Objective: To evaluate the prevalence of sarcopenia in COPD patients, as well as to determine whether sarcopenia correlates with the severity and prognosis of COPD. Methods: A cross-sectional study with COPD patients followed at the pulmonary outpatient clinic of our institution. The patients underwent dual-energy X-ray absorptiometry. The diagnosis of sarcopenia was made on the basis of the skeletal muscle index, defined as appendicular lean mass/height2 only for low-weight subjects and adjusted for fat mass in normal/overweight subjects. Disease severity (COPD stage) was evaluated with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. The degree of obstruction and prognosis were determined by the Body mass index, airflow Obstruction, Dyspnea, and Exercise capacity (BODE) index. Results: We recruited 91 patients (50 females), with a mean age of 67.4 ± 8.7 years and a mean BMI of 25.8 ± 6.1 kg/m2. Sarcopenia was observed in 36 (39.6%) of the patients, with no differences related to gender, age, or smoking status. Sarcopenia was not associated with the GOLD stage or with FEV1 (used as an indicator of the degree of obstruction). The BMI, percentage of body fat, and total lean mass were lower in the patients with sarcopenia than in those without (p < 0.001). Sarcopenia was more prevalent among the patients in BODE quartile 3 or 4 than among those in BODE quartile 1 or 2 (p = 0.009). The multivariate analysis showed that the BODE quartile was significantly associated with sarcopenia, regardless of age, gender, smoking status, and GOLD stage. Conclusions: In COPD patients, sarcopenia appears to be associated with unfavorable changes in body composition and with a poor prognosis.

Keywords: Sarcopenia; Body composition; Pulmonary disease, chronic obstructive; Severity of illness index.

Objective: To establish a cut-off point for clinical and functional variables to determinate sarcopenia and dynapenia in COPD patients, and to analyze the impact of skeletal muscle dysfunction (SMD) on these variables. Methods: Cross-sectional study, screened COPD patients for sarcopenia or dynapenia through low muscle mass and hand grip strength (HGS). Clinical variables: pulmonary function, respiratory muscle strength and functional capacity (FC). The precision of the variables in determining points of predictive cut-off for sarcopenia or dynapenia were performed using the Receiver Operating Characteristic curve and two-way analysis of variance. Results: 20 COPD patients stratified for sarcopenia (n = 11) and dynapenia (n = 07). Sarcopenia group presented lower lean mass and lower maximal inspiratory pressure (MIP), decreased HGS, reduced FC (p<0.050). Dynapenia group presented reduced MIP, lower HGS and walked a shorter distance at Incremental shuttle walk test (ISWT) (p<0.050). We found cut-off points of forced expiratory volume in one second (FEV1), MIP and maximal expiratory pressure (MEP) and ISWT. It is possible to identify sarcopenia or dynapenia in these patients. We found the coexistence of the conditions (SMD effect) in COPD - reduction in the distance in the ISWT (p = 0.002) and %ISWT (p = 0.017). Conclusion: In moderate to very severe COPD patients the sarcopenia could be predicted by FEV1 (%predicted) < 52, MIP < 73 cmH2O, MEP < 126 cmH2O and distance traveled of < 295 m in ISWT. Whereas dynapenia could be predicted by FEV1 < 40%, MIP < 71 cmH2O, MEP < 110 cmH2O and distance of < 230 m traveled in ISWT.

Keywords: Sarcopenia; Chronc obstructive pulmonary disease; Musculoskeletal system.

