摘要:

Emphysema is believed to result from destruction of elastic fibers due to an imbalance between proteases and their inhibitors in the lung. The imbalance can arise from a primary failure of secretion of the inhibitors. as occurs in hereditary alpha-I-protease inhibitor deficiency, or as the result of complex interactions of environmental agents with the lung. Environmental agents may produce their effects by stimulating degradation of elastic fibers by neutrophils and macrophages, damaging protease inhibitors by oxidative or proteolytic mechanisms or by impairing the biosynthetic repair of damage to the connective tissue.Protease excess has also been consistently observed in purulent sputum. Since experimentally administered proteases stimulate secretion of mucus and damage mucociliary clearance, protease – antiprotease imbalance might be involved in the pathogenesis of bronchitis and bronchiectasis as well as emphysema. Because the protease inhibitors of bronchial mucus are distinct from those of the acinar units, and no hereditary deficiencies are known, there is no direct proof of this hypothesis in man.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The anatomy and pathophysiology of obstructive airways diseases are reviewed, with emphasis on the pivotal functional roles of the respiratory and terminal bronchioles. The array of radiologic findings associated with abnormal airways, large or small, is correlated with gross pathologic changes, using surgical and autopsy cases. Examples of inflammatory changes of smaller airways are also drawn from pathologically unproven clinical material. Peripheral linear and nodular densities, which can be distinguished from vascular shadows or septal lines, are seen in association with small bronchial and bronchiolar inflammation. In many cases it is possible to distinguish airways disease patterns from those of “alveolar” or “interstitial” disease.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Asthma is a common disease characterized by hyperreactivity of airways to a variety of stimuli Efficacy studies have shown that while in adults there is no positive predictive value between radiographic abnormalities and certain clinical parameters, in children there may be some correlation with age and the presence of rates. In the Yale – New Haven Emergency Service it is suggested that certain clinical criteria be used to determine which patients receive chest radiographs. A retrospective review of 563 adult asthmatics who presented to the Yale Emergency Room revealed that one third of the patients were radiographed; 50% of these were over 50 years of age, and the overall incidence of radiographic abnormalities that would change patient management was only 3%. Radiographic findings have been categorized into two groups, uncomplicated and complicated asthma, depending on whether bronchodilators will effect a response.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Patterns of radioaerosol deposition in patients with COPD may be interpreted on the basis of derangements in convective ventilation. Thus, in patients with asthma, central deposition is consistently associated with increased airway resistance, in the absence of acute attack, indicating that in this condition major airways are usually the site of bronchial constriction. In patients with chronic bronchitis, inhomogeneous and spotty deposition patterns are strongly associated with indexes of uneven and wasted ventilation and may be explained on the basis of destruction or obstruction of peripheral airways. Spotty deposition is ascribed to very uneven convective ventilation reduced to a limited number of air streams, as opposed to the normal situation of a very high number of air streams giving rise to the uniform pattern of radioaerosol deposition.Patients with emphysema show less distinctive patterns of deposition and may resemble those of the patients with asthma and chronic bronchitis. Nevertheless, the deposition features are very useful to better characterize the patient even in the emphysematous group.From the practical point of view, the features of aerosol deposition provide useful information for evaluation and treatment of the patient with COPD. They may also prove useful to better define and characterize the different disease entities grouped as COPD.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The application of99mTc-DTPA radioaerosols to a variety of clinical disorders is described. With the development of simple equipment that can deliver very small droplets, this approach has become increasingly popular for measurements of the distribution of ventilation in patients with obstructive lung disease and suspected pulmonary embolism. In addition. by determining the rate at which the radionuclide is cleared from the lung, information has been obtained concerning the permeability of the pulmonary epithelium to extracellular indicators. Accelerated clearance rates have been found in patients with a variety of chronic interstitial lung diseases indicating that epithelial permeability is increased. Accelerated clearance rates have also been found with acute inflammation of the lung such as the adult respiratory distress syndrome and pneumocystis pneumonia. Furthermore, rapidly reversible increases in99mTc-DTPA clearance occur in smokers and may be related to the inflammatory changes that contribute to the development of emphysema.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A variety of imaging techniques are now available for evaluating cardiovascular function. Plain chest radiographs, radionuclide angiocardiography.20Tl myocardial imaging, and M-mode and two-dimensional echocardiography have been used to detect pulmonary hypertension, right ventricular enlargement. and occult ventricular performance disturbances in patients with chronic obstructive pulmonary disease (COPD). Furthermore, radionuclide angiocardiography and echocardiography combined with hemodynamic measurements have been used to assess short- and long-term cardiovascular effects of such therapeutic agents as theophylline, beta-adrenergics, vasodilators, digitalis, and oxygen. This review evaluates these imaging techniques and their application to COPD patients.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A locali7ed area of hypertransradiance ofien leads to surgical refcrral. Among 608 cases. 115 were due to local lesions of airways, blood vessels, or parenchyma. Among the rema~ning 493 w~th bullae from diffuse emphysema, 21% underwent surgery. Good restoration of funct~on occurred in patients with rapidly progressive dyspnea who did not have a bronchitic component, recurrent infections, or CO? retention. Physiologically, preoperative findings suggestive of tension pneumothorax, ~ncluding aevere restriction, marked air trapping, and little ventilationlperfusion mismatch suggested good results. Favorable radiographic findings included well-defined, large air spaces without stlgmata of diffuse emphysema, serial films showing rapid enlargement of bullae, and expiration films with good thoracic motion and obscuration of lung around bullae. Compressed but otherwise intact lung was best demonstrated by angiography and CT scans. Palliative bullectomy in severe diffuse emphysema sometimes had gratifying clin~cal results. Resection of small bullae never caused Improvement. Localized giant bullae most often were associated with paraseptal or periacinar emphysema, and the best surgical results were obtained in thls group

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

To assess the ability of CT to demonstrate the different types of emphysema, the CT appearance was compared with the corresponding barium-impregnated pathologic specimens cut in the transverse plane, in four patlents with emphysema. The CT appearance was also compared with the chest radiographs of two patients with irregular emphysema associated with progressive massive fibrosis. The parenchymal destruction visualized on CT in the patients with mild and moderate centriacinar emphysema was distinctly different from that seen in the patient with panacinar emphysema in appearance and distribution. Paraseptal and irregular emphysema were also well demonstrated using CT. Window widths between 800 and 1,500 were found to demonstrate the parenchymal changes most accurately. We conclude that CT can help to identify the presence of emphysema and to distinguish radiologic characteristlcs of the different types of emphysema.

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Future radionuclide studles in the lung will encompass not only improved evaluation of regional ventilation and perfusion in pulmonary embolism and lung cancer, but should also provide new information about alveolar-capillary permeability, cell kinetics in the lung, and pulmonary metabolism and receptors. With this increase in the scope of pulmonary nuclear medicine must come further refinement of current imaging techniques and development of new radiopharmaceuticals. Pulmonary emission tomography (via single photons or positrons), which reduces or eliminates functional superimposilion in the lung, seems to be the most promising technique for performing such studies. In the area of new radiopharmaceuticals, radiolabeled monoclonal antibodies appear promising for studies of lung cancer. These developments suggest that the next few years will be exciting ones for those interested in pulmonary radionuclide studies

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0883-5993    

出版商:OVID    

年代:1986

数据来源: OVID