Bronchial hyperreactivity to inhaled histamine in patients with farmer's lung

[Environmental causes of the distal airways disease. Hypersensitivity pneumonitis and rare causes]

Hypersensitivity pneumonitis is one of the most frequent causes of distal airways disease. It is associated with inflammation of the bronchioles, predominantly by lymphocytic infiltrates, and with granuloma formation causing bronchial obstruction. This inflammation explains the clinical manifestations and the airways obstruction seen on pulmonary function tests, most often in the distal airways but proximal in almost 20%. CT scan abnormalities reflect the lymphocytic infiltrates and air trapping and, in some cases, the presence of emphysema. Bronchiolitis induced by chronic inhalation of mineral particles or acute inhalation of toxic gases (such as NO2) are other examples of small airways damage due to environmental exposure. The pathophysiological mechanisms are different and bronchiolar damage is either exclusive or predominant. Bronchiolitis induced by tobacco smoke exposure, usually classified as interstitial pneumonitis, is easily diagnosed thanks to broncho-alveolar lavage. Its prognosis is linked to the other consequences of tobacco smoke exposure including respiratory insufficiency. Finally, the complex lung exposure observed in some rare cases (such as the World Trade Center fire or during wars) may lead to a less characteristic pattern of small airways disease.

[Bronchial involvement in hypersensitivity pneumonitis]

Hypersensitivity pneumonitis is a respiratory disease resulting from the inhalation of antigens to which the exposed subject has been previously sensitized. Hypersensitivity pneumonitis is characterized by a diffuse and predominantly mononuclear cell inflammation of the alveolar regions that involves the small airways in most cases. It explains the presence of mosaic attenuation and expiratory air trapping at HRCT Scan. Chronic bronchitis, an obstructive defect at lung function tests and emphysema as long-term outcome are frequent consequences of this bronchial involvement.

Follow up investigation of workers in synthetic fibre plants with humidifier disease and work related asthma

OBJECTIVE

To investigate the clinical and sociomedical outcome in patients with various clinical manifestations of humidifier disease and work related asthma after removal from further exposure.

METHODS

Follow up investigation (range 1-13 years) of respiratory symptoms, spirometry, airway responsiveness, sickness absence, and working situation in patients with (I) humidifier fever (n = 12), (II) obstructive type of humidifier lung (n = 8), (III) restrictive type of humidifier lung (n = 4), and (IV) work related asthma (n = 22). All patients were working at departments in synthetic fibre plants with microbiological exposure from contaminated humidification systems or exposure to small particles (< 1 micron) of oil mist.

RESULTS

At follow up patients with work related asthma were less often symptom free (37%, 7/19) than patients with humidifier disease (I, II, III) (67%, 16/24). Mean forced expiratory volume in one second (FEV1) of patients with obstructive impairment had been increased significantly at follow up but still remained below the predicted value. Mean forced vital capacity (FVC) of patients with initially restrictive impairment had returned to normal values at follow up. Airway hyperresponsiveness at diagnosis persisted in patients with obstructive impairment (II + IV 14/17, but disappeared in patients with humidifier fever (3/3) and restrictive type of humidifier lung (2/2). In patients with obstructive impairment (II + IV), FVC and FEV1 at diagnosis were negatively associated with the duration between onset of symptoms and diagnosis and the number of years of exposure. Those with positive pre-employment history of respiratory disease had a lower FEV1 at diagnosis. Sickness absence due to respiratory symptoms decreased in all groups of patients after removal from further exposure, but this was most impressive in patients with the humidifier lung (II, III) and patients with work related asthma (IV). At follow up 83% of the patients were still at work at the same production site, whereas 11% received a disability pension because of respiratory disease.

CONCLUSION

In patients with work related respiratory disease caused by exposure from contaminated humidification systems or oil mist, removal from further exposure resulted in clinical improvement, although, especially in those with obstructive impairment, signs persisted. Because of the possibility of transferring patients to exposure-free departments most patients could be kept at work.

Hypersensitivity pneumonitis and airways hyperreactivity induced by occupational exposure to penicillin

A patient with penicillin-induced hyperreactive airways in association with hypersensitivity pneumonitis is described. Patch tests and intradermal tests to penicillin were positive. Bronchoalveolar lavage demonstrated a relative lymphocytosis and mild neutrophilia. Symptoms and physiologic abnormalities of pulmonary function and gas exchange resolved on cessation of exposure to penicillin.

