Paid employment in subjects with and without chronic obstructive pulmonary disease in five Latin American cities: the PLATINO study.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a costly condition that frequently causes permanent work disabilities. Little information exists regarding the impact of COPD on work force participation and the indirect costs of the disease in developing countries. OBJECTIVE: To examine the frequency of paid employment and factors influencing it in a Latin-American population-based study. METHODS: Post-bronchodilator FEV(1)/FVC < 0.70 (forced expiratory volume in 1 s/forced vital capacity) was used to define COPD. Information regarding paid work was assessed by the question 'At any time in the past year, have you worked for payment?' RESULTS: Interviews were conducted with 5571 subjects; 5314 (759 COPD and 4554 non-COPD) subjects underwent spirometry. Among the COPD subjects, 41.8% reported having paid work vs. 57.1% of non-COPD (P < 0.0001). The number of months with paid work was reduced in COPD patients (10.5 ± 0.17 vs. 10.9 ± 0.06, P < 0.05). The main factors associated with having paid work in COPD patients were male sex (OR 0.33, 95%CI 0.23-0.47), higher education level (OR 1.05, 95%CI 1.01-1.09) and younger age (OR 0.90, 95%CI 0.88-0.92). COPD was not a significant contributor to employment (OR 0.83, 95%CI 0.69-1.00, P = 0.054) in the entire population. CONCLUSIONS: Although the proportion of persons with paid work is lower in COPD, having COPD appears not to have a significant impact on obtaining paid employment in the overall population of developing countries.

Sex-related differences in COPD in five Latin American cities: the PLATINO study.

There is evidence to suggest sex differences exists in chronic obstructive pulmonary disease (COPD) clinical expression. We investigated sex differences in health status perception, dyspnoea and physical activity, and factors that explain these differences using an epidemiological sample of subjects with and without COPD. PLATINO is a cross-sectional, population-based study. We defined COPD as post-bronchodilator forced expiratory volume in 1 s/forced vital capacity ratio <0.70, and evaluated health status perception (Short Form (SF)-12 questionnaire) and dyspnoea (Medical Research Council scale). Among 5,314 subjects, 759 (362 females) had COPD and 4,555 (2,850 females) did not. In general, females reported more dyspnoea and physical limitation than males. 54% of females without COPD reported a dyspnoea score ≥ 2 versus 35% of males. A similar trend was observed in females with COPD (63% versus 44%). In the entire study population, female sex was a factor explaining dyspnoea (OR 1.60, 95%CI 1.40-1.84) and SF-12 physical score (OR -1.13, 95%CI -1.56- -0.71). 40% of females versus 28% of males without COPD reported their general health status as fair-to-poor. Females with COPD showed a similar trend (41% versus 34%). Distribution of COPD severity was similar between sexes, but currently smoking females had more severe COPD than currently smoking males. There are important sex differences in the impact that COPD has on the perception of dyspnoea, health status and physical activity limitation.

Worldwide burden of COPD in high- and low-income countries. Part II. Burden of chronic obstructive lung disease in Latin America: the PLATINO study.

SETTING: Five Latin American cities: São Paulo, Brazil; Mexico City, Mexico; Montevideo, Uruguay; Santiago, Chile; Caracas, Venezuela. OBJECTIVE: To describe the burden of chronic obstructive pulmonary disease (COPD) in Latin America. DESIGN: This is a multicentre study. Post-bronchodilator spirometry was used and the main outcome measure was FEV(1)/FVC < 0.7 (fixed ratio criterion). Global Obstructive Lung Disease (GOLD) stages were also analysed. RESULTS: The combined population aged > or =40 years in the five countries included in the study was approximately 85.3 million. Of these, it was estimated that 12.2 million have airflow obstruction, which corresponds to our prevalence estimate of 14.3%. The proportion of subjects in Stages II-IV of the GOLD classification was 5.6%. Risk factors presenting the highest aetiological fractions for COPD were age, current smoking, indoor exposure to coal and exposure to dust in the workplace. Smoking, the modifiable factor with the strongest aetiological fraction for COPD, affects 29.2% of adults aged > or =40 years in these cities, corresponding to approximately 25 million smokers in this age group. CONCLUSION: Prevention of smoking and exposure to pollutants, such as coal and dust, are the interventions most likely to succeed against COPD in Latin America. The information obtained by a collaborative study has been vast and encouraging for other similar studies.

Tuberculosis and airflow obstruction: evidence from the PLATINO study in Latin America.

