Abstract

Introduction: Non Specific Spirometric pattern (NSP) is uncommon and overlooked by most chest physicians. It is characterized by normal ratio of Forced Expiratory Volume in 1s/Forced Vital Capacity (FEV1/FVC) and an homogeneous reduction of FEV1 and FVC contrasting with a normal Total Lung Capacity (TLC).

Aim: The aims of this study were to evaluate spirometric evolution of NSP and to seek possible association between the evolutionary spirometric pattern and basic functional data.

Methods: This observational and longitudinal  study (from 2016 to 2020) included 32 patients diagnosed with NSP. However, we only maintained those with at least two medical controls spaced at least 6 months apart. All included patients had total body plethysmography and reversibility tests at each medical visit

Results: The average age was 50±19 years, sex-ratio was 0.45, and BMI was 30 ± 9 Kg/m2. NSP was related to asthma asthma (25%), interstitial lung disease (22%), obstructive sleep apnea (25%), bronchectasis (6%), neuromuscular diseases (13%),  bronchopulmonary cancer (3%) and tobacco smoking  in  15,6%.  Control PFT data revealed no change in spirometric pattern in  36% and evolution to other spirometric pattern in 64% of patients : restriction (47%), Obstruction (3%) and normal pattern (9%).  Restrictive evolutionary pattern was related to female gender (p=0,001), initial BMI (p=0,04) and basic VR and TLC.  

Conclusion: These results highlighted that clinical and basic functional data may be helpful  to predict specially evolution of NSP to restrictive pattern.  Given rarity of this pattern, we plan to continue this study in order to enlarge our study population and refine our results.