Hyaluronic acid (hyaluronan) in BAL fluid distinguishes farmers with allergic alveolitis from farmers with asymptomatic alveolitis

Pulmonary function measurements, bronchoalveolar lavage (BAL), and analyses of precipitating antibodies in blood were performed in 12 farmers wtih no symptoms from the airways and 12 farmers who were admitted to the hospital due to acute symptoms of alveolitis (all nonsmokers). In addition, a bronchial methacholine provocation test was performed in the asymptomatic farmers. In 11 of the 12 symptomatic farmers but in none of the asymptomatic farmers, precipitating antibodies against one or more of the microorganisms which usually occur in a farmer's environment were found. In the farmers with symptomatic alveolitis, a restrictive impairment of pulmonary function was found, while pulmonary function was normal in all asymptomatic farmers. Findings in the BAL fluid showed increased concentrations of total cells, lymphocytes, and neutrophils and elevated levels of albumin, fibronectin, and angiotensin-converting enzyme in asymptomatic farmers compared with our own reference group. The same analyses in BAL fluid from the symptomatic farmers revealed a further increase in all parameters compared with the asymptomatic farmers. The BAL fluid from asymptomatic farmers had normal levels of hyaluronic acid (hyaluronan) and procollagen 3 N-terminal peptide, while these levels were significantly increased in the symptomatic group. We conclude that inflammation in the alveolar space and signs of activation of alveolar macrophages are present in farmers regardless of respiratory symptoms, although these findings are more pronounced in the presence of symptoms of acute alveolitis; however, the findings of impaired pulmonary function and the occurrence of precipitins and elevated levels of hyaluronic acid and procollagen 3 N-terminal peptide in BAL fluid were exclusively found in the farmers with airways symptoms. We postulate the hyaluronic acid, due to its pronounced ability to immobilize water, may be of importance in the development of the pulmonary function impairment observed in farmer's lung disease.

Lung function and precipitating antibodies in low exposed wood trimmers in Sweden

Wood trimmers are exposed to molds that periodically grow on timber that may induce alveolitis and obstructive lung disease. We have evaluated respiratory symptoms, bronchial reactivity, and lung function in 28 wood trimmers at a Swedish sawmill and in 19 unexposed office workers. Eleven (sero-positive) of the wood trimmers had precipitating antibodies in peripheral blood against one or several molds. The exposure to dust (median 0.26 mg/m3), viable mold spores (median 2950 cfu/m3), viable bacteria (median 370 cfu/m3), airborne endotoxins (range 0.0015-0.0025 microgram/m3), and terpenes (range 0.4-23 mg/m3) was lower than levels that earlier have been reported to affect lung function. The wood trimmers reported an increased prevalence of cough and breathlessness. They also showed signs of a mild obstructive impairment with a tendency to increase bronchial sensitivity to metacholine and decreased FEV1 after 2 days free from exposure. FEV1 decreased more during the working week in the sero-positive workers than among the sero-negative workers, and for the whole group the decrease in FEV1 and MEF25 was correlated to the degree of mold exposure.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis or extrinsic allergic alveolitis is an immunologically mediated lung disease caused by repeated inhalations of organic antigens. The basic histologic lesion consists of a diffuse mononuclear cell infiltration of alveolar wall, alveoli, terminal bronchioles, and neighboring interstitium. The inflammation is often followed by granulomas, which then may progress to fibrosis. Although there is no single radiologic, physiologic, or immunologic test specific for hypersensitivity pneumonitis, the diagnosis can often be suspected on the basis of a compatible temporal relationship of pulmonary symptoms to the history of environmental or occupational exposure. Once the diagnosis is suspected, the presence of serum precipitating antibodies (IgG), suppressor cytotoxic lymphocytosis in bronchoalveolar lavage fluid, and granulomatous alveolitis in lung biopsy specimens are extremely helpful in confirming the diagnosis. In patients where the diagnosis is confirmed, avoidance of the causative antigen is the best therapy, although corticosteroids are used to suppress inflammation. Once the fibrosis is set in, the patient may gradually slide into respiratory failure, cor pulmonale, and death.

Causes of prolonged cough in patients referred to a chest clinic

The aim of this study was to evaluate the causes of prolonged cough in a patient population referred to a chest clinic during a single year. One hundred and ninety-eight patients (11%) of the total yearly 1745 adult admissions fulfilled our criteria of prolonged cough. Asthma, suspicion of asthma and postnasal drip were the commonest causes of prolonged cough in 147 patients with normal chest roentgenograms (26%, 9% and 16%, respectively), and in 45% the cough was of unexplained origin. Nonspecific bronchial hyperreactivity was common in this latter group of patients probably due to a previous respiratory infection. Lung cancer (37%), tuberculosis (16%), sarcoidosis (16%), and allergic alveolitis (9%) were the most important findings in patients with abnormal chest roentgenograms.

