Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline

Impact of treating obesity hypoventilation syndrome on body mass index

STUDY OBJECTIVES

To evaluate the impact of positive airway pressure (PAP) therapy on body mass index (BMI) in patients with obesity hypoventilation syndrome (OHS) associated with obstructive sleep apnea (OSA). Methods: A systematic review using the following terms: "obesity hypoventilation syndrome" AND "treatment" AND "randomized" using Cochrane Central Register of Controlled Trials, Medline and Web of Science was performed from the first data available until February 10, 2023. The inclusion criteria were: (1) original article; (2) adult OHS with concomitant OSA (apnea-hypopnea index or AHI ≥5 events/h); (3) randomized trial with PAP arm and standard care (control); (4) BMI evaluation at baseline and after the first months. We performed an individual participant data meta-analysis of randomized controlled trials.

RESULTS

Our initial search retrieved 32 articles and 3 randomized studies fulfilled study criteria and were included in the final analysis, leading to a total of 342 participants. Patients were predominantly females (62%) and had OHS associated with at least mild OSA. As compared to baseline, a decrease in BMI was observed at study endpoint but this difference was not different intergroups (-0.50 ± 1.49 and -0.50 ±1.83, in control and PAP groups respectively (p=0.939)). Weight change was not associate with PAP adherence, OSA severity or use of supplemental oxygen.

CONCLUSIONS

In contrast to treatment of eucapnic OSA with PAP that is associated with weight gain, treatment of OSA+OHS patients with or without PAP is associated with weight loss. Future studies are necessary to elucidate the mechanism by which weight loss occurs.

Obesity hypoventilation syndrome: Current status and future directions for optimizing care of a complex and diverse condition (a narrative review)

The global obesity pandemic contributes to an increase in the prevalence of obesity hypoventilation syndrome (OHS). OHS is associated with poor prognosis and early mortality. Definitions of OHS and disease severity classifications differ between international guidelines, and consideration of polysomnographic features is often lacking. To address this, the European Respiratory Society has proposed a severity classification approach. It is also important to consider the possibility that patients with OHS might have multiple factors contributing to hypercapnia, including obesity-related changes in the respiratory system, alterations in central respiratory drive, and different sleep-disordered breathing (SDB) abnormalities. There are also multiple health trajectories that occur before an OHS diagnosis. Positive airway pressures such as continuous positive airway pressure or non-invasive ventilation are the mainstay of OHS treatment. The choice of therapy needs to be guided by appropriate SDB phenotyping and daytime hypercapnia severity. Comorbidities are common in patients with OHS and these trigger and increase the risk of acute on chronic respiratory failure. Appropriate management of comorbidities, and weight loss management, are essential (including behavioral interventions, physical activity, pharmacotherapy, and metabolic/bariatric procedures, as appropriate for each individual). Newer pharmacological treatments such as glucagon-like peptide-1 receptor agonists, recombinant human leptin, and orexin receptor antagonists are promising, but have not yet been specifically investigated in OHS populations. Overall, there is a need for a significant redesign in assessment and care to facilitate the evidence-based management of the complex and diverse OHS presentations in clinical practice.

Obesity and sleep disorders: A bidirectional relationship

AIMS

Obesity and sleep disorders are highly prevalent conditions with profound implications for public health. Emerging evidence highlights a bidirectional relationship between these two conditions, with each exacerbating the other in a complex interplay of behavioral, physiological, and hormonal mechanisms. Sleep deprivation and poor sleep quality contribute to energy imbalance through dysregulation of appetite hormones (e.g., leptin and ghrelin), increased caloric intake, and reduced physical activity. Conversely, sleep disorders such as obstructive sleep apnea syndrome (OSAS), insomnia, and restless leg syndrome (RLS) are significantly more common in individuals with obesity.

DATA SYNTHESIS

This review explores the pathophysiological mechanisms underlying this relationship, including the roles of inflammation, autonomic dysregulation, and neuroendocrine pathways. Sleep loss exacerbates metabolic syndrome components, including insulin resistance and dyslipidemia, further perpetuating weight gain. Similarly, obesity-induced sleep disorders lead to pro-inflammatory states, vascular dysfunction, and sympathetic overactivation, compounding cardiometabolic risks. Specific conditions like OSA and RLS are examined as models of this interdependence, emphasizing their shared pathways and clinical implications.

CONCLUSIONS

The bidirectional link between obesity and sleep disorders underscores the importance of integrating sleep assessment and management into obesity treatment strategies. Addressing this relationship could mitigate the progression of cardiometabolic comorbidities and improve overall health outcomes. Moreover, the intertwined dynamics between obesity, sleep disorders, and mental health-mediated by inflammatory pathways, hormonal dysregulation, and neurobehavioral factors-highlight the critical need for integrated treatment approaches targeting physical, psychological, and sleep-related dimensions to enhance health and quality of life.

Noninvasive ventilation for respiratory failure: When does it work and when it does not?

Noninvasive positive pressure ventilation (NIV) is a positive pressure ventilation method employed across various disease processes, utilizing noninvasive interfaces such as helmets and facemasks rather than invasive methods such as endotracheal intubation. The benefits of NIV are significant in both the acute care setting, such as improving work of breathing and avoiding the need for endotracheal intubation, as well as in the chronic care setting, improving quality of life and mortality. While new guidelines broaden the application of NIV across various disease areas and introduce emerging modalities, uncertainty persists regarding the appropriate timing and circumstances for NIV utilization. We present a detailed review of the literature with up-to-date studies assessing the indications and limitations of NIV in a variety of conditions associated with acute and chronic respiratory failure. The review also summarizes the current guidelines on the use of NIV in the acute care setting. Although primarily targeted towards the acute indications of NIV, we believe this review will aid in better understanding and managing noninvasive ventilation for clinicians across both the inpatient and outpatient settings.

Endotypic Traits Characterizing Obesity and Sleep-related Hypoventilation in Patients with Obstructive Sleep Apnea

Rationale: Sleep-related hypoventilation disorder (SHD) is common among obese patients with obstructive sleep apnea (OSA), but the pathological endotypes associated with obesity and SHD remain unclear. Objectives: To investigate the relationship between endotypes with body mass index (BMI) among patients with OSA and to explore endotypic traits of patients with comorbid SHD. Methods: We prospectively collected polysomnographic studies of 1,364 patients with OSA and overnight transcutaneous CO2 measurements among 420 obese patients. Endotypic traits were estimated using polysomnographic signals. SHD was determined using transcutaneous CO2 > 55 mm Hg for ⩾10 minutes. We illustrated the nonlinear relationship between BMI and endotypic traits. Differences in endotypic traits between nonobese patients with OSA, obese patients with simple OSA, and obese patients with comorbid OSA and SHD were examined using Kruskal-Wallis tests and multiple regression analysis. Results: A unit increase in BMI was associated with a 1.02%eupnea increase in arousal threshold, 1.16%eupnea increase in collapsibility, 0.01 increase in loop gain, and 0.48%eupnea increase in compensation, with a ceiling effect. SHD was observed in 18-36% of obese patients with OSA, depending on the criteria. Among obese patients with OSA, those with SHD exhibited a 0.06 higher loop gain than those with simple OSA, after adjusting for BMI. Conclusions: A ceiling effect of upper airway compensation function coupled with worse collapsibility and high loop gain characterizes pathological endotypes of obese patients with OSA. Patients with SHD exhibited a more sensitive respiratory pattern, indicated by increased loop gain.

