Distinctive features of the pulmonary functional status in patients with interstitial lung disease

Abstract

Introduction. Interstitial lung diseases (ILD) are a group of disorders that are generally thought to share a common pattern of physiologic abnormality characterized by a restrictive ventilatory defect and reduced diffusing capacity (DLCO). Aim of the study. To find distinctive features of the pulmonary function tests results in different types of ILD. Materials and methods. We have analyzed the data collected from 40 consecutive patients admitted to the Institute of Pthisiopneumology, Chisinau, Republic of Moldova, during January 2019 – February 2020. We have included patients with ILD that are different from a morphological and pathogenetical point of view and distributed the patients as follows: Sarcoidosis patients – 10 cases, Idiopathic pulmonary fibrosis (IPF) patients – 8 cases, Nonspecific Idiopatic Insterstitial pneumonia (NSIP) patients – 7 patients, Hypersensitivity pneumonitis (HP) patients – 9 subjects and 6 Histiocytosis (Hx) cases. All patients have been evaluated by pulmonary function tests, 6MWT, Sa02, MRC scale for dyspnea, etc. Results. The mean age was 58.95 ±14.1 years, having the oldest patients (mean 69.7 ±8.3 years) in the IPF subgroup, and the youngest in the Hx group (mean 38.3±15.6 years), p ˂0.001. The majority of patients were women (55%), and non-smoker patients (75%). Overall, the sarcoidosis and HP patients were 100% non-smokers, while all Hx patients were ever-smokers, p ˂0.001. The MRC dyspnea score median was 3 [2;3]. When compared by subgroups, the degree of dyspnea in sarcoidosis and in Hx patients was similar (p˃0.05). Moreover, IPF patients expressed significantly more dyspnea when compared to Sarcoidosis (p=0.01), or the Hx subgroup (p=0.025). Similarly, HP patients complained of more severe dyspnea when compared to sarcoidosis patients (p=0.029). In terms of pulmonary function tests we found normal mean FEV1 and FVC values (80.7±21.7 and 78.4±21.5 respectively), a slightly increased mean RV (127.5±42.1), a mildly decreased mean TLC (88.8±22.3) and a moderately decreased DLCO (52.6±21.5). Analyzing PFT parameters within the subgroups we found a predominant restrictive pattern, when defined as FEV1/FVC above 80%, in more than 70% of patients from all the subgroups. But when we applied the bodyplethismographic parameters, we have found that an air-trapping pattern, defined as an elevated RV combined with a normal TLC was identified in about 40% cases of patients with Hx, HP and sarcoidosis.Conclusions. PFT can help identifying individual features of different types of ILD being able to show even obstructive changes in a group of diseases thought to be strictly restrictive.