Six-minute Stepper Test to Set Pulmonary Rehabilitation Intensity in Patients with COPD – A Retrospective Study

Pulmonary rehabilitation (PR) improves outcomes in patients with chronic obstructive pulmonary disease (COPD). Optimal assessment includes cardiopulmonary exercise testing (CPET), but consultations are limited. Field tests could be used to individualize PR instead of CPET. The six-minute stepper test (6MST) is easy to set up and its sensitivity and reproducibility have previously been reported in patients with COPD. The aim of this study was to develop a prediction equation to set intensity in patients attending PR, based on the 6MST. The following relationships were analyzed: mean heart rate (HR) during the first (HR_1–3) and last (HR_4–6) 3 minutes of the 6MST and HR at the ventilatory threshold (HRvt) from CPET; step count at the end of the 6MST and workload at the Ventilatory threshold (VT) (Wvt); and forced expiratory volume in 1 second and step count during the 6MST. This retrospective study included patients with COPD referred for PR who underwent CPET, pulmonary function evaluations and the 6MST. Twenty-four patients were included. Prediction equations were HRvt = 0.7887 × HR_1–3 + 20.83 and HRvt = 0.6180 × HR_4–6 + 30.77. There was a strong correlation between HR_1–3 and HR_4–6 and HRvt (r = 0.69, p < 0.001 and r = 0.57, p < 0.01 respectively). A significant correlation was also found between step count and LogWvt (r = 0.63, p < 0.01). The prediction equation was LogWvt = 0.001722 × step count + 1.248. The 6MST could be used to individualize aerobic training in patients with COPD. Further prospective studies are needed to confirm these results.     

Effects of 3-week Outpatient Pulmonary Rehabilitation on Exercise Capacity, Dyspnea, and Quality of Life in COPD

The effects of intensive 3-week outpatient pulmonary rehabilitation (PR) on exercise capacity, dyspnea, and health-related quality of life (HRQL) were investigated in patients with COPD. Two hundred ten patients with COPD (mean FEV₁ = 54%pred) underwent PR consisting of exercise training, patient and psychosocial education, breathing and relaxation therapy, nutrition counseling, and smoking cessation support. Before and after PR, exercise capacity was assessed with 6-min walking tests (6MWT) and constant cycle ergometer exercise (CEE). Dyspnea was measured after 6MWTs with a Borg scale and after PR with the Transition Dyspnoea Index (TDI). HRQL was examined with the Medical Outcomes Study Short Form 36 (SF-36). Results showed improvements in the 6MWT (+39 m, p < 0.001) and CEE (+241 W × min, p < 0.001) after PR, paralleled by decreased dyspnea during the 6MWT (−0.5, p < 0.001) and during activities (TDI score = 3.6). Increases in all SF-36 subscales reflected improved HRQL after PR (p < 0.001). No gender differences were found. Patients with milder versus more severe COPD improved similarly in most outcomes. Regression analyses revealed that TDI scores were the most important predictor of improvements in HRQL. The results suggest that intensive 3-week outpatient PR is associated with improvements in exercise capacity, dyspnea, and HRQL in male and female patients with COPD irrespective of COPD severity. Reduced dyspnea during activities contributed the most to improvements in HRQL.     

Prevention of exercise-induced hypoglycemia in 12 patients with type 1 diabetes running the Paris Marathon using continuous glucose monitoring: A prospective,single-center observational study

