Revista Portuguesa de Pneumologia Revista Portuguesa de Pneumologia
Rev Port Pneumol 2017;23:132-8 - Vol. 23 Num.3 DOI: 10.1016/j.rppnen.2017.01.004
Original article
Ventilation distribution and small airway function in patients with systemic sclerosis
B.R.A. Silvaa, R. Rufinob, C.H. Costab, V.S. Vilelac, R.A. Levyc, A.J. Lopesa,,
a Laboratory of Respiratory Physiology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil
b Department of Pulmonology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil
c Department of Rheumatology, State University of Rio de Janeiro, and Postgraduate Programme in Medical Sciences, State University of Rio de Janeiro, Rio de Janeiro, Brazil
Received 08 October 2016, Accepted 09 January 2017
Abstract
Background

Despite the importance of traditional pulmonary function tests (PFTs) in managing systemic sclerosis (SSc), many patients with pulmonary disease diagnosed by computed tomography (CT) present with normal PFTs.

Objective

To evaluate the efficacy of the nitrogen single-breath washout (N2SBW) test in diagnosing SSc and to correlate N2SBW parameters with the PFT indexes used in the follow-up of these patients, clinical data, and CT findings.

Methods

Cross-sectional study in which 52 consecutive SSc patients were subjected to spirometry, body plethysmography, analysis of the diffusing capacity for carbon monoxide (DLCO), analysis of respiratory muscle strength, N2SBW testing, and CT analysis.

Results

Twenty-eight patients had a forced vital capacity (FVC) that was <70% of the predicted value. In the N2SBW test, 44 patients had a phase III slope (Phase III slopeN2SBW) that was >120% of the predicted value, while 15 patients had a closing volume/vital capacity (CV/VC) that was >120% of the predicted value. A significant difference in Phase III slopeN2SBW was observed when the patients with predominant traction bronchiectasis and honeycombing were compared to the patients with other CT patterns (p<0.0001). The Phase III slopeN2SBW was correlated with FVC (rs=−0.845, p<0.0001) and DLCO (rs=−0.600, p<0.0001), and the CV/VC was correlated with FVC (rs=−0.460, p=0.0006) and residual volume/total lung capacity (rs=0.328, p=0.017).

Conclusion

Ventilation heterogeneity is a frequent finding in SSc patients that is associated with restrictive damage, changes in pulmonary diffusion, and CT patterns. In addition, approximately one-third of the patients presented with findings that were compatible with small airway disease.

Keywords
Systemic sclerosis, Respiratory function tests, Nitrogen single-breath washout test
Rev Port Pneumol 2017;23:132-8 - Vol. 23 Num.3 DOI: 10.1016/j.rppnen.2017.01.004