biostudies-literatureUnknown179(4)Sankri-Tarbichi AG<h4>Rationale</h4>Ventilatory motor output is an important determinant of upper airway patency during sleep.<h4>Objectives</h4>We hypothesized that central hypocapnic hypopnea would lead to increased expiratory upper airway resistance and pharyngeal narrowing during non-REM sleep.<h4>Methods</h4>Noninvasive positive pressure ventilation was used to induce hypocapnic hypopnea in 20 healthy subjects. Expiratory pressure was set at the lowest pressure (2 cm H(2)O), and inspiratory pressure was increased gradually during each 3-minute noninvasive positive pressure ventilation trial by increments of 2 cm H(2)O. Analysis 1 (n = 9) included measured retropalatal cross-sectional area (CSA) using nasopharyngoscope to compare CSA at five points of the respiratory cycle between control (eupneic) and American journal of respiratory and critical care medicine313-9https://www.ebi.ac.uk/biostudies/studies/S-EPMC2643080biostudies-literatureExpiratory pharyngeal narrowing during central hypocapnic hypopnea.PMC2643080Rowley JASankri-Tarbichi AGBadr MSfalseExpiratory pharyngeal narrowing during central hypocapnic hypopnea.<h4>Rationale</h4>Ventilatory motor output is an important determinant of upper airway patency during sleep.<h4>Objectives</h4>We hypothesized that central hypocapnic hypopnea would lead to increased expiratory upper airway resistance and pharyngeal narrowing during non-REM sleep.<h4>Methods</h4>Noninvasive positive pressure ventilation was used to induce hypocapnic hypopnea in 20 healthy subjects. Expiratory pressure was set at the lowest pressure (2 cm H(2)O), and inspiratory pressure was increased gradually during each 3-minute noninvasive positive pressure ventilation trial by increments of 2 cm H(2)O. Analysis 1 (n = 9) included measured retropalatal cross-sectional area (CSA) using nasopharyngoscope to compare CSA at five points of the respiratory cycle between control (eupneic) and 2009-01-01T00:00:00Z2009 Feb2025-04-22T06:47:33.899Z2019-03-27T00:20:45ZS-EPMC26430801920192910.1164/rccm.200805-741OC10.1164/rccm.200805-741oc