Early pathophysiology-driven airway pressure release ventilation versus low tidal volume ventilation strategy for patients with moderate-severe ARDS: study protocol for a randomized, multicenter, controlled trial.

BACKGROUND: Conventional Mechanical ventilation modes used for individuals suffering from acute respiratory distress syndrome have the potential to exacerbate lung injury through regional alveolar overinflation and/or repetitive alveolar collapse with shearing, known as atelectrauma. Animal studies have demonstrated that airway pressure release ventilation (APRV) offers distinct advantages over conventional mechanical ventilation modes. However, the methodologies for implementing APRV vary widely, and the findings from clinical studies remain controversial. This study (APRVplus trial), aims to assess the impact of an early pathophysiology-driven APRV ventilation approach compared to a low tidal volume ventilation (LTV) strategy on the prognosis of patients with moderate to severe ARDS. METHODS: The APRVplus trial is a prospective, multicenter, randomized clinical trial, building upon our prior single-center study, to enroll 840 patients from at least 35 hospitals in China. This investigation plans to compare the early pathophysiology-driven APRV ventilation approach with the control intervention of LTV lung-protective ventilation. The primary outcome measure will be all-cause mortality at 28 days after randomization in the intensive care units (ICU). Secondary outcome measures will include assessments of oxygenation, and physiology parameters at baseline, as well as on days 1, 2, and 3. Additionally, clinical outcomes such as ventilator-free days at 28 days, duration of ICU and hospital stay, ICU and hospital mortality, and the occurrence of adverse events will be evaluated. TRIAL ETHICS AND DISSEMINATION: The research project has obtained approval from the Ethics Committee of West China Hospital of Sichuan University (2019-337). Informed consent is required. The results will be submitted for publication in a peer-reviewed journal and presented at one or more scientific conferences. TRIAL REGISTRATION: The study was registered at Clinical Trials.gov (NCT03549910) on June 8, 2018.

Sleep Apnea and Heart Failure-Current State-of-The-Art.

Sleep-disordered breathing (SDB), including obstructive and central sleep apnea, significantly exacerbates heart failure (HF) through adverse cardiovascular mechanisms. This review aims to synthesize existing literature to clarify the relationship between SDB and HF, focusing on the pathophysiological mechanisms, diagnostic challenges, and the effectiveness of treatment modalities like continuous positive airway pressure (CPAP) and adaptive servo-ventilation ASV. We analyzed peer-reviewed articles from 2003 to 2024 sourced from PubMed, EMBASE, Scopus, and Web of Science databases. The prevalence of SDB in HF patients is high, often underdiagnosed, and underappreciated. Management strategies, including CPAP and ASV, have been shown to mitigate symptoms and improve cardiac function. However, despite the availability of effective treatments, significant challenges in screening and diagnosis persist, affecting patient management and outcomes. DB significantly impacts HF prognosis. Enhanced screening strategies and broader utilization of therapeutic interventions like CPAP and ASV are essential to improve the management and outcomes of HF patients with concomitant SDB. Future research should focus on refining diagnostic and treatment protocols to optimize care for HF patients with SDB.

Asthma and obstructive sleep apnea: Unveiling correlations and treatable traits for comprehensive care.

Asthma and obstructive sleep apnea (OSA) are common respiratory disorders. They share characteristics such as airway obstruction, poor sleep quality, and low quality of life. They are often present as comorbidities, along with obesity, gastroesophageal reflux disease (GERD), and allergic rhinitis (AR), which impacts the disease's control. In recent years, there has been discussion about the association between these conditions and their pathophysiological and clinical consequences, resulting in worse health outcomes, increased healthcare resource consumption, prolonged hospital stays, and increased morbidity and mortality. Some studies demonstrate that treatment with continuous positive airway pressure (CPAP) can have a beneficial effect on both pathologies. This review summarizes the existing evidence of the association between asthma and OSA at their pathophysiological, epidemiological, clinical, and therapeutic levels. It intends to raise awareness among healthcare professionals about these conditions and the need for further research.

Understanding adherence to continuous positive airway pressure in patients with obstructive sleep apnea post-stroke: A prospective study based on the Andersen model.

