Brazilian Journal of Pulmonology

ISSN (on-line): 1806-3756 | ISSN (printed): 1806-3713

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Using the forced oscillation technique to evaluate respiratory resistance in individuals with silicosis

Avaliação das características resistivas do sistema respiratório de indivíduos portadores de silicose pela técnica de oscilações forçadas

Jayme Alves de Mesquita Júnior, Agnaldo José Lopes, José Manoel Jansen, Pedro Lopes de Melo

J Bras Pneumol.2006;32(3):213-220

Abstract PDF PT PDF EN Portuguese Text

Objective: To evaluate the resistance values obtained through the use of the forced oscillation technique in patients with varying degrees of airway obstruction resulting from silicosis. Methods: A total of 40 never-smoking volunteers were analyzed: 10 were healthy subjects with no history of pulmonary disease or silica exposure, and 30 had silicosis. The forced oscillation technique was used to examine the subjects, and spirometry was used as a reference in order to classify the obstruction by degree. This classification resulted in five groups: control (n = 10); normal exam, composed of individuals diagnosed clinically and radiologically with silicosis but presenting normal spirometry results (n = 7); mild obstruction (n = 10); moderate obstruction (n = 8); and severe obstruction (n = 5). Results: The reduction observed in the spirometric values corresponded to a significant increase in the total respiratory resistance (p < 0.001), as well as in airway resistance (p < 0.003). A significant reduction in ventilation homogeneity was also observed (p < 0.004). Conclusion: In individuals with silicosis, the additional respiratory resistance-related data obtained through the use of the forced oscillation technique can complement spirometric data. Therefore, the forced oscillation technique presents great potential for the analysis of such patients.

 


Keywords: Pneumoconiosis; Silicosis; Forced expiratory volume; Oscillometry; Respiratory function tests

 


Analysis of the ventilatory mechanics by forced oscillations technique: main concepts and clinical applications

Avaliação de mecânica ventilatória por oscilações forçadas: fundamentos e aplicações clínicas

Pedro Lopes de Melo, Marcelo Martins Werneck, Antonio Giannella-Neto

J Bras Pneumol.2000;26(4):194-206

Abstract PDF PT

Requesting passive cooperation from the patient and supplying new parameters for the analysis of the ventilatory mechanics, the forced oscillations technique (FOT) has complementary characteristics to the classical methods of lung evaluation. In this work, a review of the principles of this technique is initially presented together with a discussion about its advantages and present limitations. The performance of the technique is compared to classical methods in the detection of breathing disorders. The main clinical applications reported previously in the literature, including the evaluation of the ventilatory mechanics in children, studies in neonates, monitoring of patients under mechanical ventilation, occupational medicine, and evaluation of respiratory sleep disturbances are reviewed and discussed. Based on this review and on the results obtained in studies made in their laboratory, the authors concluded that FOT could render a more detailed examination and facilitate the accomplishment of lung function tests under conditions in which traditional techniques are not appropriate.

 


Keywords: respiratory mechanics, oscillometry, respiratory function tests

 


Bronchodilation in COPD: beyond FEV1-the effect of albuterol on resistive and reactive properties of the respiratory system

Broncodilatação na DPOC: muito além do VEF1-efeito do salbutamol nas propriedades resistivas e reativas do sistema respiratório

Gerusa Marítimo da Costa, Alvaro Camilo Dias Faria, Ana Maria Gonçalves Tavares Di Mango, Agnaldo José Lopes, José Manoel Jansen, Pedro Lopes de Melo

J Bras Pneumol.2009;35(4):325-333

Abstract PDF PT PDF EN Portuguese Text

Objective: Current debates on the bronchodilator response in COPD patients and whether the variation in FEV1 can be considered as an indicator of complete reversibility in such patients motivated us to conduct this study. The objective of the study was to determine the effect of albuterol on the resistive and reactive properties of the respiratory system in COPD patients. Methods: We evaluated 70 patients with COPD, divided into two groups based on spirometry findings: bronchodilator (BD)-negative (n = 39); and BD-positive (n = 31). We used the forced oscillation technique (FOT) to evaluate the following parameters: resistance at the intercept (R0), associated with the total resistance of the respiratory system; mean resistance (Rm), associated with central airway resistance; dynamic compliance (Cdyn); and the slope of resistance (S) and mean reactance (Xm), both of which are associated with the homogeneity of the respiratory system. Results: The use of albuterol resulted in significant reductions in R0 (p < 0.00002) and Rm (p < 0.0002). There were also significant increases in S (p < 0.0001), Cdyn (p < 0.0001) and Xm (p < 0.00004). These modifications occurred in both groups, the changes in FOT parameters being greater than those observed for spirometric parameters. Conclusions: The use of albuterol improved the resistive and reactive properties of the respiratory system of the COPD patients under study. These changes occurred regardless of the FEV1-based classification, thereby indicating that the use of this parameter in isolation might not suffice to identify the physiological effects involved.