ObjectiveTo investigate the glycemic balance before, during and after the 2016 Paris Marathon using a real-time continuous glucose monitoring (RT-CGM) system in patients with type 1 diabetes mellitus in a prospective single-center observational study.MethodsInclusion criteria were as follows: type 1 diabetes mellitus; age ≥18 years; HbA1c < 9%. Participants performed two 2h-preparatory races (PR) before the Marathon and were monitored with RT-CGM 24h before, during and 72h after each race. Hypoglycemic events were prevented via carbohydrate intake / insulin dose adjustments. The primary outcome was area under the curve (AUC) < 70 and > 200 mg/dl and percentage of time spent in euglycemia, hypoglycemia, and hyperglycemia during the races.ResultsTwelve patients (2F/10M; median HbA1c=6.8%) were included and completed the study. Median AUC < 70 and time spent in hypoglycemia (< 70 mg/dl) during the PRs and Marathon were equal to 0. However, no hypoglycemic episodes occurred during Marathon, while two patients experienced hypoglycemia during PR1 and PR2. There was a significant increase in AUC > 200 mg/dl during races between PR2 and Marathon (P = 0.009) although the median time spent > 200mg/dl was not statistically different in Marathon versus PR2 (48.4% versus 18.4%; P = 0.09). Median time spent in euglycemia (70-200 mg/dl) was lower in Marathon versus PR2 (51.6 versus 58%; P = 0.03).ConclusionOur study proposes a medical support protocol for extreme endurance physical activity in patients with type 1 diabetes mellitus. Our results suggest that RT-CGM, coupled with adjustments in carbohydrate intake and insulin doses, appears to be effective to prevent hypoglycemia during and after exercise.     

Distinct Trajectories of Physical Activity Among Patients with COPD During and After Pulmonary Rehabilitation

Little is known about longitudinal trends in objectively measured physical activity (PA) during and after pulmonary rehabilitation (PR) for individuals with Chronic Obstructive Pulmonary Disease (COPD). The purpose of this study was to examine the PA trajectories of patients with COPD during and after PR and whether demographic, clinical, or program characteristics differed across these trajectories. The study was approved by Research Ethics Boards at all participating institutions, and written informed consent was obtained from each participant prior to study inclusion. COPD patients (N = 190) completed a questionnaire and wore a pedometer for 7 days at baseline, end of PR, and 3 and 9 months after completing PR. Latent class growth analyses showed that two distinct PA trajectories emerged. Active Maintainers averaged 9177 steps/day at baseline, and maintained this level throughout the assessment and post rehabilitation period. In contrast, Inactive Maintainers averaged 3133 steps/day at baseline, which also remained stable during and after PR. Follow-up analyses showed the Inactive Maintainers were more likely to be retired from work and have lower baseline scores for their stress tests and 6-minute walk tests compared to Active Maintainers (all p < 0.05). These results suggest that two distinct steps/day trajectories exist for COPD patients during and after completing PR that are partially explained by specific demographic and clinical characteristics.     

Outpatient pulmonary rehabilitation for severe asthma with fixed airway obstruction: Comparison with COPD

Background: The benefit of exercise has been demonstrated in asthma, but the role of pulmonary rehabilitation (PR) in people with severe asthma, especially with airway obstruction, has been less investigated. The activity limitation mechanisms differ in asthma and COPD, so the effect of a PR program not specific to asthma is unclear. Methods: We retrospectively compared the effect of an ambulatory PR program in nonsmoking patients with severe asthma and airway obstruction (FEV1/FVC ratio <70% and FEV1?<?80% measured twice, not under an exacerbation) and sex-, age-, FEV1-, and BMI-matched COPD controls. Results: We included 29 patients, each with asthma and COPD. Airway obstruction was moderate (median FEV1 57% [44–64]). VO₂ at peak was higher for asthma than COPD patients (19.0 [15.7–22.2] vs 16.1 [15.3–19.6] ml.min^?1.kg^?1, p?=?0.05). After PR, asthma and COPD groups showed a significant and similar increase in constant work cycling test of 378 [114–831] s and 377 [246–702] s. Changes in Hospital Anxiety and Depression Scale (HAD) total score were similar (–2.5 [–7.0 to 0.0] vs –2.0 [–5.0 to 2.0], p?>?0.05). Quality of life on the St. George’s Respiratory Questionnaire (SGRQ) was significantly improved in both groups (–14.0 [–17.7 to –2.0], p?<?0.005 and –8.3 [–13.0 to –3.6], p?<?0.0001). Conclusion: Outpatient PR is feasible and well tolerated in patients with severe asthma with fixed airway obstruction. A nondedicated program strongly improves HAD and SGRQ scores and constant work-rate sub-maximal cycling, with similar amplitude as with COPD.     

