At the second visit, the FEV1/VC at presentation was still below the normal range in all subjects, thus confirming the repeatability of the parameter. dos0 ? ). This was also observed in four subjects with rhinitis and 10 with COPD. In the latter, the slope of FVC versus FEV1 was significantly >1 (p = 0.048) and steeper (1.24±0.40, p = 0.002) than in any other groups (fig. 4 ? ), suggesting that all of the fall in FEV1 was due to the decrease in FVC, i.e. to trapping of air. Moreover, the y-intercept was lower (1.19±0.82, p = 0.013) than in asymptomatic and rhinitis groups. Similarly, the y-intercept of V?maximum versus V?region in COPD was lower (0.28±0.14, p = 0.006) than in the control and rhinitis groups, suggesting a reduced bronchodilator effect of DI.
Indicate linear regression studies of good) absolute philosophy (L) out-of pressed vital capacity (FVC) in place of pressed expiratory volume for the step 1 s (FEV
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Mean linear regression data out-of an excellent) pure thinking (L) regarding pressed important capabilities (FVC) versus pushed expiratory frequency when you look at the 1 s (FEV
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1) and b) of instantaneous maximal (V?max) and partial (V?part) flows (L·s ?1 ) at 40% of control FVC at each step of methacholine challenge in the five groups. By regressing FVC against FEV1 values, an increase of slope or a decrease of y-intercept suggests enhanced gas trapping and vice versa. Similarly, an increase of slope or a decrease of y-intercept of V?max versus V?part values suggests a reduced bronchodilator effect of deep inspiration. ?: control; ?: asymptomatic; ?: rhinitis; 0: asthma; ?: chronic obstructive pulmonary disease. —–: line of identity. See text for statistical differences among groups.
Discussion
The present study was conceived to investigate whether a low FEV1/VC ratio with an FEV1 within the predicted normal range may represent a physiological variant or an early sign of obstructive abnormalities. Our findings suggest that routine lung function tests are of little help to resolve this issue. In contrast, in most (33 out of 40) of these individuals, the use of clinical questionnaires of symptoms with additional tests of airway mechanics, such as bronchodilator and bronchoconstrictor responses and SBN2W-O, revealed abnormalities consistent with early airflow obstruction. In the remaining few subjects (seven out of 40), who were https://datingmentor.org/cs/russian-dating-cs classified as asymptomatic by respiratory questionnaires, the results of additional lung function tests were within normal ranges and indistinguishable from those of the control group, except for a borderline airway hyperresponsiveness to MCh in one subject with a symptoms score of zero.
Within the arrangement that have latest guidance 11, twelve, an obstructive respiratory condition are recognized whenever symptoms is actually verified from the appropriate practical examination. In the event that, the theory is that, such as for example a statement is voice and signifies the basis of our own every day scientific routine, one thing are not very quick in the event the problem is at their initially stage and/or even the useful testing tell you borderline philosophy. This might be the actual situation inside our research. In order to reveal this problem, we combined the outcome off logical forms with an increase of pulmonary form testing.
As for the choice of the functional tests, we used lung volumes, DL,CO, and the response to the bronchodilator and bronchoconstrictor agents. The latter was slightly modified to examine the response of the airways to DI, as repeatedly reported in bronchial asthma 31, 32 and COPD 22, 23, 33. We also included the SBN2W-O by virtue of its high sensitivity to detect inhomogeneous distribution of ventilation 34.
The DL,CO measurements did not reveal any significant differences between groups with low FEV1/VC ratio. The MCh challenge documented the presence of airway hyperresponsiveness in all subjects with a history of bronchospasm, thus confirming the results of the questionnaire. Surprisingly, however, we did not see significantly different responses to the DI in these asthmatics, as previously reported 31, 32. In an attempt to explain such an unexpected finding, we postulate that at the transition from health to disease, and with normal or near normal lung function, the bronchodilator effect of DI may still be preserved 31, 32. In COPD, we observed a high rate of airway hyperresponsiveness and evidence of increased airway closure with gas trapping both at rest (increased RV/TLC and decreased OC) and after exposure to MCh (increased slope and decreased y-intercept of the FVC versus FEV1 regression), as well as signs of impaired bronchodilation either with salbutamol (low ?FEV1 and ?V?part as % of control) or DI during the bronchial challenge (reduced y-intercept of the V?max versus V?part regression). With the assumption that these subjects were properly assigned to the COPD group, our findings would suggest that increased airway closure with gas trapping and impaired response to large inflation or bronchodilator agents are already part of the early stages of the disease 22, 23.