PULMONARY FUNCTION STUDIES IN PATIENTS WITH FARMER'S LUNG

Pulmonary function testing in idiopathic interstitial pneumonias

Diffuse parenchymal lung diseases are a group of disorders that involve the space between the epithelial and endothelial basement membranes and are generally segregated into four major categories. These include the idiopathic interstitial pneumonias, which are further categorized into seven clinical/radiologic/pathologic subsets. These disorders generally share a common pattern of physiologic abnormality characterized by a restrictive ventilatory defect and reduced diffusing capacity (DLCO). Pulmonary function testing is often used and recommended in their assessment and management. The potential clinical application of physiologic testing includes to aid in diagnosis, although its value in differential diagnosis is limited. Pulmonary function testing also aids in establishing disease severity and in defining prognosis. In nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis, severely decreased DLCO has proven valuable in this regard. Similarly, exertional desaturation to less than 88% at baseline testing and a decrease in FVC (greater than 10%) over the course of short-term follow-up identify patients at particular risk of mortality. Finally, physiologic testing, especially spirometry and DLCO, have demonstrated value in monitoring response to therapy and identifying disease progression.

Pulmonary function tests in interstitial lung disease: what role do they have?

Pulmonary function tests have been widely accepted and utilized in the management of interstitial lung diseases. Although the tests performed have changed little over the past several decades, extensive literature has been published highlighting their clinical role in the diagnosis, staging, prognostication, and follow-up of patients with a wide variety of interstitial lung diseases.

The role of pulmonary function testing in pulmonary fibrosis

Interstitial lung diseases are characterized by disruption of the distal pulmonary parenchyma. The clinical history manifestations, cough and dyspnea, and physical exam manifestations, inspiratory crackles, are nonspecific. Pulmonary function testing aids in the evaluation and management of patients with interstitial lung disease although the pattern of abnormality is nonspecific. Pulmonary function testing can provide an estimate of histologic severity but not a definitive quantification of histologic fibrosis or inflammation. Pulmonary function tests can provide a baseline estimation of prognosis and be used to monitor disease progression or response to therapy. The forced vital capacity and diffusion capacity are the most valuable serial measurements, but further data are required to examine composite scoring and exercise gas exchange.

Recovery of pulmonary function in farmer's lung. A five-year follow-up study

The recovery of pulmonary function in farmer's lung (FL) was studied during a 5-yr follow-up in 101 patients (20 men and 81 women, mean age 47 yr). At the initial evaluation all patients had the first diagnosed attack of FL. Spirometry, measurement of pulmonary diffusing capacity, and arterial blood gas analysis were done at the time of the diagnosis and 1, 3, 6, 12, and 24 months thereafter. The last follow-up measurements were made 4 to 6 yr after the initial evaluation. Mean FVC improved significantly for up to 1 yr. In mean DLCO there was improvement for up to 2 yr. Mean PaO2 rose to its maximum within 1 month of the initial examination and did not change significantly thereafter. No patient had diagnosed asthma at the time of the diagnosis of FL, but asthma was later diagnosed in 7 patients during the follow-up. In conclusion, the pulmonary function of FL patients improved for up to 2 yr after the initial acute episode. In general, PaO2 improved most rapidly; the improvement in FVC was slower, and the recovery of DLCO took the longest time.

Diffuse pulmonary alveolar fibrosis

Scadding, J. G. (1974).Thorax, 29, 271-281. Diffuse pulmonary alveolar fibrosis. The problems of diagnostic categorization of diffuse pulmonary alveolar fibrosis are outlined, and attention is drawn to the different implications of categories defined aetiologically and histopathologically. The pattern of pulmonary insufficiency associated with changes of these sorts is described, and the importance of using a terminology of pulmonary insufficiency which refers unequivocally to disorders of function is emphasized. The usage of the word `interstitial' in the context of inflammations of the lung is critically examined. It seems to be used to imply predominant involvement of alveolar walls, which in other contexts would be regarded as `parenchyma'. This unresolved conflict which accepted anatomical usage can be avoided by general acceptance of complementary conventions that `pneumonia' refers to inflammations of the lung characterized by exudation into alveolar spaces leading to consolidation, and `alveolitis' to those affecting predominantly alveolar walls. Some cases of alveolitis, so defined, can be shown to be due to reactions with inhaled organic dusts in the gas-exchanging part of the lungs in specifically sensitized individuals, constituting a group of aetiologically defined categories `extrinsic allergic alveolitis'. A few are due to ingested toxic substances. Many remain of unknown cause and show a strong and early tendency to alveolar wall fibrosis: they constitute a histopathologically defined category `cryptogenic fibrosing alveolitis'.

Mushroom-worker's lung

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Pulmonary function studies in bird breeder's lung

Pulmonary function studies were performed at the time of diagnosis in 10 patients, aged between 11 and 51 years, with bird breeder's lung due to exposure of between 9 months and 42 years. The studies were repeated after a varying interval in nine of these patients, following removal from exposure. In initial tests, diffusing capacity was impaired in eight patients and the arterial oxygen tension at rest was below 80 mm. Hg in seven. Five patients had a low vital capacity and three showed evidence of airway obstruction. One patient continued to breed pigeons, against medical advice, and his pulmonary function, repeated after nine months, showed further deterioration. The others with abnormal pulmonary function showed significant improvement on repeat studies. Pulmonary function studies appear to be helpful in the diagnosis, irrespective of radiographic changes, and in the follow-up of patients.