Margaret K. Covey

Subjective fatigue, influencing variables, and consequences in chronic obstructive pulmonary disease

Background: Fatigue is a common symptom of chronic obstructive pulmonary disease (COPD), but little is known about the specific nature of COPD-related fatigue and its impact on daily life. Objectives: To (a) describe characteristics of fatigue in people with COPD and (b) test a theoretically and empirically supported model of the relationships among subjective fatigue, dyspnea, functional performance, anxious and depressed moods, and sleep quality in people with COPD. Methods: A cross-sectional descriptive study was conducted with 130 people with moderate to severe COPD. Measures included the following: a Numerical Rating Scale (NRS) for frequency, intensity, and distress of fatigue and dyspnea; Fatigue Assessment Instrument (FAI); Chronic Respiratory Disease Questionnaire (CRQ); Profile of Mood States (POMS); Pittsburgh Sleep Quality Index (PSQI); Functional Performance Inventory (FPI); and spirometry. Path analysis was used to examine the relationships among variables. Results: Participants reported moderate amounts of fatigue, which was described as situation-specific, had considerable consequences, and was responsive to rest and sleep. Dyspnea was slightly greater than fatigue, as measured by the NRSs (p <.001), and there was a strong relationship between fatigue and dyspnea (r =.74, p < .001). Dyspnea, depressed mood, and sleep quality accounted for 42% of the variance in subjective fatigue. Fatigue, dyspnea, airflow obstruction, and anxious mood accounted for 36% of the variance in functional performance. Conclusions: Fatigue is an important problem that affects performance of daily activities in people with COPD. The relationships or interactions that exist among fatigue and other symptoms are complex.

High-intensity inspiratory muscle training in patients with chronic obstructive pulmonary disease and severely reduced function.

PURPOSE This study examined the effects of inspiratory muscle training (IMT) with high-intensity inspiratory pressure loads on respiratory muscle performance and exertional dyspnea. METHODS This was a randomized single-blind clinical trial. Twenty-seven patients with chronic obstructive pulmonary disease (18 men, 9 women) with severe to very severe airflow obstruction and severely limited functional performance were assigned randomly to an IMT group (n = 12) or an educational control group (n = 15). The IMT group trained with a threshold loaded device for 30 minutes a day for 16 weeks using interval training techniques. Training was initiated with inspiratory pressure loads equal to 30% of maximal inspiratory pressure (Plmax) and increased as tolerated to 60% of Plmax. Dependent variables were measured before and after 4 months of IMT: inspiratory muscle strength (Plmax), respiratory muscle endurance (discontinuous incremental threshold loading test [DC-ITL]), dyspnea (Chronic Respiratory Disease Questionnaire [CRQ]), and the Borg Category-Ratio Scale ratings of perceived breathing difficulty (RPBD) at equal loads during the DC-ITL. RESULTS In the IMT group, Plmax increased from 64 +/- 15 to 75 +/- 17 cm H2O (P < .05), performance on the DC-ITL test increased from a maximal load of 37 +/- 12 to 53 +/- 13 cm H2O (P < .05), RPBD decreased from 5.5 +/- 2.5 to 3.8 +/- 2.6 for equal loads on the DC-ITL (P < .05) and the CRQ Dyspnea Scale improved from 18.1 +/- 5.1 to 22.4 +/- 5.2 (P < .05). CONCLUSIONS Inspiratory muscle training at high-intensity loads significantly improved inspiratory muscle strength, respiratory muscle endurance, and respiratory symptoms during daily activities and respiratory exertion.

Inspiratory muscle training in patients with chronic obstructive pulmonary disease

The effects of 6 months of muscle training with an inspiratory pressure load equal to 30% of the maximal inspiratory pressure (PImax) was compared with sham training with a light inspiratory pressure load. In this double-blind randomly assigned study, 67 patients with chronic obstructive pulmonary disease were followed for 6 months. Both groups demonstrated improvements in performance of PImax, respiratory muscle endurance time for breathing against an inspiratory pressure load equal to 66% of PImax, 12-minute distance walk, and dyspnea. The treatment group did not demonstrate significant effects beyond those observed in the control group. Improvements in performance were related to improved coordination of the inspiratory muscles and desensitization to dyspnea.

Reliability and validity of the functional performance inventory in patients with moderate to severe chronic obstructive pulmonary disease.

