Detection of interstitial lung disease in systemic sclerosis through partitioning of lung transfer for carbon monoxide.
BACKGROUND
Interstitial lung disease (ILD) is a leading cause of death in systemic sclerosis (SSc). Sensitivities and specificities of the current pulmonary function tests (PFTs) for the detection of ILD in SSc are poor.


OBJECTIVE
To determine whether diffusion capacity of the lungs for carbon monoxide (DLCO) partitioned into membrane conductance for CO (DmCO) and alveolar capillary blood volume (Vcap) could provide more sensitive clues to ILD than current PFTs.


METHODS
DmCO and Vcap were determined in 35 consecutive SSc patients in whom a cardiac and/or pulmonary vascular abnormality had been rejected according to the recommended screening algorithm. ILD was diagnosed with high-resolution computed tomography.


RESULTS
Among 35 patients [6 men; median age (first-third quartile) 61.9 years (49.5-67.7)], 22 had no ILD and 13 did. Total lung capacity (TLC), vital capacity and DLCO [percentage of predicted value (%pred)] were lower in patients with ILD [86 (82-103) vs. 106 (98-112), p = 0.01, 96 (88-112) vs. 114 (104-121), p = 0.04, and 67 (59-81) vs. 80 (71-94), p = 0.02, respectively]. DmCO (%pred) and the ratio of DmCO to Vcap were much lower in patients with ILD [54 (48-72) vs. 83 (66-92), p < 0.001, and 0.22 (0.21-0.27) vs. 0.40 (0.35-0.53), p < 0.0001, respectively]. According to receiver operating characteristic analysis, the DmCO:Vcap ratio displayed higher sensitivity and specificity than TLC, vital capacity and DLCO in identifying ILD in our study group (p < 0.01).


CONCLUSIONS
These results suggest that the partitioning of DLCO might be of interest for identifying ILD in SSc patients.
Department of Physiology, University Hospital, Faculty of Medicine, University of Franche-Comté, Besançon, France.
Julien
J
Pernot
Eve
E
Puzenat
Nadine
N
Magy-Bertrand
Philippe
P
Manzoni
Anne
A
Gondouin
Hubert
H
Bourdin
Marie-Laure
ML
Simon-Rigaud
Jacques
J
Regnard
Bruno
B
Degano
D000328:Adult; D000368:Aged; D001810:Blood Volume; D001944:Breath Tests; D002196:Capillaries; D002248:Carbon Monoxide / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000098:blood supply / Q000000981:diagnostic imaging; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity; D012372:ROC Curve; D012129:Respiratory Function Tests; D012595:Scleroderma, Systemic / Q000150:complications*; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
D002248:Carbon Monoxide