Cardiorespiratory measurements during field tests in CF: Use of an ambulatory monitoring system

Respiratory inductive plethysmography (e.g., LifeShirt) may offer in‐depth study of the cardiorespiratory responses during field exercise tests. The aims of this study were to assess the reliability, discriminate validity, and responsiveness of cardiorespiratory measurements recorded by the LifeShirt during field exercise tests in adults with CF. To assess reliability and discriminate validity, participants with CF and stable lung disease and healthy participants performed the 6‐Minute Walk Test (6MWT) and Modified Shuttle Test (MST) on two occasions. To assess responsiveness, participants with CF experiencing an exacerbation performed the 6MWT at the start and end of an admission for intravenous antibiotics. The LifeShirt was worn during all exercise tests. Reliability and discriminate validity were assessed in 18 participants with CF (mean (SD) age: 26 (10) years; FEV₁ %predicted: 69.2 (23)%) and 18 healthy participants (age: 24 (5) years, FEV₁ %predicted: 92 (8)%). There was no difference in 6MWT and MST performance between days and reliability of cardiorespiratory measures was acceptable (bias: P > 0.05; CV < 10%). Participants with CF demonstrated a significantly greater response to exercise (e.g., ventilation, respiratory rate) compared to healthy participants indicating discriminate validity. Responsiveness was assessed in 12 participants with CF: clinical measurements and 6MWT performance improved (61 (81) min; P < 0.05) however, cardiorespiratory measurements recorded by the LifeShirt remained the same (bias: P > 0.05; CV < 10%). This study provides evidence that cardiorespiratory responses can be measured non‐invasively during field exercise tests in adults with CF. Reliability and discriminate validity of key cardiorespiratory measurements recorded by the LifeShirt were demonstrated. Some information on responsiveness is reported. Pediatr Pulmonol. 2011; 46:253–260. © 2011 Wiley‐Liss, Inc.     

Effects of Pulmonary Rehabilitation Including Inspiratory Muscle Training in Patients with Chronic Obstructive Pulmonary Disease after Stratification by the Degree of Static Hyperinflation

Background

Inspiratory muscle training (IMT) improves inspiratory muscle strength, exercise capacity and health status in patients with chronic obstructive pulmonary disease (COPD). However, there is no additional effect on top of comprehensive pulmonary rehabilitation (PR). It is unclear whether patients with different baseline degrees of static hyperinflation respond differentially to IMT as part of a PR program. Therefore, the aim was to study the effects of IMT as an add-on on PR after stratification for baseline degrees of static hyperinflation.

Methods

In this single center retrospective study data were extracted between June 2013 and October 2020 of COPD patients who participated in a comprehensive PR program including IMT. IMT was performed twice daily, one session consisted of 3 series of 10 breaths and training intensity was set initially at a load of approximately 50% of patients’ maximal static inspiratory mouth pressure (MIP). The primary outcome measure was MIP. Secondary outcomes were the distance achieved on the 6-min walk test (6MWD), endurance cycling exercise capacity at 75% of the peak work rate (CWRT) and disease-specific health status using the COPD assessment test.

Results

754 patients with COPD were screened for eligibility and 328 were excluded because of repeated PR programs, missing data or baseline residual volume (RV)?>?350%. In total, 426 COPD patients were categorized into RV categories 50–130% (n?=?84), 131–165% (n?=?86), 166–197% (n?=?86), 198–234% (n?=?85) and 235–349% (n?=?85). In the whole sample, MIP, endurance exercise capacity and health status improved significantly. The change in 6MWD was higher in the lowest baseline degree of static hyperinflation [+?39 (9–92) m] compared with the baseline highest degree of static hyperinflation [+?11 (??18–54) m] (p?<?0.05).