Ventilation in the obese: physiological insights and management

Obesity can have profound adverse effects on the respiratory system, including an impact on pulmonary function, respiratory mechanics, respiratory muscle strength and endurance, gas exchange, control of breathing, and exercise capacity. Lung mechanics are modified by increased pleural pressure resulting from increased abdominal mass and subsequent peripheral airway occlusion and worsening of lung compliance due to reduced functional residual capacity without impairment of chest wall compliance. Arterial blood gases are frequently altered in these subjects and these abnormalities are directly proportional to body mass index. Mechanisms that may account for gas exchange abnormalities are multiple: ventilation/perfusion inequality (responsible for isolated hypoxaemia) and alveolar hypoventilation (responsible for so-called "obesity hypoventilation syndrome" (OHS)). Hypoventilation in obese patients results from a diversity of mechanisms, among which the two most frequently raised are mechanical limitation and blunted ventilatory drive. OHS is frequently underappreciated and diagnosis is frequently made during a first acute exacerbation. Obstructive sleep apnoea is a condition frequently associated with obesity and must be systematically screened for in this population because of its impact on morbidity and therapeutic management. Ventilatory management of these patients will depend on the patient's underlying situation, clinical presentation and physiology, including sleep study results; it may include continuous positive airway pressure or non-invasive ventilation. The goal of this narrative review is to provide a physiological-based overview of the impact of obesity on the respiratory system with a special focus on ventilatory management of patients with obesity-related respiratory disturbances.

Hemodynamic Effects of Positive Airway Pressure: A Cardiologist's Overview

Positive airway pressure (PAP) therapy is widely used to manage both acute and chronic respiratory failure and plays an increasingly important role in cardiology, particularly in treating patients with respiratory comorbidities. PAP, including continuous positive airway pressure and noninvasive ventilation, significantly impacts hemodynamics by altering intrathoracic pressure, affecting preload, afterload, and stroke volume. These changes are crucial in conditions such as acute cardiogenic pulmonary edema, where PAP can enhance gas exchange, reduce the work of breathing, and improve cardiac output. PAP reduces the left ventricular afterload, which in turn increases stroke volume and myocardial contractility in patients with left-sided heart failure. However, the role of PAP in right ventricular function and its effects on venous return and cardiac output are critical in the cardiac intensive care setting. While PAP provides respiratory benefits, it must be used cautiously in patients with right heart failure or preload-dependent conditions to avoid adverse outcomes. Additionally, in recent years, the use of PAP has expanded in the treatment of severe obstructive sleep apnea and obesity hypoventilation syndrome, both of which significantly influence cardiovascular events and heart failure. This review provides an in-depth analysis of the hemodynamic effects of PAP in cardiovascular disease, focusing on its impact on ventricular function in both acute and chronic conditions. Evaluating clinical studies, guidelines, and recent advancements offers practical insights into the physiological mechanisms and key clinical considerations. Furthermore, this review aims to serve as a helpful guide for clinicians, assisting in decision-making processes where PAP therapy is applied.

Home Mechanical Ventilation and Risk of Hospitalization in Obesity Hypoventilation Syndrome: The Population-based DISCOVERY Study

Rationale: Patients with obesity hypoventilation syndrome (OHS) have high risk of hospitalization, which might be decreased by home mechanical ventilation (HMV). Objectives: To evaluate annualized hospitalization rate (AHR) and changes in AHR in patients with OHS starting HMV and explore if there were any differences in AHR by starting HMV acutely or electively. Methods: This was a population-based longitudinal study of patients with OHS starting HMV in the Swedish DISCOVERY (Swedish Population-based Course of Disease in Patients Reported to the Swedish CPAP Oxygen and Ventilatory Registry) cohort between 1996 and 2018, cross-linked with the National Patient Registry for national data on hospital admissions. AHR was calculated for each patient for 3 years before (Years -3, -2, and -1) and 3 years after (Years 1, 2, and 3) the year of starting HMV (Year 0; start date ± 6 mo). Differences in AHR were analyzed using Wilcoxon signed-rank test (between years) and Mann-Whitney U test (between acute/elective). The proportion of patients hospitalized in each year was analyzed, and a comparison between years was done with McNemar's test. Factors associated with change in AHR were identified using multivariate linear regression models. Results: In total, 2,445 patients were included: 47% females, mean age 62.3 ± 12.2 years, and 1,418 (58%) started HMV electively. Overall, AHR decreased, with 0.88 (95% confidence interval, 0.74-1.02) hospitalizations/yr after start of HMV, and starting treatment acutely was associated with a greater decrease in AHR. There was no statistically significant difference in AHR in Year 1 between acute and elective start (P = 0.199). The year after the start of HMV, the proportion of patients hospitalized decreased from 84% to 54% (P < 0.05). Conclusions: Initiation of HMV was associated with reduced hospitalization rate in patients with OHS, irrespective of acute or elective start. The majority of patients with OHS are hospitalized in the year of HMV initiation.

Unmasking the Complex Interplay of Obesity Hypoventilation Syndrome, Heart Failure, and Sleep Dysfunction: A Physiological and Psychological Perspective in a Digital Health World

Obesity hypoventilation syndrome (OHS) is a multifaceted condition characterized by significant respiratory, cardiovascular, and psychological consequences. Positive airway pressure (PAP) therapy remains the cornerstone treatment, improving respiratory function, neurocognition, and mental health disorders such as depression and anxiety. However, its long-term impact on quality of life, physical activity, and broader health outcomes is not fully understood. Challenges such as residual apnoea/hypopnea index, reduced physical activity, and impaired quality of life persist despite high adherence rates. Factors like hypercapnia and daytime respiratory symptoms play a pivotal role in patient outcomes, underscoring the need for strategies beyond adherence alone. This review explores the interplay between OHS, heart failure, and sleep dysfunction, advocating for personalized PAP settings, targeted management of residual respiratory events, and enhanced patient education. Digital health technologies, including remote monitoring and feedback systems, present promising tools to optimize care delivery and foster holistic management. By integrating physiological, psychological, and digital health perspectives, this narrative review aims to advance understanding and improve outcomes for patients with OHS and other complex sleep-disordered breathing conditions.

Gender Differences in Outcomes of Ambulatory and Hospitalized Patients With Obesity Hypoventilation Syndrome

BACKGROUND

Obesity hypoventilation syndrome (OHS) is associated with high morbidity and mortality. There are few data on whether there are gender differences in outcomes.

RESEARCH QUESTION

Do women with OHS experience worse outcomes in ambulatory and hospitalized settings compared to men?

STUDY DESIGN AND METHODS

Post hoc analyses were performed on two separate OHS cohorts: (1) stable ambulatory patients from the two Pickwick randomized controlled trials; and (2) hospitalized patients with acute-on-chronic hypercapnic respiratory failure from a retrospective international cohort. We first conducted bivariate analyses of baseline characteristics and therapeutics between genders. Variables of interest from these analyses were then grouped into linear mixed effects models, Cox proportional hazards models, or logistic regression models to assess the association of gender on various clinical outcomes.

RESULTS

The ambulatory prospective cohort included 300 patients (64% self-identified as women), and the hospitalized retrospective cohort included 1,162 patients (58% self-identified as women). For both cohorts, women were significantly older and more obese than men. Compared with men, baseline Paco2 was similar in ambulatory patients but higher in hospitalized women. In the ambulatory cohort, in unadjusted analysis, women had increased risk of emergency department visits. However, gender was not associated with the composite outcome of emergency department visit, hospitalization, or all-cause mortality in the fully adjusted model. In the hospitalized cohort, prescription of positive airway pressure was less prevalent in women at discharge. In unadjusted analysis, hospitalized women had a higher mortality at 3, 6, and 12 months following hospital discharge compared with men. However, after adjusting for age, gender was not associated with mortality.