Objective: To determine whether COPD severity correlates with sputum cell counts, atopy, and asthma. Methods: This was a cross-sectional study involving 37 patients with COPD and 22 healthy subjects with normal lung function (controls). Sputum cell counts were determined by microscopy after centrifugation of samples. Skin prick tests were performed, and serum cytokines were determined by ELISA. Results: Patients were stratified by bronchodilator response: a non-reversible airflow limitation (nonRAL) group comprised 24 patients showing no significant post-bronchodilator change in FEV1; and a partially reversible airflow limitation (partialRAL) group comprised 13 patients showing FEV1 reversibility (post-bronchodilator FEV1 increase ≥ 12%). The proportion of eosinophils in sputum was higher in the partialRAL group than in the nonRAL group (p < 0.01), and there was an inverse correlation between the proportion of eosinophils and FEV1 (p < 0.05). However, none of the patients had a history of asthma and skin prick test results did not differ between the two groups. In the patient sputum samples, neutrophils predominated. Serum levels of TNF, IL-6, IL-8, and RANTES (CCL5) were higher in patients than in controls (p < 0.001) but did not differ between the two patient groups. Conclusions: COPD patients with partial FEV1 reversibility appear to have higher sputum eosinophil counts and greater airway hyperresponsiveness than do those with no FEV1 reversibility. However, we found that COPD severity did not correlate with atopy or with the cytokine profile.

Keywords: Pulmonary disease, chronic obstructive; Cytokines; Chemokines; Eosinophils; Sputum/cytology; Forced expiratory volume.

Objective: Impaired respiratory mechanics and gas exchange may contribute to sleep disturbance in patients with COPD. We aimed to assess putative associations of different domains of lung function (airflow limitation, lung volumes, and gas exchange efficiency) with polysomnography (PSG)-derived parameters of sleep quality and architecture in COPD. Methods: We retrospectively assessed data from COPD 181 patients = 40 years of age who underwent spirometry, plethysmography, and overnight PSG. Univariate and multivariate linear regression models predicted sleep efficiency (total sleep time/total recording time) and other PSG-derived parameters that reflect sleep quality. Results: The severity of COPD was widely distributed in the sample (post-bronchodilator FEV1 ranging from 25% to 128% of predicted): mild COPD (40.3%), moderate COPD (43.1%), and severe-very severe COPD (16.6%). PSG unveiled a high proportion of obstructive sleep apnea (64.1%) and significant nocturnal desaturation (mean pulse oximetry nadir = 82.2% ± 6.9%). After controlling for age, sex, BMI, apnea-hypopnea index, nocturnal desaturation, comorbidities, and psychotropic drug prescription, FEV1/FVC was associated with sleep efficiency (ß = 25.366; R2 = 14%; p < 0.001), whereas DLCO predicted sleep onset latency (ß = -0.314; R2 = 13%; p < 0.001) and rapid eye movement sleep time/total sleep time in % (ß = 0.085; R2 = 15%; p = 0.001). Conclusions: Pulmonary function variables reflecting severity of airflow and gas exchange impairment, adjusted for some potential confounders, were weakly related to PSG outcomes in COPD patients. The direct contribution of the pathophysiological hallmarks of COPD to objectively measured parameters of sleep quality seems to be less important than it was previously assumed.

Keywords: Pulmonary disease, chronic obstructive; Respiratory function tests; Sleep; Sleep apnea, obstructive; Comorbidity.

Objective: To evaluate clinical predictors of poor sleep quality in COPD patients with and without obstructive sleep apnea (OSA). Methods: Consecutive stable patients with COPD were evaluated for OSA by means of overnight polysomnography; for sleep quality by means of the Pittsburgh Sleep Quality Index (PSQI); and for disease impact by means of the COPD Assessment Test. COPD severity was graded in accordance with the 2020 GOLD guidelines. Predictors of poor sleep quality were evaluated by multivariate logistic regression analysis. Results: We studied 51 patients with COPD alone and 51 patients with COPD and OSA. Both groups had similar age (66.2 ± 9.2 years vs. 69.6 ± 10.7, p = 0.09) and airflow limitation (p = 0.37). Poor sleep quality was present in 74.8% of the study participants, with no significant difference between COPD patients with and without OSA regarding PSQI scores (p = 0.73). Polysomnography showed increased stage 1 non-rapid eye movement sleep and arousal index, as well as reduced sleep efficiency and stage 3 non-rapid eye movement sleep, in the group of patients with COPD and OSA (p < 0.05). Independent predictors of poor sleep quality were GOLD grade C/D COPD (OR = 6.4; 95% CI, 1.79-23.3; p < 0.01), a COPD Assessment Test score = 10 (OR = 12.3; 95% CI, 4.1-36.5; p < 0.01), and lowest SaO2 < 80% (p < 0.0001). Conclusions: Poor sleep quality is quite common in patients with COPD and is associated with severe COPD and poor health status, having a negative impact on overall quality of life. Despite changes in polysomnography, OSA appears to have no impact on subjective sleep quality in COPD patients.

