Lung diffusing capacity for nitric oxide and carbon monoxide in relation to morphological changes as assessed by computed tomography in patients with cystic fibrosis.
BACKGROUND
Due to large-scale destruction, changes in membrane diffusion (Dm) may occur in cystic fibrosis (CF), in correspondence to alterations observed by computed tomography (CT). Dm can be easily quantified via the diffusing capacity for nitric oxide (DLNO), as opposed to the conventional diffusing capacity for carbon monoxide (DLCO). We thus studied the relationship between DLNO as well as DLCO and a CF-specific CT score in patients with stable CF.


METHODS
Simultaneous single-breath determinations of DLNO and DLCO were performed in 21 CF patients (mean +/- SD age 35 +/- 9 y, FEV1 66 +/- 28%pred). Patients also underwent spirometry and bodyplethysmography. CT scans were evaluated via the Brody score and rank correlations (rS) with z-scores of functional measures were computed.


RESULTS
CT scores correlated best with DLNO (rS = -0.83; p < 0.001). Scores were also related to the volume-specific NO transfer coefficient (KNO; rS = -0.63; p < 0.01) and to DLCO (rS = -0.79; p < 0.001) but not KCO. Z-scores for DLNO were significantly lower than for DLCO (p < 0.001). Correlations with spirometric (e.g., FEV1, IVC) or bodyplethysmographic (e.g., SRaw, RV/TLC) indices were weaker than for DLNO or DLCO but most of them were also significant (p < 0.05 each).


CONCLUSIONS
In this cross sectional study in patients with CF, DLNO and DLCO reflected CT-morphological alterations of the lung better than other measures. Thus the combined diffusing capacity for NO and CO may play a future role for the non-invasive, functional assessment of structural alterations of the lung in CF.
Dressel
Holger
H
Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Ziemssenstr, 1, D-80336 München, Germany. Holger.Dressel@med.uni-muenchen.de
Filser
Laura
L
Fischer
Rainald
R
Marten
Katharina
K
Müller-Lisse
Ullrich
U
de la Motte
Dorothea
D
Nowak
Dennis
D
Huber
Rudolf M
RM
Jörres
Rudolf A
RA
D000328:Adult; D002248:Carbon Monoxide / Q000378:metabolism*; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000503:physiopathology; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D010993:Plethysmography, Whole Body; D011653:Pulmonary Diffusing Capacity / Q000502:physiology*; D012189:Retrospective Studies; D013147:Spirometry; D014057:Tomography, X-Ray Computed
D009569:Nitric Oxide; D002248:Carbon Monoxide