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Page 1 Environmental
and Occupational Lung Diseases
The environmental and occupational lung disorders are an important aspect of clinical medicine. It is important that physicians, employers, employees and the general population become aware of the epidemiological and clinical findings associated with these disorders, and how to treat and prevent them. Classification Several methods can be used for the classification of these disorders. The classification used in Table 1 is based on exposures. Criteria for Diagnosis of Occupational Lung Disease Four criteria can be used as a guide for the diagnosis of an occupational lung disease Table 2. First, there should be an exposure to a known documented hazardous agent. Not all pungent smells or white powders are toxic. Analysis of the substance can be helpful. Product labeling requirements have resulted in a marked improvement in knowledge of exposures and can be useful. Second, the timing of exposure and onset of symptoms should be appropriate. A twenty-year latency period is usually required before asbestosis can be diagnosed, thus an exposure from a few days previously would not result in a detectable abnormal finding. Third, the clinical syndrome should be consistent with the syndrome related to the exposure. Finally, there should be no other more likely explanation for the signs and symptoms. This fourth criterion is important because of the occurrence of cigarette smoking and associated abnormalities. These criteria serve as general guidelines and are helpful in most patient or worker evaluations. Exceptions to these rules occur, e.g., two diseases may be present or a new type of exposure may cause a disorder that was previously unknown. Specific criteria have been proposed for disorders such as asbestosis (1-2) and beryllium lung disease (3). Evaluation by the Pulmonary Clinician Evaluation generally begins with the type and frequency of pulmonary symptoms Table 3. It is helpful to classify the degree of dyspnea from none to severe on a scale of zero to four, i.e., severe class four is defined as breathlessness or dyspnea while dressing or performing routine activities. The questionnaire developed by the European Community for Coal and Steel (4) has a similar grading system of dyspnea: Grade 1 - breathlessness going up one flight of stairs, Grade 2 - breathlessness while walking with other persons of the same age on the flat, Grade 3 - stopping for breath when walking on the flat, and Grade 4 - breathlessness when dressing or undressing. The frequency of cough and amount of sputum should then be noted as well as the presence of hemoptysis. The frequency and timing of wheezing such as during the evenings or Monday mornings may be important in occupationally-related asthma. The amount of cigarette smoking should be noted as age started smoking, number of packs per day, and age stopped. It is also important to note lung diseases occurring in the family. Past pulmonary diseases, such as asthma, pneumonia, bronchitis, postnasal drip, or sinus infections should be noted. Allergies to dusts, foods, and medications should be listed. General medical disorders, such as diabetes, hypertension, peptic ulcer disease, and previous surgical procedures, should be noted. Current medications and dosages should be documented. Several methods can be used to obtain occupational and environmental respiratory exposure information (5,6). It is easiest to begin by asking the date and place of birth of the patient and then proceed to summer jobs and exposures Table 4. Questions should be asked about the military service, with the branch of service, dates, and specific exposures noted. The clinician should then determine the patient's first job with the title and description. Titles often change with time and may no longer relate to important exposure information. Then, proceed through each successive job until the present. If a hazardous exposure is found, the clinician should determine the type of exposure, amount of exposure, the year the patient was first exposed, and the year exposure stopped. In addition, the patient should be asked whether the ventilation was adequate, whether masks were used, and whether pulmonary disorders developed in other workers. Other information should include the occupations of the spouse and of the children, hobbies, travel, and the type of heating, humidification, and air conditioning systems, and if there are pets. Physical examination includes documentation of the vital signs Table 5. The degree of respiratory distress and the presence of finger clubbing or cyanosis should be recorded. A search for lymphadenopathy should be made. The intensity of breath sounds, the presence of wheezing, and the timing (early or late inspiratory) and type (fine or course) of crackles should be recorded. Cardiac examination should be performed. Abdominal examination should consist of an evaluation for liver and spleen enlargement. The examination should conclude with an evaluation for the presence or absence of pedal edema. Posteroanterior and lateral chest roentgenograms should then be obtained Table 6. Hyperinflation and other findings consistent with airflow disorders should be noted. For the diffuse infiltrative lung diseases, there should be a description of the type and location of opacities and a grading of the severity from mild to severe. The International Labor Organization (ILO) classification should be used if appropriate (7). Studies such as computed tomography (CT) of the chest, may be helpful for evaluation of pleural abnormalities, lung nodules, infiltrates, and lymph node enlargement. High-resolution CT of the chest may be helpful in interstitial disorders (8). Pulmonary function studies Table 7 should be performed using standard-ized methods and equipment meeting expected specifications (9-11). Spirometry including the vital capacity, forced expiratory volume in one second (FEV1), and flow rates should be performed on all patients. Lung volumes should be obtained for confirmation of airflow abnormalities. Single breath diffusing capacity (Dsb) should be performed in patients with exposure to fibrogenic dusts or exposure resulting in a diffuse infiltrative process, in patients with dyspnea out of prop-ortion to the spirometric findings, and if small opacities are seen in the chest radiograph. Ventilation/profusion scans are rarely needed except to exclude other disorders. Magnetic resonance (MR) imaging of the chest has limited value, although it may be useful for surgical evaluation of unusual mediastinal abnormalities. Inhalation challenge studies are useful for determination of airway reactivity. Sputum analysis may be helpful for bacterial evaluation and cytology; bronchoalveolar lavage can be performed in patients with occupationally related disorders to confirm the diagnosis or to determine potential response to therapy. Transbronchial biopsy may be useful in patients with granulomatous disorders, such as hypersensitivity pneumonitis or berylliosis. An open lung biopsy is rarely recommended for the sole purpose of determining an occupational lung disease for legal reasons; however, an open lung biopsy is useful in patients with a diffuse infiltrative process of unknown cause.
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