TY - JOUR T1 - Effect of simulated obstructive sleep apnea on thoracic fluid volume and lower airway resistance in asthmatics JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.congress-2020.4990 VL - 56 IS - suppl 64 SP - 4990 AU - Xiaoshu Cao AU - T. Douglas Bradley AU - Swati A. Bhatawadekar AU - Shumit Saha AU - Susan M. Tarlo AU - Matthew Stanbrook AU - Mark Inman AU - Azadeh Yadollahi Y1 - 2020/09/07 UR - http://erj.ersjournals.com/content/56/suppl_64/4990.abstract N2 - Background: The high prevalence of obstructive sleep apnea (OSA) in asthmatics and its relationship to asthma severity are recognized, suggesting a pathophysiological link between the two, but the underlining mechanism for this has not been identified. We aimed to examine the role of fluid shift as a potential link and hypothesized that exaggerated negative intrathoracic pressure during OSA in asthmatics will increase thoracic fluid volume (TFV) and increase lower airway resistance (RLA).Methods: We randomized asthmatics to breathe normally (control) or perform 25 Mueller maneuvers (MM) by inspiring against a closed mouthpiece for 30 mins while supine to simulate obstructive apneas (intervention). Participants then crossed over to the other arm. Before and after each arm, we measured TFV and indices of lower airway narrowing assessed by oscillometry, including respiratory system reactance at 5Hz (X5), difference between resistance at 5 and 19Hz (R5-19) and reactance area (Ax).Results: MM arm significantly increased ΔTFV (Fig 1A), reduced ΔX5 (Fig 1B), increased ΔR5-19 (Fig1C) and increased ΔAx (Fig 1D) indicating an increase in RLA.Conclusion: MMs draw fluid into the thorax in asthmatics, accompanied by increased RLA. This suggests that increases in TFV resulting from negative intrathoracic pressure swings during obstructive apneas are one mechanism by which OSA could worsen asthma at night.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 4990.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.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). ER -