At the second visit, the FEV_{step one}/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?_area 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.

Mean linear regression data away from a great) absolute thinking (L) off forced essential strength (FVC) in place of Salem escort service pushed expiratory frequency inside step one s (FEV

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Mean linear regression investigation regarding a good) pure viewpoints (L) out of pressed essential capacity (FVC) versus pressed expiratory frequency within the step one 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.

Dialogue

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 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.

From inside the arrangement that have latest assistance eleven, several, an obstructive respiratory situation was detected when attacks try confirmed by appropriate practical screening. In the event the, theoretically, such as for instance a statement try sound and stands for the foundation your every day clinical practice, one thing tends to be not too quick if problem was at the 1st phase and you can/or the practical screening let you know borderline philosophy. This is exactly the fact within data. To try to reveal this problem, we mutual the outcome regarding medical forms with increased pulmonary form screening.

As for the choice of the functional tests, we used lung volumes, D_L,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 D_L,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.