Radiological patterns and pulmonary function values of lung involvement in primary Sjögren’s syndrome: A pilot analysis

Background

Lung involvement in primary Sjögren’s syndrome (pSS) may vary from 9 to 90%. Interstitial lung disease and tracheobronchial alterations are the most typical findings. The evidence of primarily emphysematous changes at computed tomography of the chest of pSS patients has occasionally been described but poorly characterized. This study aims to assess pulmonary involvement and the impact on respiratory function in a cohort of pSS patients.

Materials and methods

A total of 22 consecutive patients diagnosed with pSS underwent pulmonary function tests to investigate the presence of ventilatory impairment and evaluate the exchanges of alveolar gases. All patients underwent a chest high-resolution computed tomography (HRTC).

Results

Dynamic volumes were within the normal range in 21 patients (95.4%). A reduction in the diffusing capacity of the lung for carbon monoxide (DLCO) was observed in 18 patients (81.8%). Ten (45.5%) patients showed a mild degree deficit, while 8 patients (36%) showed a moderate degree deficit. Analysis of DLCO revealed a significant difference between pSS patients and controls [t(30.98) = −10.77; p < 0.001], showing a higher DLCO value for the healthy controls (mean ± SE; 101.27 ± 6.08) compared to pSS patients (mean ± SE; 65.95 ± 12.78). Emphysema was found in 21 (94.5%) patients and was the most widespread pulmonary injury. Tracheal thickness was reduced in 15 (67%) patients. Micronodules were observed in 10 (45%) patients in all the pulmonary fields. Bronchial wall thickening and bronchiectasis were observed in 8 (36%) patients, mainly in the lower lobes. Ground glass was found in 5 (22.5%) patients in lower and higher lobes. Cysts were observed in two patients (9%).

Conclusion

The reduction of the DLCO could be related to early emphysematous alterations in the absence of spirometric alterations and relevant respiratory symptoms. In conclusion, emphysema might be seen as an early pulmonary involvement mark in patients suffering from pSS.

Value of lung diffusing capacity for nitric oxide in systemic sclerosis

A decreased lung diffusing capacity for carbon monoxide (DL_CO ) in systemic sclerosis (SSc) is considered to reflect losses of alveolar membrane diffusive conductance for CO (DM_CO ), due to interstitial lung disease, and/or pulmonary capillary blood volume (V_C ), due to vasculopathy. However, standard DL_CO does not allow separate DM_CO from V_C . Lung diffusing capacity for nitric oxide (DL_NO ) is considered to be more sensitive to decrement of alveolar membrane diffusive conductance than DL_CO . Standard DL_CO and DL_NO were compared in 96 SSc subjects with or without lung restriction. Data showed that DL_NO was reduced in 22% of subjects with normal lung volumes and DL_CO , whereas DL_CO was normal in 30% of those with decreased DL_NO . In 30 subjects with available computed tomography of the chest, both DL_CO and DL_NO were negatively correlated with the extent of pulmonary fibrosis. However, DL_NO but not DL_CO was always reduced in subjects with ≥ 5% fibrosis, and also decreased in some subjects with < 5% fibrosis. DM_CO and V_C partitioning and Doppler ultrasound-determined systolic pulmonary artery pressure could not explain individual differences in DL_CO and DL_NO . DL_NO may be of clinical value in SSc because it is more sensitive to DM_CO loss than standard DL_CO , even in nonrestricted subjects without fibrosis, whereas DL_CO partitioning into its subcomponents does not provide information on whether diffusion limitation is primarily due to vascular or interstitial lung disease in individual subjects. Moreover, decreased DL_CO in the absence of lung restriction does not allow to suspect pulmonary arterial hypertension without fibrosis.

Pulmonary function tests as outcomes for systemic sclerosis interstitial lung disease

Interstitial lung disease (ILD) is the leading cause of morbidity and mortality in systemic sclerosis (SSc). We performed a systematic review to characterise the use and validation of pulmonary function tests (PFTs) as surrogate markers for systemic sclerosis-associated interstitial lung disease (SSc-ILD) progression.Five electronic databases were searched to identify all relevant studies. Included studies either used at least one PFT measure as a longitudinal outcome for SSc-ILD progression (i.e. outcome studies) and/or reported at least one classical measure of validity for the PFTs in SSc-ILD (i.e. validation studies).This systematic review included 169 outcome studies and 50 validation studies. Diffusing capacity of the lung for carbon monoxide (DLCO) was cumulatively the most commonly used outcome until 2010 when it was surpassed by forced vital capacity (FVC). FVC (% predicted) was the primary endpoint in 70.4% of studies, compared to 11.3% for % predicted DLCO Only five studies specifically aimed to validate the PFTs: two concluded that DLCO was the best measure of SSc-ILD extent, while the others did not favour any PFT. These studies also showed respectable validity measures for total lung capacity (TLC).Despite the current preference for FVC, available evidence suggests that DLCO and TLC should not yet be discounted as potential surrogate markers for SSc-ILD progression.

Combined measurement of carbon monoxide and nitric oxide lung transfer does not improve the identification of pulmonary hypertension in systemic sclerosis

Screening is important to determine whether patients with systemic sclerosis (SSc) have pulmonary hypertension because earlier pulmonary hypertension treatment can improve survival in these patients. Although decreased transfer factor of the lung for carbon monoxide (TLCO) is currently considered the best pulmonary function test for screening for pulmonary hypertension in SSc, small series have suggested that partitioning TLCO into membrane conductance (diffusing capacity) for carbon monoxide (DMCO) and alveolar capillary blood volume (VC) through combined measurement of TLCO and transfer factor of the lung for nitric oxide (TLNO) is more effective to identify pulmonary hypertension in SSc patients compared with TLCO alone. Here, the objective was to determine whether combined TLCO–TLNO partitioned with recently refined equations could more accurately detect pulmonary hypertension than TLCO alone in SSc.

