Comorbidities and mortality in hypercapnic obese under domiciliary noninvasive ventilation

Long-term oxygen therapy to reduce length of hospital stay in COVID-19

OBJECTIVE

The aim of this study was to evaluate the efficacy of long-term oxygen therapy as a strategy to reduce hospitalization time in patients affected by COVID-19.

METHODS

Between April and December 2021, COVID-19 patients with stable clinical conditions needing supplementary oxygen therapy during hospitalization were oriented to have hospital discharge with long-term oxygen therapy and reassessment after 15 days.

RESULTS

A total of 62 patients were evaluated and, 15 days after discharge, 69% of patients had suspended long-term oxygen therapy, with no difference between the groups admitted to the intensive care unit or the ward (p=0.319). Among the individuals who needed to maintain long-term oxygen therapy, in addition to worse P/F ratio (265±57 vs. 345±51; p<0.001) and lower partial pressure of oxygen (55±12 vs. 72±11 mmHg; p<0.001), were those more obese (37±8 vs. 30±6 kg/m2; p=0.032), needed more time for invasive mechanical ventilation (46±27 vs. 20±16 days; p=0.029), had greater persistence of symptoms (p<0.001), and shorter time between the onset of symptoms and the need for hospitalization (7 [2-9] vs. 10 [6-12] days; p=0.039).

CONCLUSION

Long-term oxygen therapy is an effective strategy for reducing hospitalization time in COVID-19 patients, regardless of gravity. Additionally, more obese patients with persistence of respiratory symptoms, faster disease evolution, and more days of invasive mechanical ventilation needed to maintain the long-term oxygen therapy longer.

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.

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.

Does PaCO2 correction have an impact on survival of patients with chronic respiratory failure and long-term non-invasive ventilation?

Background and objective

Non-invasive ventilation (NIV) improves survival of patients with chronic respiratory failure (CRF). Most often, pressure settings are made to normalize arterial blood gases. However, this objective is not always achieved due to intolerance to increased pressure or poor compliance. Few studies have assessed the effect of persistent hypercapnia on ventilated patients' survival. Data from the Pays de la Loire Respiratory Health Research Institute cohort were analyzed to answer this question.

Study design and methods

NIV-treated adults enrolled between 2009 and 2019 were divided into 5 subgroups: obesity-hypoventilation syndrome (OHS), COPD, obese COPD, neuromuscular disease (NMD) and chest wall disease (CWD). PaCO2 correction was defined as the achievement of a PaCO2 < 6 kPa or a 20% decrease in baseline PaCO₂ in COPD patients. The endpoint was all-cause mortality. Follow-up was censored in case of NIV discontinuation.

Results

Data from 431 patients were analyzed. Median survival was 103 months and 148 patients died. Overall, PaCO2 correction was achieved in 74% of patients. Bivariate analysis did not show any survival difference between patients who achievedPaCO₂ correction and those who remained hypercapnic: overall population: p = 0.74; COPD: p = 0.97; obese COPD: p = 0.28; OHS: p = 0.93; NMD: p = 0.84; CWD: p = 0.28.

Conclusion

Moderate residual hypercapnia under NIV does not negatively impact survival in CRF patients. In individuals with poor tolerance of pressure increases, residual hypercapnia can therefore be tolerated under long-term NIV. Larger studies, especially with a higher number of patients with residual PaCO2 > 7 kPa, are needed to confirm these results.

A history of home mechanical ventilation: The past, present and future

This state-of-the-art review provides an overview of the history of home mechanical ventilation (HMV), including early descriptions of mechanical ventilation from ancient and Renaissance perspectives and the mass development of ventilators designed for long-term use during the poliomyelitis epidemic. Seminal data from key clinical trials supports the application of HMV in certain patients with chronic obstructive pulmonary disease, neuromuscular disease and obesity-related respiratory failure. Innovative engineering coupled with refined physiological understanding now permits widespread delivery of home mechanical ventilation to a global population, using portable devices with advanced ventilatory modes and telemonitoring capabilities. Exponential growth in digital technology continues, and ongoing research is needed to understand how to harness clinical and physiological data to benefit patients and healthcare services in a clinically- and cost-effective manner.

