Oxygen free radicals are molecules that present unpaired electrons in their outer orbit and can transform other molecules such as proteins, carbohydrates, lipids and deoxyribonucleic acid. Oxygen free radicals are produced in various clinical conditions in which hypoxic microenvironments are generated and reoxygenation follows. Such situations include clinical shock, septicemia, systemic inflammatory response, fulminant hepatitis, organ transplant and respiratory failure. In this review, we discuss the main concepts related to oxygen free radicals: the principal types and their formation, as well as the way in which they affect cellular structures and cause significant tissue damage. We present also the main antioxidants that guard against oxidative stress, including glutathione, glutathione peroxidase, superoxide dismutase, catalase, and N-acetylcysteine. The influence of oxygen free radicals on the principal pulmonary diseases are also discussed, with special emphasis given to oxygen free radicals in cigarette smoke, chronic obstructive pulmonary disease, asthma, sleep apnea syndrome and acute respiratory distress syndrome.

Keywords: Key words: Oxygen free radicals. Antioxidant substances. Oxidative stress. Lung diseases.

Objective: Assess the relationship between adherence to long-term oxygen therapy (LTOT) with mortality in patients with chronic obstructive pulmonary disease (COPD) and chronic respiratory failure and their clinical features. Methods: Longitudinal retrospective analysis of 254 patients with COPD and chronic respiratory failure from 2008 to 2016. At baseline, we evaluated the diagnosis, spirometry values, arterial blood gas analysis, blood count, pulse oximetry, body composition and health questionnaires (dyspnea, quality of life, anxiety and depression). For referred adherence analysis to LTOT we included 199 patients, divided according to prescription of oxygen: 12h/day (G1), 15h/day (G2) and 24h/day (G3). The cause of death and dates were studied over the five-year period. Results: In five years we identified 124 deaths (62.3%). No significant difference was found in mortality between the adherence groups (p=0.75) nor did we find differences in the clinical parameters evaluated. LTOT prescription was not associated with mortality (p=0.07). In Cox regression analysis, there was no association between mortality and non-adherence to LTOT (HR: 0.75; IC95%: 0.21-2.70). The risk of mortality was increased in G3 compared with G1 (HR: 7.16; IC 95%: 1.44-35.38) and in those with a higher depression score (HR: 1.35; IC: 1.14-1.59). Conclusion: No association was found between LTOT adherence and mortality in patients with COPD and respiratory failure. There were no clinical differences between the adherence groups.

Keywords: Chronic obstructive pulmonary disease; Oxygen therapy; Cooperation and treatment adherence; Morbidity and mortality indicators.

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension. Surgical biopsy was usually required for diagnostic confirmation. However, the morbidity, mortality and limited benefit of this procedure have generated discussion regarding noninvasive diagnostic techniques. We present the case of a female patient with progressive dyspnea, hypoxemia and pulmonary hypertension, the last diagnosed via catheterization. Computed tomography revealed septal thickening and diffuse micronodules. Bronchoalveolar lavage revealed occult alveolar hemorrhage. Treatment with an endothelin antagonist was started, resulting in symptomatic and functional improvement. Occult alveolar hemorrhage differentiates PVOD from idiopathic pulmonary hypertension. We believe that this finding, in combination with characteristic tomographic findings, is sufficient to establish a diagnosis of PVOD.

Keywords: Hypertension, pulmonary; Pulmonary veno-occlusive disease; Bronchoalveolar lavage; Receptors, endothelin/antagonists & inhibitors.

Recent studies have suggested an association between pulmonary arterial hypertension (PAH) and thyroid diseases (hypothyroidism and hyperthyroidism). This combination has a good prognosis, because the increase in the pulmonary artery pressure is usually slight and reverses after the treatment of the thyroid disease. Although the exact mechanism involved in the pathogenesis of this combination has not yet been established, it has been hypothesized that thyroid hormones and autoimmunity have a direct influence. Due to the high prevalence of thyroid disease in patients with PAH, thyroid function tests should be considered in the investigation of every patient with PAH. In this review, we describe the prevalence of PAH in patients with thyroid diseases and the prevalence of thyroid disease in patients with PAH, as well as addressing the principal effects that thyroid diseases have on the respiratory system. In addition, we report the treatment effects in patients with these diseases.

