Comorbidity modulates non invasive ventilation-induced changes in breath print of obstructive sleep apnea syndrome patients

Background:in patients with OSAS,long-term CPAP causes important changes in exhaled volatile organic compounds (VOCs).It is unknown whether this change reflects the effect of CPAP treatment or simply the acute relief of hypoxia, nor which are the determinants of this mutation in breath composition.Objective:verify whether changes in VOCs pattern are detectable after the first night of CPAP and to identify predictors,if any,of these changes.Type of study:observational studyMethod:fifty OSAS patients underwent a multidimensional assessment and breath print (BP) analysis through 28-sensors e-nose at baseline and after the first night of CPAP.Cluster Analysis of basal and post CPAP BPs via K-means technique and Partial Least Square Discriminant Analysis (PLS-DA),the latter with Leave-One-Out as Cross-validation criterion,were used to verify whether basal BP could predict post CPAP BP. Groups were compared by ANOVA and Fisher exact t.Results:CPAP was effective in all the patients (delta AHI-31 events/hour;residual AHI 5.8 events/hour).According to ANOVA,BP collected by individual sensors did not change significantly after a single night C-PAP trial.However,Kmeans identified groups with distinctive basal BP and BP changes after CPAP.The average number of comorbid diseases and the prevalence of selected comorbidity,were the only features distinguishing groups.Conclusions:BP change after a single night successful CPAP administration is easily predictable in patients free from major comorbidity. Comorbidity likely contributes to phenotypic variability in OSAS population might qualify as a fast track index of the response to and,later, compliance to CPAP.