Long-Term Mortality following Acute Noninvasive Ventilation for Obesity-Related Respiratory Failure: A Retrospective Single-Centre Study

Introduction

Determinants of long-term mortality following acute hypercapnic respiratory failure have been extensively studied in patients with chronic obstructive pulmonary disease. However, respiratory failure due to obesity has not been studied to the same extent. This retrospective survey aims to identify whether admission pH is associated with long-term mortality in patients requiring acute noninvasive ventilation (NIV) for obesity-related respiratory failure (ORRF).

Methods

Records from April 2013 to March 2020 were accessed from a NIV quality database at an acute teaching hospital. Adults with hypercapnic ORRF requiring acute NIV were included. pH data were grouped by threshold (pH≤ and >7.25) and correlated with time from presentation to death; multivariable analysis was performed using Cox proportional hazards.

Results

A total of 277 acute NIV episodes were included. Two-year mortality was similar for patients in both pH categories. Univariable analysis identified pH ≤ 7.25 to increase risk of two-year mortality by 43%. However, multivariable analysis identified that pH was not a significant determinant of long-term mortality, although male sex, older age, and higher admission pCO2 increased the risk of death at two years by 76%, 3% per year of age, and 16% per 1 kPa of pCO2 increase, respectively.

Conclusion

Severity of hypercapnia on admission, male sex, and older age are associated with worse two-year mortality in patients requiring acute NIV for ORRF. There is scope for further analyses including investigating the role of domiciliary NIV in ORRF patients.

Factors Associated with the Efficiency of Home Non-Invasive Ventilation in Patients with Obesity-Hypoventilation Syndrome in Martinique

Obesity-hypoventilation syndrome (OHS) is a respiratory complication of obesity characterized by chronic hypercapnic respiratory failure. It is often associated with several comorbidities and is treated by positive airway pressure (PAP) therapy. This study aimed to identify factors associated with persistent hypercapnia in patients receiving home non-invasive ventilation (NIV). We performed a retrospective study including patients with documented OHS. In total, 143 patients were included (79.7% women, age 67 ± 15.5 years, body mass index 41.6 ± 8.3 kg/m²). After 4.6 ± 4.0 years of follow-up, 72 patients (50.3%) remained hypercapnic. In bivariable analysis, clinical data showed no difference in follow-up duration, number of comorbidities, comorbidities, or circumstance of discovery. Patients with persistent hypercapnia on NIV were generally older, with lower BMI and more comorbidities. (5.5 ± 1.8 versus 4.4 ± 2.1, p = 0.001), female sex (87.5% versus 71.8%), was treated by NIV (100% versus 90.1%, p < 0.01), had lower FVC (56.7 ± 17.2 versus 63.6 ± 18% of theoretical value, p = 0.04), lower TLC (69.1 ± 15.3 versus 74.5 ± 14.6% of theoretical value, p = 0.07), lower RV (88.4 ± 27.1 versus 102.5 ± 29.4% of theoretical value, p = 0.02), higher pCO2 at diagnosis (59.7 ± 11.7 versus 54.6 ± 10.1 mmHg, p = 0.01) and lower pH (7.38 ± 0.03 versus 7.40 ± 0.04, p = 0.007), higher pressure support (12.6 ± 2.6 versus 11.5 ± 2.4 cmH₂O, p = 0.04) and lower EPAP (8.2 ± 1.9 versus 9 ± 2.0 cmH₂O, p = 0.06). There was no difference in non-intentional leaks and daily use between patients between both groups. By multivariable analysis, sex, BMI, pCO2 at diagnosis, and TLC were independent risk factors for persistent hypercapnia on home NIV. In individuals with OHS, persistent hypercapnia on home NIV therapy is frequent. Sex, BMI, pCO2 at diagnosis, and TLC were all associated with an increased risk of persistent hypercapnia in persons treated with home NIV.

Causes of hypercapnic respiratory failure and associated in-hospital mortality

BACKGROUND AND OBJECTIVE

Hypercapnic respiratory failure (HRF) can occur due to severe respiratory disease but also because of multiple coexistent causes. There are few data on the prevalence of antecedent causes for HRF and the effect of these causes on prognosis, especially where study inclusion has not been biased with respect to primary diagnosis, interventions received or clinical outcome. We sought to determine the prevalence of pre-specified conditions among patients with HRF and to determine the effect of these causes on in-hospital mortality.