The aim of the present study was to evaluate the association between history of tuberculosis and airflow obstruction. A population-based, multicentre study was carried out and included 5,571 subjects aged > or =40 yrs living in one of five Latin American metropolitan areas: Sao Paulo (Brazil); Montevideo (Uruguay); Mexico City (Mexico); Santiago (Chile); and Caracas (Venezuela). Subjects performed pre- and post-bronchodilator spirometry and were asked whether they had ever been diagnosed with tuberculosis by a physician. The overall prevalence of airflow obstruction (forced expiratory volume in one second/forced vital capacity post-bronchodilator <0.7) was 30.7% among those with a history of tuberculosis, compared with 13.9% among those without a history. Males with a medical history of tuberculosis were 4.1 times more likely to present airflow obstruction than those without such a diagnosis. This remained unchanged after adjustment for confounding by age, sex, schooling, ethnicity, smoking, exposure to dust and smoke, respiratory morbidity in childhood and current morbidity. Among females, the unadjusted and adjusted odds ratios were 2.3 and 1.7, respectively. In conclusion, history of tuberculosis is associated with airflow obstruction in Latin American middle-aged and older adults.

Prevalence of oxygen desaturation and use of oxygen at home in adults at sea level and at moderate altitude.

The aim of this study was to determine the prevalence of oxygen desaturation in adults aged>or=40 yrs as altitude above sea level increases. A population-based, cross-sectional study with a multistage cluster sampling of 1,063 subjects from metropolitan Mexico City (Mexico; 2,240 m above sea level), 1,357 from Caracas (Venezuela; 950 m) and 943 from Montevideo (Uruguay; 35 m). The mean of six measurements of arterial oxygen saturation (SP,O2) was estimated using a pulse oximeter. Mean SP,O2 decreased with altitude. No subject from Montevideo had a mean SP,O288%. In conclusion, the prevalence of hypoxaemia was closely related to altitude. Priorities for oxygen prescription must be defined in moderate altitudes because it is unfeasible to provide it to all subjects fulfilling the criteria commonly used.

Skeletal muscle inflammation and nitric oxide in patients with COPD.

In chronic obstructive pulmonary disease (COPD) the presence of systemic inflammation has been associated with peripheral muscle abnormalities and weight loss. To study whether inflammatory factors are important in these processes, the present study compared the skeletal muscle levels of nitrite, nitrate, nitrotyrosine, neuronal, endothelial and inducible nitric oxide synthases (nNOS, eNOS, and iNOS, respectively), and inflammatory markers (tumour necrosis factor (TNF)-alpha, CD154 and CD163) in 15 patients (forced expiratory volume in one second 43+/-11%) and 14 controls. All these markers were also compared between patients with normal and low body weight. Nitrite (12.5+/-2.6 versus 17.0+/-3.4 micromol.mg(-1) protein), nitrate (20.7+/-2.4 versus 24.4+/-4.5 micromol.mg(-1) protein) and eNOS (31.9+/-4.6 versus 43.6+/-7.5 ng.mg(-1) protein) were lower in COPD patients than in controls. Nitrotyrosine (25.6+/-5.4 versus 6.6+/-3.3 ng.mg(-1) protein), iNOS expression (32+/-9.5 versus 7.16+/-2.7 ng.mg(-1) protein), TNF-alpha (257+/-160 versus 48.3+/-4.4 pg.mg(-1) protein) and CD163 (6.4+/-2.1 versus 0.8+/-0.4 ng.mg(-1) protein) were higher in COPD patients than in controls. CD154 levels were 15.7+/-7.0 ng.mg(-1) protein in COPD patients and undetectable in controls. Similar levels of all these markers were observed in COPD patients with normal and low body weight. In conclusion, these findings suggest the presence of an inflammatory process in the muscle tissue of chronic obstructive pulmonary disease patients, and argue in favour of its participation in the pathogenesis of skeletal muscle abnormalities.

[Changes in exercise tolerance, health related quality of life, and peripheral muscle characteristics of chronic obstructive pulmonary disease patients after 6 weeks' training]. / Cambios en la tolerancia al ejercicio, calidad de vida relacionada con la salud y características de los músculos periféricos después de 6 semanas de entrenamiento en pacientes con EPOC.

OBJECTIVE: This study was designed to assess changes in skeletal muscle characteristics after 6 weeks' high-intensity physical training of patients with moderate to severe chronic obstructive pulmonary disease (COPD) and to determine how the changes were related to improvements in exercise tolerance and health related quality of life (HRQL). PATIENTS AND METHODS: Ten patients with a mean (SD) age of 60 (10) years and a forced expiratory volume in 1 second of 32% (9%) were enrolled. The effect of training on the 6-minute walk test, HRQL questionnaires, and skeletal muscles was examined for the 8 patients who completed the program. The structural and chemical characteristics of skeletal muscles before and after training were studied in vastus lateralis muscle biopsies. RESULTS: Training significantly modified the 6-minute walk test (P<.01), HRQL (P<.05), and citrate synthetase activity (P<.05). Changes in distances walked during the 6-minute walk test were significantly related to changes in the mean area of fibers (r=0.81). CONCLUSIONS: The results of this study indicate that 6 weeks of high-intensity physical training of COPD patients produces moderate changes in skeletal muscles which could partly explain improvements observed in exercise tolerance after respiratory rehabilitation.

