The effects of Aspergillus fumigatus challenge on exhaled and nasal NO levels.

Several studies have previously shown that exposure to indoor air microbes from moisture-damaged buildings can cause adverse health effects. Aspergillus fumigatus is one of the best-documented moulds causing health problems to those exposed. In this study, inhalation of a commercial A. fumigatus solution was assessed, to establish if it would have effects on fractional exhaled (FeNO) and nasal (FnNO) nitric oxide levels and on lung function. The results were compared with placebo challenge. A total of 28 subjects were divided into three study groups: group 1 had been exposed to occupational mould; group 2 consisted of atopic subjects; and group 3 was a control group. Some 3 h after A. fumigatus challenge, there was a considerable increase in FeNO, and a significant difference was observed between the A. fumigatus and placebo inhalations. The difference was seen in all study groups. No such differences were found in the levels of FnNO or nitrite in nasal lavage fluid. Subjects reported significantly more frequent respiratory tract symptoms after the A. fumigatus inhalation compared with placebo challenge. In conclusion, it was shown here that inhalation challenge of Aspergillus fumigatus elevated fractional exhaled nitric oxide levels. An increase in fractional exhaled nitric oxide may serve as an indicator of respiratory inflammation of acute mould exposure.

Changes in pro-inflammatory cytokines in association with exposure to moisture-damaged building microbes.

Several epidemiological studies have described an association between adverse health effects and exposure to mould and microbes present in the indoor air of moisture-damaged buildings. However, the biochemical linkage between microbial exposure and the large variety of reported respiratory symptoms is poorly understood. In the present study, the authors compared the respiratory symptoms, the production of inflammatory mediators interleukin (IL)-1, IL-4, IL-6, tumour necrosis factor-alpha (TNF-alpha) and cell count in nasal lavage fluid and induced sputum samples of subjects working in moisture-damaged and control school buildings. The sampling was performed and the questionnaires were completed at the end of the spring term, at the end of the summer vacation (2.5 months), during the winter term and after a 1-week winter holiday. The authors found a significant elevation of IL-1, TNF-alpha and IL-6 in nasal lavage fluid and IL-6 in induced sputum during the spring term in the subjects from the moisture-damaged school building compared to the subjects from the control building. The exposed workers reported sore throat, phlegm, eye irritation, rhinitis, nasal obstruction and cough in parallel with these findings. The present data suggests an association between microbial exposure, and symptoms as well as changes in pro-inflammatory mediators detected from both the upper and lower airways.

Simple forced oscillatory technique and spirometry in assessment of bronchial responsiveness in non-asthmatic and asthmatic subjects.

Simple validity controlled forced oscillatory respiratory resistance (Rrsfo) at 8 Hz frequency was compared with flow-volume spirometry in detection of bronchial changes during induced bronchoconstriction. The methacholine provocation test was performed in subjects with mild asthma (n = 18) and in non-asthmatic subjects (n = 61) of which 44 were classified as responders (delta FEV1 > or = 15% in methacholine test). According to the index of maximal response/coefficient of variation for immediately repeated measurements (delta max/Coeffvar), Rrsfo was shown to be at least as sensitive indicator of bronchoconstriction as FEV1, and better than MMEF and FVC. The shape of the dose-response curves were similar for all parameters. In the non-asthmatic group, there were similar plateaux in Rrsfo, FEV1, and FVC at the same methacholine concentrations. In the asthmatic group, the provocative concentrations for Rrsfo and spirometric parameters correlated significantly (PC60-Rrsfo versus PC10-FEV1, P < 0.05; PC60-Rrsfo versus PC25-MMEF, P < 0.01). In the non-asthmatic responsive subjects, the correlations between PC60-Rrsfo and PC25-MMEF were significant (P < 0.05). Thus, Rrsfo at a fixed 8 Hz frequency and built-in validity control was shown to be at least as sensitive an indicator for changes in lung function in asthmatic and non-asthmatic responsive subjects as spirometry. Compared to spirometry, it may give additional information with fewer confounding factors during performance.

Short-term variations in oscillatory and spirometric lung function parameters of non-asthmatic adults.

Oscillatory respiratory resistance (Rrsfo) at 8 Hz was compared to flow-volume spirometry with regard to immediate, within-day, day-to-day and week-to-week variations in seven female and four male non-smoking, non-asthmatic volunteers. The lung functions were measured at 08:00, 12:00, 16:00 and 20:00 h on each of the four study days, i.e. two consecutive days in two consecutive weeks. During each visit there were three immediately repeated measurements of Rrsfo, followed by three spirometric recordings. The intra-subject coefficient of variation (Coeffvar) for the immediately repeated measurements was largest for Rrsfo (11.8%). When a simple reliability index (+/- 2 SD of the differences between the repeated measurements) was applied to the Rrsfo data, the Coeffvar reduced to 7.5%. In spirometry, the airflow parameters at defined lung volumes showed larger immediate variations (MEF50 = 5.6%, MEF25 = 8.3%, MMEF = 4.4%) than FEV1 (1.5%) and PEF (3.2%). The within-day variations were larger than the day-to-day or week-to-week variations, and the variations were largest in Rrsfo. A significant diurnal pattern was shown in spirometric parameters but not in Rrsfo. About 38% of the total variance in Rrsfo was due to variation within subjects, while the corresponding proportions in spirometric parameters were 1.8-18.4%. In conclusion, Rrsfo showed larger intrasubject variations than the spirometric parameters at all time intervals. Application of a simple reliability index and standardization of the time of day of the measurement reduced the variations and improved the quality of the Rrsfo data.

Short-term variations in oscillatory and spirometric lung function indices among school children.

The aim of this study was to compare immediate, daily and weekly variation in respiratory resistance measured by means of the forced oscillation technique (Rrs,FOT) to spirometric indices in 7-12 year old children with chronic respiratory symptoms. The lung function measurements were performed in 19 children on 4 days, i.e. two consecutive days during two consecutive weeks. On each day, the measurements were carried out at the same time of day and always repeated three times. In addition, Rrs,FOT and spirometric lung function indices were compared with an exercise challenge test in 12 children. Intrasubject coefficients of variation (CoVs) for Rrs,FOT were larger than those for spirometric indices. Only in the immediately repeated measurements was the CoV of maximal expiratory flow at 25% vital capacity larger than that of Rrs,FOT (16.6 vs 14.9%). At all time intervals, the smallest CoVs were observed in forced vital capacity (FVC) or in the ratio of forced expiratory volume in one second to FVC (2.0-2.6%). When excluding Rrs,FOT values which were not within 2 SD (0.11 kPa.L-1.s) of the differences between the immediately repeated measurements, the CoV of the immediately repeated measurements of Rrs,FOT was reduced to 9.1%, being smaller than that of maximal mid-expiratory flow (10.1%). However, even then the day-to-day variation in Rrs,FOT was clearly larger (16.0%) than those of the airflow indices at specified lung volumes (7.2-8.3%). This was also true for the weekly variation. In the exercise challenge test, there were larger changes in Rrs,FOT values than in the spirometric indices, but Rrs,FOT was the most sensitive index to detect changes in the respiratory system. In conclusion, the variation in Rrs,FOT values was larger than that of most spirometric indices. When a reliability index was applied, the immediate variation in Rrs,FOT values was comparable to those of the airflow indices at specified lung volumes. Rrs,FOT was also the most sensitive index in the exercise challenge test, and therefore it seems to be suitable for detection of short-term functional changes in the respiratory system. However, the relatively low repeatability of Rrs,FOT over days and weeks may limit its applicability to longer-term follow-ups.