METHODS

Cross-sectional study of patients with HRF from 2013 to 2017. Inclusion criteria were PaCO₂  >45 mm Hg and pH ≤7.45. Causes of interest were identified using diagnosis codes from hospital records. We used directed acyclic graphs to inform logistic regression models for the outcome of in-hospital death.

RESULTS

We identified 873 persons with HRF in the study period. Mean (SD) age was 69 years and 50.4% were males. Acidosis (pH <7.35) was present in 488 (55%) cases. Most (83%) had one or more of the following: obstructive lung disease, lower respiratory tract infection, congestive cardiac failure, sleep disordered breathing, neuromuscular disease, opioid or benzodiazepine use. In-hospital mortality was 12.8%. Obstructive lung disease and cardiac failure were associated with a lower risk of death, whereas respiratory tract infection and neuromuscular disease were associated with increased risk of death.

CONCLUSION

HRF is associated with a range of potentially causative conditions, which significantly impact hospital survival. Systematic evaluation of patients with HRF may increase detection of treatable comorbidities.

Domiciliary noninvasive ventilation for chronic respiratory diseases

Patients with chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), neuromuscular diseases, kyphoscoliosis and obstructive sleep apnoea-obesity hypoventilation syndrome (OSA-OHS), are at a higher risk of decompensation in the form of hypercapnic respiratory failure leading to intensive care unit (ICU) admission and increased mortality. This article reviews the evidence of role of domiciliary noninvasive ventilation (NIV) in patients with diseases with chronic ventilatory failure, including the mechanism of the effect of (NIV).

The prevalence of non-invasive ventilation and long-term oxygen treatment in Helsinki University Hospital area, Finland

BACKGROUND

Chronic respiratory failure (CRF) can be treated at home with non-invasive ventilation (NIV) and/or long-term oxygen (LTOT). The prevalence of these treatments is largely unknown. We aimed to clarify the prevalence and indications of the treatments, and the three-year mortality of the treated patients in the Helsinki University Hospital (HUH) area in Finland.

METHODS

In this retrospective study we analyzed the prevalence of adult CRF patients treated with NIV and/or LTOT on 1.1.2018 and followed these patients until 1.1.2021. Data collected included the underlying diagnosis, patient characteristics, information on treatment initiation and from the last follow-up visit, and mortality during the three-year follow-up. Patients with home invasive mechanical ventilation or sleep apnea were excluded.

RESULTS

On 1.1.2018, we had a total of 815 patients treated with NIV and/or LTOT in the Helsinki University Hospital (HUH) area, with a population of 1.4 million. The prevalence of NIV was 35.4 per 100,000, of LTOT 24.6 per 100,000 and of the treatments combined 60.0 per 100,000. Almost half, 44.5%, were treated with NIV, 41.0% with LTOT, and 14.4% underwent both. The most common diagnostic groups were chronic obstructive pulmonary disease (COPD) (33.3%) and obesity-hypoventilation syndrome (OHS) (26.6%). The three-year mortality in all patients was 45.2%. In the COPD and OHS groups the mortality was 61.3% and 21.2%. In NIV treated patients, the treatment durations varied from COPD patients 5.3 years to restrictive chest wall disease patients 11.4 years. The age-adjusted Charlson co-morbidity index (ACCI) median for all patients was 3.0.

CONCLUSIONS

NIV and LTOT are common treatments in CRF. The prevalence in HUH area was comparable to other western countries. As the ACCI index shows, the treated patients were fragile, with multiple co-morbidities, and their mortality was high. Treatment duration and survival vary greatly depending on the underlying diagnosis.