INTERPRETATION

Our findings indicate that although the diagnosis of OHS is established at a more advanced age in women, gender is not independently associated with worse clinical outcomes after adjusting for age. Future studies are needed to examine gender-related health disparities in diagnosis and treatment of OHS.

Staging of obesity-associated hypoventilation in patients with morbid obesity scheduled for bariatric surgery

Background: Almost 20% of Polish citizens aged >15 years are obese and this number is increasing. Numerous obesity-associated diseases include, quite notably, also sleep-related breathing disorders and hypoventilation. This study aimed to analyse the prevalence of obesity hypoventilation syndrome (OHS) and hypoventilation staging in a group of patients qualified for bariatric surgery within the Comprehensive Specialist Care in Bariatrics (KOS-BAR) pilot program designed and running in Poland since 2021. Methods: Prior to the bariatric procedure, the participants were referred to a pulmonologist for assessment. We retrospectively analysed the records of 134 patients. Results: Almost all of the tested bariatric patients (n = 122, 91.0%) had obstructive sleep apnea mainly classified as severe (59.0%). Hypoventilation was confirmed in 30 patients (22.4%), and in 37.9% of them, increased levels of serum bicarbonate were found. Chronic diurnal hypercapnia was confirmed in 7.9% of patients (10/122). Conclusions: Hypoventilation as well as obstructive sleep apnea in the obese population is a significant issue. The presented study group included patients in stages 0-IV of obesity-associated hypoventilation. The conducted analysis suggests that the most common form of hypoventilation among patients qualified for bariatric surgery is obesity-associated sleep hypoventilation (stage I).

Comparison of oronasal and nasal masks in home mechanical ventilation: an observational cohort and bench study

BACKGROUND

In patients with chronic respiratory failure, home non-invasive ventilation (NIV) is delivered through oronasal or nasal masks. Masks are a cornerstone for NIV success but can be associated with side-effects. However, the type, frequency and consequences of these side-effects are unknown. Here, we aimed to study the prevalence, nature and impact of mask-related adverse events in a cohort of stable patients. We then investigated differences between oronasal and nasal masks both in our cohort and in a bench study.

METHODS

This was a prospective observational cohort including patients established on long-term NIV admitted for their elective review. Data regarding mask-related side-effects were assessed using a structured questionnaire. Our bench study was performed using a three-dimensional printed head connected to an artificial lung.

RESULTS

800 patients were included, of whom 84% had an oronasal mask. Moderate to very severe mask-related side-effects occurred in 47% of patients and severe to very severe side-effects occurred in 18% of patients. Side-effects were associated with poorer daytime arterial partial pressure of carbon dioxide (p=0.005), poorer subjective sleep quality (p=0.003) and poorer quality of life (p<0.001). Mask-related side-effects were more frequently reported with the use of oronasal masks compared to nasal masks (p=0.023). Our bench study showed that nasal masks were more stable than oronasal masks (p<0.001).

CONCLUSIONS

Mask-related side-effects are frequent and associated with poorer outcomes. Our data suggest that nasal masks may have a better tolerance profile and should be used as a first-line interface.

[S3 Guideline: Treating Chronic Respiratory Failure with Non-invasive Ventilation]

The S3 guideline on non-invasive ventilation as a treatment for chronic respiratory failure was published on the website of the Association of the Scientific Medical Societies in Germany (AWMF) in July 2024. It offers comprehensive recommendations for the treatment of chronic respiratory failure in various underlying conditions, such as COPD, thoraco-restrictive diseases, obesity-hypoventilation syndrome, and neuromuscular diseases. An important innovation is the separation of the previous S2k guideline dating back to 2017, which included both invasive and non-invasive ventilation therapy. Due to increased scientific evidence and a significant rise in the number of affected patients, these distinct forms of therapy are now addressed separately in two different guidelines.The aim of the guideline is to improve the treatment of patients with chronic respiratory insufficiency using non-invasive ventilation and to make the indications and therapy recommendations accessible to all involved in the treatment process. It is based on the latest scientific evidence and replaces the previous guideline. This revised guideline provides detailed recommendations on the application of non-invasive ventilation, ventilation settings, and the subsequent follow-up of treatment.In addition to the updated evidence, important new features of this S3 guideline include new recommendations on patient care and numerous detailed treatment pathways that make the guideline more user-friendly. Furthermore, a completely revised section is dedicated to ethical issues and offers recommendations for end-of-life care. This guideline is an important tool for physicians and other healthcare professionals to optimize the care of patients with chronic respiratory failure. This version of the guideline is valid for three years, until July 2027.

Management of Acute and Chronic Hypercapnic Respiratory Failure in Severe Obesity-Hypoventilation Syndrome: A Case Study of Multi-Modal Therapy and Long-Term Weight Loss

BACKGROUND Obesity-hypoventilation syndrome (OHS), also known as Pickwickian syndrome, is a respiratory consequence of morbid obesity, usually treated with non-invasive positive airway pressure (PAP) therapies and weight loss. This study reports a 53-year-old woman with a body mass index of 49 kg/m² who experienced acute hypercapnic respiratory failure due to OHS. Her treatment involved mechanical ventilation, home oxygen therapy, and long-term weight loss of >30 kg. CASE REPORT A 53-year-old woman (109 kg) presented with acute hypercapnic respiratory failure due to OHS, which improved with mechanical ventilation and diuretics. After discharge from the hospital, she was treated with nocturnal non-invasive positive-pressure ventilation (NPPV) and home oxygen therapy. Over a 5-year period, following loss of >30 kg, she was re-evaluated for the discontinuation of NPPV and oxygen therapy. She was evaluated with various NPPV settings and oxygen doses, monitored by transcutaneous pressure of carbon dioxide (PtcCO₂). On NPPV, PtcCO₂ levels ≥55 mmHg were maintained within 10 min, indicating that the durations of PtcCO₂ ≥50 mmHg were too prolonged for her to be switched to continuous PAP therapy. Nonetheless, oxygen therapy was discontinued because the duration of peripheral blood oxygen saturation <90% was brief. CONCLUSIONS For patients with OHS treated with NPPV and oxygen therapy, weight loss alone may not improve hypoventilation and wean the patient from NPPV. Besides obesity, various factors influence respiratory compromise in OHS; hence, a comprehensive assessment of hypoventilation, including PtcCO₂ monitoring, is essential to determine whether NPPV withdrawal is possible after body weight loss.

Clinical review of non-invasive ventilation

Non-invasive ventilation (NIV) is the mainstay to treat patients who need augmentation of ventilation for acute and chronic forms of respiratory failure. The last several decades have witnessed an extension of the indications for NIV to a variety of acute and chronic lung diseases. Evolving advancements in technology and personalised approaches to patient care make it feasible to prioritise patient-centred care models that deliver home-based management using telemonitoring and telemedicine systems support. These trends may improve patient outcomes, reduce healthcare costs and improve the quality of life for patients who suffer from chronic diseases that precipitate respiratory failure.

Treatment of OSA and its Impact on Cardiovascular Disease, Part 2: JACC State-of-the-Art Review

Many studies have shown an association of obstructive sleep apnea (OSA) with incident cardiovascular diseases, particularly when comorbid with insomnia, excessive sleepiness, obesity hypoventilation syndrome, and chronic obstructive pulmonary disease. Randomized controlled trials (RCTs) have demonstrated that treatment of OSA with positive airway pressure devices (CPAP) improves systemic hypertension, particularly in those with resistant hypertension who are adherent to CPAP. However, large RCTs have not shown long-term benefits of CPAP on hard cardiovascular outcomes, but post hoc analyses of these RCTs have demonstrated improved hard outcomes in those who use CPAP adequately. In theory, low CPAP adherence and patient selection may have contributed to neutral results in intention-to-treat analyses. Only by further research into clinical, translational, and basic underlying mechanisms is major progress likely to continue. This review highlights the various treatment approaches for sleep disorders, particularly OSA comorbid with various other disorders, the potential reasons for null results of RCTs treating OSA with CPAP, and suggested approaches for future trials.