Adherence to continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA) post-stroke is often problematic, despite potential benefits. This study aimed to evaluate CPAP adherence in patients with OSA post-stroke based on the Andersen behavioral model of health services utilization. A total of 227 eligible participants were recruited from a Chinese hospital. After baseline assessment, participants were followed for 6 months to determine short-term CPAP adherence. Those with good short-term adherence were followed for an additional 6 months to explore long-term adherence and influencing factors. Short-term CPAP adherence rate was 33%. Being married or living with a partner, having an associate degree or baccalaureate degree or higher, and stronger health beliefs independently predicted short-term CPAP adherence. Only 25% of participants from the adherent group showed good long-term adherence. The factor associated with long-term CPAP adherence was participants not using alcohol. Adherence to CPAP is suboptimal among patients having OSA post-stroke. Addressing unfavorable predisposing factors and modifying health beliefs are suggested.

Chronic Cough and Obstructive Sleep Apnea.

Chronic cough, defined as a cough lasting more than 8 weeks, is a common medical condition occurring in 5% to 10% of the population. Its overlap with another highly prevalent disorder, obstructive sleep apnea (OSA), is therefore not surprising. The relationship between chronic cough and OSA extends beyond this overlap with higher prevalence of OSA in patients with chronic cough than in the general population. The use of continuous positive airway pressure can result in improvement in chronic cough although further studies are needed to understand which patients will experience benefit in their cough from the treatment of comorbid OSA.

Ventilatory Assistance Before Umbilical Cord Clamping in Extremely Preterm Infants: A Randomized Clinical Trial.

Importance: Providing assisted ventilation during delayed umbilical cord clamping may improve outcomes for extremely preterm infants. Objective: To determine whether assisted ventilation in extremely preterm infants (23 0/7 to 28 6/7 weeks' gestational age [GA]) followed by cord clamping reduces intraventricular hemorrhage (IVH) or early death. Design, Setting, and Participants: This phase 3, 1:1, parallel-stratified randomized clinical trial conducted at 12 perinatal centers across the US and Canada from September 2, 2016, through February 21, 2023, assessed IVH and early death outcomes of extremely preterm infants randomized to receive 120 seconds of assisted ventilation followed by cord clamping vs delayed cord clamping for 30 to 60 seconds with ventilatory assistance afterward. Two analysis cohorts, not breathing well and breathing well, were specified a priori based on assessment of breathing 30 seconds after birth. Intervention: After birth, all infants received stimulation and suctioning if needed. From 30 to 120 seconds, infants randomized to the intervention received continuous positive airway pressure if breathing well or positive-pressure ventilation if not, with cord clamping at 120 seconds. Control infants received 30 to 60 seconds of delayed cord clamping followed by standard resuscitation. Main Outcomes and Measures: The primary outcome was any grade IVH on head ultrasonography or death before day 7. Interpretation by site radiologists was confirmed by independent radiologists, all masked to study group. To estimate the association between study group and outcome, data were analyzed using the stratified Cochran-Mantel-Haenszel test for relative risk (RR), with associations summarized by point estimates and 95% CIs. Results: Of 1110 women who consented to participate, 548 were randomized and delivered infants at GA less than 29 weeks. A total of 570 eligible infants were enrolled (median [IQR] GA, 26.6 [24.9-27.7] weeks; 297 male [52.1%]). Intraventricular hemorrhage or death occurred in 34.9% (97 of 278) of infants in the intervention group and 32.5% (95 of 292) in the control group (adjusted RR, 1.02; 95% CI, 0.81-1.27). In the prespecified not-breathing-well cohort (47.5% [271 of 570]; median [IQR] GA, 26.0 [24.7-27.4] weeks; 152 male [56.1%]), IVH or death occurred in 38.7% (58 of 150) of infants in the intervention group and 43.0% (52 of 121) in the control group (RR, 0.91; 95% CI, 0.68-1.21). There was no evidence of differences in death, severe brain injury, or major morbidities between the intervention and control groups in either breathing cohort. Conclusions and Relevance: This study did not show that providing assisted ventilation before cord clamping in extremely preterm infants reduces IVH or early death. Additional study around the feasibility, safety, and efficacy of assisted ventilation before cord clamping may provide additional insight. Trial Registration: ClinicalTrials.gov Identifier: NCT02742454.

Obstructive Sleep Apnea Effects on Chronic Airway Disease Exacerbations-Missed Opportunities for Improving Outcomes in Chronic Obstructive Pulmonary Disease and Asthma.

