Daytime approach to Obstructive Sleep Apnea phenotyping

Background: OSA is a common respiratory sleep disorder with multiple pathological traits. Identifying them is pivotal for a phenotype-tailored therapy. The reference phenotyping method is based on measurements obtained by a complex polysomnographic protocol conducted by CPAP manipulation during sleep.Aim: To find out whether it is possible to measure the same phenotypic traits with simpler daytime tests in OSA patients.Methods: 10 OSA patients underwent the reference protocol (gold standard) to identify pathological traits: high upper airway passive collapsibility and loop gain (LG), low arousal threshold (AT) and upper airway gain (UAG). Subsequently, they performed day-time maximum breath holding test and negative expiratory pressure test (NEP), as proxy of LG and upper airway collapsibility, respectively. Basal PSGs were used to assess AT. A new formula combining basal PSG and NEP was created to evaluate UAGd.Results: The volume exhaled in the first 0.5s with NEP at -5 cmH2O (V0.5) was related to pharyngeal collapsibility (r2=0.76, p=0.0009). The second breath after max apnea (V2nd as%Vt) was related to loop gain (r2=0.79,p=0.0005). AT score (1 point each for AHI<30, hypopnea fraction >58.3%, nadirSpO2 >82.5%) was related to ventilation reduction needed to cause an arousal. The daytime upper airway gain formula we developed was related to UAG (r2=0.89,p=0.0001).Conclusions: As each trait was rightly identified, this study proves daytime OSA phenotyping is possible and could have a wider impact on treating patients with best phenotype-tailored therapies.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 2508.This abstract was presented at the 2020 ERS International Congress, in session { extquotedblleft}Respiratory viruses in the "pre COVID-19" era{ extquotedblright}.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).