Keywords: Pulmonary disease, chronic obstructive; Sleep Quality; Sleep apnea, obstructive; Health status.

Objective: To evaluate diaphragmatic mobility in relation to lung function, respiratory muscle strength, dyspnea, and physical activity in daily life (PADL) in patients with COPD. Methods: We included 25 patients with COPD, classified according to the Global Initiative for Chronic Obstructive Lung Disease criteria, and 25 healthy individuals. For all of the participants, the following were evaluated: anthropometric variables, spirometric parameters, respiratory muscle strength, diaphragmatic mobility (by X-ray), PADL, and the perception of dyspnea. Results: In the COPD group, diaphragmatic mobility was found to correlate with lung function variables, inspiratory muscle strength, and the perception of dyspnea, whereas it did not correlate with expiratory muscle strength or PADL. Conclusions: In patients with COPD, diaphragmatic mobility seems to be associated with airway obstruction and lung hyperinflation, as well as with ventilatory capacity and the perception of dyspnea, although not with PADL.

Keywords: Pulmonary disease, chronic obstructive; Diaphragm; Spirometry; Dyspnea; Maximal respiratory pressures.

To describe the intra-rater and inter-rater reliability of the Brazilian Portuguese version of the fatigue severity scale (FSS) in patients with COPD and to identify the presence of its association with parameters of pulmonary function, dyspnea, and functional capacity. Methods: This was an observational cross-sectional study involving 50 patients with COPD, who completed the FSS in interviews with two researchers in two visits. The FSS scores were correlated with those of the Medical Research Council (MRC) scale, as well as with FEV1, FVC, and six-minute walk distance (6MWD). Results: The mean age of the patients was 69.4 ± 8.23 years, whereas the mean FEV1 was 46.5 ± 20.4% of the predicted value. The scale was reliable, with an intraclass correlation coefficient of 0.90 (95% CI, 0.81-0.94; p < 0.01). The FSS scores showed significant correlations with those of MRC scale (r = 0.70; p < 0.01), as well as with 6MWD (r = −0.77; p < 0.01), FEV1 (r = −0.38; p < 0.01), FVC (r = −0.35; p < 0.01), and stage of the disease in accordance with the Global Initiative for Chronic Obstructive Lung Disease criteria (r = 0.37; p < 0.01). Conclusions: The Brazilian Portuguese version of the FSS proved reliable for use in COPD patients in Brazil and showed significant correlations with sensation of dyspnea, functional capacity, pulmonary function, and stage of the disease.

Keywords: Fatigue; Pulmonary disease, chronic obstructive; Reproducibility of results; Validation studies.

Objective: Elevated values of body mass index (BMI) have been associated with higher prevalence of asthma in adults. The aim of the present study is to evaluate the association between obesity and asthma severity. Methods: Medical records of two hundred patients older than 20 years of age were evaluated retrospectively. Asthma severity was established after the evaluation of the medical history and diagnosis recorded, spirometry results and the medicines prescribed. BMI was calculated and patients were classified as obese when the BMI was ≥ 30 kg/m2. Results: 23% of the patients presented intermittent asthma, 25.5% presented mild persistent asthma, 24% presented moderate persistent asthma, and 27.5% presented severe persistent asthma. Values of BMI ≤ 29.9 kg/m2 were observed in 68% of the patients and in 32% the BMI was ≥ 30 kg/m2. The odds ratio of the correlation between obesity and asthma severity was 1.17 (95% CI: 0.90-1.53; p > 0.05). Conclusions: In the sample evaluated in this study no correlation between obesity and asthma severity was found for either gender.

