Chest
Volume 122, Issue 1, July 2002, Pages 363-368
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Occupational and Environmental Lung Disease
Bronchial Responsiveness to Eucapnic Hyperventilation and Methacholine Following Exposure to Organic Dust

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Study objective

Inhalation of dust in a swine confinement building causes an intense airway inflammatory reaction in the airways and increased bronchial responsiveness to methacholine. The aims of the present study were to investigate whether exposure to organic dust also influences bronchial responsiveness to an indirect stimulus, and to assess the duration of increased postexposure bronchial responsiveness.

Design

Twenty-two healthy nonatopic, nonsmoking subjects were exposed to dust for 3 h in a swine confinement building. Lung function was assessed, and either a methacholine bronchial provocation (n = 11) or a challenge with eucapnic hyperventilation of dry air (n = 11) was performed before exposure and at 7 h, 1 week, 2 weeks, and 4 weeks after exposure.

Results

Vital capacity and FEV1 decreased 3% and 6%, respectively (p < 0.001), and airway resistance increased 15% (p < 0.05) after exposure. The median provocative dose of methacholine causing a 20% decline in FEV1 fell from 1.38 mg (25th to 75th percentiles, 0.75 to 7.20 mg) before exposure to 0.18 mg (0.11 to 0.30 mg) after exposure (p = 0.004). Corresponding values for the dose-response slope were 15.3%/mg (2.88 to 25.3%/mg) and 100.2%/mg (2.1 to 27.3%/mg), respectively (p = 0.01). Bronchial responsiveness to eucapnic hyperventilation was not affected by the exposure: FEV1 fell 4.3% (− 7.2 to − 1.8%) before and 4.8% (− 6.7 to − 1.6%) after exposure (p = 0.72). One week after exposure, the bronchial responsiveness to methacholine was normalized.

Conclusions

The bronchial responsiveness to methacholine but not to dry air increases after exposure to swine house dust. Thus, exposure to organic dust induces increased bronchial responsiveness with different characteristics from that frequently found in asthma.

Section snippets

Materials and Methods

Twenty-two healthy, nonsmoking subjects (7 men; mean age, 24 years; range, 21 to 39 years) were exposed to dust for 3 h while weighing pigs in a swine confinement building. The subjects were nonatopic and nonasthmatic as determined by history and a questionnaire, and all denied ongoing respiratory infections. They had not previously been exposed to swine dust. All subjects gave their informed consent, and the study was approved by the ethics committee at the Karolinska Institute.

One week or 2

Results

The oral temperature increased from 36.5°C (range, 35.8 to 37.0°C) prior to exposure to 37.2°C (range, 36.7 to 37.9°C) after exposure (p < 0.001). Maximal temperature was, in most subjects, found between 7 h and 8 h after the beginning of exposure. Symptoms like shivering, headache, and malaise increased significantly (p ≤ 0.001), while muscle pain and nausea occurred only in exceptional cases. Also, stuffy and runny nose was reported. There were no significant differences between the two

Discussion

In the present study, we demonstrated an increase in the bronchial response to methacholine but not to eucapnic hyperventilation of dry air after exposure to organic dust in a swine confinement building. Seven hours after the beginning of exposure, bronchial responsiveness to methacholine increased approximately three doubling concentration steps in all subjects. We also confirmed that 3 h of exposure to swine dust causes increase in body temperature and symptoms such as shivering, headache,

ACKNOWLEDGMENT

The authors thank Siw Siljerud, Fernado Acevedo, and Alexandra Ek for technical assistance.

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  • Cited by (0)

    This study was supported by The Swedish Heart-Lung Foundation.

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