For that purpose, 572 unselected consecutive SSc patients were retrospectively recruited in seven French centres.

Pulmonary hypertension was diagnosed with right heart catheterisation in 58 patients. TLCO, TLNO and VC were all lower in SSc patients with pulmonary hypertension than in SSc patients without pulmonary hypertension. The area under the receiver operating characteristic curve for the presence of pulmonary hypertension was equivalent for TLCO (0.82, 95% CI 0.79–0.85) and TLNO (0.80, 95% CI 0.76–0.83), but lower for VC (0.75, 95% CI 0.71–0.78) and DMCO (0.66, 95% CI 0.62–0.70).

Compared with TLCO alone, combined TLCO–TLNO does not add capability to detect pulmonary hypertension in unselected SSc patients.

Pulmonary involvement in systemic sclerosis

Systemic sclerosis (SSc) is a multi-systemic autoimmune disease that mainly affects the skin, lungs, gastrointestinal tract, heart and kidneys. Pulmonary disease in patients with SSc is strongly associated with mortality. The mechanisms involved into its pathophysiology include the activation of autoimmune cells and hyperplasia of fibroblasts with an increased capacity to produce collagen and diminished collagen breakdown. Although pulmonary biopsy is the gold standard for the diagnosis of interstitial lung disease in SSc, the most commonly used method is high-resolution computed tomography due to its high sensitivity and specificity. Herein, a comprehensive review on the pulmonary involvement in SSc is presented highlighting the radiologic-pathologic correlations.

[Pulmonary CO/NO transfer: physiological basis, technical aspects and clinical impact]

Diseases affecting the alveolar-capillary membrane or the capillary blood vessels can impair pulmonary gas exchanges and lung diffusion. The single-breath transfer factor of the lung for carbon monoxide (TL,CO) is the classical technique for measuring gas transfer from the alveolus to the pulmonary capillary blood. Pulmonary gas exchanges can also be explored by the transfer factor of the lung for nitric oxide (TL,NO). TL,NO represents a better index for the diffusing capacity of the alveolar-capillary membrane whereas TL,CO is more influenced by red blood cell resistance. Membrane diffusing capacity (DM) and pulmonary capillary blood volume (Vc) derivated from TL,CO and TL,NO by the Roughton-Forster equation can give additional insights into pulmonary pathologies. The clinical impact of the CO/NO transfer has still to be precised even if this measurement seems to provide an alternative way of investigating the alveolar membrane and the blood reacting with the gas.

Relevance of partitioning DLCO to detect pulmonary hypertension in systemic sclerosis

We investigated whether partitioning DLCO into membrane conductance for CO (DmCO) and pulmonary capillary blood volume (Vcap) was helpful in suspecting precapillary pulmonary (arterial) hypertension (P(A)H) in systemic sclerosis (SSc) patients with or without interstitial lung disease (ILD). We included 63 SSc patients with isolated PAH (n=6), isolated ILD (n=19), association of both (n=12) or without PAH and ILD (n=26). Partitioning of DLCO was performed by the combined DLNO/DLCO method. DLCO, DmCO and Vcap were equally reduced in patients with isolated PAH and patients with isolated ILD but Vcap/alveolar volume (VA) ratio was significantly lower in the isolated PAH group. In patients without ILD, DLCO, DmCO, Vcap and Vcap/VA ratio were reduced in patients with isolated PAH when compared to patients without PAH and both Vcap/VA and DLCO had the highest AUC to detect PAH. In patients with ILD, Vcap had the highest AUC and performed better than DLCO to detect PH in this subgroup. In conclusion, Vcap/VA was lower in PAH than in ILD in SSC whereas DLCO was not different. Vcap/VA ratio and DLCO had similar high performance to detect PAH in patients without ILD. Vcap had better AUC than DLCO, DmCO and FVC/DLCO ratio to detect PH in SSC patients with ILD. These results suggest that partitioning of DLCO might be of interest to detect P(A)H in SSC patients with or without ILD.

[COPD in dairy farmers: screening, characterization and constitution of a cohort. The BALISTIC study]

BACKGROUND

A pilot study from our group suggests that the prevalence of chronic obstructive pulmonary disease (COPD) among dairy farmers is higher than in the general population although dairy workers are less frequently smokers.

OBJECTIVES AND METHODS

The study presented here aims at (i) determining the prevalence of COPD in a large and representative population of dairy farmers; (ii) characterizing these patients in terms of smoking habits, dyspnoea, quality of life, lung function, bronchial exhaled nitric oxide, systemic inflammation, arterial stiffness and exercise capacity; (iii) comparing characteristics of dairy farmers' COPD with the characteristics of COPD in patients without any occupational exposure; (iv) identifying the etiological factors of COPD in dairy farmers; and (v) constituting a cohort of COPD patients and control subjects for further longitudinal studies. Two groups of COPD patients (dairy farmers or not) and two groups of controls subjects will be selected among a representative panel of 2000 dairy workers and 2000 subjects without any occupational exposure, all aged 40 to 75 years.

EXPECTED RESULTS

A better knowledge of the epidemiology and pathophysiology of COPD in dairy farmers should guide a specific strategy of prevention. The knowledge of the characteristics of COPD occurring in dairy farmers will help to define the therapeutic modalities that might be different compared with the therapeutic recommendations for COPD secondary to tobacco smoking.