The Functional Performance inventory (FPI) is a new instrument designed to measure functional status in terms of activities that people perform on a daily basis. Psychometric characteristics were examined by a survey of 45 men and 27 women with chronic obstructive pulmonary disease (COPD). Internal consistency reliability was high and no ceiling and floor effects were observed for the Total FPI. Concurrent validity was demonstrated by correlations with the Total Sickness Impact Profile (r = -.59). Construct validity was supported by correlations with the Medical Outcomes Study Short Form-36, Physical Functioning (r = .69), the Physical Activity Scale for the Elderly (r = .62) and American Thoracic Society-Division of Lung Disease Breathlessness scale (r = - .62). The Total FPI is a reliable and valid measure of functional performance in persons with COPD.

Reliability and validity of the 12-minute distance walk in patients with chronic obstructive pulmonary disease.

Validity and test-retest liability of the 12-minute distance (12MD) walk, a measure of functional status, were examined in patients with chronic obstructive pulmonary disease. Four tests were administered at weekly intervals. Performance increased (p < .01) over the first three tests. Test-retest reliability was r34 = .98 (df = 46) for tests 3 and 4. The 12MD walk correlated with the Sickness Impact Profile, Physical Dimension (r = -.45); forced expiratory volume in 1 second % predicted ( r = .40); maximal inspiratory pressure (PImax) (r = .52); and exercise-related breathlessness (r = -.49). Exercise-related breathlessness and PImax accounted for 42% of the variance. The validity and reliability of the 12MD walk were supported.

Functional Performance in Chronic Obstructive Pulmonary Disease Declines with Time

PURPOSE it is well known that people with chronic obstructive pulmonary disease experience declines in functional performance, but little is known about the rate of decline. The purposes of this research were to describe the rate of decline in functional performance and to examine the contribution of disease severity, body composition, symptoms, and functional capacity. Functional performance was defined as the activities that people choose to engage in on a day-to-day basis. METHODS people (n = 108) with chronic obstructive pulmonary disease were enrolled and followed yearly for 3 yr with self-reported functional performance (Functional Performance Inventory), spirometry, lung volumes, diffusion capacity, body composition (dual-energy x-ray absorptiometry), dyspnea and fatigue (Chronic Respiratory Disease Questionnaire), and functional capacity (6-min walk distance (6MWD), isokinetic strength of knee flexors and extensors, handgrip strength, and maximal inspiratory pressure). A total of 88 subjects completed a (mean ± SD) of 2.7 ± 0.9 yr of follow-up. RESULTS significant negative slopes were observed for functional performance (P = 0.001), spirometry (the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC), P < 0.0001), diffusion capacity (P < 0.0001), and muscle strength (P < 0.0001)). The slopes for dyspnea, fatigue, and functional capacity were not significantly different from zero, but there was a wide individual variation. Hierarchical regression demonstrated that 31% of the variance in the slope of functional performance was accounted for by the hierarchical model, and the primary predictors were the slopes of the FEV1/FVC, 6MWD, and muscle strength (knee flexors/extensor and handgrip). CONCLUSIONS subjects experienced a slow decline in functional performance, associated with declines in functional capacity and increases in body fat. Symptoms were relatively stable and not associated with declines in functional performance.

Self-efficacy enhancing intervention increases light physical activity in people with chronic obstructive pulmonary disease

Background People with chronic obstructive pulmonary disease lead sedentary lives and could benefit from increasing their physical activity. The purpose of this study was to determine if an exercise-specific self-efficacy enhancing intervention could increase physical activity and functional performance when delivered in the context of 4 months of upper body resistance training with a 12-month follow-up. Methods In this randomized controlled trial, subjects were assigned to: exercise-specific self-efficacy enhancing intervention with upper body resistance training (SE-UBR), health education with upper body resistance training (ED-UBR), or health education with gentle chair exercises (ED-Chair). Physical activity was measured with an accelerometer and functional performance was measured with the Functional Performance Inventory. Forty-nine people with moderate to severe chronic obstructive pulmonary disease completed 4 months of training and provided valid accelerometry data, and 34 also provided accelerometry data at 12 months of follow-up. The self-efficacy enhancing intervention emphasized meeting physical activity guidelines and increasing moderate-to-vigorous physical activity. Results Differences were observed in light physical activity (LPA) after 4 months of training, time by group interaction effect (P=0.045). The SE-UBR group increased time spent in LPA by +20.68±29.30 minutes/day and the other groups decreased time spent in LPA by −22.43±47.88 minutes/day and -25.73±51.76 minutes/day. Changes in LPA were not sustained at 12-month follow-up. There were no significant changes in moderate-to-vigorous physical activity, sedentary time, or functional performance. Subjects spent most of their waking hours sedentary: 72%±9% for SE-UBR, 68%±10% for ED-UBR, and 74%±9% for ED-Chair. Conclusion The self-efficacy enhancing intervention produced a modest short-term increase in LPA. Further work is needed to increase the magnitude and duration of effect, possibly by targeting LPA.