Conclusions

IMT as part of a PR program in patients with COPD with different baseline degrees improved MIP irrespective of the degree of static lung hyperinflation. Improvement in functional exercise capacity was significantly higher in the group with the lowest degree of static hyperinflation compared with the patients with the highest degree of static hyperinflation.

     

Difference Between Slow and Forced Vital Capacity and Its Relationship with Dynamic Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease

The aim of the study was to investigate the relationship between slow and forced vital capacity (SVC–FVC) difference with dynamic lung hyperinflation (DH) during the 6-min walking test (6MWT) in subjects with chronic obstructive pulmonary disease (COPD). Twenty-four subjects with COPD (12 males; 67 ± 6 years; forced expiratory volume in first second [FEV₁] 56 ± 18% predicted) performed lung function tests by spirometry and plethysmography. DH was assessed by serial measurements of inspiratory capacity (IC) performed during the 6MWT and defined as ∆IC ≥ 150 mL or 10%. IC decrease significantly during the 6MWT (ΔCI: − 0.48 ± − 0.40 L; P < 0.0001), and 18 individuals (75%) presented DH. There was significant difference when comparing IC measured at rest with the other serial IC measurements (P < 0.0001). Correlation between the SVC–FVC difference and DH during the 6MWT was r = − 0.38; P = 0.06. The SVC–FVC difference presented only weak correlation with the development of DH during the 6MWT in patients with COPD.

     

Effect of compliance to continuous positive airway pressure on exacerbations,lung function and symptoms in patients with chronic obstructive pulmonary disease and obstructive sleep apnea (overlap syndrome)

Introduction

Patients with overlap syndrome (OS), that is obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD), are at increased risk of acute exacerbations related to COPD (AECOPD). We assessed the effect of CPAP compliance on AECOPD, symptoms and pulmonary function in OS patients.

Methods

Consecutive OS patients underwent assessment at baseline and at 12 months under treatment with CPAP of: AECOPD and hospitalizations, COPD Assessment Test (CAT) and modified British Medical Research Council (mMRC) questionnaires, pulmonary function testing and 6-min walking test (6MWT).

Results

In total, 59 patients (54 males) with OS were followed for 12 months and divided post hoc according to CPAP compliance into: group A with good (≥4 h CPAP use/night, n = 29) and group B with poor (<4 h CPAP use/night, n = 30) CPAP compliance. At 12 months, group A showed improvements in FEV₁ (p = 0.024), total lung capacity (p = 0.024), RV/TLC (p = 0.003), 6MWT (p < 0.001) and CAT (p < 0.001). COPD exacerbations decreased in patients with good CPAP compliance from baseline to 12 months (17 before vs. 5 after, p = 0.001), but not in those with poor compliance (15 before vs. 15 after, p = 1). At multivariate regression analysis, COPD exacerbations were associated with poor CPAP compliance (β = 0.362, 95% CI: 0.075–0.649, p = 0.015).

Conclusions

When compared to poorly compliant patients, OS patients with good CPAP compliance had a lower number of AECOPD and showed improved lung function and COPD related symptoms.     

Descriptive analysis of emergency department oxygen use in acute exacerbation of chronic obstructive pulmonary disease

