Resp Care
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The skill and work habits of the pulmonary function technologist are central to the quality of patient testing. Pulmonary function technologists should be chosen carefully. ⋯ Monitoring of technologist performance and technologist feedback improves the quality of testing but is utilized by only a minority of clinical laboratories. Pulmonary function laboratory accreditation is urgently needed to protect the public from potential misdiagnosis and inappropriate treatment due to spurious data.
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Pulmonary function testing is often considered the basis for diagnosis in many categories of pulmonary disease. Although most of the testing methodologies are well established and widely employed, there are still many questions regarding how tests should be performed, how to ensure that reliable data are produced, what reference values and rules should be used, and how pulmonary function tests (PFTs) should be interpreted to best support clinical decision making. This conference was organized around a set of questions aimed at many of these issues. ⋯ These topics included testing of adults and children, with concentration on important disease entities such as COPD, asthma, and unexplained dyspnea. Special emphasis was given to discussing reference values, lower limits of normal, interpretive strategies to optimize disease classification, and those factors directly affecting data quality. Established techniques for spirometry, lung volumes, diffusing capacity, exercise testing, and bronchial challenges were compared and contrasted with new technologies, and with technologies that might be part of pulmonary function laboratories in the near future.
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Lung volumes are considered part of a complete pulmonary function test, but their value for enhancing clinical decision making is unknown. Unlike spirometry and diffusing capacity of the lung for carbon monoxide (D(LCO)), which do contribute to confirming or excluding a diagnosis, there are few clear indications when lung volumes are discriminatory. Confirming "restriction" when vital capacity (VC) or FVC is reduced is perhaps the most important. ⋯ Body plethysmography is often considered more accurate than gas dilution methods in the presence of obstruction. However, the differences between techniques are not completely understood. Newer approaches such as computed tomography, although not suitable for routine testing, may help to delineate the true underlying physiology.
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Over the years a great deal of effort has been made to standardize all pulmonary function tests on adults. Many of the "rules" concerning the interpretation of the spirogram have been based entirely on adult observations. In the age of increasing conformity, and attempts to relate "adult" literature to the pediatric population, the latter was given much less emphasis than the former. ⋯ Lung function testing, particularly spirometry, has much to offer in the diagnosis of lung disease in children and the monitoring of response to therapy. With better standardization of pulmonary function testing in children, and more trained technologists, the age limits for testing can be extended to below 6 years of age and sometimes below 5. Also with better standardization the results obtained are meaningful and when interpreted in context of age offer excellent diagnostic information to better treat the child with lung disease.
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Spirometry is considered the primary method to detect the air flow limitation associated with obstructive lung disease. However, air flow limitation is the end-result of many factors that contribute to obstructive lung disease. One of these factors is increased airway resistance. ⋯ Furthermore, the FOT provides unique information about lung mechanics that is not available from analysis using spirometry, body plethysmography, or the interrupter technique. However, it is unclear whether any of these measures of airway resistance contribute clinically important information to the traditional measures derived from spirometry (FEV(1), FVC, and FEV(1)/FVC). The purpose of this paper is to review the physiology and methodology of these measures of airway resistance, and then focus on their clinical utility in relation to each other and to spirometry.