OSNOVNA SPIROMETRIJSKA MERENJA KOD RADNIKA NA FARMAMA SVINJA

Abstract

INTRODUCTION Many epidemiological and clinical studies have demonstrated an increased risk for the symptoms of respiratory disorders consistent with chronic bronchitis and asthma and alterations of pulmonary function tests in pig farmers.

AIM The aim of this study was to determine basic pulmonary function values in workers in swine confinement buildings and to compare them with the same values in the control group of unexposed persons. The next aim was to examine the association between these values with duration of professional exposure, cigarette smoking, age, and sex of the examined persons.

METHODS We randomly selected for examination 145 workers of both sex who had worked for at least 2 previous years in pig farms and spent at least 3 hours per day, 6 days per week in a swine confinement building. The farmers worked at 6 different farms with 12,383 pigs on average on each farms. The subject was eligible for the study if he had had no history of atopic disease nor any serious chronic disease, and no acute respiratory infection within 3 previous months. As control group we examined 156 subjects who had lived and/or worked in the same areas and had had no history of exposure to farming environment or any other known occupational air pollutants. In both groups the study comprised cigarette smokers and persons who had never smoked. Pulmonary function data were collected according to the standard protocol with a Micro Spirometer, (Micro Medical Ltd., England, UK). The registered parameters were FEV₁ and FVC. At least three satisfactory forced maximal expirations were performed by each subject and the best value was accepted for analyses. The results were also expressed as a percentage of predicted values and FEV₁/ /FVC×100 was calculated.

RESULTS There were no differences in the main demographic characteristics between two examined groups (Table 1). Mean duration of work in pig farming was 11.6 years (SD=8.5; range 2-40). The average values of examined pulmonary function tests are shown in table 2. The values of FEV₁ and FVC in each groups were between 92% and 97% of predicted values, and FEV₁/FVC×100 was not lower than 82%. There were no differences in the average values of FEV₁ (p=0.574) and FEV₁ % predicted (p=0.653) between pig farmers and control subjects. Pearson coefficient of correlation and Spearman nonparametric correlation test revealed a high level of correlation of FEV₁ values with sex and age and no correlation of pig farming exposure with cigarette smoking as predictor variables (Table 3). The analysis by linear regression method showed that all examined predictor variables had the effect on the value of FEV₁ (Table 4). After the elimination of the two least significant predictor variables it was possible to make the equation for prediction of FEV₁ values.

DISCUSSION In the present study there are no significant alterations in the values of the basic pulmonary function tests in pig farmers. In the majority of previous similar studies the differences in the average values of FEV₁ and FVC between pig farmers and control subjects were also not found. However, in some studies the alterations in several more specific lung function parameters were registered. The decreased values of FEV₁ during workshift were also found and they are probably connected to the bronchial hyperreactivity registered in many studies in pig farmers. Longer exposure to swine confinement environment caused more decline in FEV₁ and FVC and accelerated mean age-related annual decline in FEV₁ was observed reaching to 44 ml/yrs more than expected. The correlations between values of FEV₁ with pig farming exposure and cigarette smoking in this study were not found. However, the analysis by linear regression method showed that all examined predictor variables had the effect on the value of FEV₁. In a few previous bronchoscopic, BAL, and sputum studies some signs of inflammation and morphological changes of the respiratory tract were observed. The absence of important alterations in the basic spirometric measures in this and the majority of the previous studies suggests that early airway injuries may not be readily apparent using spirometric measures of lung function.

CONCLUSION In contrast to other world studies, our study comprised an important number of women farmers, but alterations associated to sex were not found. To asses the lung function in these pig farmers after several years may be of great importance.

Keywords: professional air pollution, pig farmers, spirometry, lung function.