Background: Inconsistencies in oxygen therapy recommendations in acute exacerbation of chronic obstructive pulmonary disease (COPD) may result in variability in emergency department (ED) oxygen management of patients with COPD. The aim of this study was to describe oxygen management in the first 4 h of ED care for patients with exacerbation of COPD. Methods: A retrospective medical record audit was conducted at four public and one private ED in Melbourne, Australia. Participants were 273 adult ED patients with COPD presenting with a primary complaint of shortness of breath from July 2006 to July 2007. Outcome measures were physiological data, including oxygen saturation (SpO₂), oxygen delivery devices and flow rates on ED arrival, 1 and 4 h. Results: Oxygen was used in 82.0% of patients. Patients who required oxygen had higher incidence of ambulance transport (P < 0.001), triage category 2 (P= 0.006), home oxygen use (P < 0.001), and increased work of breathing on ED arrival (P < 0.001), and higher median respiratory rate (P < 0.001) and heart rate (P= 0.001). SpO₂ > 90% occurred in the majority of patients (87.5%; 96.4%; 95.6%); however, a considerable number of patients with SpO₂ < 90% were not given oxygen (61.8%; 30%; 45.5%). Conclusions: A number of patients with documented hypoxaemia were not given oxygen and there may be variables other than oxygen saturation that may influence oxygen use. Future research should focus on increasing the evidence‐based supporting oxygen use and better understanding of clinicians' oxygen decision‐making in patients with COPD.     

Effects of hemodialysis on the cardiovascular system: quantitative analysis using wave intensity wall analysis and tissue velocity imaging

Cardiovascular disease is the leading cause of death in patients with end-stage renal disease (ESRD). The aim of this study was to investigate the changes in cardiovascular function induced by a single session of hemodialysis (HD) by the analysis of cardiovascular dynamics using wave intensity wall analysis (WIWA) and of systolic and diastolic myocardial function using tissue velocity imaging (TVI). Gray-scale cine loops of the left common carotid artery, conventional echocardiography, and TVI images of the left ventricle were acquired before and after HD in 45 patients (17 women, mean age 54 years) with ESRD. The WIWA indexes, W₁ and preload-adjusted W₁, W₂ and preload-adjusted W₂, and the TVI variables, isovolumic contraction velocity (IVCV), isovolumic contraction time (IVCT), peak systolic velocity (PSV), displacement, isovolumic relaxation velocity (IVRV), isovolumic relaxation time (IVRT), peak early diastolic velocity (E′), and peak late diastolic velocity (A′), were compared before and after HD. The WIWA measurements showed significant increases in W₁ (P < 0.05) and preload-adjusted W₁ (P < 0.01) after HD. W₂ was significantly decreased (P < 0.05) after HD, whereas the change in preload-adjusted W₂ was not significant. Systolic velocities, IVCV (P < 0.001) and PSV (P < 0.01), were increased after HD, whereas the AV-plane displacement was decreased (P < 0.01). For the measured diastolic variables, E′ was significantly decreased (P < 0.01) and IVRT was significantly prolonged (P < 0.05), after HD. A few correlations were found between WIWA and TVI variables. The WIWA and TVI measurements indicate that a single session of HD improves systolic function. The load dependency of the diastolic variables seems to be more pronounced than for the systolic variables. Preload-adjusted wave intensity indexes may contribute in the assessment of true LV contractility and relaxation.     

The COPD Assessment Test (CAT): Short- and Medium-term Response to Pulmonary Rehabilitation

Abstract

Background: The COPD Assessment Test (CAT) is a recently introduced instrument to assess health-related quality of life in COPD. We aimed to evaluate the longitudinal change in CAT following Pulmonary Rehabilitation (PR), and test the relationship between CAT and CRQ-Self Report (SR) over time. We hypothesised that the CAT would show similar responsiveness to PR as the CRQ-SR both in the short and medium-term. Methods: 118 COPD patients completed an eight-week outpatient multidisciplinary PR programme. CAT, CRQ-SR and the incremental shuttle walk (ISW) were measured prior to starting PR (T1), completion of PR (T2) and 6 months after completion of PR (T3). Results: There was a significant improvement in CAT, CRQ-SR and ISW immediately following PR (p?<?0.001). Although there was decline between T2 and T3, CAT, CRQ-SR and ISW remained significantly better at T3 compared with T1 (ANOVA p?<?0.001). Both between T1-T2 and between T2-T3, change in CAT correlated significantly with change in CRQ (both r = -0.44 and p?<?0.001). The slope of the relationship between CAT change and CRQ-SR change at T1-T2 and T2-T3 was not significantly different (ANCOVA: intercept p = 0.79, interaction effect p = 0.95). Conclusions: In COPD, the CAT score is immediately responsive to PR and remains improved at 6 months. There is no significant difference in the short and medium term changes in the CAT and CRQ-SR following PR. We propose that for most clinical indications for assessing health-related quality of life in COPD, the CAT is a robust and practical alternative to longer-established instruments such as the CRQ-SR.     