In patients with chronic obstructive pulmonary disease (COPD) and asthma, exacerbations determine the natural history of both diseases. Patients with both respiratory diseases who suffer from obstructive sleep apnea (OSA) as a comorbidity (overlap syndromes) have a higher risk of exacerbations and hospitalization. In cases of OSA/COPD and OSA/asthma, continuous positive airway pressure treatment is indicated. Adequate adherence to therapy appears to reduce exacerbations and their severity, especially in OSA/COPD overlap. However, there is a lack of randomized trials that definitively demonstrate this evidence.

Targeting Hypercapnia in Chronic Lung Disease and Obesity Hypoventilation: Benefits and Challenges.

Hypoventilation is a complication that is not uncommon in chronic obstructive pulmonary disease and calls for both medical treatment of the underlying disease and, frequently, noninvasive ventilation either during exacerbations requiring hospitalization or in a chronic state in the patient at home. Obesity hypoventilation syndrome by definition is associated with ventilatory failure and hypercapnia. It may or may not be accompanied by obstructive sleep apnea, which when detected becomes an additional target for positive airway pressure treatment. Intensive research has not completely resolved the best choice of treatment, and the simplest modality, continuous positive airway pressure, may still be entertained.

Role of Sleep-Disordered Breathing and Epicardial Connections in the Recurrence of Atrial Fibrillation.

The presence of epicardial connections (ECs) between the pulmonary veins (PVs) and atrium may contribute to atrial fibrillation (AF) recurrence. This study aimed to determine the impact of sleep-disordered breathing (SDB) on the presence of ECs and the interplay between SDB and ECs on AF recurrence.We retrospectively reviewed 400 consecutive non-valvular AF patients. Among them, 235 patients exhibiting a 3% oxygen desaturation index (ODI) of ≥ 10 events/hour underwent polysomnography to evaluate the SDB severity, measured by the apnea-hypopnea index (AHI). To facilitate the ablation of AF and ECs, a high-density mapping catheter (HDMC) was employed. AF recurrence was evaluated over a 12-month period post-AF ablation.The key findings included: 1) 63% of AF patients with ECs had SDB with an AHI ≥ 20 events/hour. 2) Despite achieving complete PV isolations and precise EC ablation using an HDMC, SDB presence was associated with an increased AF recurrence. 3) Continuous positive airway pressure therapy for SDB improved AF recurrence among the AF patients with both ECs and SDB (57% versus 73%; P = 0.016). 4) AHI (odds ratio [OR] = 1.91, ≥ 28.4 events/hour) and left atrial volume (LAV) (OR = 1.42, ≥ 128.3 mL) were independent predictors of the presence of ECs, and AHI (OR = 1.44, ≥ 27.8 events/hour) was an independent predictor of the presence of AF recurrence.It is essential for physicians to recognise the potential complexity of ECs and SDB in AF patients. Thus, screening and treating SDB in AF patients presenting with ECs might play a pivotal role in suppressing AF recurrence.

Association Between Sleep Apnea Treatment and Health Care Resource Use in Patients With Atrial Fibrillation.

BACKGROUND: Obstructive sleep apnea (OSA) contributes to the generation, recurrence, and perpetuation of atrial fibrillation, and it is associated with worse outcomes. Little is known about the economic impact of OSA therapy in atrial fibrillation. This retrospective cohort study assessed the impact of positive airway pressure (PAP) therapy adherence on health care resource use and costs in patients with OSA and atrial fibrillation. METHODS AND RESULTS: Insurance claims data for ≥1 year before sleep testing and 2 years after device setup were linked with objective PAP therapy use data. PAP adherence was defined from an extension of the US Medicare 90-day definition. Inverse probability of treatment weighting was used to create covariate-balanced PAP adherence groups to mitigate confounding. Of 5867 patients (32% women; mean age, 62.7 years), 41% were adherent, 38% were intermediate, and 21% were nonadherent. Mean±SD number of all-cause emergency department visits (0.61±1.21 versus 0.77±1.55 [P=0.023] versus 0.95±1.90 [P<0.001]), all-cause hospitalizations (0.19±0.69 versus 0.24±0.72 [P=0.002] versus 0.34±1.16 [P<0.001]), and cardiac-related hospitalizations (0.06±0.26 versus 0.09±0.41 [P=0.023] versus 0.10±0.44 [P=0.004]) were significantly lower in adherent versus intermediate and nonadherent patients, as were all-cause inpatient costs ($2200±$8054 versus $3274±$12 065 [P=0.002] versus $4483±$16 499 [P<0.001]). All-cause emergency department costs were significantly lower in adherent and intermediate versus nonadherent patients ($499±$1229 and $563±$1292 versus $691±$1652 [P<0.001 and P=0.002], respectively). CONCLUSIONS: These data suggest clinical and economic benefits of PAP therapy in patients with concomitant OSA and atrial fibrillation. This supports the value of diagnosing and managing OSA and highlights the need for strategies to enhance PAP adherence in this population.

