Over half of all cases of obstructive sleep apnoea (OSA) are classified as supine-related OSA; however, the pathological endotype during supine position is not fully understood. This study aims to investigate the endotypic traits of supine-predominant OSA and explore the variations in endotypic traits between the supine and lateral positions.

We prospectively recruited 689 adult patients with OSA from a single sleep centre between April 2020 and December 2022. Endotypic traits, namely arousal threshold, collapsibility, loop gain and upper airway muscle compensation, were retrieved from polysomnographic signals. We identified spOSA by a supine to non-supine apnoea–hypopnoea index (AHI) ratio >2. We cross-sectionally compared demographic and endotypic traits between supine-predominant OSA and non-positional OSA and examined the associations between supine-predominant OSA and endotypic traits. Additionally, we compared the changes in endotypic traits between supine and lateral positions in patients with supine-predominant OSA and non-positional OSA.

In our study sample, 75.8% of patients were identified as having supine-predominant OSA. Compared to non-positional OSA, supine-predominant OSA was associated with low collapsibility (β= –3.46 %_eupnoea, 95% CI –5.93– –1.00 %_eupnoea) and reduced compensation (β= –6.79 %_eupnoea, 95% CI –10.60– –2.99 %_eupnoea). When transitioning from the lateral to supine position, patients with supine-predominant OSA had a substantial decrease in compensation compared to those with non-positional OSA (–11.98 versus –6.28 %_eupnoea).

Supine-predominant OSA is the prevalent phenotype of OSA in Asian patients. Inadequate upper airway compensation appears to be a crucial underlying pathology in patients with supine-predominant OSA.

超过一半的阻塞性睡眠呼吸暂停 (OSA) 病例被归类为仰卧相关的 OSA；然而，仰卧位时的病理内型尚不完全清楚。本研究旨在调查仰卧位为主的 OSA 的内型特征，并探讨仰卧位和侧卧位之间内型特征的变化。

我们在 2020 年 4 月至 2022 年 12 月期间前瞻性地从单个睡眠中心招募了 689 名患有 OSA 的成年患者。从多导睡眠图信号中检索了内型特征，即觉醒阈值、塌陷性、环增益和上气道肌肉补偿。我们通过仰卧位与非仰卧位呼吸暂停低通气指数 (AHI) 比率 >2 来识别 spOSA。我们横断面比较了仰卧位为主的 OSA 和非体位型 OSA 之间的人口统计学和内型特征，并检查了仰卧位为主的 OSA 与内型特征之间的关联。此外，我们还比较了仰卧位为主的 OSA 和非体位型 OSA 患者仰卧位和侧卧位之间内型特征的变化。

在我们的研究样本中，75.8% 的患者被确定患有仰卧位为主的 OSA。与非体位 OSA 相比，仰卧位为主的 OSA 与低塌陷性相关（β= –3.46 % _eupnoea，95% CI –5.93– –1.​​00 % _eupnoea）和代偿减少（β= –6.79 % _eupnoea，95% CI – 10.60– –2.99 %_紫气）。当从侧卧位转换为仰卧位时，与非体位 OSA 患者相比，仰卧位为主的 OSA 患者的代偿能力显着下降（–11.98 % vs –6.28 % _eupnoea）。

仰卧位为主的 OSA 是亚洲患者中 OSA 的普遍表型。上气道代偿不足似乎是仰卧位为主的 OSA 患者的一个重要的基础病理。