High Expression of Cathepsin E is Associated with the Severity of Airflow Limitation in Patients with COPD

Background: It was reported that Cathepsin E (Cat E) plays a critical role in antigen processing and in the development of pulmonary emphysema. The aim of this study was to investigate the role of Cat E and airflow limitation in the pathogenesis of COPD. Methods: Sixty-five patients with COPD, 20 smoking control subjects without COPD and 15 non-smoking healthy control subjects were enrolled. Cat E and EIC (Elastase inhibitory capacity) expressions were measured by ELISA in sputum and serum samples and compared according to different subgroups. Results: Cat E concentrations were significantly higher in patients with COPD than smoking control and non-smoking control subjects (P < 0.01). The levels of CatE were inversely correlated with FEV₁% predicted in COPD patients (r = ?0.95, P < 0.01). The levels of EIC were inversely positively correlated with FEV₁% predicted in COPD patients (r = 0.926, P < 0.01). Levels of Cat E were also inversely correlated with the levels of EIC (r = ?0.922, P < 0.01). Conclusions: Cat E contributes to the severity of airflow limitation during progression of COPD.     

Comparison of Recording Positions of Physical Activity in Patients with Severe COPD Undergoing LTOT

Abstract

Background: Accelerometry is increasingly used to assess physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD). It is not known how the relationship of PA to clinical results depends on the position of the PA sensor. Methods: We assessed the effect of monitor position by measuring lower extremity (ankle), upper extremity (wrist) and total body movement (hip) in 52 patients with severe COPD (mean [± SD] age, 62 ± 10 years; FEV₁, 38 ± 12% predicted) undergoing long-term oxygen therapy with and without walkers during a pulmonary rehabilitation (PR) program. Sensors were worn 8.5 ± 3.1 days and data was compared to the BODE score and the 6-minute walk distance (6MWD) assessed at the beginning and end of the PR. Results: Mean ankle PA was moderately related to the 6MWD, irrespective of patients being equipped with a walker or not (p < 0.05). Mean PA values were considerably lower in COPD patients with walker compared to patients without for all sensor positions. No significant association was observed between mean hip PA data and 6MWD; however, hip and ankle PA data were moderately related in walker-free and strongly related in walker patients (p < 0.01). In a multivariate regression model only ankle activity was significantly associated with the BODE score (p < 0.01). Conclusion: The sensor position had a significant impact on the association between PA recordings and the 6MWD in very severe COPD. In our setting, ankle measurement seemed to best reflect the clinical state of patients.     

Social Determinants of Adherence to Pulmonary Rehabilitation for Chronic Obstructive Pulmonary Disease

