These subjects were part of an indoor air quality investigation and were performing repeated spirometry to assess changes in pulmonary function over the day and week—both at and away from work. To reduce fatigue and obtain better subject compliance with the testing protocol, the subjects were told they could terminate forced exhalation when the instrument beeped at 6 s after the onset of flow. Although the flow spirometer continued to collect data for up to 9 s, the resulting FVCs are actually the result of the subjects terminating their maneuvers after approximately 6 s of exhalation. To compare results using the volume spirometer with those using the flow spirometer, only the first three FVC maneuvers obtained on the volume spirometer were used. In addition, some comparisons were made using the FEV6, since the exhalation times were limited to 6 to 9 s when using the flow spirometer. Viagra super active plus Source A dynamic BTPS correction factor previously described was used to correct the FEVb FEVg, and FVC obtained from the flow spirometer, the dynamic BTPS correction factor developed in this study was used.
Besides beeping at 6 s, the instrument provided feedback to the subject concerning the adequacy of his effort. This feedback consisted of either a blinking red (insufficient effort) or green light (good effort), depending on the reproducibility of peak flow.
For each subject, averages over all test sessions were calculated for FVC and FEVi by maneuver order. Sessions were excluded from the average if the session had less than three maneuvers. That is, the mean was calculated for all results from the first maneuvers at all sessions for a subject, both for FVC and FEVi. Means were similarly calculated for all second and all third maneuvers. The percent difference of the second and third maneuvers compared with the first maneuver was then calculated for each subject and averaged to provide the results shown in Figure 1. To prevent an unsatisfactory maneuver from unduly influencing the results, any maneuver set (three maneuvers), which had an individual FVC or FEVi value that differed from other maneuvers in the set by more than ±20 percent, was eliminated from this analysis. Five of 273 sets were eliminated. Two different BTPS correction factors were used for experiment 5. The first method used a factor that was 30 percent of the BTPS correction factor calculated using room temperature. The second method estimated a dynamic BTPS correction factor based on the regression analysis results obtained from experiments 1 through 4. The independent variable used to estimate the dynamic BTPS correction factor was exit air temperature.