Keywords: Hypertension, pulmonary; Graves disease; Hyperthyroidism; Hypothyroidism; Thyroid hormones; Echocardiography.

Objective: To analyze the effects of the continuous positive airway pressure (CPAP), with 30% of FiO2 and in compressed air, used during the performance of submaximal physical activity on an ergometric treadmill. Materials and methods: Nine male individuals with COPD were submitted to physical activity on the ergometric treadmill using CPAP with 30% FiO2 .The authors evaluated the behavior of the spirometric parameters, the forced vital capacity (FVC), the forced expiratory volume in the first second (FEV1) before and after physical activity, the respiratory frequency (f), the arterial oxygen saturation (SaO2), the cardiac frequency (cf), the systolic arterial pressure (SAP), and the diastolic arterial pressure (DAP) at rest and during physical activity. Results and conclusion: Results have shown that, when using CPAP in both situations analyzed, there has been an increase in the FVC and a decrease in f and in cf with statistically significant difference (α = 0.05). SaO2 has showned a significantly higher mean when CPAP was used with 30% of FiO2 (α = 0.05). The FEV1, the SAP and DAP have maintained the same value in the statistical analyses.

Keywords: Exercise test. Forced expiratory volume. Vital capacity.

Chronic obstructive pulmonary disease is an inflammatory disease. Together with oxidant stimuli, which directly affect lung structures, macrophages, neutrophils and CD8+ lymphocytes actively participate in the pathogenesis of the disease and promote biochemical reactions that result in progressive alteration of the upper airways and irreversible lung remodeling. The release of substances promoted by inflammatory cell recruitment and by oxidative stress lead to a temporary imbalance in the pulmonary defense mechanisms. Understanding the long-term maintenance of this imbalance is key to understanding the current physiopathology of the disease. The present study explores the cellular and molecular alterations seen in chronic obstructive pulmonary disease.

Keywords: Pulmonary disease, chronic obstructive/physiopathology; Lung/metabolism; Inflammation; Oxydants; Antioxidants; Oxidative stress

Objective: To determine independent factors related to the use of oxygen and the oxygen flow rate in idiopathic pulmonary fibrosis (IPF) patients placed on a lung transplant waitlist and undergoing pulmonary rehabilitation (PR). Methods: This was a retrospective quasi-experimental study presenting functional capacity and health-related quality of life (HRQoL) data from lung transplant candidates with IPF referred for PR and receiving ambulatory oxygen therapy. The patients were divided into three groups on the basis of the oxygen flow rate: 0 L/min (the control group), 1-3 L/min, and 4-5 L/min. Data on functional capacity were collected by means of the six-minute walk test, and data on HRQoL were collected by means of the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36), being collected before and after 36 sessions of PR including aerobic and strength exercises. Results: The six-minute walk distance improved in all three groups (0 L/min: ? 61 m, p < 0.001; 1-3 L/min: ? 58 m, p = 0.014; and 4-5 L/min: ? 35 m, p = 0.031). Regarding HRQoL, SF-36 physical functioning domain scores improved in all three groups, and the groups of patients receiving ambulatory oxygen therapy had improvements in other SF-36 domains, including role-physical (1-3 L/min: p = 0.016; 4-5 L/min: p = 0.040), general health (4-5 L/min: p = 0.013), social functioning (1-3 L/min: p = 0.044), and mental health (1-3 L/min: p = 0.046). Conclusions: The use of ambulatory oxygen therapy during PR in lung transplant candidates with IPF and significant hypoxemia on exertion appears to improve functional capacity and HRQoL.