Keywords: Asthma; Body mass index, Sex distribution; Obesity.

Objective: Patients with COPD are prone to cardiac remodeling; however, little is known about cardiac function in patients recovering from an acute exacerbation of COPD (AECOPD) and its association with exercise capacity. The aim of this study was to evaluate the cardiac function and structure and to compare their relationship with exercise capacity in patients with a recent AECOPD and patients with clinically stable COPD. Methods: This was a cross-sectional study including 40 COPD patients equally divided into two groups: recent AECOPD group (AEG) and clinically stable COPD group (STG). Echocardiography was performed to assess cardiac function and chamber structure. The six-minute walk distance (6MWD) and the Duke Activity Status Index (estimated Vo2) were used in order to assess exercise capacity. Results: No significant differences in cardiac function and structure were found between the groups. The 6MWD was associated with early/late diastolic mitral filling velocity ratio (r = 0.50; p < 0.01), left ventricular posterior wall thickness (r = -0.33; p = 0.03), and right atrium volume index (r = -0.34; p = 0.04), whereas Vo2 was associated with right atrium volume index (r = -0.40; p = 0.02). Conclusions: Regardless of the clinical condition (recent AECOPD vs. stable COPD), the cardiac function and structure were similar between the groups, and exercise capacity (determined by the 6MWD and Vo2) was associated with cardiac features.

Keywords: Pulmonary disease, chronic obstructive; Echocardiography; Walk test; Pulmonary medicine.

In order to assess the relationship between the physical fitness of asthmatics and the clinical expression of the underlying disease, the authors studied 39 physically active children with moderate to severe but stable asthma. The patients (25 boys and 14 girls, aged between 9 and 16 years) were submitted to clinical evaluation; spirometry before and after bronchodilator (BD); maximal cardiopulmonary exercise test in cycle ergometer with breath-by-breath analysis of ventilatory and gas exchange variables; and, on a separate day, an exercise challenge test. As expected by the clinical stability, FEV1 post-BD was in the normal range in most of the children (mean ± SD = 93.8 ± 13.7% predicted). Maximal oxygen uptake (VO2max) was higher than the lower 95% confidence interval in 31/39 children; and in 29/39, the oxygen uptake at the anaerobic threshold (VO2AT) showed values above the lower limit of normality. Seven patients with low tolerance to exercise (reduced VO2max) presented suggestions of circulatory limitation (cardiovascular and/or peripheral) and only 1 had ventilatory limitation. There was no association or correlation between the lower ventilatory reserve (VEmax/MVV% ratio > 80%) and the decreased VO2max. Reduction in VO2AT, but not VO2max, was associated with some clinical indicators of asthma severity, e.g. (i) higher daily inhaled beclomethasone and frequent courses of oral steroids (p < 0.05) and (ii) higher exercise-induced bronchospasm occurrence (p < 0.01). The results show that (i) most patients with moderate to severe asthma, when clinically stable and physically active, present an adequate level of exercise tolerance; (ii) in estimation of the clinical severity of bronchial asthma in children, VO2AT is a better aerobic index than VO2max.

Keywords: Asthma in children. Exercise tolerance. Maximal oxygen uptake. Anaerobic threshold. Physical fitness. Exercise-induced

