Alterations of the beneficial effect of deep inspiration in scleroderma: relationships between lung function and imaging.
BACKGROUND
It has been postulated that the beneficial effects of deep inspiration are dependent on the magnitude of airway distension by virtue of airway to parenchyma interdependence.


OBJECTIVE
This study was designed to examine whether the changes that occur in pulmonary fibrosis affect the beneficial effect of deep inspiration.


METHODS
Thirty-one subjects with scleroderma underwent lung volume and diffusion capacity assessment as well as high-resolution computed tomography. To assess the effect of deep inspiration, each subject underwent methacholine provocations in the absence of deep breaths. When the targeted change in lung function was achieved, subjects were asked to take 4 consecutive deep inspirations after which lung function measurements were repeated. The inspiratory vital capacity (IVC) was used as primary outcome.


RESULTS
Only 19 subjects attained the desired reduction in IVC in the absence of deep breaths. In those subjects, deep inspiration reversed the effect of methacholine on IVC by 48 +/- 8.4%. The effect of deep inspiration correlated with DLCO% predicted (r = 0.55, p = 0.01), but not with high-resolution computed tomography abnormalities or baseline lung function measurements. When all subjects were considered, responsiveness to methacholine in the absence of deep inspiration was progressively lower with decreasing DLCO% predicted values (r = 0.51, p = 0.003).


CONCLUSIONS
In systemic scleroderma, pulmonary abnormalities resulting in mild to moderate reduction in the diffusion capacity are associated with reduced ability of deep inspiration to reverse methacholine-induced early airway closure and bronchoconstriction. When diffusion capacity is severely affected, methacholine fails to produce obstructive airway changes.
Scichilone
Nicola
N
Dipartimento di Medicina, Pneumologia, Fisiologia e Nutrizione Umana, Palermo, Italy. n.scichilone@libero.it
Reitano
Simona
S
Bellia
Maria
M
Riili
Maria
M
Togias
Alkis
A
Midiri
Massimo
M
Triolo
Giovanni
G
Bellia
Vincenzo
V
D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents / Q000008:administration & dosage; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D001239:Inhalation; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000628:therapy*; D015656:Respiratory Mechanics; D012594:Scleroderma, Localized / Q000628:therapy*; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride