Reference equations for pulmonary diffusing capacity of carbon monoxide and nitric oxide in adult Caucasians.

The aim of this study was to determine reference equations for the combined measurement of diffusing capacity of the lung for carbon monoxide (CO) and nitric oxide (NO) (DLCONO). In addition, we wanted to appeal for consensus regarding methodology of the measurement including calculation of diffusing capacity of the alveolo-capillary membrane (Dm) and pulmonary capillary volume (Vc).DLCONO was measured in 282 healthy individuals aged 18-97 years using the single-breath technique and a breath-hold time of 5 s (true apnoea period). The following values were used: 1) specific conductance of nitric oxide (θNO)=4.5 mLNO·mLblood-1·min-1·mmHg-1; 2) ratio of diffusing capacity of the membrane for NO and CO (DmNO/DmCO)=1.97; and 3) 1/red cell CO conductance (1/θCO)=(1.30+0.0041·mean capillary oxygen pressure)·(14.6/Hb concentration in g·dL-1).Reference equations were established for the outcomes of DLCONO, including DLCO and DLNO and the calculated values Dm and Vc Independent variables were age, sex, height and age squared.By providing new reference equations and by appealing for consensus regarding the methodology, we hope to provide a basis for future studies and clinical use of this novel and interesting method.

New-onset asthma and the effect of environment and occupation among farming and nonfarming rural subjects.

BACKGROUND: Many factors, including environmental exposures, have been related to the increase in the prevalence of asthma, but only few have been tested for in longitudinal studies. OBJECTIVE: We studied farming students to determine whether their environment during childhood and as adults was a factor determining subsequent onset of asthma. METHODS: From 1994 to 1998, new cases of asthma were identified by means of an annual posted questionnaire followed by a telephone interview in a prospective cohort consisting of 1964 farming-school students and 407 nonfarming subjects aged 16 to 26 years. For each case, we selected a control subject from the cohort with no asthma in a case-based design, and all underwent an interview and a clinical examination. RESULTS: We found 122 new cases of asthma. In a multiple regression model the odds ratio for new asthma was 3.3 (95% CI, 1.7-6.3) for smoking; 3.4 (95% CI, 1.6-7.0), 2.5 (95% CI, 1.1-5.3), and 7.0 (95% CI, 1.2-41.6) for exposure to swine, dairy production, and welding, respectively; and 11.7 (95% CI, 2.4-56.4) for bronchial hyperresponsiveness at baseline. Being born and raised on a farm significantly reduced the risk odds ratio (0.5 [95% CI, 0.3-0.98]), whereas atopy had no influence. CONCLUSION: Exposure to swine and dairy confinements, welding, smoking, and bronchial hyperresponsiveness are risk factors for nonallergic asthma, and being born and raised on a farm reduces the subsequent risk. These findings support the theory that immune and inflammatory responses can be influenced by environmental exposure to early childhood, reducing the risk of asthma later in life.

Occupational chronic obstructive pulmonary disease: a systematic literature review.

OBJECTIVE: Occupational-attributable chronic obstructive pulmonary disease (COPD) presents a substantial health challenge. Focusing on spirometric criteria for airflow obstruction, this review of occupational COPD includes both population-wide and industry-specific exposures. METHODS: We used PubMed and Embase to identify relevant original epidemiological peer-reviewed articles, supplemented with citations identified from references in key review articles. This yielded 4528 citations. Articles were excluded for lack of lung function measurement, insufficient occupational exposure classification, lack of either external or internal referents, non-accounting of age or smoking effect, or major analytic inadequacies preventing interpretation of findings. A structured data extraction sheet was used for the remaining 147 articles. Final inclusion was based on a positive qualitative Scottish Intercollegiate Guidelines Network (SIGN) score (≥2+) for study quality, yielding 25 population-wide and 34 industry/occupation-specific studies, 15 on inorganic and 19 on organic dust exposure, respectively. RESULTS: There was a consistent and predominantly significant association between occupational exposures and COPD in 22 of 25 population-based studies, 12 of 15 studies with an inorganic/mineral dust exposure, and 17 of 19 studies on organic exposure, even though the studies varied in design, populations, and the use of measures of exposure and outcome. A nearly uniform pattern of a dose-response relationship between various exposures and COPD was found, adding to the evidence that occupational exposures from vapors, gas, dust, and fumes are risk factors for COPD. CONCLUSION: There is strong and consistent evidence to support a causal association between multiple categories of occupational exposure and COPD, both within and across industry groups.

[Occupational exposure for dust and gases is an important risk factor for developing COPD]. / Erhvervseksposition for støv og dampe er en betydende risikofaktor for KOL.

Some patients with chronic obstructive pulmonary disease (COPD) are never-smokers, which suggests that there must be other important risk factors. This paper describes the evidence for an association between occupational exposure and COPD. In several studies a consistent and predominantly significant association between occupational exposures and COPD is found, even though the studies vary in design, enrolled populations and in measures of exposure and outcome. Strong evidence supports a causal association between multiple categories of occupational exposure and COPD, both within and across industry groups.

Respiratory health and allergy among young farmers and non-farming rural males in Denmark: the SUS study.

The respiratory health of 230 female and 1,734 male farming students (FS) and 407 male rural controls was analyzed. A significantly increased prevalence of cough (6.9%) was reported among the male FS compared to the controls (2.5%). Measured FEV1 and FVC did not differ between the male FS and the controls, as opposed to significantly higher values among the female FS compared to a random sample of urban females stratified for height. Skin prick test (SPT) to house dust and storage mites was significantly more prevalent among the controls (18.7%) compared to the male FS (12.8%) and the female FS (11.9%). The size of the house dust mite weal and the number of positive skin prick reactions were significantly associated with bronchial hyperreactivity. The difference in lung function among the female FS and the lower prevalence of skin reaction among the male FS and female FS probably reflects a healthy workers selection.