Regional body composition: cross-calibration of DXA scanners-QDR4500W and Discovery Wi.

Differences exist in body composition assessed by dual‐energy X‐ray absorptiometers (DXAs) between devices produced by different manufacturers and different models from the same manufacturer. Cross‐calibration is needed to allow body composition results to be compared in multicenter trials or when scanners are replaced. The aim was to determine reproducibility and extent of agreement between two fan‐beam DXA scanners (QDR4500W, Discovery Wi) for body composition of regional sites. The sample was: 39 women 50.6 ± 9.6 years old with BMI 26.8 ± 5.5 kg/m2, body fat 33 ± 7%. Four whole body scans (two on each device) were performed over 3 weeks. Major variables were fat mass, nonosseous lean mass, and bone mineral content (BMC) for the truncal and appendicular regions. Extent of agreement was assessed using Bland and Altman plots. Both devices demonstrated good precision with mean test–retest differences close to zero for fat mass, nonosseous lean mass, and BMC of the truncal and appendicular regions. Evaluation of interdevice agreement revealed significant differences for truncal and appendicular BMC, nonosseous lean mass, and fat mass. The greatest interdevice difference was for truncal fat mass (0.69 ± 0.60 kg). Differences in truncal and appendicular fat mass increased in magnitude at higher mean values. Furthermore, differences in truncal and appendicular fat mass were strongly related to BMI (R = −0.61, R = −0.55, respectively). In conclusion, in vivo cross‐calibration is important to ensure comparability of regional body composition data between scanners, especially for truncal fat mass and for subjects with higher BMI.

Reliability of submaximal exercise tests in patients with COPD

UNLABELLED Submaximal constant work rate exercise tests are often used to measure the efficacy of an exercise intervention, but the reliability of these tests in patients with chronic obstructive pulmonary disease (COPD) has not been established. PURPOSE To examine the reproducibility of submaximal exercise responses of COPD patients compared with those of healthy elderly subjects. METHODS Sixteen COPD patients and 15 healthy subjects performed four weekly submaximal exercise tests against two different constant work rates: 20 W and 50% of the peak work rate (PWR). Spirometry was performed before each exercise test. COPD patients and healthy subjects were: age 69 +/- 5 and 65 +/- 5 yr, body mass index 26.4 +/- 3.9 and 26.7 +/- 3.0 kg x m(-2), respectively. RESULTS Both groups had no change in minute ventilation (V(E)), oxygen uptake (VO2), breathlessness (RPB), and leg fatigue (RPLF) for either work rate over repeated measures (P > 0.05). At 50% PWR test-retest reliability coefficients for V(E) and VO2 ranged from r = 0.88 to r = 0.96 for COPD patients and from r = 0.72 to r = 0.97 for healthy subjects; for RPB and RPLF test-retest reliability ranged from r = 0.76 to r = 0.89 for COPD patients and from r = 0.70 to r = 0.91 for healthy subjects. Intrasubject mean absolute differences for repeated measures of V(E), VO2, RPB, or RPLF were low and there were no group differences (P > 0.05). Percent error for V(E) and VO2 ranged from 6 +/- 3 to 9 +/- 7%, and for RPB and RPLF ranged from 19 +/- 18 to 68 +/- 65% for both groups at each work rate. CONCLUSIONS Submaximal exercise responses were reliable over a 1-month period, and measures of the physiological and psychophysical responses of COPD patients were as reliable as those of healthy subjects.

Importance of cross-calibration when replacing DXA scanners: QDR4500W and Discovery Wi.

The aim of the study was to determine reproducibility and extent of agreement between 2 dual-energy X-ray absorptiometers (Hologic QDR4500W, Discovery Wi). The average age of the sample (n = 42) was 50.4 (SD = 9.9) years old and 27.1 (SD = 6.1) kg/m2 body mass index. Four scans were performed with each subject (2 on each device) over ∼3 weeks. Whole body, proximal femur, and spine scans were performed at each visit. Major variables were whole body bone mineral content (BMC), fat mass, and nonosseous lean mass, and bone mineral density (BMD) of total proximal femur, femoral neck, total spine. Bland and Altman plots assessed the extent of the agreement. Regression analysis was used to develop correction equations if indicated. Both devices demonstrated good precision for whole body composition and BMD of central sites (<1% different). Interdevice agreement was acceptable for BMD of central sites (<1% different), but there were systematic differences for whole body composition between the 2 devices. It was concluded that when replacing an existing scanner with a new model, in vivo cross-calibration is important to ensure comparability of scan data, especially for whole body composition.