Objective: To determine whether COPD patients with diaphragmatic dysfunction present higher risk of mortality than do those without such dysfunction. Methods: We evaluated pulmonary function, diaphragm mobility and quality of life, as well as determining the Body mass index, airway Obstruction, Dyspnea, and Exercise capacity (BODE) index, in 42 COPD patients. The patients were allocated to two groups according to the degree to which diaphragm mobility was impaired: low mobility (LM; mobility ≤ 33.99 mm); and high mobility (HM; mobility ≥ 34.00 mm). The BODE index and the quality of life were quantified in both groups. All patients were followed up prospectively for up to 48 months in order to determine the number of deaths resulting from respiratory complications due to COPD. Results: Of the 42 patients evaluated, 20 were allocated to the LM group, and 22 were allocated to the HM group. There were no significant differences between the groups regarding age, lung hyperinflation or quality of life. However, BODE index values were higher in the LM group than in the HM group (p = 0.01). During the 48-month follow-up period, there were four deaths within the population studied, and all of those deaths occurred in the LM group (15.79%; p = 0.02). Conclusions: These findings suggest that COPD patients with diaphragmatic dysfunction, characterized by low diaphragm mobility, have a higher risk of death than do those without such dysfunction.

Keywords: Pulmonary disease, chronic obstructive/mortality; Diaphragm; Exercise tolerance; Quality of life.

Objective: To evaluate the frequency of asthma-COPD overlap (ACO) in patients with COPD and to compare, from a clinical, laboratory, and functional point of view, patients with and without ACO, according to different diagnostic criteria. Methods: The participants underwent evaluation by a pulmonologist, together with spirometry and blood tests. All of the patients were instructed to record their PEF twice a day. The diagnosis of ACO was based on the Proyecto Latinoamericano de Investigación en Obstrucción Pulmonar (PLATINO, Latin American Project for the Investigation of Obstructive Lung Disease) criteria, the American Thoracic Society (ATS) Roundtable criteria, and the Spanish criteria. We investigated patient histories of exacerbations and hospitalizations, after which we applied the COPD Assessment Test and the modified Medical Research Council scale, to classify risk and symptoms in accordance with the GOLD criteria. Results: Of the 51 COPD patients, 14 (27.5%), 8 (12.2%), and 18 (40.0) were diagnosed with ACO on the basis of the PLATINO, ATS Roundtable, and Spanish criteria, respectively. The values for pre-bronchodilator FVC, post-bronchodilator FVC, and pre-bronchodilator FEV1 were significantly lower among the patients with ACO than among those with COPD only (1.9 ± 0.4 L vs. 2.4 ± 0.7 L, 2.1 ± 0.5 L vs. 2.5 ± 0.8 L, and 1.0 ± 0.3 L vs. 1.3 ± 0.5 L, respectively). When the Spanish criteria were applied, IgE levels were significantly higher among the patients with ACO than among those with COPD only (363.7 ± 525.9 kU/L vs. 58.2 ± 81.6 kU/L). A history of asthma was more common among the patients with ACO (p < 0.001 for all criteria). Conclusions: In our sample, patients with ACO were more likely to report previous episodes of asthma and had worse lung function than did those with COPD only. The ATS Roundtable criteria appear to be the most judicious, although concordance was greatest between the PLATINO and the Spanish criteria.

Keywords: Asthma/diagnosis; Pulmonary disease, chronic obstructive/diagnosis; Asthma-chronic obstructive pulmonary disease overlap syndrome/diagnosis.

Objective: To identify symptoms of dysphagia in individuals with COPD, based on their responses on a self-perception questionnaire. Methods: The study comprised 35 individuals with COPD and 35 healthy individuals, matched for age and gender. The study group was assessed regarding COPD severity; sensation of dyspnea; body mass index (BMI); and symptoms of dysphagia. The control group was assessed regarding BMI and symptoms of dysphagia. Results: The most common symptoms of dysphagia in the study group were pharyngeal symptoms/airway protection (p < 0.001); esophageal symptoms/history of pneumonia (p < 0.001); and nutritional symptoms (p < 0.001). Positive correlations were found between the following pairs of variables: FEV1 and BMI (r = 0.567; p < 0.001); pharyngeal symptoms/airway protection and dyspnea (r = 0.408; p = 0.015); and esophageal symptoms/history of pneumonia and pharyngeal symptoms/airway protection (r = 0.531; p = 0.001). There was a negative correlation between nutritional symptoms and BMI (r = −0.046; p < 0.008). Conclusions: Our results show that the individuals with COPD presented with symptoms of dysphagia that were associated with the pharyngeal and esophageal phases of swallowing, as well as with the mechanism of airway protection, a history of pneumonia, and nutritional symptoms.

