses to inspiratory threshold loading in COPD.

BACKGROUND: Progressive threshold loading (PTL) is a common test of respiratory muscle endurance. Healthy naive subjects improve endurance with successive exposures to PTL by altering their breathing responses, thus necessitating a familiarization period before reproducible measures can be obtained. This study sought to determine whether a similar "learning effect" is evident in patients with COPD, and what the mechanism of any such effect may be. METHODS: Ten subjects with COPD (FEV1 34+/-13% predicted) underwent PTL on four occasions (>24 h apart). During PTL measurements were obtained of breathing pattern and maximum threshold pressure (Pthmax) achieved. Maximum inspiratory pressure (PImax) was measured on each occasion. RESULTS: Over the four tests PImax improved by 21+/-16% (SD) (P<0.05) and Pthmax by 32+/-21% (P<0.05) with a plateau in these measures achieved by test three. Pthmax/PImax was unchanged, being 61+/-11% at test one and 67+/-12% at test four. In contrast to healthy subjects, PTL was not associated with increased expiratory time or decreased end-expiratory lung volume. CONCLUSIONS: In contrast to PImax and Pthmax, which changed with successive tests, a single measure of the ratio Pthmax/PImax may present a useful guide to the endurance capacity of the respiratory muscles in patients with COPD.

Questioning the use of heart rate and dyspnea in the prescription of exercise in subjects with chronic obstructive pulmonary disease.

PURPOSE: This study examined the heart rate and dyspnea responses during constant submaximal lower limb endurance exercise in subjects with chronic obstructive pulmonary disease (COPD) to determine the appropriateness of using target heart rate or dyspnea for the prescription of endurance exercise intensity. METHODS: The study participants were 15 men, ages 55 to 75 years, with stable moderate to severe COPD (forced expiratory volume in 1 second, 38.7 +/- 15.6% pred). All the participants completed the incremental shuttle walking test (ISWT) to estimate peak oxygen consumption (VO(2peak)), followed by the endurance shuttle walking test (ESWT) at an intensity equivalent to 60% VO(2peak). Heart rate and dyspnea were monitored before, immediately after, and at 1-minute intervals during each test. RESULTS: The study was completed by 11 subjects. Heart rate and dyspnea increased significantly between 4.5 and 20 minutes during the ESWT (P <.01) despite walking at a constant submaximal workload. Heart rate and dyspnea attained at the end of the ESWT exceeded levels observed during the ISWT at the equivalent workload (P <.05). Four subjects were unable to walk for at least 10 minutes on the ESWT because of severe dyspnea and were withdrawn. CONCLUSIONS: Setting heart rate and dyspnea targets for endurance training at an intensity equivalent to 60% VO(2peak) may be inappropriate for subjects with moderate to severe COPD because heart rate and dyspnea increase independently of workload at this intensity.