[Evaluation of exercise tolerance in patients treated with praziquantel for chronic schistosomiasis with no signs of cardiopulmonary impairment]. / Evaluación de la tolerancia al ejercicio en pacientes con shistosomiasis crónica sin evidencias clínicas de compromiso cardiopulmonar tratados con praziquantel.

OBJECTIVE: The purpose of this study was to evaluate whether a progressive cycle ergometer test (PCET) can detect minimal functional abnormalities that might indicate compromise of the pulmonary vascular bed in patients treated with praziquantel for chronic schistosomiasis who have no clinical signs of cardiopulmonary impairment. PATIENTS AND METHOD: We studied 9 patients (whose mean (SD) age was 38 (18) years and 10 control subjects aged 32 (14) years. Both groups were evaluated by spirometry and a PCET to determine maximum oxygen consumption, heart rate, minute ventilation and gas exchange. Echocardiograms were used to rule out the presence of associated heart disease. RESULTS: Lung function was similar among patients and controls. Slight decreases in maximum oxygen consumption and heart rate reserve were observed with effort during the PCET, with normal respiratory response. No echocardiographic abnormalities that might indicate the presence of pulmonary vascular occlusive disease were observed. CONCLUSIONS: The results showed that the resting lung function is normal in these patients. However, there was a slight decrease in exercise tolerance, probably related to physical detraining. The data obtained during exercise indicated that pulmonary vascular occlusive disease is unlikely in these patients. Abnormalities may appear in later stages of the disease or in patients who do not receive early medical treatment.

Bronchial sensitivity to histamine in former asthmatics: redevelopment of symptoms during a year of followup.

The aim of this protocol was to study bronchial responsiveness in 23 former asthmatics who were free of symptoms for at least 5 years. Bronchial hyperreactivity (BHR) was evaluated with histamine challenge test and the results were compared with those of 20 normal subjects and 20 current asthmatic patients. Among the former asthmatics 65% fulfilled the criteria of BHR. During 1 year of followup, two former asthmatics redeveloped asthma symptoms. Interestingly, one patient had no BHR when initially tested. These findings suggest that the absence of BHR does not guarantee the nonrecurrence of asthma symptoms in former asthmatics.

Characterization of local memory cells in stage-classified pulmonary tuberculosis: preliminary observations.

Immunophenotype analysis and proliferative responses were investigated in bronchoalveolar lavage (BAL) cells from 21 patients with stage-classified tuberculosis: six with localized pulmonary infiltrate (LPI); seven with diffuse pulmonary infiltrate (DPI); and eight with pleural effusions (PE). Bronchoalveolar lavage cells from these patients contained a high number of cells/ml. The macrophage number was significantly lower in the DPI group (P < 0.05) compared to the LPI or PE groups. Conversely, neutrophils were markedly increased in DPI patients compared to LPI (P < 0.01) and PE (P < 0.01) patients. Lymphocyte infiltration (97.7 +/- 2.3% CD3+, > 83% alphabeta+ and CD4+ > CD8+) was observed in the three groups. A significant increase in the number of total lymphocytes (P < 0.01) and CD4+ cells (P < 0.05) was observed in the LPI group compared to the PE group. In the LPI group CD4+CD45RO+ cell infiltration was higher than CD4+CD45RA+ cells (P < 0.001), contrasting to similar numbers of these subpopulations in the DPI group. Lymphocytes from three out of three LPI patients (alphabeta+CD4+CD45RO+) responded against tuberculin purified protein derivative contrasting to the unresponsiveness of five patients with either DPI or PE. This impaired response was reverted in two out of five patients by using peripheral blood monocytes instead of alveolar macrophages. It is suggested that, in humans, alphabetaCD4+CD45RO cells are the main lymphocyte type involved in the initial local cell-mediated immune response against Mycobacterium tuberculosis.

[Liver cirrhosis: pulmonary function]. / Cirrosis hepática: función pulmonar.