Keywords: Deglutition disorders; Pulmonary disease, chronic obstructive; Pathological conditions, signs and symptoms.

Objective: To determine the prevalence of atopy and to evaluate clinical, laboratory, and radiological profiles in patients with COPD. Methods: This was a cross-sectional study involving outpatients with stable COPD (defined by the clinical history and a post-bronchodilator FEV1/FVC < 70% of the predicted value). The patients completed a questionnaire regarding clinical characteristics and atopy, after which they underwent nasal lavage cytology, skin prick testing, chest X-rays, arterial blood gas analyses, and determination of total serum IgE. Results: Of the 149 subjects studied, 53 (35.6%), 49 (32.8%), and 88 (59.1%) presented with nasal eosinophilia, a positive skin prick test result, and symptoms of allergic rhinitis, respectively. Correspondence analysis confirmed these findings, showing two distinct patterns of disease expression: atopy in patients with COPD that was less severe; and no evidence of atopy in those with COPD that was more severe (reduced FEV1 and hyperinflation). There was a statistically significant association between nasal eosinophilia and a positive bronchodilator response. Conclusions: Using simple and reproducible methods, we were able to show that there is a high frequency of atopy in patients with COPD. Monitoring inflammation in the upper airways can be a useful tool for evaluating respiratory diseases in the elderly and in those with concomitant asthma and COPD, a clinical entity not yet fully understood.

Keywords: Pulmonary disease, chronic obstructive; Allergy and immunology; Nasal lavage fluid; Asthma; Rhinitis, allergic, perennial.

Objective: There are few studies on chronic obstructive pulmonary disease (COPD) establishing differences between the functional parameters of the disease and variants of sleep. The aim of the authors is to describe the sleep patterns of these patients and to investigate possible correlations among spirometric, gasometric, and polysomnographic variants. Methods: Transversal study using patients with COPD, submitted to spirometry, arterial gasometry, and polysomnography. Results: 21 male patients were studied with average age = 67 ± 9, 7 ± 4 average points in the Epworth sleep scale, average FEV1/FVC% = 54 ± 13.0, average PaO2 = 68 ± 11 mmHg, average PaCO2 = 37 ± 6 mmHg. Sleep efficiency decreased (65 ± 16%) with the decrease in slow wave sleep (8 ± 9%) and in rapid eye movement (REM) sleep (15 ± 8%). Average T90 = 43 ± 41%. Average apnea-hypopnea index (AHI) = 3 ± 5/h, two patients (9.5%) presented overlap syndrome. In the correlation analysis a correlation was observed between PaO2 and T90 (p < 0.01), PaCO2 and T90 (p < 0.05), and AHI and the cardiac rate in REM (p < 0.01). There was no correlation between spirometric and polysomnographic variants. Conclusion: The low sleep efficiency, the high number of awakenings, and shift in stages show the low quality of sleep. There were no linear correlations between the spirometric and polysomnographic variants.

Objective: To evaluate sleep-onset time variability, as well as sleep characteristics on weekday and weekend nights, in individuals with moderate-to-severe COPD. Methods: Sleep was objectively assessed by an activity/sleep monitor for seven consecutive nights in individuals with COPD. For analysis, individuals were divided into two groups according to sleep-onset time variability results, characterized by intrasubject standard deviation of sleep-onset time (SOTV) = 60 min or < 60 min. Results: The sample comprised 55 individuals (28 males; mean age = 66 ± 8 years; and median FEV1 % of predicted = 55 [38-62]). When compared with the SOTV<60min group (n = 24), the SOTV=60min group (n = 31) presented shorter total sleep time (5.1 ± 1.3 h vs. 6.0 ± 1.3 h; p = 0.006), lower sleep efficiency (73 ± 12% vs. 65 ± 13%; p = 0.030), longer wake time after sleep onset (155 ± 66 min vs. 115 ± 52 min; p = 0.023), longer duration of wake bouts (19 [16-28] min vs. 16 [13-22] min; p = 0.025), and higher number of steps at night (143 [104-213] vs. 80 [59-135]; p = 0.002). In general, sleep characteristics were poor regardless of the day of the week, the only significant difference being that the participants woke up about 30 min later on weekends than on weekdays (p = 0.013). Conclusions: Sleep-onset time varied over 1 h in a standard week in the majority of individuals with COPD in this sample, and a more irregular sleep onset indicated poor sleep quality both on weekdays and weekends. Sleep hygiene guidance could benefit these individuals if it is integrated with their health care.