Long-term myocardial effects of noninvasive ventilation in patients with obesity hypoventilation syndrome

INTRODUCTION

Chronic effects of noninvasive ventilation on myocardial function in patients with obesity hypoventilation syndrome (OHS) are scarcely understood. The aim of the present study was to evaluate the long-term effects of volume-targeted bilevel positive airway pressure ventilation (BiPAP) on cardiac parameters and myocardial biomarkers in patients with OHS.

METHODS

Clinically stable patients with OHS referred to the tertiary center for the initiation of long-term BiPAP therapy were consecutively enrolled. At baseline, all participants underwent overnight cardiorespiratory polygraphy. BiPAP therapy using volume-targeted spontaneous/timed mode delivered via an oro-nasal mask was initiated. Beat-to-beat noninvasive monitoring by impedance cardiography was used to assess heart function at baseline and after 3 and 12 months of BiPAP use. Serum troponin 1, N-Terminal Pro-B-Type Natriuretic Peptide (NT-ProBNP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) were monitored.

RESULTS

Thirteen patients (10 men; mean age, 55.8 ± 9.8 years; mean body mass index of 47.8 ± 5.9 kg/m2) were recruited. From baseline to 3, and to 12 months of BiPAP use, left ventricular stroke volume (SV), ejection time (LVET), and ejection time index significantly increased (P = 0.030; P < 0.001; P = 0.003, respectively), while heart rate and systolic time ratio significantly decreased (P = 0.004; P = 0.034, respectively). Reductions in serum NT-proBNP, IL-6 and TNF-α were observed (P = 0.045; P = 0.018; P = 0.003, respectively). No significant changes in serum troponin were detected throughout the study.

CONCLUSIONS

The present findings of increased SV, in association with lengthening of LVET, reductions of NT-proBNP and reductions in circulatory inflammatory markers in patients with stable OHS and chronic moderate-to-severe daytime hypercapnia treated with BiPAP over 1 year support the role of this therapeutic mode in such patients.

Assessment of Chronic Hypercapnic Respiratory Failure

Undiagnosed chronic hypercapnic respiratory failure may be encountered during the evaluation of sleep-related breathing disorders at the sleep clinic. This article reviews the mechanism of chronic hypercapnic respiratory failure and the systematic approach to the assessment of specific sleep disorders associated with nocturnal hypoventilation encountered in clinical practice.

Screening and Perioperative Management of Obesity Hypoventilation Syndrome

Obesity hypoventilation syndrome (OHS) can often be underdiagnosed or misdiagnosed and has been shown to pose significant risks in perioperative situations. Patients with OHS have a higher prevalence of baseline morbid conditions like hypertension, congestive heart failure (CHF), diabetes mellitus, atrial fibrillation, and pulmonary hypertension (PH), which contribute to adverse postoperative outcomes. The potential challenges include difficult intubation and loss of airway, postoperative respiratory failure, worsening heart failure, pulmonary hypertensive crisis, and opioid-induced respiratory depression (OIRD). It is, therefore, important to screen all obese patients for obstructive sleep apnea (OSA) and OHS before elective surgical procedures. The aim of this review is to discuss the preoperative screening and evaluation and safe anesthetic and up-to-date ventilatory management of this complex group of patients. This review also intends to increase the awareness of OHS in the adult population among hospitalists, surgeons, and cardiologists who may find themselves taking care of these patients in complex multidisciplinary settings.

Update in Noninvasive Home Mechanical Ventilation: A Narrative Review of Indications, Outcomes, and Monitoring

Hypercapnic respiratory failure arises due to an imbalance in the load-capacity-drive relationship of the respiratory muscle pump, typically arising in patients with chronic obstructive pulmonary disease, obesity-related respiratory failure, and neuromuscular disease. Patients at risk of developing chronic respiratory failure and those with established disease should be referred to a specialist ventilation unit for evaluation and consideration of home noninvasive ventilation (NIV) initiation. Clinical trials demonstrate that, following careful patient selection, home NIV can improve a range of clinical, patient-reported, and physiological outcomes. This narrative review provides an overview of the pathophysiology of chronic respiratory failure, evidence-based applications of home NIV, and monitoring of patients established on home ventilation and describes technological advances in ventilation devices, interfaces, and monitoring to enhance comfort, promote long-term adherence, and optimise gas exchange.

Obesity hypoventilation syndrome, literature review

Obesity is a global health concern that has been increasing over the years, and it is associated with several pathophysiological changes affecting the respiratory system, including alveolar hypoventilation. Obesity hypoventilation syndrome (OHS) is one of the six subtypes of sleep-hypoventilation disorders. It is defined as the presence of obesity, chronic alveolar hypoventilation leading to daytime hypercapnia and hypoxia, and sleep-disordered breathing. The existence of a sleep disorder is one of the characteristics that patients with OHS present. Among them, 90% of patients have obstructive sleep apnea (OSA), and the remaining 10% of patients with OHS have non-obstructive sleep hypoventilation without OSA or with mild OSA. This review aims to provide a comprehensive understanding of the epidemiological and pathophysiological impact of OHS and to highlight its clinical features, prognosis, and severity, as well as the available treatment options.

Intermittent Versus Sustained Hypoxemia from Sleep-disordered Breathing: Outcomes in Patients with Chronic Lung Disease and High Altitude

In a variety of physiologic and pathologic states, people may experience both chronic sustained hypoxemia and intermittent hypoxemia ("combined" or "overlap" hypoxemia). In general, hypoxemia in such instances predicts a variety of maladaptive outcomes, including excess cardiovascular disease or mortality. However, hypoxemia may be one of the myriad phenotypic effects in such states, making it difficult to ascertain whether adverse outcomes are primarily driven by hypoxemia, and if so, whether these effects are due to intermittent versus sustained hypoxemia.

The Role of Obstructive Sleep Apnea in Hypercapnic Respiratory Failure Identified in Critical Care, Inpatient, and Outpatient Settings

An emerging body of literature describes the prevalence and consequences of hypercapnic respiratory failure. While device qualifications, documentation practices, and previously performed clinical studies often encourage conceptualizing patients as having a single "cause" of hypercapnia, many patients encountered in practice have several contributing conditions. Physiologic and epidemiologic data suggest that sleep-disordered breathing-particularly obstructive sleep apnea (OSA)-often contributes to the development of hypercapnia. In this review, the authors summarize the frequency of contributing conditions to hypercapnic respiratory failure among patients identified in critical care, emergency, and inpatient settings with an aim toward understanding the contribution of OSA to the development of hypercapnia.

Obstructive Sleep Apnea, Obesity Hypoventilation Syndrome, and Pulmonary Hypertension: A State-of-the-Art Review

The pathophysiological interplay between sleep-disordered breathing (SDB) and pulmonary hypertension (PH) is complex and can involve a variety of mechanisms by which SDB can worsen PH. These mechanistic pathways include wide swings in intrathoracic pressure while breathing against an occluded upper airway, intermittent and/or sustained hypoxemia, acute and/or chronic hypercapnia, and obesity. In this review, we discuss how the downstream consequences of SDB can adversely impact PH, the challenges in accurately diagnosing and classifying PH in the severely obese, and review the limited literature assessing the effect of treating obesity, obstructive sleep apnea, and obesity hypoventilation syndrome on PH.

