Objectives: . Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes. Methods: . We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models. Results: . We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05). Conclusion . Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.

Objectives: . Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes. Methods: . We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models. Results: . We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05). Conclusion . Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.

Objectives: . Endotype-based interventions have shown promise in the treatment of patients with obstructive sleep apnea, and upper airway surgery is a key therapeutic option. However, responses to surgery vary among patients with obstructive sleep apnea. This study aims to examine changes in endotypic traits following upper airway surgery and to explore their association with surgical outcomes. Methods: . We prospectively recruited 25 patients with obstructive sleep apnea who visited a single sleep center for upper airway surgery. These patients underwent polysomnographic studies both before and after surgical intervention. During non-rapid eye movement and rapid eye movement sleep, we estimated endotypic traits—including collapsibility (Vpassive), arousal threshold, loop gain, and upper airway compensation—with the phenotyping using polysomnography method. Based on improvements in the apnea-hypopnea index, patients were classified as either responders or non-responders. We compared the preoperative endotypic traits between these groups using Mann-Whitney tests. Additionally, we compared changes in endotypic traits pre- and post-surgery between responders and non-responders using generalized linear mixed models. Results: . We identified 12 responders and 13 non-responders. Compared to non-responders, responders exhibited improved collapsibility during rapid eye movement sleep (22.3 vs. −8.2%eupnea in Vpassive, P=0.01), and their arousal threshold decreased during non-rapid eye movement sleep (−22.4%eupnea, P=0.02). No endotypic trait predicted surgical response; however, the apnea-hypopnea index during rapid eye movement sleep was higher among responders than non-responders (51.8/hr vs. 34.4/hr, P=0.05). Conclusion . Upper airway surgery significantly reduced collapsibility during rapid eye movement sleep in responders. The target pathology for upper airway surgery is a compromised upper airway during rapid eye movement sleep.