Assessing Symptom Burden and Depression in Subjects With Chronic Respiratory Insufficiency

Objectives: Patients with chronic respiratory insufficiency suffer from advanced disease, but their overall symptom burden is poorly described. We evaluated the symptoms and screening of depression in subjects with chronic respiratory insufficiency by using the Edmonton symptom assessment system (ESAS). Methods: In this retrospective study, 226 subjects with chronic respiratory insufficiency answered the ESAS questionnaire measuring symptoms on a scale from 0 (no symptoms) to 10 (worst possible symptom), and the depression scale (DEPS) questionnaire, in which the cut-off point for depressive symptoms is 9. Results: The most severe symptoms measured with ESAS (median [interquartile range]) were shortness of breath 4.0 (1.0-7.0), dry mouth 3.0 (1.0-7.0), tiredness 3.0 (1.0-6.0), and pain on movement 3.0 (0.0-6.0). Subjects with a chronic obstructive pulmonary disease as a cause for chronic respiratory insufficiency had significantly higher scores for shortness of breath, dry mouth, and loss of appetite compared to others. Subjects with DEPS ≥9 reported significantly higher symptom scores in all ESAS categories than subjects with DEPS <9. The area under the receiver operating characteristic curve for ESAS depression score predicting DEPS ≥9 was 0.840 (P < .001). If the ESAS depression score was 0, there was an 89% probability of the DEPS being <9, and if the ESAS depression score was ≥4, there was an 89% probability of the DEPS being ≥9. The relation between ESAS depression score and DEPS was independent of subjects' characteristics and other ESAS items. Conclusions: Subjects with chronic respiratory insufficiency suffer from a high symptom burden due to their advanced disease. The severity of symptoms increases with depression and 4 or more points in the depression question of ESAS should lead to a closer diagnostic evaluation of depression. Symptom-centered palliative care including psychosocial aspects should be early integrated into the treatment of respiratory insufficiency.

Effectiveness of CPAP vs. Noninvasive Ventilation Based on Disease Severity in Obesity Hypoventilation Syndrome and Concomitant Severe Obstructive Sleep Apnea

RATIONALE

Obesity hypoventilation syndrome (OHS) with concomitant severe obstructive sleep apnea (OSA) is treated with CPAP or noninvasive ventilation (NIV) during sleep. NIV is costlier, but may be advantageous because it provides ventilatory support. However, there are no long-term trials comparing these treatment modalities based on OHS severity.

OBJECTIVE

To determine if CPAP have similar effectiveness when compared to NIV according to OHS severity subgroups.

METHODS

Post hoc analysis of the Pickwick randomized clinical trial in which 215 ambulatory patients with untreated OHS and concomitant severe OSA, defined as apnoea-hypopnea index (AHI)≥30events/h, were allocated to NIV or CPAP. In the present analysis, the Pickwick cohort was divided in severity subgroups based on the degree of baseline daytime hypercapnia (PaCO₂ of 45-49.9 or ≥50mmHg). Repeated measures of PaCO₂ and PaO₂ during the subsequent 3 years were compared between CPAP and NIV in the two severity subgroups. Statistical analysis was performed using linear mixed-effects model.

RESULTS

204 patients, 97 in the NIV group and 107 in the CPAP group were analyzed. The longitudinal improvements of PaCO₂ and PaO₂ were similar between CPAP and NIV based on the PaCO₂ severity subgroups.

CONCLUSION

In ambulatory patients with OHS and concomitant severe OSA who were treated with NIV or CPAP, long-term NIV therapy was similar to CPAP in improving awake hypercapnia, regardless of the severity of baseline hypercapnia. Therefore, in this patient population, the decision to prescribe CPAP or NIV cannot be solely based on the presenting level of PaCO₂.

Defining obesity hypoventilation syndrome

With increasing prevalence of obesity, the substantial contribution of obesity hypoventilation syndrome (OHS) to morbidity and mortality is likely to increase. It is therefore crucial that the condition has a clear definition to allow timely identification of patients. OHS was first described as “Pickwickian syndrome” in the 1950s; in subsequent decades, case reports did not clearly delineate between patients suffering from OHS and those suffering from obstructive sleep apnoea. In 1999, the American Academy of Sleep Medicine published a guideline that delineated the cause of daytime hypercapnia as either predominantly upper airway or predominantly hypoventilation. This was the first formal definition of OHS as the presence of daytime alveolar hypoventilation (arterial carbon dioxide tension >45 mmHg) in patients with body mass index >30 kg·m⁻² in the absence of other causes of hypoventilation. This definition is reflected in the most recent guidelines published on OHS. Recent developments in defining OHS include proposed classification systems of severity and demonstrating the value of using serum bicarbonate to exclude OHS in patients with a low index of suspicion.