Sleep-disordered breathing - clinical spectrum

The clinical spectrum of sleep-disordered breathing comprises a range of diverse conditions including obstructive sleep apnoea, central sleep apnoea and sleep-related hypoventilation syndromes. These distinct conditions have specific diagnostic features and are managed differently from one another. Therefore, it is useful for dental practitioners to have a working knowledge of sleep-disordered breathing beyond that of uncomplicated obstructive sleep apnoea (OSA). This review paper summarizes the diagnosis and management of commonly encountered clinical sleep-disordered breathing syndromes, with a particular focus on management from a dental perspective.

Obstructive Sleep Apnea and Sarcoidosis Interactions

Obstructive sleep apnea (OSA) is very prevalent in sarcoidosis patients. Sarcoidosis of the upper respiratory tract may affect upper airway patency and increase the risk of OSA. Weight gain due to steroid use, upper airway myopathy due to steroids and sarcoidosis itself, and interstitial lung disease with decreased upper airway patency are other reasons for the higher OSA prevalence seen in sarcoidosis. Several clinical manifestations such as fatigue, hypersomnolence, cognitive deficits, and pulmonary hypertension are common to both OSA and sarcoidosis. Therefore, early screening and treatment for OSA can improve symptoms and overall patient quality of life.

Analysis and applications of respiratory surface EMG: report of a round table meeting

Surface electromyography (sEMG) can be used to measure the electrical activity of the respiratory muscles. The possible applications of sEMG span from patients suffering from acute respiratory failure to patients receiving chronic home mechanical ventilation, to evaluate muscle function, titrate ventilatory support and guide treatment. However, sEMG is mainly used as a monitoring tool for research and its use in clinical practice is still limited-in part due to a lack of standardization and transparent reporting. During this round table meeting, recommendations on data acquisition, processing, interpretation, and potential clinical applications of respiratory sEMG were discussed. This paper informs the clinical researcher interested in respiratory muscle monitoring about the current state of the art on sEMG, knowledge gaps and potential future applications for patients with respiratory failure.

Contribution of Transcutaneous PCO2 in Obesity Hypoventilation Syndrome

BACKGROUND

Increasing numbers of patients have obesity-hypoventilation syndrome (OHS) because of the increasing prevalence of obesity. The accuracy of transcutaneous [Formula: see text] ([Formula: see text]) has recently been validated. However, no study evaluated systematically measuring nocturnal [Formula: see text] in the follow-up of patients with OHS and home mechanical ventilation to detect residual nocturnal hypoventilation. We aimed to evaluate the contribution of nocturnal [Formula: see text] to assess nocturnal hypoventilation compared with current routine examinations, that is, daytime arterial blood gases and nocturnal pulse oximetry.

METHODS

A prospective monocentric pilot study was conducted from August 2018 to November 2019. Patients with stable OHS and who were treated with home noninvasive ventilation for at least 6 months were eligible to participate. After oral consent, we performed both diurnal arterial blood gases and combined home oximetry and capnography. The primary end point was the presence of residual nocturnal hypoventilation, defined as [Formula: see text] > 45 mm Hg or bicarbonate ≥ 27 mmol/L, [Formula: see text] < 90% for ≥ 10% of the night, or [Formula: see text]> 49 mm Hg for ≥ 10% of the night.

RESULTS

A total of 32 subjects were included. Twenty-nine subjects with nocturnal [Formula: see text] were analyzed. Eighteen of the 29 subjects showed residual nocturnal hypoventilation. The association of diurnal arterial blood gases and nocturnal pulse oximetry revealed nocturnal hypoventilation in only 9 subjects. Among the 19 subjects with both normal blood gases and normal nocturnal pulse oximetry, 11 had nocturnal hypoventilation detected with transcutaneous capnography. Only one subject presented with hypoventilation symptoms (asthenia).

CONCLUSIONS

The assessment of [Formula: see text] in comparison with nocturnal pulse oximetry and arterial blood gases provides important information for the diagnosis of residual nocturnal hypoventilation in the subjects with OHS who were ventilated at home.

Sleep-disordered Breathing and Inpatient Outcomes in Nonsurgical Patients: Analysis of the Nationwide Inpatient Cohort

Rationale: Sleep-disordered breathing (SDB) is associated with increased complications and length of stay (LOS) after surgery. SDB-related adverse consequences for nonsurgical admissions are not well defined. Objectives: Evaluate associations between SDB and subtypes and LOS, cost, and mortality in nonsurgical patients. Methods: This retrospective cohort analysis used adult nonsurgical admissions from the 2017 National Inpatient Sample of the Healthcare Costs and Utilization Project. SDB associations with LOS (primary outcome), costs, and mortality were evaluated via logistic regression. Covariates included age, sex, Elixhauser Comorbidity Index, socioeconomic status, hospital type, and insurance type. Results: The cohort included 6,046,544 hospitalizations. Compared with those without SDB, patients with SDB were older (63.6 ± 13.5 vs. 57.4 ± 20.7 yr), higher proportion male (55.8% vs. 40.9%), and more likely to be White (75.7% vs. 66.5%). SDB was associated with increased odds of increased LOS and hospitalization costs (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.16-1.17 and OR, 1.67; 95% CI, 1.66-1.67 in adjusted analyses, respectively) but lower mortality (OR, 0.79; 95% CI, 0.77-0.81). The results for obstructive sleep apnea (OSA) echoed those for SDB. Obesity hypoventilation syndrome had substantially increased LOS (OR, 3.05; 95% CI, 2.98-3.13), mortality (1.76; 95% CI, 1.66-1.86), and costs (OR, 2.67; 95% CI, 2.60-2.73) even after adjustment. Conclusions: Obesity hypoventilation syndrome is associated with higher LOS, mortality, and costs during hospitalization, whereas OSA, despite higher LOS and costs, is associated with decreased mortality. Investigation is warranted on whether paradoxically higher costs but lower mortality in OSA may be indicative of less vigilance in hospitalized patients with undiagnosed SDB.

High-flow nasal cannula may prolong the length of hospital stay in patients with hypercapnic acute COPD exacerbation

BACKGROUND

High-flow nasal cannula (HFNC) is increasingly used in patients with acute exacerbation of COPD (AECOPD). We aimed to confirm whether the baseline bicarbonate is an independent predictor of outcomes in patients with hypercapnic AECOPD receiving HFNC.

METHODS

This was a secondary analysis of a multicentre randomised trial that enrolled 330 patients with non-acidotic hypercapnic AECOPD supported by HFNC or conventional oxygen treatment (COT). We compared the length of stay (LOS) in hospital and the rate of non-invasive positive pressure ventilation (NPPV) use according to baseline bicarbonate levels using the log-rank test or Cox proportional hazard model.

RESULTS

In the high bicarbonate subgroup (n = 165, bicarbonate 35.0[33.3-37.9] mmol/L, partial pressure of arterial carbon dioxide [PaCO2] 56.8[52.0-62.8] mmHg), patients supported by HFNC had a remarkably prolonged LOS in hospital when compared to COT (HR 1.59[1.16-2.17], p = 0.004), whereas patients in the low bicarbonate subgroup (n = 165, bicarbonate 28.8[27.0-30.4] mmol/L, PaCO2 48.0[46.0-50.0] mmHg) had a comparable LOS in hospital regardless of respiratory support modalities. The rate of NPPV use in patients with high baseline bicarbonate level was significantly higher than that in patients with low baseline bicarbonate level (19.4 % vs. 3.0 %, p < 0.0001). Patients with high bicarbonate level in HFNC group had a lower rate of NPPV use compared to COT group (15.4 % vs. 23.0 %, p = 0.217).