Keywords: Oxygen; Exercise therapy; Idiopathic pulmonary fibrosis; Rehabilitation; Quality of life.

We report the case of a patient with chronic obstructive pulmonary disease and bronchiectasis, chronically using corticosteroids, who acquired pulmonary nocardiosis, which presented as multiple cavitated nodules. The principal symptoms were fever, dyspnea and productive cough with purulent sputum. Chest X-ray and computed tomography of the chest revealed nodules, some of which were cavitated, in both lungs. Sputum smear microscopy and culture revealed the presence of Nocardia spp. The patient was treated with imipenem and cilastatin, which produced an excellent clinical response.

Keywords: Pulmonary disease, chronic obstructive; Nocardia infections; Bronchiectasis.

Objective: To evaluate the presence and severity of symptoms of anxiety and depression in individuals with asthma or chronic obstructive pulmonary disease. Methods: In order to evaluate symptoms of anxiety and depression, specific instruments of quantification (the State-Trait Anxiety Inventory and the Beck Depression Inventory, respectively) were administered to patients at an outpatient clinic for the treatment of asthma and chronic obstructive pulmonary disease. The population comprised 189 randomly and prospectively selected patients that were divided into three study groups (each with a different therapeutic objective): 40 patients with controlled asthma, 100 patients with uncontrolled asthma, and 49 patients with chronic obstructive pulmonary disease. Included among the variables studied, as part of the methodology, were symptoms of anxiety and depression. The data obtained were compared taking into consideration demographic and functional aspects, as well as the severity of the symptoms of anxiety and depression. Results: Among the asthma patients, the prevalence of moderate or severe anxiety was significantly higher than that observed among those with chronic obstructive pulmonary disease (p <  0.001). The uncontrolled asthma group presented significantly higher rates of depressive symptoms than did the controlled asthma group (p < 0.05). Conclusion: The frequency of symptoms of anxiety and depression is greater among asthma patients than among patients with chronic obstructive pulmonary disease, which can make clinical control difficult.

Keywords: Anxiety; Depression; Asthma; Pulmonary disease; Chronic obstructive

Objective: To determine cell profiles, as well as to identify CD4+ and CD8+ lymphocyte subgroups, in induced sputum (IS) and peripheral venous blood (PVB) of patients with chronic obstructive pulmonary disease (COPD). Methods: Total cell counts and counts of individual cell types, including CD4+ and CD8+ T lymphocytes, were determined in the IS and PVB of 85 subjects (38 with COPD without exacerbation, 29 smokers without obstruction and 18 nonsmokers). Mann-Whitney and Spearman non-parametric tests were used in the statistical analysis, and values of p < 0.05 were considered statistically significant. Results: Comparing the IS of subjects with COPD to that of nonsmokers, neutrophil, eosinophil and CD8+ T lymphocyte counts were higher (respectively p = 0.005, p < 0.05 and p < 0.05), whereas the percentage of macrophages was lower (p = 0.003). There were weak linear correlations (r2 < 0.1) between each cell type in IS and forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio. Eosinophil and CD8+ T lymphocyte counts were also higher in PVB (p = 0.04 and p = 0.02). Conclusions: In patients with stable COPD, CD8+ T lymphocyte counts were higher in PVB, whereas total leukocyte counts were similar to those of the other two groups analyzed, suggesting systemic inflammatory involvement. The CD8+ T lymphocyte count in blood can be a useful marker of systemic inflammation and can help identify smokers who already present a COPD inflammatory pattern.

Keywords: Sputum; T-lymphocytes; Neutrophils; Macrophages; Eosinophils; Pulmonary disease, chronic obstructive.

Behçet disease has been associated to pulmonary manifestations and may be lethal if not treated correctly. The authors describe a case of a 53 year-old male with aneurysmatic pulmonary artery dilatation, pulmonary hypertension, and hemoptysis. A review is presented about the diagnosis and the medical and surgical treatment of this disease.

