Pulmonology Unit, Department of Medical Surgical and Health Sciences, Hospital of Cattinara, University of Trieste, 34149, Trieste, Italy.
Pulmonology Unit, Department of Medical Surgical and Health Sciences, Hospital of Cattinara, University of Trieste, 34149, Trieste, Italy.
Respir Med. 2024 Nov-Dec;234:107820. doi: 10.1016/j.rmed.2024.107820. Epub 2024 Sep 25.
Loop Gain (LG), a concept borrowed from engineering used to describe the stability of electrical circuits under negative feedback, has emerged as a crucial pathophysiological trait in sleep respiratory disorders. In simple terms, LG measures how the respiratory control system reacts to changes in breathing. A high LG suggests that minor disturbances in breathing prompt exaggerated responses, potentially leading to instability and oscillations in respiratory patterns. Conversely, a low LG implies that the system responds more gently to disturbances, resulting in stable and well-regulated breathing. However, understanding the concept of loop gain presents challenges due to its dynamic nature across various sleep respiratory disorders, sleep stages, positions, and interactions with other pathophysiological traits. Recent efforts have aimed to identify a non-invasive method for assessing LG, with some evidence suggesting that information regarding pathophysiological traits can be extracted from polysomnography. There exists a clinical imperative for physician to unravel the intricacies of LG when managing Obstructive Sleep Apnea (OSA) patients, because LG abnormalities delineate a distinct pathophysiological phenotype of OSA. Specifically, certain patients exhibit a high LG as the primary factor driving sleep apnea, influencing treatment outcomes. For instance, individuals with high LG may respond differently to therapies such as continuous positive airway pressure (CPAP) or oral appliances compared to those with normal LG, or they can be treated with specific drugs or combination therapies. Thus, understanding LG becomes paramount for precise assessment of OSA patients and is fundamental for optimizing a personalized and effective treatment approach.
环增益（LG）是一个从工程学中借来的概念，用于描述在负反馈下电回路的稳定性，现已成为睡眠呼吸障碍中关键的病理生理特征。简单来说，LG 衡量了呼吸控制系统对呼吸变化的反应程度。高 LG 表明，呼吸轻微扰动会引发过度反应，可能导致呼吸模式不稳定和振荡。相反，低 LG 意味着系统对干扰的反应更为温和，从而产生稳定且调节良好的呼吸。然而，由于其在各种睡眠呼吸障碍、睡眠阶段、体位以及与其他病理生理特征相互作用中的动态性质，理解环增益的概念具有挑战性。最近的努力旨在确定一种评估 LG 的非侵入性方法，有证据表明，有关病理生理特征的信息可以从多导睡眠图中提取出来。在管理阻塞性睡眠呼吸暂停（OSA）患者时，医生迫切需要解开 LG 的复杂性，因为 LG 异常描绘了 OSA 的独特病理生理表型。具体来说，某些患者的高 LG 是导致睡眠呼吸暂停的主要因素，影响治疗效果。例如，高 LG 的个体可能对持续气道正压通气（CPAP）或口腔器械等治疗方法的反应与 LG 正常的个体不同，或者可以用特定的药物或联合疗法进行治疗。因此，理解 LG 对于精确评估 OSA 患者至关重要，是优化个性化有效治疗方法的基础。