CONCLUSIONS

Among patients with non-acidotic hypercapnic AECOPD with high baseline bicarbonate level, HFNC is significantly associated with a prolonged LOS in hospital, which may be due to the reduced escalation of NPPV treatment.

TRIAL REGISTRATION

clinicaltrials.gov (NCT03003559).

Using intra-breath oscillometry in obesity hypoventilation syndrome to detect tidal expiratory flow limitation: a potential marker to optimize CPAP therapy

BACKGROUND

Continuous positive airway pressure (CPAP) therapy has profound effects in obesity hypoventilation syndrome (OHS). Current therapy initiation focuses on upper airway patency rather than the assessment of altered respiratory mechanics due to increased extrapulmonary mechanical load.

METHODS

We aimed to examine the viability of intra-breath oscillometry in optimizing CPAP therapy for OHS. We performed intra-breath oscillometry at 10 Hz in the sitting and supine positions, followed by measurements at increasing CPAP levels (none-5-10-15-20 cmH2O) in awake OHS patients. We plotted intra-breath resistance and reactance (Xrs) values against flow (V') and volume (V) to identify tidal expiratory flow limitation (tEFL).

RESULTS

Thirty-five patients (65.7% male) completed the study. We found a characteristic looping of the Xrs vs V' plot in all patients in the supine position revealing tEFL: Xrs fell with decreasing flow at end-expiration. Intra-breath variables representing expiratory decrease of Xrs became more negative in the supine position [end-expiratory Xrs (mean ± SD): -1.9 ± 1.8 cmH2O·s·L- 1 sitting vs. -4.2 ± 2.2 cmH2O·s·L- 1 supine; difference between end-expiratory and end-inspiratory Xrs: -1.3 ± 1.7 cmH2O·s·L- 1 sitting vs. -3.6 ± 2.0 cmH2O·s·L- 1 supine, p < 0.001]. Increasing CPAP altered expiratory Xrs values and loop areas, suggesting diminished tEFL (p < 0.001). 'Optimal CPAP' value (able to cease tEFL) was 14.8 ± 4.1 cmH2O in our cohort, close to the long-term support average of 13.01(± 2.97) cmH2O but not correlated. We found no correlation between forced spirometry values, patient characteristics, apnea-hypopnea index and intra-breath oscillometry variables.

CONCLUSIONS

tEFL, worsened by the supine position, can be diminished by stepwise CPAP application in most patients. Intra-breath oscillometry is a viable method to detect tEFL during CPAP initiation in OHS patients and tEFL is a possible target for optimizing therapy in OHS patients.

Home NIV treatment quality in patients with chronic respiratory failure having participated to the French nationwide telemonitoring experimental program (The TELVENT study)

BACKGROUND

The ETAPES program is a national telemedicine experiment conducted in France between 2018 and 2023 to investigate whether home non-invasive ventilation (NIV) telemonitoring improves healthcare pathways in patients with chronic respiratory failure (CRF) and impacts healthcare organization. The program provides a combination of therapeutic education and NIV telemonitoring with data processed by an algorithm generating alerts. The TELVENT study objective was to analyze the evolution of ventilation quality in patients included in the ETAPES program.

METHODS

Multicentric cohort study on patients undergoing long-term NIV included in the ETAPES program between September 2018 and December 2020 and who did not refuse the use of their data for this research. Data were obtained from homecare provider databases. The primary endpoint was to attain successful NIV treatment, which was determined by a combination of daily NIV usage for > 4 h per day, low leaks, and a low apnea-hypopnea index (AHI) identified by the NIV device. Respiratory disability was assessed using the DIRECT questionnaire.

RESULTS

329 patients were included in the study of which 145 had COPD and 83 had started NIV and ETAPES within one-month delay. Approximately 25% of patients did not achieve the criteria for successful NIV at ETAPES entry. The proportion of patients with successful NIV treatment increased to 86.8% at six months (p = 0.003, Cochran-Armitage trend test) regardless of NIV history and continued to increase at 12 months in newly equipped NIV patients (93.8%, at month 12, p = 0.0026 for trend test). Over time, a significant increase in NIV use and compliance was observed, while AHI significantly decreased in the overall population. No significant decrease was observed for non-intentional leaks. Approximately 4.9 alerts were generated per patient per 6 months. Their number and type (low NIV use, high AHI or leaks) differed among patients based on their NIV history. Respiratory disability score decreased over time compared with baseline.

CONCLUSION

The TELVENT study highlights the importance of remote NIV monitoring to rapidly identify patients with unsuccessful ventilation. The combination of remote monitoring and therapeutic education may improve the quality of home NIV, especially in the first months of treatment.

Impact of Previous Continuous Positive Airway Pressure Use on Noninvasive Ventilation Adherence and Quality in Obesity Hypoventilation Syndrome: A Pragmatic Single-Center Cross-Sectional Study in Martinique

There is a strong relationship between obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS). When OHS is combined with severe OSA, treatment consists of continuous positive airway pressure (CPAP), followed by noninvasive ventilation (NIV) in the case of CPAP failure. Currently, the impact of a previous use of CPAP on the quality of NIV is unknown. We conducted a cross-sectional study with OHS patients, to assess the quality of NIV according to previous CPAP use. We included 75 patients with OHS on NIV (65 women, 87%). Among these, 40 patients (53.3%) who had had prior CPAP (CPAP+ group) were compared to the remaining 35 patients (46.7%) (CPAP- group). Key characteristics were comparable between the CPAP+ and the CPAP- groups: age at diagnosis of OHS was 67 ± 3 vs. 66 ± 4 years (p = 0.8), age at inclusion was 73 ± 15 vs. 69 ± 15 years (p = 0.29), number of comorbidities was 3.7 ± 1.2 vs. 3.3 ± 1.5, the Charlson index was 5.1 ± 2 vs. 4.6 ± 1.8, and BMI was 41.6 ± 7.6 kg/m2 vs. 41.2 ± 8.2, respectively, all p > 0.05. Follow-up length was greater in CPAP+ vs. CPAP- patients (5.6 ± 4.2 vs. 2.9 ± 2.9 years, p = 0.001). The quality of NIV based on daily adherence, pressure support, apnea-hypopnea index (AHI) and leaks was similar in both groups. Reduced adherence (less than 4 h daily) was found in 10 CPAP+ patients (25%) versus 7 CPAP- patients (20%), p = 0.80. NIV efficacy was also similar. This study found no difference in the quality of NIV or in adherence between patients who had had prior CPAP and those who had not. Previous CPAP does not appear to improve the quality of NIV.

Nocturnal Hypoventilation in the Patients Submitted to Thoracic Surgery

Introduction

Nocturnal hypoventilation may occur due to obesity, concomitant chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and/or the use of narcotic analgesics. The aim of the study was to evaluate the risk and severity of nocturnal hypoventilation as assessed by transcutaneous continuous capnography in the patients submitted to thoracic surgery.

Materials and Methods

The material of the study consisted of 45 obese (BMI 34.8 ± 3.7 kg/m2) and 23 nonobese (25.5 ± 3.6 kg/m2) patients, who underwent thoracic surgery because of malignant (57 patients) and nonmalignant tumors. All the patients received routine analgesic treatment after surgery including intravenous morphine sulfate. Overnight transcutaneous measurements of CO2 partial pressure (tcpCO2) were performed before and after surgery in search of nocturnal hypoventilation, i.e., the periods lasting at least 10 minutes with tcpCO2 above 55 mmHg.

