Reliability of 24-h measurement of physical activity, sleep, and sedentary time in adult patients with asthma using a triaxial accelerometer.

OBJECTIVE: Physical activity (PA), sleep, and sedentary time (SST) are important outcomes to monitor and to improve as part of patients' asthma management. This study aimed to assess the number of measurement days needed to reliably measure PA and SST. Secondly, the influence of external factors on the reliability of measuring PA and SST was studied. METHODS: Adult patients with stable asthma were asked to wear a triaxial accelerometer for at least four days, with at least 22.5 h of wear time per day. The Intraclass Correlation Coefficients (ICCs) between different number of measurement days were used to determine reliability. Values ≥0.75 indicated good reliability. RESULTS: Data from 452 patients were analyzed (63% women; age: 49 ± 16 years; FEV1: 87 ± 17% predicted). PA could reliably be measured with four valid measurement days (ICC 0.761). For SST, three days were needed (ICC 0.778). In summer and autumn, three days were needed to reliably measure PA, in winter four, in spring six. For SST, five days were needed in spring for good reliability, and two in all other seasons. CONCLUSION: Based on data from four valid days, PA and SST can reliably be measured with an accelerometer in patients with asthma. Seasonal influences are present, especially during spring. When measuring for four days, using only weekdays or three weekdays and one weekend day is recommended. The degree of asthma control, dyspnea or spirometric values did not influence the reliability.

Non-invasive ventilation abolishes the IL-6 response to exercise in muscle-wasted COPD patients: a pilot study.

Systemic inflammation in patients with chronic obstructive pulmonary disease (COPD) has been related to the development of comorbidities. The level of systemic inflammatory mediators is aggravated as a response to exercise in these patients. The aim of this study was to investigate whether unloading of the respiratory muscles attenuates the inflammatory response to exercise in COPD patients. In a cross-over design, eight muscle-wasted stable COPD patients performed 40 W constant work-rate cycle exercise with and without non-invasive ventilation support (NIV vs control). Patients exercised until symptom limitation for maximally 20 min. Blood samples were taken at rest and at isotime or immediately after exercise. Duration of control and NIV-supported exercise was similar, both 12.9 ± 2.8 min. Interleukin- 6 (IL-6) plasma levels increased significantly by 25 ± 9% in response to control exercise, but not in response to NIV-supported exercise. Leukocyte concentrations increased similarly after control and NIV-supported exercise by ∼15%. Plasma concentrations of C-reactive protein, carbonylated proteins, and production of reactive oxygen species by blood cells were not affected by both exercise modes. This study demonstrates that NIV abolishes the IL-6 response to exercise in muscle-wasted patients with COPD. These data suggest that the respiratory muscles contribute to exercise-induced IL-6 release in these patients.

Can COPD patients who hyperinflate during daily life activities be identified by laboratory tests?

BACKGROUND: Identification of patients with chronic obstructive pulmonary disease (COPD) who develop dynamic hyperinflation (DH) during activities in daily life (ADL) is important, because of the association between DH and dyspnea and exercise limitation. OBJECTIVE: We aimed to answer the question whether measurements of DH during metronome-paced tachypnea (MPT) or cardiopulmonary exercise testing (CPET) can be used to identify patients who develop DH during ADL. METHODS: DH was measured by tracking changes in inspiratory capacity during CPET, MPT and ADL. Bland-Altman plots were used to evaluate agreement in DH between methods. With a receiver operating characteristic (ROC) analysis, the overall accuracy of MPT and CPET to identify patients who hyperinflate during ADL was assessed. RESULTS: There are broad limits of agreement in DH between methods. ROC curve analyses showed good overall accuracy of both CPET and MPT to identify patients who hyperinflate during ADL. For CPET, area under the curve (AUC) = 0.956 (95% CI 0.903-1.009). For MPT, AUC = 0.840 (95% CI 0.699-0.981). Sensitivity and specificity to identify patients who hyperinflate during ADL with CPET were 96 and 83%, respectively, and with MPT, they were 89 and 77%, respectively. CONCLUSION: Both CPET and MPT can serve as screening tools to identify patients who are susceptible to developing DH during ADL. In practice, MPT is the most simple and inexpensive surrogate. However, the sensitivity of MPT is not optimal. When DH does not occur during CPET, it is unlikely to occur during ADL.

