The correlations between pulmonary function tests and polysomnographic parameters in overlap syndrome

Abstract

Aim: This study aims to reveal the relationship between Pulmonary Function Tests (PFTs) parameters and polysomnographic parameters. It aims to determine the guiding values in treatment selection, with the hypothesis that easily accessible PFTs parameters can be useful in clinical evaluation for patients with restrictive or obstructive type disorders. Material and Method: One hundred and forty-six patients with obstructive and/or restrictive pulmonary dysfunction who underwent polysomnography in the sleep clinic of our hospital between June 2019 and December 2019 were included in the study. Polysomnography (PSG) parameters and PFTs results were obtained. Age, gender, body mass index (BMI), Epworth Sleepiness Scale (ESS) score, PFTs parameters, apnea-hypopnea index (AHI), nocturnal oxygen saturation, tolerable positive airway therapy modality, and pressures were recorded. Results: Of 146 patients 34.9% were women and most (92.5%) had an obstructive disorder in PFTs. Of the patients with the obstructive disorder, 71 were being followed up with a diagnosis of chronic obstructive pulmonary disease (COPD) and 64 with a diagnosis of asthma. Interstitial lung disease was observed in 5 out of 11 cases (7.5%) with restrictive type disorder, and obesity resulted in restrictive disorder for the remaining 6 cases. Simple snoring was observed in 5.5%. Mild OSAS was observed at a rate of 30.1%. Moderate-severe OSAS was detected in 64.4% of the patients. When the relationship between optimal inspiratory/ expiratory positive airway pressure (IPAP/EPAP) values determined by automatic bilevel positive airway pressure (ABPAP) titration and PFTs parameters were analyzed, a moderate negative correlation was observed between IPAP value and forced vital capacity (FVC) (L) (r=-0.432, p=0035) Discussion: The results of this study show that PFTs parameters can be used to predict polysomnographic findings for patients with obstructive/ restrictive disorders. Almost two-thirds of the patients with obstructive sleep apnea (OSA)-related symptoms in this group were observed to have moderate-severe obstructive sleep apnea syndrome (OSAS). Based on our results in ROC analysis, we believe that it would be appropriate to recommend titration with bilevel devices, especially for patients with forced expiratory volume in one second (FEV1)<60% and maximum expiratory flow between 25% and 75% of FVC (MEF25-75)<30%. Bilevel devices may be useful for patients with reduced MEF25-75 (representing peripheral airways), through alveolar recruitment and pressure support. Conclusion: In our study, we demonstrated that the optimal IPAP value for treatment had a positive correlation with the oxygen desaturation index (ODI) and AHI and a negative correlation with minimum finger pulse oximetry (SpO2), as well as a negative correlation with FVC value. Simple spirometric data along with polysomnographic data can also be helpful when determining baseline pressures in bilevel positive airway pressure (BPAP) titration for OSAS patients with respiratory dysfunction.