Rachael A. Evans

Systematic Review of Supervised Exercise Programs After Pulmonary Rehabilitation in Individuals With COPD

BACKGROUND The success of pulmonary rehabilitation (PR) is established, but how to sustain benefits over the long term is less clear. The aim of this systematic review was to determine the effect of supervised exercise programs after primary PR on exercise capacity and health-related quality of life (HRQL) in individuals with COPD. METHODS Randomized controlled trials of postrehabilitation supervised exercise programs vs usual care for individuals with COPD were identified after searches of six databases and reference lists of appropriate studies. Two reviewers independently assessed study quality. Standardized mean differences (SMDs) with 95% CIs were calculated using a fixed-effect model for measures of exercise capacity and HRQL. RESULTS Seven randomized controlled trials, with a total of 619 individuals with moderate to severe COPD, met the inclusion criteria. At 6-month follow-up there was a significant difference in exercise capacity in favor of the postrehabilitation interventions (SMD, -0.20; 95% CI, -0.39 to -0.01), which was not sustained at 12 months (SMD, -0.09; 95% CI, -0.29 to 0.11). There was no difference between postrehabilitation interventions and usual care with respect to HRQL at any time point. CONCLUSIONS Supervised exercise programs after primary PR appear to be more effective than usual care for preserving exercise capacity in the medium term but not in the long term. In this review, there was no effect on HRQL. The small number of studies precludes a definitive conclusion as to the impact of postrehabilitation exercise maintenance on longer-term benefits in individuals with COPD.

Has My Patient Responded?: Interpreting Clinical Measurements such as the Six Minute Walk Test

To correctly interpret clinical measurements it is necessary to understand the standard deviation and the standard error; the former reflects the range or variability of individuals within a sample and the latter reflects the precision for which the group parameters have been estimated. When evaluating an individual patient, test measurement properties such as repeatability will assist in concluding whether a repeated test, measured to monitor the response to an intervention, has changed beyond its natural variability. Using the “best” test has an inherent bias and ignores the natural test variation, whereas the average of repeated tests is more representative of the true value, making it more discriminative to change. Serial measurements to follow progress will increase a clinicians confidence in the observed effects of treatment.

Properties of Self-Paced Walking in Chronic Respiratory Disease A Patient Goal-Oriented Assessment

BACKGROUND Patients with chronic respiratory diseases often have the simple goal of wanting to walk for longer. We evaluated the properties of a patient goal-oriented, symptom-limited, self-paced walk (SPW). METHODS Patients with symptomatic chronic respiratory disease, referred for a 6-week course of pulmonary rehabilitation (PR), were screened for eligibility. Baseline assessments included two SPWs with both time and speed measured, two 6-min walk tests (6MWTs), and the Medical Research Council dyspnea scale. On program completion, two SPWs and one 6MWT were performed. The repeatability, responsiveness, and validity of the SPW were assessed. RESULTS Two SPWs were completed by 50 and 37 patients before and after rehabilitation, respectively. The speed (r = -0.54, P < .001) but not the time (r = -0.23, P = .19) of the SPW correlated with Medical Research Council dyspnea grade. The mean SPW time increased on the second day of testing from 15.1 ± 8.4 min to 17.9 ± 7.7 min (P = .004), and the effect of test day was unaltered by PR (P = .80). The coefficient of repeatability for SPW time was 16.1 min. Both the mean SPW time (10.6 min; 95% CI, 6.6-14.5 min; P < .001) and the mean speed (3.5 m/min; 95% CI, 1.3-5.7 m/min; P < .01) increased after rehabilitation. CONCLUSIONS The SPW time is an easily understandable, patient goal-oriented assessment with construct validity that is highly responsive to the effects of PR. The variability in SPW time makes it better suited to interpreting group rather than individual changes. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT00781183; URL: www.clinicaltrials.gov.

Do Field Walking Tests Produce Similar Cardiopulmonary Demands to an Incremental Treadmill Test in Obese Individuals With Treated OSA

BACKGROUND Cardiorespiratory fitness, assessed during cardiopulmonary exercise tests by peak oxygen uptake (Vo2pk), is an independent predictor of mortality in obesity. We investigated whether Vo2pk and systemic responses measured during field walking tests were similar to those measured during an incremental treadmill test (ITMT) in obese individuals with treated OSA. METHODS Individuals with treated OSA and a BMI > 30 kg/m2 were recruited. Participants completed an ITMT, two 6-min walk tests (6MWTs), and two incremental shuttle walk tests (ISWTs) on three separate days in a randomized order. Expired gas analysis was performed during all tests. RESULTS The study was completed by 16 patients (nine men) (mean [SD] age, 58 [12] y; BMI, 36.1 [7.6] kg/m2). There was no difference (P = .27) in Vo2pk assessed by the ITMT and the ISWT (2,266 [478] and 2,017 [561] mL/min, respectively). The Vo2pk measured by the 6MWT (1,778 [360] mL/min) was lower than that measured by the ITMT (P < .01). The limits of agreement for Vo2pk between the ISWT and the ITM were ± 730 mL/min. Cardiorespiratory responses during the ISWT and the ITMT reflected a graded response to a peak, whereas the 6MWT demonstrated a rapid rise to a plateau. CONCLUSIONS The ISWT can be used instead of an ITMT and in preference to the 6MWT to assess cardiorespiratory fitness for a cohort of obese people with treated OSA. However, the imprecision of the agreement in Vo2pk between the ITMT and ISWT means they cannot be used interchangeably in an individual. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT01930513; www.clinicaltrials.gov.