Organic dust toxic syndrome among farmers

Clinical symptoms and exposure conditions were investigated in 80 farmers with organic dust toxic syndrome, defined as the occurrence of febrile reactions after exposure to organic dust in subjects with no evidence of allergic alveolitis. The material was compiled from a field study of febrile reactions in the farming community and the diagnosis was based on interviews performed by physicians. Of the 75 men (mean age 44) and five women (mean age 39), only 13% of the men and none of the women were current smokers. One attack had been experienced by 44% and the remaining subjects had had two or more attacks, often several years apart. The duration of symptoms was 24 hours or less in 46% of the farmers and in 95% of the cases the symptoms lasted less than one week. The attacks were most common in the autumn and were usually provoked by handling grain (80% of the farmers with organic dust toxic syndrome). Other causes were hay, straw, wood chips, and silocapping material. The material was usually described as extremely mouldy and the episodes were usually provoked by unusual work tasks such as cleaning grain bins or removing mouldy feed. Twenty three farmers had consulted physicians: five of nine examined during symptoms had slightly abnormal chest radiographs and two of four examined had decreased arterial oxygen tension. Spirometry performed during a symptom free interval was normal.

Farmer's lung--a 5-year follow-up of eighty-six patients

We studied the clinical course of eighty-six patients with farmer's lung for a period of 5 years. The patients were first evaluated at an acute or sub-acute stage of the disease and 1, 3, 6, 12 and 60 months thereafter. Special attention was paid to the development of lung function and radiological findings with reference to corticosteroid treatment and antigen contact during the follow-up. Many of the patients were severely ill at the acute stage of the disease. Most of the recovery took place during the first month. Significant improvement of lung function happened up to 6 months, thereafter the improvement was insignificant. After 5 years, respiratory symptoms were reported by 65% and minor respiratory dysfunction (lowered diffusing capacity) was observed in about 40% of the farmers. Thirty-two per cent of the patients showed diffuse opacities in chest X-ray. Corticosteroid treatment had no effect on long term prognosis. There was no difference in the recovery of lung function between those who returned to work compared with those who did not. Exacerbations happened in 8% of the patients during the follow-up. We conclude that respiratory symptoms, minor airway dysfunction and mild radiological fibrosis are common findings after 5 years of an acute or sub-acute stage of the farmer's lung. However, in Finland two-thirds of the patients return back to their previous occupation of farming and cattle feeding.

Radiologic findings in farmer's lung. Prognosis and correlation to lung function

We classified the radiologic findings of 93 patients with acute or subacute farmer's lung (FL) disease by type and severity of the change in chest x-ray film. Acute radiologic changes, further divided as nodular, ground-glass, or striated patchy opacities, were found in 78/93 patients at the first evaluation; 11 showed chronic changes (radiologic "fibrosis"), which persisted unchanged throughout the follow-up period; and four initially had a normal chest x-ray film. Patients were followed up 23 months on an average. The more severe the radiologic change at the first evaluation, the more impaired the diffusing capacity (Dsb). Severe radiologic changes disappeared more slowly than the less severe ones. The differences in the initial pulmonary function values between the two groups disappeared during the follow-up. The type of acute change did not predict the recovery of respiratory performance. Treatment with oral corticosteroids did not affect the outcome of lung function or appearance of chronic changes, although corticosteroids seemed to hasten the disappearance of diffuse opacities. At the final evaluation, the chest x-ray film was normal in 55/93 patients. Chronic changes were detected in 38 patients. Severe radiologic appearance and striated patchy opacities predisposed to development of chronic changes.

Bronchial reactivity in patients with recent pulmonary sarcoidosis

Non-specific bronchial reactivity was assessed in 17 consecutive non-smoking and non-steroid treated patients with recently diagnosed pulmonary sarcoidosis, 11 with stage I disease and six with stage II disease. Bronchial reactivity was measured by recording the FEV1 after increasing doses of methacholine. Three subjects with asthma were hyperreactive. The 14 subjects with no asthma had a mean FEV1 of 96% predicted. Only one was hyperreactive, with a fall in FEV1 of over 15% after 0.1% methacholine. The median provocative concentration causing a 15% fall in FEV1 did not differ from that in a normal population studied previously. It is concluded that sarcoidosis seldom induces airway hyperreactivity within one year of diagnosis in patients with normal spirometric values.