Early Respiratory Mechanics Alterations in Smokers: Correlative Analysis of the Forced Oscillation Technique and Computerized Spirometry.

Introduction: Smoking remains a significant public health concern, associated with a myriad of diseases, including chronic obstructive pulmonary disease, cardiovascular diseases, and various cancers. While spirometry is the gold standard for assessing lung function, it may lack sensitivity in detecting early changes in respiratory mechanics induced by smoking. This study aims to evaluate the clinical potential of the forced oscillation technique (FOT) in detecting early changes in the respiratory mechanics of smokers and its correlation with computerized spirometry. This study aims to bridge this gap by investigating the utility of FOT, a noninvasive method requiring less patient cooperation, in detecting early changes in respiratory mechanics among smokers.

Method:  The study was conducted on 36 healthy nonsmokers and 36 healthy smokers. We conducted FOT and computerized spirometry, comparing these parameters between the two groups and finding correlations between FOT and spirometry parameters.

Result:  A statistically significant difference was found across different smoking indices for computerized spirometer parameters forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), marginal significance for peak expiratory flow, and no statistically significant for FEV1/FVC ratio and forced expiratory flow between 25 and 75% of vital capacity. We did not find statistically significant differences across different smoking indexes for FOT parameters, resistance at 5 Hz (R5), resistance at 20 Hz (R20), resistance difference between 5 and 20 Hz (R5-20), reactance at 5 Hz, reactance at 20 Hz (X20), area under the reactance curve (AX), resonance frequency (Fres), and resistance at resonance. However, Fres had shown marginal significance. The study revealed notable negative correlations between airway resistance parameters (such as R5 and R5-20) and the FEV1/FVC ratio, and significant negative correlations were also identified between airway reactance parameters (AX and Fres) and FEV1.

Conclusion:  The results emphasize that FVC and FEV1 appear to be early markers of damage. The smoking index (1-70) did not significantly influence the FOT parameters in the examined population with the Quark i2m FOT machine (COSMED, Italy). Nevertheless, marginal significance in FOT Fres parameters suggests potential alterations with longer smoking durations, warranting further investigation. Also, significant negative correlations were found between the FOT and pulmonary function test parameters.