Obesity hypoventilation syndrome is defined as daytime alveolar hypoventilation in obese patients in the absence of other causes of hypoventilation. Classifications of severity are now needed to target treatment at the most appropriate individuals.https://bit.ly/3yLuiL9

Impact of Healthcare Non-Take-Up on Adherence to Long-Term Positive Airway Pressure Therapy

Background: The effectiveness of positive airway pressure therapies (PAP) is contingent on treatment adherence. We hypothesized that forgoing healthcare may be a determinant of adherence to PAP therapy.

Research Question: The objectives were: (i) to assess the impact of forgoing healthcare on adherence to PAP in patients with Chronic Respiratory Failure (CRF) and patients with Obstructive Sleep Apnea Syndrome (OSAS); (ii) to compare forgoing healthcare patterns in these two chronic conditions.

Study design and methods: Prospective cohort of patients with OSAS or CRF, treated with PAP therapies at home for at least 12 months. At inclusion, patients were asked to fill-in questionnaires investigating (i) healthcare forgone, (ii) deprivation (EPICES score), (iii) socio-professional and familial status. Characteristics at inclusion were extracted from medical records. PAP adherence was collected from the device's built-in time counters. Multivariable logistic regression models were used to assess the associations between healthcare forgone and the risk of being non-adherent to CPAP treatment.

Results: Among 298 patients included (294 analyzed); 33.7% reported forgoing healthcare. Deprivation (EPICES score > 30) was independently associated with the risk of non-adherence (OR = 3.57, 95%CI [1.12; 11.37]). Forgoing healthcare had an additional effect on the risk of non-adherence among deprived patients (OR = 7.74, 95%CI [2.59; 23.12]). OSAS patients mainly forwent healthcare for financial reasons (49% vs. 12.5% in CRF group), whereas CRF patients forwent healthcare due to lack of mobility (25%, vs. 5.9 % in OSAS group).

Interpretation: Forgoing healthcare contributes to the risk of PAP non-adherence particularly among deprived patients. Measures tailored to tackle forgoing healthcare may improve the overall quality of care in PAP therapies.

Clinical Trial Registration: The study protocol was registered in ClinicalTrials.gov, identifier: NCT03591250.

Cardiovascular disease in obesity hypoventilation syndrome - A review of potential mechanisms and effects of therapy

Cardiovascular disease is common in patients with obesity hypoventilation syndrome (OHS) and accounts in part for their poor prognosis. This narrative review article examines the epidemiology of cardiovascular disease in obesity hypoventilation syndrome, explores possible contributing factors and the effects of therapy. All studies that included cardiovascular outcomes and biomarkers were included. Overall, there is a higher burden of cardiovascular disease and cardiovascular risk factors among patients with obesity hypoventilation syndrome. In addition to obesity and sleep-disordered breathing, there are several other pathophysiological mechanisms that contribute to higher cardiovascular morbidity and mortality in OHS. There is evidence emerging that positive airway pressure therapy and weight loss have beneficial effects on the cardiovascular system in obesity hypoventilation syndrome patients, but further research is needed to clarify whether this translates to clinically important outcomes.

Nasal versus oronasal masks for home non-invasive ventilation in patients with chronic hypercapnia: a systematic review and individual participant data meta-analysis

BACKGROUND

The optimal interface for the delivery of home non-invasive ventilation (NIV) to treat chronic respiratory failure has not yet been determined. The aim of this individual participant data (IPD) meta-analysis was to compare the effect of nasal and oronasal masks on treatment efficacy and adherence in patients with COPD and obesity hypoventilation syndrome (OHS).

METHODS

We searched Medline and Cochrane Central Register of Controlled Trials for prospective randomised controlled trials (RCTs) of at least 1 month's duration, published between January 1994 and April 2019, that assessed NIV efficacy in patients with OHS and COPD. The main outcomes were diurnal PaCO₂, PaO₂ and NIV adherence (PROSPERO CRD42019132398).