 


Keywords: Pulmonary disease, chronic obstructive; Bronchodilator agents; Spirometry; Albuterol.

 


Correlation of tomographic findings with pulmonary function parameters in nonsmoking patients with idiopathic pulmonary fibrosis

Correlação dos achados tomográficos com parâmetros de função pulmonar na fibrose pulmonar idiopática em não fumantes

Agnaldo José Lopes, Domenico Capone, Roberto Mogami, Daniel Leme da Cunha, Pedro Lopes de Melo, José Manoel Jansen

J Bras Pneumol.2007;33(6):671-678

Abstract PDF PT PDF EN Portuguese Text

Objective: To correlate tomographic findings with pulmonary function parameters in patients with idiopathic pulmonary fibrosis (IPF). Methods: A cross-sectional study was carried out, in which 30 nonsmoking patients with IPF were evaluated. Using a semiquantitative scoring system, the following high-resolution computerized tomography (HRCT) findings were quantified: total interstitial disease (TID), reticular abnormality/honeycombing, and ground-glass opacity (GGO). The functional variables were measured by spirometry, forced oscillation technique (FOT), helium dilution method, as well as the single-breath method of measuring diffusion capacity of the lung for carbon monoxide (DLCO). Results: Of the 30 patients studied, 18 were female, and 12 were male, with a mean age of 70.9 years. We found that TID and reticular abnormality and honeycombing correlated significantly (negative correlations) with the measurements of forced vital capacity (FVC), total lung capacity (TLC), DLCO, and dynamic respiratory compliance were found, as well as that GGO correlated significantly (and positively) with residual volume/TLC. The ratio of forced expiratory flow between 25 and 75% of FVC to FVC (FEF25-75%/FVC) correlated positively with TID, reticular abnormality/honeycombing, and GGO. Conclusion: In IPF patients, the measurements of volume, diffusion, and dynamic compliance are the physiological variables which best reflect the extent of the interstitial disease on HRCT scans.

 


Keywords: Lung diseases, interstitial; Pulmonary fibrosis; Tomography, X-ray computed; Respiratory function tests.

 


Effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of patients with asthma

Efeito da obstrução de vias aéreas nas variações das propriedades resistivas e elásticas do sistema respiratório de asmáticos, mediadas pelo uso de salbutamol

Juliana Veiga, Agnaldo José Lopes, José Manoel Jansen, Pedro Lopes de Melo

J Bras Pneumol.2009;35(7):645-652

Abstract PDF PT PDF EN Portuguese Text

Objective: To investigate the effects of airway obstruction on albuterol-mediated variations in the resistive and elastic properties of the respiratory system of adult patients with asthma. Methods: This study comprised 24 healthy controls and 69 patients with asthma, all of whom were nonsmokers. The patients were divided into three groups according to the severity of airway obstruction (mild, moderate or severe). Each of the three groups was divided into two subgroups according to the bronchodilator response (BR): positive (BR+) or negative (BR−). These measurements were conducted before and after albuterol use (300 µg). Airway obstruction was determined by means of spirometry, and the resistive and elastic properties were determined by means of the forced oscillation technique. Results: The resistance at the intercept (R0) presented greater reductions in the groups with higher obstruction. This reduction was more evident in the BR+ subgroups than in the BR− subgroups (p < 0.02 and p < 0.03, respectively). There was a significant difference between the control group and the BR+ subgroup with severe obstruction (p < 0.002). The reductions in dynamic elastance (Edyn) were significantly greater in proportion to the degree of obstruction, in the BR− subgroups (p < 0.03), and in the BR+ subgroups (p < 0.003). The reductions in Edyn were significantly greater in the BR− subgroup with moderate obstruction (p < 0.008) and in the BR+ subgroup with severe obstruction (p < 0.0005) than in the control group. Conclusions: In patients with asthma, increased airway obstruction results in greater reductions in R0 and Edyn after albuterol use. These reductions are greater among BR+ patients than among BR− patients.