Maximal exercise capacity in chronic obstructive pulmonary disease: a limited indicator of the health status.

BACKGROUND: Dyspnoea and diminished functional status are pivotal features of the health status (HS) in chronic obstructive pulmonary disease (COPD). However, it is still not fully understood how pulmonary function tests and cardiopulmonary exercise testing relate to these aspects. This may be due to incomplete assessment and/or deficient definitions of HS. Especially regarding peak oxygen consumption, inconsistent results have been reported. OBJECTIVES: To determine the value of maximal cycle ergometry in relation to a broad spectrum of HS aspects. METHODS: 129 patients with COPD, stage II and III according to the GOLD classification, performed a cardiopulmonary exercise test. Sixteen independent sub-domains of HS were assessed according to the Nijmegen Integral Assessment Framework, covering physiological functioning, complaints, functional impairments and quality of life as main domains. VO(2)(max) and HS sub-domains were correlated by bivariate analysis. RESULTS: Weak correlations of VO(2)(max) with most sub-domains were found, except for exercise capacity; the other 5 sub-domains of physiological functioning did not correlate. Between different types of exercise limitation (5 types were differentiated), no significant differences were noted in the scores of 13/16 HS sub-domains. CONCLUSIONS: VO(2)(max) is indeed correlated with most aspects of HS, except for physiological variables, but associations are weak. No single exercise limitation type is associated with specific HS problems. Thus separate assessment of all HS sub-domains is advocated to ensure adequate planning of therapeutic interventions.

Physiologic limitations during daily life activities in COPD patients.

INTRODUCTION: Patients with COPD are known to be limited in their performance of activities of daily life (ADL). This observational study aims to investigate the ventilatory and metabolic demand of ADL in home settings of patients and evaluate possible mechanisms involved in physiological limitation during ADL in COPD. METHODS: In their home settings, 21 stable patients with COPD (GOLD II-IV, mean FEV(1) 43% predicted) were asked to perform their most dyspnea causing activities at their usual pace until symptoms discouraged further performance. Ten healthy control subjects, matched for age and gender, performed comparable activities. Ventilatory and metabolic demands of the ADL were studied using a portable breath-by-breath system. RESULTS: Compared with healthy controls, ADL time was shorter in patients (530 +/- 38 s vs. 318 +/- 37 s respectively) and activities resulted in important complaints of dyspnea. Oxygen consumption (V O(2)) during the activities was higher in patients compared to healthy subjects (957 +/- 51 vs. 768 +/- 63 mL/min resp.). Ventilatory demand (V E) for comparable activity (at isoV O(2)) was higher in patients and went together with complaints of dyspnea in patients, but not in healthy subjects. Ventilatory constraints like low ventilatory reserve and inspiratory reserve volume and dynamic hyperinflation occurred in more than 80% of the patients, especially in (very) severe patients. CONCLUSION: Patients with COPD experience limitations in the performance of ADL, which lead to reductions in ADL time and dyspnea complaints. There appears to be an important role for ventilatory limitations, which become more prominent as disease progresses.

Exercise in systemic sclerosis intensifies systemic inflammation and oxidative stress.