FINDINGS

Of 1576 articles identified, 34 RCTs met the inclusion criteria and IPD were obtained for 18. Ten RCTs were excluded because only one type of mask was used, or mask data were missing. Data from 8 RCTs, including 290 IPD, underwent meta-analysis. Oronasal masks were used in 86% of cases. There were no differences between oronasal and nasal masks for PaCO₂ (0.61 mm Hg (95% CI -2.15 to 3.38); p=0.68), PaO₂ (-0.00 mm Hg (95% CI -4.59 to 4.58); p=1) or NIV adherence (0·29 hour/day (95% CI -0.74 to 1.32); p=0.58). There was no interaction between the underlying pathology and the effect of mask type on any outcome.

INTERPRETATION

Oronasal masks are the most used interface for the delivery of home NIV in patients with OHS and COPD; however, there is no difference in the efficacy or tolerance of oronasal or nasal masks.

The Role of Positive Airway Pressure Therapy in Adults with Obesity Hypoventilation Syndrome. A Systematic Review and Meta-Analysis

Rationale: Obesity hypoventilation syndrome (OHS) is an undesirable complication of severe obesity. Although weight loss is an accepted component of management, it is difficult to achieve and sustain the degree of weight loss necessary to reverse OHS. As such, positive airway pressure (PAP) during sleep has become the cornerstone therapy for most patients with OHS. However, the value of PAP therapy remains uncertain.Objective: To perform a systematic review to determine whether adults with OHS should be treated with PAP therapy or not.Methods: This systematic review informed an international, multidisciplinary panel of experts who had converged to develop a clinical practice guideline on OHS for the American Thoracic Society. MEDLINE, the Cochrane Library, and Embase were searched from January 1946 to March 2019 for studies that compared PAP therapy (i.e., continuous PAP or noninvasive ventilation) to no PAP therapy in patients with OHS. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach was used to appraise the quality of evidence.Results: The search identified 2,994 unique articles. The full text of 56 articles was reviewed, and 25 studies were selected, including 3 randomized trials, 12 nonrandomized comparative studies, and 10 randomized and nonrandomized studies without a comparator group. Sample size ranged from 21 to 1,527 patients. PAP was associated with increased resolution of OHS and improvements in mortality, gas exchange, daytime sleepiness, sleep quality, quality of life, and emergency department visits. Nearly half of patients experienced trivial adverse effects related to PAP therapy. Certainty in the estimated effects was low or very low for most outcomes.Conclusions: The panel made a conditional (i.e., weak) recommendation that PAP therapy during sleep be offered to patients with OHS to improve outcomes. This recommendation was based on very low-quality evidence.

Survival and end-of-life aspects among subjects on long-term noninvasive ventilation

Background

The need for noninvasive ventilation (NIV) is commonly considered a predictor of poor survival, but life expectancy may vary depending on the underlying disease. We studied the factors associated with decreased survival and end-of-life characteristics in an unselected population of subjects starting NIV.

Methods

We conducted a retrospective study including 205 subjects initiating NIV from 1/1/2012-31/12/2015 who were followed up until 31/12/2017.

Results

The median survival time was shorter in subjects needing help with activities of daily living than in independent subjects (hazard ratio (HR) for death 1.7, 95% CI 1.2–2.6, P = 0.008) and was also shorter in subjects on long-term oxygen therapy (LTOT) than in those not on LTOT (HR for death 2.8, 95% CI 1.9–4.3, P < 0.001). There was marked difference in survival according to the disease necessitating NIV, and subjects with amyotrophic lateral sclerosis or interstitial lung disease seemed to have the shortest survival. The two most common diseases resulting in the need for NIV were chronic obstructive pulmonary disease (COPD) and obesity hypoventilation syndrome (OHS). The median survival time was 4.4 years in COPD subjects, but the median survival time was not reached in subjects with OHS (HR for death COPD vs. OHS: 3.2, 95% CI 1.9–5.5, P < 0.001). Most of the deceased subjects (55.6%) died in the hospital, while only 20.0% died at home. The last hospitalization admission leading to death occurred through the emergency room in 44.4% of the subjects.