Defining hyperinflation as ‘dynamic’: Moving toward the slope

Measuring the severity of dynamic hyperinflation is a useful clinical approach to assess the effect of therapeutic interventions and explain their impact on exercise tolerance. Dynamic hyperinflation is typically quantified by the change in end expiratory lung volume from rest to the end of exercise. The result may be inconsistent with disease severity and does not clearly explain how exercise tolerance improves with therapy. Using a re-examination of selected studies, we suggest an operational definition of dynamic hyperinflation using the slope derived from serial measures of inspiratory capacity expressed as a linear function of ventilation that clearly differentiates whether therapies affect static or dynamic hyperinflation or affect lung volume only as a consequence of reducing ventilation. With this approach, the magnitude of the result is consistent with disease severity and is a more reliable outcome as it uses serial measures rather than a single time point estimate. The therapies re-evaluated are breathing helium or hyperoxic gas mixtures, bronchodilation and exercise training. A clear definition of dynamic hyperinflation will assist clinicians in assessing the impact of therapeutic interventions.

The effects of exercise modality and intensity on energy expenditure and cardiorespiratory response in adults with obesity and treated obstructive sleep apnoea

To inform recommendations for the exercise component of a healthy lifestyle intervention for adults with obesity and treated obstructive sleep apnoea (OSA), we investigated the total energy expenditure (EE) and cardiorespiratory response to weight-supported (cycling) and unsupported (walking) exercise. Individuals with treated OSA and a body mass index (BMI) > 30 kg/m2 performed an incremental cardiopulmonary exercise test on a cycle ergometer and a treadmill to determine the peak oxygen uptake ( V . O 2 pk ) . Participants subsequently completed two endurance tests on each modality, matched at 80% and 60% of the highest V . O 2 pk determined by the incremental tests, to intolerance. The cardiorespiratory response was measured and total EE was estimated from the V . O 2 . Sixteen participants completed all six tests: mean [SD] age 57 [13] years and median [IQ range] BMI 33.3 [30.8–35.3] kg/m2. Total EE during treadmill walking was greater than cycling at both high (158 [101] vs. 29 [15] kcal; p < 0.001) and moderate (178 [100] vs. 85 [59] kcal; p = 0.002) intensities, respectively, with similar cardiorespiratory responses and pattern of EE during rest, exercise and recovery. Contrary to current guidelines, walking might be the preferred training modality to achieve the combination of weight loss and increased cardiorespiratory fitness in adults with obesity and treated OSA.

Saving Time for Patients with Moderate to Severe COPD: Endurance Test Speed Set Using Usual and Fast Walk Speeds

Background: For assessing the effects of interventions on exercise tolerance, the tolerable duration (tlimit) of a high-intensity constant-speed endurance test is recommended. The test intensity is determined by the test speed (stest) which should be individualized to target a tlimit of 3 to 15 minutes. We determined the accuracy of setting the stest to achieve a targeted tlimit of 3 to 15 minutes using the participants easily measured and non-fatiguing usual (susual) and fast (sfast) walk speeds. Methods: Participants with COPD were asked to walk at their usual and fast walk speeds to establish their susual and sfast. This required that they walk for less than 1 minute. The individualized stest was calculated from a previously developed equation (0.57 x [sfast - susual]) + susual. Participants then completed a constant-speed endurance test, walking at this calculated stest to intolerance, to determine if the resultant tlimit occurred within 3 to 15 minutes. Results: Twenty-nine participants (forced expiratory volume in 1 second [FEV1] standard deviation [SD ]=43 [25] %predicted; FEV1 to forced vital capacity [FVC]ratio= 41 [13]%; susual = 57.3 [10.4] meters per minute (m·min-1 ); sfast = 71.7 [10.7] m·min-1) completed the study. During testing, 24 (83%) participants used supplemental oxygen and 16 (55%) used a walking aid. The derived stest was 65.6 [10.3] m·min-1 with the observed tlimit of 6.0 [5.0] minute. Twenty-four of 29 (83 %) endurance tests were within 3 to 15 minutes. Conclusion: Using the usual and fast walk speeds provides a simple, quick, inexpensive method for clinicians to set an acceptable endurance walk speed.

Has My Patient Responded

To correctly interpret clinical measurements it is necessary to understand the standard deviation and the standard error; the former reflects the range or variability of individuals within a sample and the latter reflects the precision for which the group parameters have been estimated. When evaluating an individual patient, test measurement properties such as repeatability will assist in concluding whether a repeated test, measured to monitor the response to an intervention, has changed beyond its natural variability. Using the “best” test has an inherent bias and ignores the natural test variation, whereas the average of repeated tests is more representative of the true value, making it more discriminative to change. Serial measurements to follow progress will increase a clinicians confidence in the observed effects of treatment.