Keywords: Behcet's syndrome. Pulmonary artery. Pulmonary hypertension. Aneurysm. Hemoptysis.

Objectives: To perform a review of the mechanisms involved in the origin of malnutrition in patients with chronic obstructive pulmonary disease (COPD) and a systematic review of randomized controlled studies to clarify the contribution of nutritional supplementation in patients with stable COPD. Methods: Systematic review of article published in this subject, in all languages from several sources, including Medline, Embase, Cinahl and Cochrane Registry in COPD, as well as studies presented in American and European. Results: Studies with nutritional supplementation longer than two weeks showed that the effect was not big and did not reach statistical significance. A study with linear regression showed that old age, relative anorexia, and high inflammatory response are associated with non-response to nutritional therapy. Conclusion: Currently, there is no evidence of the efficacy of nutritional supplementation in patients with COPD. Factors related to lack of response suggest a relationship with the degree of inflammation, including high levels of TNF alpha. Measuring inflammation markers may be useful to determine prognostic and adequate therapy. Treatment with anti-inflammatory cytokines or cytokine inhibitors are promising for the future.

Objective: To correlate the postbronchodilator (post-BD) inspiratory capacity (IC), % of predicted, with other markers of severity and prognostic factors in chronic obstructive pulmonary disease (COPD). Methods: Eighty stable patients with COPD performed forced vital capacity and slow vital capacity maneuvers, as well as the 6-min walk test, prior to and after receiving albuterol spray (400 μg). Patients were divided into four groups, based on post-BD forced expiratory volume in one second. Several variables were tested to establish correlations with the post-BD distance walked, using univariate and multivariate analysis. Post-BD IC was found to correlated with Global Initiative for Chronic Obstructive Lung Disease (GOLD) staging and with the Body mass index, airway Obstruction, Dyspnea, and Exercise capacity (BODE) index. Results: Multivariate regression analysis revealed that the distance walked, % predicted, correlated significantly with the IC post-BD, % predicted (p = 0.001), long-term oxygen use (p = 0.014), and number of medications used in the treatment (p = 0.044). IC ≤ 70% was observed in 56% patients in GOLD stages 3 or 4 vs. 20% in GOLD 1 or 2 (p < 0.001). IC ≤ 70% was observed in (60%) patients with BODE score 3 or 4 vs. (33%) BODE score 1 or 2 (p = 0.02). Conclusion: Post-BD IC% predicted is the best functional predictor of distance walked and is significantly associated with GOLD staging and BODE index. Therefore, We propose that the inspiratory capacity should be added to the routine evaluation of the COPD patients.

Keywords: Pulmonary disease, chronic obstructive; Walking; Respiratory function tests; Inspiratory capacity.

Objective: To compare the efficacy, safety, and tolerability of azithromycin and amoxicillin in the treatment of patients with infectious exacerbation of chronic obstructive pulmonary disease. Methods: This study was conducted at six medical centers across Brazil and included 109 patients from 33 to 82 years of age. Of those, 102 were randomized to receive either azithromycin (500 mg/day for three days, n = 49) or amoxicillin (500 mg every eight hours for ten days, n = 53). The patients were evaluated at the study outset, on day ten, and at one month. Based on the clinical evaluation of the signs and symptoms present on day ten and at one month, the outcomes were classified as cure, improvement, or treatment failure. The microbiological evaluation was made through the culture of sputum samples that were considered appropriate samples only after leukocyte counts and Gram staining. Secondary efficacy evaluations were made in order to analyze symptoms (cough, dyspnea, and expectoration) and pulmonary function. Results: There were no differences between the groups treated with azithromycin or amoxicillin in terms of the percentages of cases in which the outcomes were classified as cure or improvement: 85% vs. 78% (p = 0.368) on day ten; and 83% vs. 78% (p = 0.571) at one month. Similarly, there were no significant differences between the two groups in the secondary efficacy variables or the incidence of adverse effects. Conclusion: Azithromycin and amoxicillin present similar efficacy and tolerability in the treatment of acute exacerbation of chronic obstructive pulmonary disease.