Keywords: Pulmonary disease, chronic obstructive; Sleep; Actigraphy.

Objective: To infer the prevalence and variables predictive of isolated nocturnal hypoxemia and obstructive sleep apnea (OSA) in patients with COPD and mild hypoxemia. Methods: This was a cross-sectional study involving clinically stable COPD outpatients with mild hypoxemia (oxygen saturation = 90-94%) at a clinical center specializing in respiratory diseases, located in the city of Goiânia, Brazil. The patients underwent clinical evaluation, spirometry, polysomnography, echocardiography, arterial blood gas analysis, six-minute walk test assessment, and chest X-ray. Results: The sample included 64 patients with COPD and mild hypoxemia; 39 (61%) were diagnosed with sleep-disordered breathing (OSA, in 14; and isolated nocturnal hypoxemia, in 25). Correlation analysis showed that PaO2 correlated moderately with mean sleep oxygen saturation (r = 0.45; p = 0.0002), mean rapid eye movement (REM) sleep oxygen saturation (r = 0.43; p = 0.001), and mean non-REM sleep oxygen saturation (r = 0.42; p = 0.001). A cut-off point of PaO2 ≤ 70 mmHg in the arterial blood gas analysis was significantly associated with sleep-disordered breathing (OR = 4.59; 95% CI: 1.54-13.67; p = 0.01). The model showed that, for identifying sleep-disordered breathing, the cut-off point had a specificity of 73.9% (95% CI: 51.6-89.8%), a sensitivity of 63.4% (95% CI: 46.9-77.9%), a positive predictive value of 81.3% (95% CI: 67.7-90.0%), and a negative predictive value of 53.1% (95% CI: 41.4-64.4%), with an area under the ROC curve of 0.69 (95% CI: 0.57-0.80), correctly classifying the observations in 67.2% of the cases. Conclusions: In our sample of patients with COPD and mild hypoxemia, the prevalence of sleep-disordered breathing was high (61%), suggesting that such patients would benefit from sleep studies.

Keywords: Pulmonary disease, chronic obstructive/complications; Sleep wake disorders/epidemiology; Anoxia/etiology.

Objective: To evaluate the magnitude of diurnal changes in the parameters of pulmonary function and respiratory muscle strength/endurance in a sample of patients with COPD. Methods: A group of 7 patients underwent spirometry, together with determination of MIP and MEP, at two distinct times (between 8:00 and 8:30 a.m. and between 4:30 and 5:00 p.m.) on a single day. Between assessments, the patients remained at rest in the laboratory. Results: In accordance with the Global Initiative for Chronic Obstructive Pulmonary Disease staging system, COPD was classified as moderate, severe, and very severe in 1, 3, and 3 of the patients, respectively. From the first to the second assessment, there were significant decreases in FVC, FEV1, and MEP (of 13%, 15%, and 10%, respectively), as well as (less than significant) decreases in PEF, MIP, and maximal voluntary ventilation (of 9%, 3%, and 11%, respectively). Conclusions: In this sample of COPD patients, there were diurnal variations in the parameters of pulmonary function and respiratory muscle strength. The values of FEV1, FVC, and MEP were significantly lower in the afternoon than in the morning.

Keywords: Pulmonary disease, chronic obstructive; Respiratory function tests; Respiratory muscles.