Results

Nocturnal hypoventilation during the first night after thoracic surgery was detected in 10 patients (15%), all obese, three of them with COPD, four with high suspicion of moderate-to-severe OSA syndrome, and one with chronic daytime hypercapnia. In the patients with nocturnal hypoventilation, the mean tcpCO2 was 53.4 ± 6.1 mmHg, maximal tcpCO2 was 59.9 ± 8.4 mmHg, and minimal tcpCO2 was 46.4 ± 6.7 mmHg during the first night after surgery. In these patients, there were higher values of minimal, mean, and maximal tcpCO2 in the preoperative period. Nocturnal hypoventilation in the postoperative period did not influence the duration of hospitalization. Among 12 patients with primary lung cancer who died during the first two years of observation, there were 11 patients without nocturnal hypoventilation in the early postoperative period.

Conclusion

Nocturnal hypoventilation may occur in the patients after thoracic surgery, especially in obese patients with bronchial obstruction, obstructive sleep apnea, or chronic daytime hypercapnia, and does not influence the duration of hospitalization.

Ketogenic diet acutely improves gas exchange and sleep apnoea in obesity hypoventilation syndrome: A non-randomized crossover study

BACKGROUND AND OBJECTIVE

Obesity hypoventilation syndrome (OHS) causes hypercapnia which is often refractory to current therapies. We examine whether hypercapnia in OHS can be improved by a ketogenic dietary intervention.

METHODS

We conducted a single-arm crossover clinical trial to examine the impact of a ketogenic diet on CO2 levels in patients with OHS. Patients were instructed to adhere to 1 week of regular diet, 2 weeks of ketogenic diet, followed by 1 week of regular diet in an ambulatory setting. Adherence was assessed with capillary ketone levels and continuous glucose monitors. At weekly visits, we measured blood gases, calorimetry, body composition, metabolic profiles, and sleep studies. Outcomes were assessed with linear mixed models.

RESULTS

A total of 20 subjects completed the study. Blood ketones increased from 0.14 ± 0.08 during regular diet to 1.99 ± 1.11 mmol/L (p < 0.001) after 2 weeks of ketogenic diet. Ketogenic diet decreased venous CO2 by 3.0 mm Hg (p = 0.008), bicarbonate by 1.8 mmol/L (p = 0.001), and weight by 3.4 kg (p < 0.001). Sleep apnoea severity and nocturnal oxygen levels significantly improved. Ketogenic diet lowered respiratory quotient, fat mass, body water, glucose, insulin, triglycerides, leptin, and insulin-like growth factor 1. Rebound hypercapnia was observed after resuming regular diet. CO2 lowering was dependent on baseline hypercapnia, and associated with circulating ketone levels and respiratory quotient. The ketogenic diet was well tolerated.

CONCLUSION

This study demonstrates for the first time that a ketogenic diet may be useful for control of hypercapnia and sleep apnoea in patients with obesity hypoventilation syndrome.

Clinical Evaluation of the Sleepy and Sleepless Patient

OBJECTIVE

This article addresses the approach to the evaluation of patients who present to a neurologist with excessive daytime sleepiness or difficulty sleeping.

LATEST DEVELOPMENTS

Greater emphasis on the importance of sleep reflects the growing scientific understanding that sleep is critical to overall health and well-being. Consumer sleep technologies, which measure parameters related to sleep, may provide insight into an individual's sleep-related symptoms and tendencies and have a role in patient-centered sleep evaluation when used within an appropriate clinical context.

ESSENTIAL POINTS

A thorough review of a patient's history and physical examination findings are important components of the assessment and management of their sleep-related symptoms. An understanding of how the clinical context relates to the categorization of sleep disorders can impact a patient's symptoms, comorbid neurologic disorders, and overall well-being. Many neurologic conditions are strongly associated with sleep disturbance, risk factors for the development of a sleep disorder, or both. Therefore, it is critical for neurologists to be familiar and comfortable with taking a focused sleep history. Modalities such as in-laboratory polysomnography, home sleep apnea testing, multiple sleep latency testing, and actigraphy, as well as contextualized and prudent use of data obtained from consumer sleep technologies, can be helpful in appropriately selected patients. Mindful integration of these objective data facilitates the diagnosis and management of sleep disorders.

Screening and treatment of pre-bariatric surgical patients with obesity related sleep disordered breathing

BACKGROUND

There is a significant burden of sleep disordered breathing (SDB) in patients living with severe and complex obesity undergoing pre-bariatric surgery assessment. This longitudinal observational study evaluated the burden of obesity hypoventilation syndrome (OHS) in this cohort of patients and the therapeutic compliance of patients commenced on positive airway pressure treatment.

METHODS

All pre-bariatric surgery patients referred to the sleep clinic for review after an abnormal screening study between 2018 and 2022 were included. We collected data on their sleep study results, anthropometrics, co-morbid medical conditions, clinical observations, spirometry and arterial blood gas (ABG). Patients commenced on therapy were followed-up longitudinally and compliance data collected via remote monitoring.

RESULTS

A total of 116 patients were included [age: mean ± standard deviation (SD) 48.8±10.8 years; body mass index (BMI) 49.2±8.5 kg/m2; Epworth Sleepiness Scale (ESS) 8.7±5.1 points]. Fifteen patients (12.9% of cohort) were diagnosed with hypercapnic respiratory failure (pH 7.40±0.02; pO2 11.00±1.04 kPa; pCO2 6.15±0.08 kPa). Compared to eucapnic obstructive sleep apnoea (OSA) patients, they were older (51.1 vs. 48.5 years; P=0.311), had a higher BMI (51.5 vs. 48.9 kg/m2; P=0.266), more likely to be female (66.7% vs. 53.5%; P=0.275) and had a higher ESS score (10.4 vs. 8.5 points; P=0.177). On binomial regression analysis insulin dependent diabetes was the only patient characteristic of significance with prevalence increased in patients with OHS (26.7% vs. 8.9%; P=0.042). Forced vital capacity (FVC) and oxygen saturation (SpO2) cut-offs demonstrated high specificity (96.8%) but low sensitivity (13.3%) to diagnosed hypercapnia. Fifty percent of the patients with hypercapnia required bi-level ventilation. On follow-up 44.9% of patients were compliant with therapy (>4 hours usage/night).

CONCLUSIONS

In minimally symptomatic patients living with severe and complex obesity who have an abnormal overnight oximetry, over 1 in 10 demonstrated chronic respiratory failure. Clinic spirometry and daytime SpO2 excluded those with hypercapnia. Overall adherence to prescribed therapy is low. Screening, appropriate pre-operative optimisation and peri-operative planning are important in preventing complications in this patient cohort.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Profiles of Elderly Patients with Obesity Hypoventilation Syndrome in Martinique: A Single-Center Study

Obesity hypoventilation syndrome (OHS) is a form of chronic respiratory insufficiency related to obesity that affects young and old people. Age appears to be associated with poorer response to treatment by nighttime ventilation. This study aimed to describe the characteristics of elderly subjects (>65 years) with OHS compared to younger patients, with a view to adapting therapy in older individuals. We conducted a retrospective study comparing socio-demographic, clinical, functional characteristics as well as treatment and outcomes between young (<65 years) and older (65 years and older) individuals with OHS at the University Hospital of Martinique. We included 143 patients (114 women), of whom 82 were 65 years or older (57%). Charlson index was higher in the older group. Patients in ≥65 years group were less frequently obese, but more frequently had diabetes mellitus, cardiac arrythmia and arterial hypertension compared to younger patients. There was no difference in the circumstances of diagnosis or arterial blood gas at diagnosis. At follow up, partial pressure of carbon dioxide (pCO₂) was higher in ≥65 years group. Despite comparable NIV settings, apart from lower expiratory positive airway pressure (EPAP) with higher apnea-hypopnea index (AHI), patients in the ≥65-year-old group remained more frequently hypercapnic. In conclusion, over half (57%) of patients with OHS in our cohort were aged over 65 years. Older patients developed OHS at lower BMI levels than their younger counterparts, and more frequently, had comorbidities such as diabetes, hypertension and cardiac arrhythmia. Increased Charlson index, lower BMI and female sex were independent factors associated with OHS in the elderly.

