Promoting the Inclusion of Lung Volumes in the Reversibility Evaluation—Reply

Conor T McCartney; Gregg L Ruppel; Ravi P Nayak

doi:10.4187/respcare.05411

In reply:

We greatly appreciate the thoughts Dr Ben Saad has shared with us about hyperinflation and our research. We think his research on lung volume reversibility¹ complements ours.² The question of whether residual volume change was more sensitive than FEV₁ or FVC change is a problematic one because all thresholds for responsiveness are arbitrary and can be manipulated by setting them higher or lower. What we found was that residual volume change correlated poorly with FEV₁ and FVC, which led us to conclude that we were describing a novel group of responders.

The research of Dr Ben Saad¹ shows that there were more residual volume responders in the hyperinflated group but not the control, which suggests that there are probably differences between hyperinflated people and those that are not hyperinflated. This makes us wonder whether we should use obstructed patients to help guide us to what expected change is and not use healthy subjects.³

Ultimately, we think the more we expand our knowledge about lung volumes the better off we will be understanding obstructive lung diseases. We think residual volume changes add important information about obstructive lung diseases.

Footnotes

The authors have disclosed no conflicts of interest.

References

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. Residual volume and total lung capacity to assess reversibility in obstructive lung disease. Respir Care 2016;61(11):1505–1512.
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