Surfactant administration methods for premature newborns: LISA vs. INSURE comparative analysis.

INTRODUCTION: Respiratory Distress Syndrome (RDS) is the most common respiratory disorder among premature infants. The use of surfactant has significantly reduced respiratory complications and mortality. There are two conventional methods for administering surfactant: Intubate-Surfactant-Extubate (INSURE) and Less Invasive Surfactant Administration (LISA). This study aims to compare the effects of surfactant administration using these two methods on the treatment outcomes of premature newborns. MATERIALS AND METHODS: In this retrospective cohort study, we included 100 premature newborns with RDS and spontaneous breathing who were admitted to the Neonatal Intensive Care Unit of Besat Hospital in Sanandaj city in 2021. Exclusion criteria comprised congenital anomalies and the needing for intubation for resuscitation at birth. The outcomes of epmericaly trated with two methods were compared: the LISA (50 neonates) and the INSURE (50 neonates). Our interesting outcomes were needing for mechanical ventilation, duration of ventilation, pneumothorax, pulmonary hemorrhage, severe retinopathy, CPAP duration, and bronchopulmonary dysplasia. Finally, we entered the data into STATA-14 statistical software and analyzed it using chi-square and t-tests. RESULTS: In this study, 69% of the neonates were boys. The LISA group exhibited significantly lower rates of need for mechanical ventilation (P = 0.003) and ventilation duration (P < 0.001) compared to the INSURE group. Conversely, there were no significant differences between the two groups (P > 0.05) in terms of pneumothorax, pulmonary hemorrhage, severe retinopathy, CPAP duration, and bronchopulmonary dysplasia rates. CONCLUSION: The results of this study suggest that the LISA method is a safe and non-invasive approach for surfactant administration. Notably, it resulted in a reduced need for mechanical ventilation and decreased ventilation duration compared to the INSURE method.

Non-invasive versus invasive respiratory support in preterm infants.

Respiratory insufficiency is almost ubiquitous in infants born preterm, with its incidence increasing with lower gestational age. A wide range of respiratory support management strategies are available for these infants, separable into non-invasive and invasive forms of respiratory support. Here we review the history and evolution of respiratory care for the preterm infant and then examine evidence that has emerged to support a non-invasive approach to respiratory management where able. Continuous positive airway pressure (CPAP) is the non-invasive respiratory support mode currently with the most evidence for benefit. CPAP can be delivered safely and effectively and can commence in the delivery room. Particularly in early life, time spent on non-invasive respiratory support, avoiding intubation and mechanical ventilation, affords benefit for the preterm infant by virtue of a lessening of lung injury and hence a reduction in incidence of bronchopulmonary dysplasia. In recent years, enthusiasm for application of non-invasive support has been further bolstered by new techniques for administration of exogenous surfactant. Methods of less invasive surfactant delivery, in particular with a thin catheter, have allowed neonatologists to administer surfactant without resort to endotracheal intubation. The benefits of this approach appear to be sustained, even in those infants subsequently requiring mechanical ventilation. This cements the notion that any reduction in exposure to mechanical ventilation leads to alleviation of injury to the vulnerable preterm lung, with a long-lasting effect. Despite the clear advantages of non-invasive respiratory support, there will continue to be a role for intubation and mechanical ventilation in some preterm infants, particularly for those born <25 weeks' gestation. It is currently unclear what role early non-invasive support has in this special population, with more studies required.

Effect of Nasal Continuous Positive Airway Pressure on Retinopathy of Prematurity in Preterm Newborns: A Comparative Analysis with Mechanical Ventilation and High-Flow Nasal Cannula Therapy.