Quality of life in patients with chronic respiratory failure on home mechanical ventilation

Home mechanical ventilation (HMV) is a treatment for chronic respiratory failure that has shown clinical and cost effectiveness in patients with underlying COPD, obesity-related respiratory failure and neuromuscular disease (NMD). By treating chronic respiratory failure with adequate adherence to HMV, improvement in patient-reported outcomes including health-related quality of life (HRQoL) have been evaluated using general and disease-specific quantitative, semi-qualitative and qualitative methods. However, the treatment response in terms of trajectory of change in HRQoL is not uniform across the restrictive and obstructive disease groups. In this review, the effect of HMV on HRQoL across the domains of symptom perception, physical wellbeing, mental wellbeing, anxiety, depression, self-efficacy and sleep quality in stable and post-acute COPD, rapidly progressive NMD (such as amyotrophic lateral sclerosis), inherited NMD (including Duchenne muscular dystrophy) and obesity-related respiratory failure will be discussed.

Respiratory Center Function and Its Impact in Obesity Hypoventilation Syndrome Treatment

INTRODUCTION

Patients with obesity hypoventilation syndrome (OHS) need treatment with positive pressure either with continuous (CPAP) or double pressure (NIV). The apnea-hypopnea index (AHI) is considered a key data for making therapeutic decisions. We hypothesized that HR may be an useful tool to establish different phenotypes and individualize treatment in patients with OHS. Our objective was to analyze the role of the respiratory center response to hypercapnia (HR) in the adequacy of positive airway pressure therapy.

METHOD

We included subjects with OHS treated with CPAP or NIV according to AHI and baseline pCO₂. We analyzed therapeutic effectiveness and treatment changes prioritizing CPAP if AHI>30/h. Therapy was considered adequate if it was effective after two years. HR was measured with the p0.1/pEtCO₂ ratio and its capability to select therapy was analyzed. The statistical study was performed by means comparison (Student's t) and multivariate analysis (logistic regression).

RESULTS

67 subjects were included of 68(11) years old, 37 (55%) males, initially 45 (67%) treated with NIV and 22 (33%) with CPAP, one case was excluded and in 25 (38%) the treatment was changed. Finally, CPAP was adequate for 29 subjects (44%) and NIV for 37 (56%). The CPAP group showed AHI 57/h (24) and p0.1/pEtCO₂ 0.37cmH₂O/mmHg (0.23), NIV group AHI 43/h (35) and p0.1/pEtCO₂ 0.24 (0.15) with p=0.049 and 0.006. In multivariate analysis, p0.1/pEtCO₂ (p=0.033) and AHI>30 (p=0.001) were predictors of adequate therapy.

CONCLUSION

Measuring the RH of the respiratory center helps to select the most appropriate treatment for patients with OHS.

Does one size fit all? An update on chronic ventilatory support in different respiratory illnesses

Home noninvasive ventilation (HNIV) improves outcomes in different disease categories. In this article, we discuss indications for when and how to initiate HNIV in COPD, obesity hypoventilation syndrome (OHS) and neuromuscular disorders (NMD). While in COPD, significant diurnal hypercapnia and high-intensity HNIV are essential ingredients for success, in NMD and OHS, early respiratory changes are best detected during sleep through oxy-capnography associated (or not) with respiratory polygraphy. In COPD and OHS, it is crucial to consider the coexistence of obstructive sleep apnoea because treatment with continuous positive airway pressure may be the simplest and most effective treatment that should be proposed even in hypercapnic patients as first-line therapy. In NMD, the need for continuous HNIV and eventual switching to tracheostomy ventilation makes this group's management more challenging. Achieving successful HNIV by improving quality of sleep, quality of life and keeping a good adherence to the therapy is a challenge, above all in COPD patients. In OHS patients, on top of HNIV, initiation of other interventions such as weight loss management is crucial. More resources should be invested in improving all these aspects. Telemonitoring represents a promising method to improve titration and follow-up of HNIV.

A retrospective study of the role of hypercapnia in patients with acromegaly

BACKGROUND

Acromegaly is a multisystemic disease characterized by an excessive release of growth hormone (GH) and insulin-like growth factor-1. Obstructive sleep apnea (OSA) is a common consequence of acromegaly, and hypercapnia is frequently observed in patients with acromegaly, OSA, and obesity. However, the effects of hypercapnia on acromegaly remain unknown. This study was designed to investigate whether there are differences in clinical symptoms, sleep variables, and biochemical remission after surgery for acromegaly in patients with OSA with or without hypercapnia.

METHODS

A retrospective analysis was conducted involving patients with acromegaly and OSA. The pharmacotherapy history for acromegaly before surgery, anthropometric measures, blood gas, sleep monitoring data, and biochemical assays of hypercapnic and eucapnic individuals were collected 1-2 weeks before surgery. Univariate and multivariate logistic regression analyses were performed to determine the risk factors for failed postoperative biochemical remission.

RESULTS

In this study, 94 patients with OSA and acromegaly were included. Among them, 25 (26.6%) had hypercapnia. The hypercapnic group had higher body mass index (92% vs. 62.3%; p = 0.005) and poorer nocturnal hypoxemia index. No serological differences were found between the two groups. According to the post-surgery GH level, 52 patients (55.3%) reached biochemical remission. Univariate logistic regression analysis revealed that diabetes mellitus (odds ratio [OR], 2.59; 95% confidence interval [CI], 1.02-6.55), instead of hypercapnia (OR, 0.61; 95% CI, 0.24-1.58), was associated with lower remission rates. Patients who received pharmacotherapy for acromegaly before surgery (OR, 0.21; 95% CI, 0.06-0.79) and had higher thyroid-stimulating hormone levels (OR, 0.53; 95% CI, 0.32-0.88) were more likely to have biochemical remission after surgery. Multivariate analysis further showed that only diabetes mellitus (OR, 3.29; 95% CI, 1.15-9.46) and preoperative pharmacotherapy (OR, 0.21; 95% CI, 0.06-0.83) remained significant. Hypercapnia, hormone levels, and sleep indicators had no effect on biochemical remission after surgery.

CONCLUSIONS

Single-center evidence shows that hypercapnia alone may not be a risk factor for lower biochemical remission rates. Correcting hypercapnia does not appear to be required before surgery. More evidence is needed to further support this conclusion.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Acute hypercapnic respiratory failure in patients with obesity hypoventilation syndrome during the COVID-19 pandemic: Four case reports

Obesity hypoventilation syndrome (OHS) can cause acute hypercapnic respiratory failure (AHRF). The onset of AHRF in four patients with OHS during the coronavirus disease 2019 (COVID-19) pandemic is reported in this study. Two men (23 and 45 years old) and two women (both 77 years old) presented to our hospital with AHRF. In the two elderly women, a prolonged supine position due to falls seemed to be the cause of AHRF. Treatment was started with bilevel positive airway pressure for all patients. While one patient died, the condition of the other three improved; they were discharged with continuous positive airway pressure. AHRF due to OHS was rarely reported in the rural region of Japan. It is suggested that increased rates of obesity due to lifestyle changes during the COVID-19 pandemic may be responsible for an increase in the prevalence of OHS-associated AHRF.