Adherence to pulmonary rehabilitation (PR) is low. Previous studies have focused on clinical predictors of PR completion. We aimed to identify social determinants of adherence to PR. A cross-sectional analysis of a database of COPD patients (N = 455) in an outpatient PR program was performed. Adherence, a ratio of attended-to-prescribed sessions, was coded as low (<35%), moderate (35–85%), and high (>85%). Individual-level measures included age, sex, race, BMI, smoking status, pack-years, baseline 6-minute walk distance (6MWD: <150, 150–249, ≥250), co-morbidities, depression, and prescribed PR sessions (≤20, 21–30, >30). Fifteen area-level measures aggregated to Census tracts were obtained from the U.S. Census after geocoding patients' addresses. Using exploratory factor analysis, a neighborhood socioeconomic disadvantage index was constructed, which included variables with factor loading >0.5: poverty, public assistance, households without vehicles, cost burden, unemployment, and minority population. Multivariate regression models were adjusted for clustering on Census tracts. Twenty-six percent of patients had low adherence, 23% were moderately adherent, 51% were highly adherent. In the best fitted full model, each decile increase in neighborhood socioeconomic disadvantage increased the risk of moderate vs high adherence by 14% (p < 0.01). Smoking tripled the relative risk of low adherence (p < 0.01), while each increase in 6MWD category decreased that risk by 72% (p < 0.01) and 84% (p < 0.001), respectively. These findings show that, relative to high adherence, low adherence is associated with limited functional capacity and current smoking, while moderate adherence is associated with socioeconomic disadvantage. The distinction highlights different pathways to suboptimal adherence and calls for tailored intervention approaches.     

Pulmonary Rehabilitation Improves Sleep Quality in Chronic Lung Disease

Abstract

Sleep-related disorders are common in patients with chronic obstructive pulmonary disease (COPD) and, possibily, other lung disorders. Exercise has been shown to improve sleep disturbances. In patients with COPD, pulmonary rehabilitation (PR) produces important health benefits with improvement in symptoms, exercise tolerance, and quality of life. However, the effect of PR on sleep quality remains unknown. The aim of this observational study was to evaluate sleep quality in patients with chronic lung disease and the role of PR as a non-pharmacologic treatment to improve sleep. Sixty-four patients with chronic lung disease enrolled in an 8-week comprehensive PR program, and completed the study (48% male; obstructive [72%], restrictive [20%], mixed [8%]; 44% on supplemental oxygen). Baseline spirometry [mean (SD)]: FEV₁% pred = 48.9 (17.4), FVC% pred = 72.5 (18.1), and FEV₁/FVC% = 53.1 (18.9). Exercise tolerance and questionnaires related to symptoms, health-related quality of life (HRQL), and sleep quality using the Pittsburgh Sleep Quality Index (PSQI) were obtained before and after PR. 58% reported poor sleep quality (PSQI > 5) at baseline. Sleep quality improved by 19% (p = 0.017) after PR, along with significant improvements in dyspnea, exercise tolerance, self-efficacy, and HRQL. Sleep quality in patients with chronic lung disease was poor. In addition to expected improvements in symptoms, exercise tolerance, and HRQL after PR, the subgroup of patients with COPD had a significant improvement in sleep quality. These findings suggest that PR may be an effective, non-pharmacologic treatment option for sleep problems in patients with COPD.     

Clinical significance of aromatase protein expression in axillary node negative breast cancer

Purpose Aromatase catalyzes the conversion of androgens to estrogens; its high expression in breast cancers may be responsible for the local high levels of estrogen and may promote tumor growth and progression; however, the clinical importance of aromatase remains unclear and needs to be further researched. Methods By immunochemistry, we detected aromatase, MMP2 and MMP9 immunoreactivity in 244 axillary lymph node negative breast cancers. Results Aromatase immunoreactivity was positively associated with co-expression of MMP2 and MMP9 (MMP2/9) in the estrogen receptor and/or progestin receptor- (ER/PR) positive patients (P < 0.05), but not in the ER and PR negative patients (P > 0.05); aromatase status positively associated with tumor size in the postmenopausal patients (P < 0.05) but not in the premenopausal patients (P > 0.05). The proportional hazards assumption was violated for aromatase status (global test, P < 0.05), and aromatase was an unfavorable prognostic factor for disease-free survival (DFS) (P = 0.04) in multivariate analysis of time-dependent non-proportional Cox regression. In the ER/PR-positive patients, positive aromatase staining was significantly associated with decreased overall survival (OS) (P = 0.04), but there was no such association in the ER and PR negative patients (P > 0.05). Conclusions Our study suggested that local estrogen production by aromatase plays important roles in the growth and invasiveness of breast cancer; tumor aromatase status may be indicative of breast cancer prognosis in some patients.     