OBJECTIVE: Exercise testing can be used (i) to evaluate functional limitations of systemic sclerosis (SSc) and (ii) to study whether the inflammatory and oxidative systems are activated after a physical stimulus. The aim of this study was to determine exercise-induced inflammatory and oxidative responses in SSc compared with healthy subjects. METHODS: Eleven patients with SSc and pulmonary involvement and 10 healthy subjects underwent maximal cardiopulmonary exercise testing (CPET). Physiological responses were followed continuously during cycling. Blood samples were taken at rest, during and after maximal exercise to measure inflammatory and oxidative markers. RESULTS: In nine of the 11 SSc patients, cardiocirculatory limitation and gas exchange impairment limited exercise capacity. Basal inflammatory cells, interleukin (IL)-6, and oxidative stress were increased in SSc compared to healthy subjects and intensified after exercise. Basal and exercise-induced inflammation and oxidative stress were correlated with the modified Rodnan skin score. CONCLUSIONS: Although exercise capacity is impaired in patients with SSc, physical activity intensifies the already increased basal levels of systemic inflammation and oxidative stress. These data support the concept of a role for systemic inflammation and oxidative stress in the ongoing systemic effects of SSc.

Systemic immunological response to exercise in patients with chronic obstructive pulmonary disease: what does it mean?

Chronic obstructive pulmonary disease (COPD) is no longer seen as a pulmonary disease, but is increasingly associated with systemic effects with important clinical relevance. Systemic immunological changes in COPD patients are characterized by an increased number of circulating inflammatory cells, functional changes of the inflammatory cells, elevated plasma levels of cytokines, and oxidative stress. Physical exercise induces an abnormal systemic inflammatory and oxidative response in COPD patients, which is seen in both the circulation and the peripheral muscles. Although mechanisms and consequences of these effects are not yet fully understood, they could be harmful in COPD patients by inducing damage or functional changes in, for example, skeletal muscles. Whether these changes of the immune system can also affect the susceptibility to infections in these patients is unknown. The concept of COPD as a systemic rather than only a pulmonary disease also opens new perspectives on the development for new therapeutic interventions. The effects of new antioxidative and anti-inflammatory agents are investigated. A better understanding of the complexity of the systemic effects will aid the development of new therapies and management strategies for patients with COPD.

Corticotropin-releasing hormone in the teleost stress response: rapid appearance of the peptide in plasma of tilapia (Oreochromis mossambicus).

High concentrations (up to 600 pg/ml) of corticotropin-releasing hormone (CRH) were detected in plasma of the teleost fish Oreochromis mossambicus (tilapia) when screening peripheral tissues of tilapia exposed to stress. Notably, the plasma CRH response to stressors in tilapia is much more pronounced than that in higher vertebrates, such as rats. After characterisation by RIA, by spiking plasma with synthetic tilapia CRH and by methanol-acid extraction, it is concluded that the immunoreactive (ir) material in plasma represents tilapia CRH(1-41). Results indicate that a CRH-binding protein is absent in tilapia plasma. Unstressed fish had plasma CRH levels under the limit of detection (<2 pg/ml), but following capture stress plasma CRH levels (170-300 pg/ml) as well as plasma cortisol levels (120 ng/ml) increased rapidly to plateau levels, which were reached after approximately 5 min. Tilapia CRH(1-41) tested at concentrations between 10(-11) and 10(-7) M in vitro did not stimulate the cortisol release from interrenal tissue. Also pretreatment of interrenal tissue with 10(-9) M CRH did not sensitise the cortisol-producing cells to a subsequent ACTH challenge. Forty-eight hours of net confinement or 48 h of cortisol treatment abolished the plasma CRH response and cortisol response to capture stress. The rapidity of the plasma CRH response and its inhibition after 48 h of stress or cortisol treatment point to release by central nervous tissue. Therefore the distribution of glucocorticoid receptors (GRs) in the brain and pituitary of tilapia was investigated. Main GR-ir cell clusters were found in the medial part (Dm) and posterior part of the dorsal telencephalon, in the preoptic region, in the inferior lobe of the hypothalamus and in the cerebellum. We conclude from comparison of CRH brain contents of unstressed and stressed fish that plasma CRH was released by CRH-ir cells located in the lateral part of the ventral telencephalon (Vl), and suggest that the cortisol feedback on CRH release by Vl is mainly exerted via the forebrain Dm region. We propose that CRH is mobilised during stress to fulfil peripheral functions, such as the regulation of circulating leukocytes or of cardiac output, as CRH receptors have been reported in these organs for fish species.