Elsevier

Respiratory Medicine

Volume 101, Issue 6, June 2007, Pages 1355-1362
Respiratory Medicine

Flow and volume responses after routine salbutamol reversibility testing in mild to very severe COPD

https://doi.org/10.1016/j.rmed.2006.09.024Get rights and content
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Summary

Background

Flow response after administration of a bronchodilator is widely used as an indicator of reversibility of airflow limitation in chronic obstructive pulmonary disease (COPD). We hypothesized that the association between flow and volume responses would reverse along with the progression of the disease.

Methods

We used the database of a large primary care diagnostic centre containing pre- and postbronchodilator tests of patients referred for spirometry by their GP. Patients ⩾40 years with a smoking history were categorized into Global initiative for chronic obstructive lung disease (GOLD) stages I–IV. Flow and volume responses (ΔFVC and ΔFEV1, respectively) were calculated and compared between the GOLD stages using linear regression analysis.

Results

About 2210 patients (63% males, 49% current smokers) were analysed. Four hundred and forty-two patients were classified into GOLD stage I, 1297 in GOLD II, 426 in GOLD III, and 45 in GOLD IV. The overall mean values for ΔFEV1 and ΔFVC were 0.180 (sd 0.150) and 0.226 l (sd 0.227). ΔFEV1 decreased as the GOLD stage was more severe, whereas ΔFVC increased (P<0.001). There was a clear positive correlation between ΔFEV1 and ΔFVC within each GOLD stage (P<0.01), but when FVC response was plotted against FEV1 response the slope of the regression line became gradually steeper with each more severe GOLD stage (P<0.001).

Conclusions

Our hypothesis that COPD patients on the mild side of the severity spectrum differ from patients on the severe side regarding the association between their bronchodilator flow and volume responses was confirmed. The difference is probably explained by the higher degree of loss of lung elastic recoil and/or compression of the smaller airways due to enlarged air spaces that accompanies the progression of COPD to the more severe stages.

Keywords

COPD
Bronchodilator
Spirometry
Reversibility testing
General practice

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