Guarnieri Gabriella, Zanatta Elisabetta, Mason Paola, Scarpa Maria Cristina, Pigatto Erika, Maestrelli Piero, Cozzi Franco
Department of Cardiologic, Thoracic and Vascular Sciences, University of Padova, Padova, Italy.
Rheumatology Unit, Department of Medicine, University of Padova, Padova, Italy.
Clin Exp Rheumatol. 2015 Jul-Aug;33(4 Suppl 91):S80-6. Epub 2015 Apr 16.
Lung diffusing capacity for carbon monoxide (DLCO) is impaired in interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) associated to systemic sclerosis (SSc), but the mechanism of DLCO reduction remains controversial. We hypothesised that the determinants of DLCO impairment differ in interstitial or vascular involvement of the lung of SSc patients.
DLCO was partitioned into alveolar-capillary membrane conductance (Dm) and pulmonary capillary blood volume (Vc) using combined single-breath DLNO and DLCO measurements. Seventeen SSc patients without pulmonary involvement (SSc), 20 SSc patients with ILD (SSc-ILD), with and without PAH, and 21 healthy controls were included.
DLNO and Dm were reduced in SSc patients as compared with controls, whereas Vc was not significantly different. SSc-ILD patients showed a highly significant decrease in Dm and Vc as compared with SSc patients and controls. Vc tended to be more reduced than Dm in SSc-ILD patients with PAH. Dm and Vc were negatively correlated with PAPs and HCRT scores, but the relationship with the HRCT score was stronger.
DLNO is more sensitive than DLCO in detecting functional impairment in SSc without radiologic or haemodynamic alterations. A disproportional reduction of Dm relative to Vc suggests a thickening of the blood-gas diffusion barrier in these patients. In SSc patients with detectable ILD, the gas exchange impairment is due to both components of lung diffusing capacity, and partitioning of DLCO in Dm and Vc is of little use in distinguishing the patients with only ILD from those with ILD complicated by PAH.
在与系统性硬化症（SSc）相关的间质性肺疾病（ILD）和肺动脉高压（PAH）中，一氧化碳肺弥散量（DLCO）受损，但DLCO降低的机制仍存在争议。我们假设SSc患者肺部间质或血管受累时，DLCO受损的决定因素有所不同。
采用单次呼吸DLNO和DLCO联合测量，将DLCO分为肺泡-毛细血管膜传导率（Dm）和肺毛细血管血容量（Vc）。纳入17例无肺部受累的SSc患者（SSc组）、20例有ILD的SSc患者（SSc-ILD组，有或无PAH）以及21名健康对照者。
与对照组相比，SSc患者的DLNO和Dm降低，而Vc无显著差异。与SSc患者及对照组相比，SSc-ILD患者的Dm和Vc显著降低。在合并PAH的SSc-ILD患者中，Vc的降低往往比Dm更明显。Dm和Vc与肺动脉压（PAPs）和高分辨率计算机断层扫描（HRCT）评分呈负相关，但与HRCT评分的关系更强。
在无放射学或血流动力学改变的SSc中，DLNO在检测功能损害方面比DLCO更敏感。Dm相对于Vc不成比例地降低提示这些患者的血气扩散屏障增厚。在可检测到ILD的SSc患者中，气体交换受损是由于肺弥散能力的两个组成部分，将DLCO分为Dm和Vc对区分仅患有ILD的患者与合并PAH的ILD患者作用不大。