BACKGROUND Retinopathy of prematurity (ROP), originally described as retrolental fibroplasia, represents an abnormal growth of blood vessels in the premature retina that can occur in response to oxygen therapy. The association between ROP and invasive mechanical ventilation has been widely studied in the literature; however, the relationships between different types of ventilation and ROP have not been as well documented. This study aimed to compare the association of ROP incidence with mechanical ventilation (MV), nasal continuous positive airway pressure (nCPAP), and high-flow nasal cannula (HFNC) therapies in 130 pre-term infants with gestational ages <32 weeks. MATERIAL AND METHODS The study includes 130 premature newborns, out of which 54 underwent MV therapy, either alone or in combination with nCPAP or HFNC therapy, 63 underwent nCPAP therapy, either alone or in combination with MV or HFNC therapy, and 23 underwent HFNC therapy, either alone or in combination with MV or nCPAP therapy. The relationships between ROP and the 3 types of ventilation were analyzed by univariate followed by multivariate logistic regression. RESULTS When adjusting for covariates, only nCPAP and birth weight were significantly associated with ROP, the former being a strong risk factor, with an adjusted odds ratio (AOR) of 7.264 (95% CI, 2.622-20.120; P<0.001), and the latter being a weak protective factor, with an AOR of 0.998 (95% CI, 0.996-0.999; P<0.05). CONCLUSIONS The results showed nCPAP was a strong ROP risk factor, birth weight was a weak ROP protective factor, and MV and HFNC were not significantly associated with increased ROP risk.

Use of CPAP Ventilation in Non-ICU Wards May Influence Outcomes in Patients with Severe Respiratory COVID-19.

Background and Objectives: The COVID-19 disease has significantly burdened the healthcare system, including all units of severe patient treatment. Non-intensive care units were established to rationalize the capacity within the Intensive Care Unit (ICU) and to create a unit where patients with Acute Respiratory Distress Syndrome (ARDS) could be treated with non-invasive Continuous Positive Air Pressure (CPAP) outside the ICU. This unicentric retrospective study aimed to assess the efficacy of NIV Treatment in Patients of the fourth pandemic wave and how its application affects the frequency and mortality of ICU-treated patients at University Hospital Rijeka compared to earlier waves of the COVID-19 pandemic. Furthermore, the study showcases the effect of the Patient/Nurse ratio (P/N ratio) on overall mortality in the ICU. Materials and Methods: The study was conducted on two groups of patients with respiratory insufficiency in the second and third pandemic waves, treated in the COVID Respiratory Centre (CRC) (153 patients). We also reviewed a cohort of patients from the fourth pandemic wave who were initially hospitalized in a COVID-6 non-intensive unit from 1 October 2021 to 1 November 2022 (102 patients), and some of them escalated to CRC. Results: The introduction of the CPAP non-invasive ventilation method as a means of hypoxic respiratory failure treatment in non-intensive care units has decreased the strain, overall number of admissions, and CRC patient mortality. The overall fourth wave mortality was 29.4%, compared to the 58.2% overall mortality of the second and third waves. Conclusions: As a result, this has decreased CRC patient admissions and, by itself, overall mortality.

Real-world impact of continuous positive airway pressure on sleepiness in patients with obstructive sleep apnea in a national registry.

OBJECTIVE: Excessive daytime sleepiness (EDS) persists in some patients with obstructive sleep apnea (OSA) despite continuous positive airway pressure (CPAP) treatment. This study characterized response to CPAP and factors associated with residual EDS. METHODS: Danish National Patient Registry data were analyzed. Patients with OSA diagnosis (1994-2016), Epworth Sleepiness Scale (ESS) scores and apnea-hypopnea index recorded before beginning CPAP (baseline) and after 1-13 months of CPAP use, and CPAP adherence were included. Odds ratios (OR) for residual EDS after CPAP treatment were estimated using multivariate logistic regression. RESULTS: Of 1174 patients (mean age, 57 years; 75.5% male), 41.1% had baseline EDS (mild, 13.2%; moderate, 14.0%; severe, 13.9%); 58.9% did not. After CPAP treatment, follow-up mean ESS scores were normal (≤10) for all baseline EDS subgroups; however, 15.6% (n = 183) of patients had residual EDS (mild, 6.7%; moderate, 5.5%; severe, 3.4%). Odds of residual EDS were higher for patients with mild (OR, 5.2; 95% confidence interval [CI], 3.2-8.6), moderate (OR, 4.5; 95% CI, 2.7-7.4), and severe (OR, 13.0; 95% CI, 8.0-21.2) EDS at baseline compared with those with normal daytime sleepiness at baseline. Patients adherent with CPAP use were 38.2% less likely to have residual EDS compared with nonadherent patients (OR, 0.62; 95% CI, 0.43-0.88). CONCLUSIONS: EDS was common in this cohort of Danish patients with OSA. Baseline EDS severity predicted higher odds of residual EDS. After CPAP treatment, adherence was associated with reduced odds of residual EDS, but EDS persisted in a subgroup of patients.