 


Keywords: Asthma; Bronchodilator agents; Respiratory mechanics; Spirometry; Albuterol.

 


Using the forced oscillation technique to evaluate bronchodilator response in healthy volunteers and in asthma patients presenting a verified positive response

Técnica de oscilações forçadas na análise da resposta broncodilatadora em voluntários sadios e indivíduos portadores de asma brônquica com resposta positiva

Juliana Veiga Cavalcanti, Agnaldo José Lopes, José Manoel Jansen, Pedro Lopes de Melo

J Bras Pneumol.2006;32(2):91-98

Abstract PDF PT PDF EN Portuguese Text

Objective: To use the forced oscillation technique to evaluate asthma patients presenting positive bronchodilator responses (confirmed through spirometry) and compare the results with those obtained in healthy individuals. Methods: The study sample consisted of 53 non-smoking volunteers: 24 healthy subjects with no history of pulmonary disease and 29 asthmatics presenting positive bronchodilator response, as determined through analysis of spirometry findings. All of the subjects were submitted to forced oscillation technique and spirometry immediately before and 20 minutes after the administration of salbutamol spray (300 g). The parameters derived from the forced oscillation technique were total respiratory resistance, total respiratory reactance, resistance extrapolated to the y axis, the slope of resistance, and dynamic compliance. The parameters measured in the spirometry evaluation tests were forced expiratory volume in one second and forced vital capacity. Results: In the control group, bronchodilator use produced a significant alteration in the resistance extrapolated to the y axis (p < 0.001), although no significant differences were observed in the slope of resistance or in dynamic compliance. Analysis of the asthma patients revealed significant differences between the prebronchodilator and postbronchodilator values for all spirometry and forced oscillation technique parameters. Values of p < 0.001 were obtained for all comparisons between the two groups. Conclusion: The modifications provoked by use of the forced oscillation technique were in direct concordance with the pathophysiology of the bronchodilator response in asthma patients, indicating that the forced oscillation technique could be useful as a complement to spirometry in these patients.

 


Keywords: Asthma; Bronchial hyperreactivity; Spirometry/methods; Bronchial provocation tests; Forced expiratory volume/physiology; Oscillometry

 


High-resolution computed tomography in silicosis: correlation with chest radiography and pulmonary function tests

Tomografia computadorizada de alta resolução na silicose: correlação com radiografia e testes de função pulmonar

Agnaldo José Lopes, Roberto Mogami, Domenico Capone, Bernardo Tessarollo, Pedro Lopes de Melo, José Manoel Jansen

J Bras Pneumol.2008;34(5):264-272

Abstract PDF PT PDF EN Portuguese Text

Objective: To correlate tomographic findings with pulmonary function findings, as well as to compare chest X-ray findings with high-resolution computed tomography (HRCT) findings, in patients with silicosis. Methods: A cross-sectional study was conducted in 44 non-smoking patients without a history of tuberculosis. Chest X-ray findings were classified according to the International Labour Organization recommendations. Using a semiquantitative system, the following HRCT findings were measured: the full extent of pulmonary involvement; parenchymal opacities; and emphysema. Spirometry and forced oscillation were performed. Pulmonary volumes were evaluated using the helium dilution method, and diffusing capacity of the lung for carbon monoxide was assessed. Results: Of the 44 patients studied, 41 were male. The mean age was 48.4 years. There were 4 patients who were classified as category 0 based on X-ray findings and as category 1 based on HRCT findings. Using HRCT scans, we identified progressive massive fibrosis in 33 patients, compared with only 23 patients when X-rays were used. Opacity score was found to correlate most closely with airflow, DLCO and compliance. Emphysema score correlated inversely with volume, DLCO and airflow. In this sample of patients presenting a predominance of large opacities (75% of the individuals), the deterioration of pulmonary function was associated with the extent of structural changes. Conclusions: In the early detection of silicosis and the identification of progressive massive fibrosis, HRCT scans are superior to X-rays.

 


Keywords: Silicosis; Occupational diseases; Tomography, x-ray computed; Respiratory function tests.

 


 

 


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