Keywords: Amoxicillin/therapeutic use; Azithromycin/therapeutic use; Bronchitis, chronic/drug therapy;

Chronic obstructive pulmonary disease is characterized by progressive and partially reversible airway obstruction. The innumerable complications that occur during the progression of the disease can affect the nutritional state of patients suffering from this illness. The objective of this study was to present a brief review of the literature regarding the nutrition therapy used in the treatment of chronic obstructive pulmonary disease. To that end, we performed a bibliographic search for related articles published within the last 18 years and indexed for the Literatura Latinoamericana y del Caribe en Ciencias de la Salud (LILACS, Latin American and Caribbean Health Sciences Literature) and Medline databases. Malnutrition is associated with a poor prognosis for patients with chronic obstructive pulmonary disease, since it predisposes such patients to infections, as well as reducing respiratory muscle force, exercise tolerance and quality of life. Despite the fact that such malnutrition is extremely common in chronic obstructive pulmonary disease patients, it should be recognized as an independent risk factor, since it can be modified through appropriate and efficacious diet therapy and monitoring. For patients with chronic obstructive pulmonary disease, nutrition therapy is initiated after the evaluation of the nutritional state of the patient, which identifies nutritional risk, thereby allowing the proper level of treatment to be established. In this evaluation, anthropometric and biochemical markers, as well as indicators of dietary consumption and body composition, should be used. The prescribed diet should contain appropriate proportions of macronutrients, micronutrients and immunonutrients in order to regain or maintain the proper nutritional state and to avoid complications. The physical characteristics of the diet should be tailored to the individual needs and tolerances of each patient. In the treatment of patients with chronic obstructive pulmonary disease, individualized nutrition therapy is extremely important and has been shown to be fundamental to improving quality of life.

Keywords: Pulmonary disease, chronic obstructive; Nutrition assessment; Malnutrition; Nutrition therapy

Objective: To compare the behavior of the oxygen uptake efficiency slope (OUES) with that of oxygen uptake at peak exertion (VO2peak). Methods: This was a prospective cross-sectional study involving 21 patients (15 men) with mild-to-moderate COPD undergoing spirometry, handgrip strength (HGS) testing, cardiopulmonary exercise testing, and determination of lactate at peak exertion (LACpeak). Results: Mean weight was 66.7 ± 13.6 kg, and mean age was 60.7 ± 7.8 years. With the exception of FEV1 and FEV1/FVC ratio (75.8 ± 18.6% of predicted and 56.6 ± 8.8%, respectively), all spirometric variables were normal, as was HGS. The patients exhibited significant metabolic and hemodynamic stress, as evidenced by the means (% of predicted) for VO2peak (93.1 ± 15.4), maximum HR (92.5 ± 10.4), and OUES (99.4 ± 24.4), as well as for the gas exchange rate (1.2 ± 0.1). The correlation between VO2peak and OUES was significant (r = 0.747; p < 0.0001). The correlation between HGS and VO2peak (r = 0.734; pX< 0.0001) was more significant than was that between HGS and OUES (r = 0.453; p < 0.05). Similar results were found regarding the correlations of VO2peak and OUES with MIP. Although LACpeak correlated significantly with VO2peak (r = −0.731; p < 0.0001), only LACpeak/maximum power correlated significantly with OUES (r = −0.605; p = 0.004). Conclusions: Our findings suggest that, in mild-to-moderate COPD, VO2 determinants other than overall muscle strength have a greater impact on OUES than on VO2peak.

Keywords: Respiratory function tests; Pulmonary disease, chronic obstructive; Muscle strength; Oxygen consumption.