We performed a functional respiratory examination which consisted of arterial gasometry, spirometry, diffusion capacity to CO2, alveolo-arterial gradient of O2 and pulmonary volumes to 8 patients with cirrhosis diagnosed by clinical history, laboratory exams, abdominal ultrasound and histology. Our results showed a slight obstructive pattern of peripheric airways (FMM: 88.87 +/- 8.7%) in the spirometry, no difference in arterial gases at upright and recumbent position was observed, with low values of apO2 (75.51 +/- 1.16 upright and 75.87 +/- 2.16 mmHg recumbent) without statistic significance. The gradient G(Aa) O2 increased to (30.89 +/- 1.06 mmHg). Besides there was a diffusion abnormality with a DLCO2/VA of (71.87 +/- 6.05%). Breathing 100% O2, did not change the gradient which allows us to postulate the existence of an abnormality of gaseous interchange due to shunts. We found no relationship between albumin levels and DLCO2/VO neither with pO2 in upright position; there was a relationship at recumbent position between the hepatic disorder and the arterial desaturation. We concluded that there is no significant hypoxia even with position changes, there is increase of G (Aa) O2 by shunt type disorders and that this is probably related with albumin levels.

Work of breathing in patients with chronic obstructive pulmonary disease in acute respiratory failure.

In 11 spontaneously breathing patients with chronic obstructive pulmonary disease (COPD) in acute ventilatory failure, we measured the total inspiratory (WItot) and total resistive (WI + Eres) work rate of breathing, together with lung mechanics (dynamic pulmonary elastance and inspiratory and expiratory pulmonary flow resistance). All variables were markedly increased compared with those in normal subjects. No significant correlation was found between WItot and WI + Eres with lung mechanics data. However, when WItot and WI + Eres were expressed per liter of ventilation, a significant positive correlation was found with all lung mechanics data. These results indicate that although in patients acutely ill with COPD, work rate and work per liter of ventilation are increased, only the latter is related to the severity of pulmonary mechanical impairment, and it could be used as one of the criteria for extubation. In addition, our results indicate that at end-expiration the alveolar pressure was positive (range, 6 to 13 cm H2O) in all patients (intrinsic PEEP), a fact that must necessarily affect hemodynamics; furthermore, it imposes an extra burden on the inspiratory muscles.

Effect of carbon dioxide on diaphragmatic function in human beings.

We studied the effects of acute changes in the partial pressure of arterial carbon dioxide on diaphragmatic contractility and performance in four normal men. To study contractility we measured the ability of the diaphragm to generate pressure at a given level of excitation by determining the relation between the electrical activity of the diaphragm and transdiaphragmatic pressure during a voluntary quasi-isometric inspiratory effort carried out at different levels of end-tidal carbon dioxide. Our results show that contractility was reduced with hypercapnia (when end-tidal carbon dioxide was 7.5 per cent or higher), although hypocapnia (end-tidal carbon dioxide, 3 per cent) had no effect on diaphragmatic contractility. We also studied the development of diaphragmatic fatigue before and during carbon dioxide breathing. Subjects were studied at the same diaphragmatic tension-time index, a value analogous to the more familiar myocardial tension-time index, while the same inspiratory flow was maintained. Electromyographic signs of fatigue appeared at a lower tension-time index during hypercapnia than during normocapnia, indicating that endurance is diminished during hypercapnia. These findings show that acute respiratory acidosis equivalent to an arterial carbon dioxide tension of about 54 mm Hg decreases the contractility and endurance time of the diaphragm in human beings.

Effects of aminophylline on diaphragmatic fatigue during acute respiratory failure.

The effects of aminophylline on diaphragmatic fatigue and recovery in the face of hypoxemia and hypercapnic acidosis were studied in anesthetized, spontaneously breathing, dogs. The phrenic nerves were stimulated supramaximally at 10, 20, 50, and 100 Hz during 2 s with electrodes placed around the fifth roots, and the resulting transdiaphragmatic pressure (Pdi) was measured with balloon catheters. The dogs were occluded before the stimulations at functional residual capacity. The latter was monitored by measuring the end-expiratory transpulmonary pressure, which remained constant throughout the experiment. Diaphragmatic fatigue was produced by resistive loaded breathing. At the end of the runs, which lasted 15 +/- 2 min, all the dogs were severely hypoxemic (30 +/- 5 mmHg), hypercapnic (65 +/- 4 mmHg), and acidotic (7.1 +/- 0.05). During the fatigue runs, phrenic stimulation resulted in a marked decrease in Pdi, which amounted at 20 Hz to 70 +/- 8% and 45 +/- 12% of the control values 5 min after the onset of the fatigue runs and at the end, respectively. After recovery (3 h), Pdi and arterial blood gas determinations returned to control values. Identical fatigue runs were repeated with aminophylline infusion (loading dose, 6 mg/kg in 10 min and maintenance dose, 1 mg/kg/h), leading to a plasmatic concentration of 16.4 +/- 2 mg/l. Aminophylline protected the diaphragm against fatigue, and despite the presence of hypoxemia and hypercapnic acidosis, the Pdi generated for a 20 Hz stimulation of the phrenic nerves at identical times of the preceding run amounting to 100 +/- 15% and 85 +/- 10% of control values, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)