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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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: OSAS is a syndrome that often presents clinically differently between men and women. The aim of this study was to assess the clinical presentation, nocturnal home sleep cardiorespiratory monitoring and therapeutic adherence to CPAP in both sexes to identify the most frequent patterns., Methods: Data from the first visit, the nocturnal home sleep cardiorespiratory monitoring and follow-up visit of 74 OSA patients were collected. Exclusion criteria included other respiratory and/or neuromuscular diseases (including Obesity hypoventilation syndrome) and other non-respiratory sleep disorders., Results: Men were older and had a higher supine AHI and ODI compared to women. In addition, BMI and age correlated positively with AHI in males. Women had a higher hypopneas frequency and better therapeutic adherence to CPAP., Conclusions: Men were associated with a higher AHI when sleeping in the supine position and this may be useful to look for new therapeutic options in combination with or as an alternative to CPAP. BMI correlated positively with AHI in men and this should be considered to stimulate weight loss as the main treatment to reduce the number of apneas/hypopneas, as men also had less therapeutic adherence to CPAP in our study. Females presented a significantly higher frequency of hypopneas than men, as well as a lower number of desaturation events per hour (ODI): these differences in the nocturnal home sleep cardiorespiratory monitoring could reflect different pathophysiological mechanisms of OSAS onset between the two sexes, which should be investigated in future scientific studies., (© 2024. The Author(s).)

Transbronchial lung cryobiopsy (TBCB) is a reliable method for obtaining histopathological findings in interstitial lung diseases. TBCB is traditionally performed during rigid bronchoscopy, positioning an endobronchial balloon blocker to facilitate bleeding management. Therefore, it can be challenging to implement in Centers without access to anesthesiologic support or dedicated beds for endoscopic procedures. We present a series of 11 patients who underwent 12 TBCBs using a flexible bronchoscope and a 5 Fr endobronchial blocker passing through an uncuffed endotracheal tube, under moderate sedation and spontaneous breathing. All procedures were carried out in an endoscopy suite, using fluoroscopy guidance but without requiring anesthesiologic assistance. TBCB was feasible in all cases, and it demonstrated similar or improved diagnostic yield (90.1%) and safety compared to rigid bronchoscopy. In 1 case, it was successfully repeated due to an inconclusive histological definition at the first attempt. The size of the samples was consistent with the literature, as it was the incidence of pneumothorax (16.6%). Four cases of moderate bleeding and 4 cases of severe bleeding were managed without further complications. To our knowledge, this is the first description of a technique allowing to perform TBCB through an artificial airway without need for either rigid bronchoscopy or general anesthesia. We believe this technique could make TBCB faster, cost-effective, and feasible even in resource-limited settings without compromising on safety. However, further studies are needed to validate these findings., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)