Serum Antioxidant Capacity is Preserved in Peritoneal Dialysis Contrary to Its Robust Depletion After Hemodialysis and Hemodiafiltration Sessions

Renal replacement therapy (RRT) may differentially affect systemic generation of reactive oxygen species and depletion of antioxidant pools of low molecular weight molecules and proteins. This study was designed to assess the magnitude of the impairment of serum total antioxidant capacity (TAC) in relation to different RRT modalities. The study included patients on continuous ambulatory peritoneal dialysis (CAPD, N = 21), hemodialysis (HD, N = 21), hemodiafiltration (HDF, N = 20), and healthy controls (N = 33). TAC was assessed by the ferric reducing ability of plasma (FRAP) and with the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay. In CAPD patients, predialysis FRAP and DPPH were increased: 1.46 mM and 10.5% vs. control 1.19 mM and 7.2%, respectively (P < 0.001 in each). In HD and HDF patients, the FRAP and DPPH were significantly increased before and lowered after the RRT session (P < 0.05) if compared with healthy controls. During an HD session, FRAP was decreased from pre-HD 1.71 ± 0.29 mM to post-HD 0.85 ± 0.20 mM (P = 0.0001). The decrease of FRAP was lower during HDF (P < 0.05 vs. HD), it decreased from pre-HDF 1.41 ± 0.43 mM to post-HDF 0.87 ± 0.23 mM (P = 0.0001 vs. pre-HDF). The HD session decreased DPPH from the pre-HD median 10.3%, interquartile range (IR) 9.3–12.0% to post-HD 2.6% IR 2.3–3.1% (P < 0.0001). The adjustment of either urate or bilirubin up to pre-HD levels did not restore lowered post-HD levels of TAC. TAC remains preserved in CAPD, whereas the robust depletion of TAC, lower after HDF than HD sessions, cannot be attributed solely to the washout of dialyzable compounds.     

Selecting Constant Work Rates for Endurance Testing in COPD: The Role of the Power-Duration Relationship

Constant work rate (CWR) exercise testing is highly responsive to therapeutic interventions and reveals physiological and functional benefits. No consensus exists, however, regarding optimal methods for selecting the pre-intervention work rate. We postulate that a CWR whose tolerated duration (t_lim) is 6 minutes (WR₆) may provide a useful interventional study baseline. WR₆ can be extracted from the power-duration relationship, but requires 4 CWR tests. We sought to develop prediction algorithms for easier WR₆ identification using backward stepwise linear regression, one in 69 COPD patients (FEV₁ 45 ± 15% pred) and another in 30 healthy subjects (HLTH), in whom cycle ergometer ramp incremental (RI) and CWR tests with t_lim of ～6 minutes had been performed. Demographics, pulmonary function, and RI responses were used as predictors. We validated these algorithms against power-duration measurements in 27 COPD and 30 HLTH (critical power 43 ± 18W and 231 ± 43W; curvature constant 5.1 ± 2.7 kJ and 18.5 ± 3.1 kJ, respectively). This analysis revealed that, on average, only corrected peak work rate ( = WR_peak–1 min × WR_slope) in RI was required to predict WR₆ (COPD SEE = 5.0W; HLTH SEE = 5.6W; R² > 0.96; p < 0.001). In the validation set, predicted and actual WR₆ were strongly correlated (COPD R² = 0.937; HLTH 0.978; p < 0.001). However, in COPD, unlike in HLTH, there was a wide range of t_lim values at predicted WR₆: COPD 8.3 ± 4.1 min (range 3.6 to 22.2 min), and HLTH 5.5 ± 0.7 min (range 3.9 to 7.0 min). This analysis indicates that corrected WR_peak in an incremental test can yield an acceptable basis for calculating endurance testing work rate in HLTH, but not in COPD patients.