Airway stability in sleep apnea: Assessing continuous positive airway pressure efficiency.

Obstructive Sleep Apnea Syndrome (OSAS) disrupts millions of lives with its burden of airway obstruction during sleep. Continuous Positive Airway Pressure (CPAP) therapy has been scrutinized for its biomechanical impact on the respiratory tract. This study leverages computational fluid dynamics to investigate CPAP's effects at 9 cm H2O (882.6 Pa) on the computed-tomography-based nasal-to-14-generation full respiratory tract model compared to ambient conditions, focusing on static pressure, airflow velocity, and shear stress. Our findings reveal that CPAP significantly increases static pressure, enhancing airway patency without adverse changes in airflow velocity or harmful shear stress on lung tissue, challenging prior concerns about its safety. Notably, the larynx experiences the highest shear stress due to its narrow anatomy, yet CPAP therapy overall supports airway walls against collapse. This investigation highlights CPAP's critical role in OSAS treatment, offering reassurance about its safety and efficacy. By clarifying CPAP therapy's physiological impacts, our study contributes vital insights for optimizing OSAS management strategies, affirming CPAP's benefit in maintaining open airways with minimal tissue strain.

Impact of posture and CPAP on nasal airflow.

Obstructive sleep apnea (OSA) patients who use continuous positive airway pressure (CPAP) often complain of nasal dryness and nasal obstruction as side effects of CPAP. The physiological mechanisms by which CPAP may cause nasal dryness and nasal obstruction remain poorly understood. It has been hypothesized that CPAP interferes with the nasal cycle, abolishing the resting phase of the cycle and leading to nasal dryness. We performed rhinomanometry measurements in 31 OSA patients sitting, laid supine, and supine after 10 min of CPAP at 10 cmH2O. A posture change from sitting to supine led to more symmetric airflow partitioning between the left and right nostrils in the supine position. CPAP did not have a significant impact on nasal resistance, unilateral airflows, or airflow partitioning. Our results suggest that airflow partitioning becomes more symmetric immediately after changing to a supine position, while CPAP had no effect on nasal airflow, thus preserving the nearly symmetric airflow partitioning achieved after the posture change.

Impact of PAP on the gut microbiome in OSA: A pilot study.

OBJECTIVE/BACKGROUND: Microbes within the gastrointestinal tract have emerged as modulators of the host's health. Obstructive sleep apnea (OSA) is characterized by intermittent partial, or complete, airway closure during sleep and is associated with increased risk of non-communicable diseases as well as dysbiosis of the gut microbiome. Thus, we investigated if improving nocturnal airway patency via positive airway pressure (PAP) therapy improves gut microbial diversity in recently diagnosed patients with moderate-to-severe OSA (apnea-hypopnea index ≥15.0 events/hr). PATIENTS/METHODS: Eight subjects (3 F, 56±9yrs, 33.5 ± 7.7 kg/m2, 45.0 ± 38.4 events/hr) provided stool samples before, and two months after, PAP therapy (mean adherence of 95 ± 6%, residual apnea-hypopnea index of 4.7 ± 4.6 events/hr). RESULTS: While the Shannon diversity index tended to increase following PAP (3.96 ± 0.52 to 4.18 ± 0.56, p = 0.08), there were no changes in the Observed (1,088 ± 237 to 1,136 ± 289, p = 0.28) nor Inverse-Simpson (22.4 ± 12.99 to 26.6 ± 18.23, p = 0.28) alpha diversity indices. There were also no changes in beta diversity assessed using the Bray-Curtis (p = 0.98), Jaccard (p = 0.99), WUniFrac (p = 0.98), GUniFrac (p = 0.98), or UniFrac (p = 0.98) methods. No changes in differential abundance taxa were found using a false discovery rate threshold of <0.20. CONCLUSIONS: Our data are the first to report that PAP therapy may not offset, or reverse, gut dysbiosis in patients with OSA. Accordingly, interventions which improve gut microbial health should be explored as potential adjunctive treatment options in patients with OSA to reduce their risk of developing non-communicable diseases.