Conclusions

Survival among subjects starting NIV in this real-life study varied greatly depending on the disease and degree of functional impairment. Subjects frequently died in the hospital after admission through the emergency department. A comprehensive treatment approach with timely advance care planning is therefore needed, especially for those needing help with activities of daily living and those with both NIV and LTOT.

Effectiveness of different treatments in obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS) is an undesirable consequence of obesity, defined as daytime hypoventilation, sleep disorder breathing and obesity; during the past few years the prevalence of extreme obesity has markedly increased worldwide consequently increasing the prevalence of OHS. Patients with OHS have a lower quality of life and a higher risk of unfavourable cardiometabolic consequences. Early diagnosis and effective treatment can lead to significant improvement in patient outcomes; therefore, such data has noticeably raised interest in the management and treatment of this sleep disorder. This paper will discuss the findings on the main current treatment modalities OHS will be discussed.

The effects of home noninvasive ventilation on the quality of life and physiological parameters of patients with chronic respiratory failure

INTRODUCTION

Home noninvasive mechanical ventilation (HNIV) in patients with chronic hypercapnic respiratory failure (CHRF) may improve the health-related quality of life (HRQoL) and reduce hospitalizations.

OBJECTIVE

To determine the effects of HNIV on HRQoL, sleep quality and hospitalization rates in restrictive thoracic diseases (RTD) and chronic obstructive pulmonary disease (COPD) patients with CHRF.

METHODS

In this prospective, single center study patients divided into two groups; the COPD and the RTD groups. HRQoL assessed by The Medical Outcome Study 36-Item Short-form Health Survey (SF-36) and Severe Respiratory Insufficiency (SRI); the sleep quality was assessed by Epworth and Pittsburgh Sleep Quality Index questionnaires. The patients were reevaluated first month, third months, sixth months and 1 year following HNIV establishment, during which time, hospitalization rates were recorded.

RESULTS

Ninety (COPD n = 50, RTD n = 40) out of 102 eligible patients completed the study. Significant improvements in blood gases and HRQoL were observed in the first month of HNIV establishment and remained stable. Mean ± SD SRI summary scale improved significantly from 30 ± 12 baseline to 65 ± 16 at 1 year in COPD group (P < 0.001) and from 39 ± 13 to 63 ± 18 in RTD group (P < 0.001). HNIV reduced hospitalization rates from a mean of 1.9 ± 1.1 to 0.5 ± 0.9 in COPD group (P < 0.001) and a mean of 1.9 ± 1 to 0.5 ± 0.7 in RTD group (P < 0.001).

CONCLUSION

HNIV improves HRQoL, sleep quality and gas exchange and reduces hospitalizations in patients with CHRF regardless of etiology.

Long-term outcome with focus on pulmonary hypertension in Obesity Hypoventilation Syndrome

INTRODUCTION

Pulmonary Hypertension (PH) is a frequent comorbidity in Obesity Hypoventilation Syndrome (OHS).

OBJECTIVE

We investigated long-term outcome of OHS with a particular emphasis on PH.

METHODS

In a prospective design, 64 patients with OHS and established noninvasive positive pressure ventilation (NPPV), were assessed by serum biomarkers, right heart catheterization, blood gases analysis, lung function, Epworth-Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), World Health Organization-functional class (WHO-FC) and health-related quality of life (HRQL) via the Severe Respiratory Insufficiency (SRI) questionnaire. After a planned follow-up of 5 years patients were reassessed regarding vital status, WHO-FC, ESS, SRI, PSQI, body mass index (BMI) and NPPV use. Prognostic markers were explored using univariate and multivariate Cox regression analyses.

RESULTS

At the 5-year follow-up, BMI tended to decrease (P = 0.05), while WHO-FC, ESS and PSQI remained unchanged. HRQL deteriorated in terms of SRI summary score and most subdomains (P < .05 each). NPPV adherence still was high (89%), while daily NPPV use increased from 6.7 (5.1; 8.0) h/d to 8.2 (7.4; 9.0) h/d (P < .05). After a 5-year follow-up, mortality was 25.8%. In univariate regression analyses only age > 69.5 years (HR = 4.145, 95%-CI = 1.180-14.565, P = 0.016), NT-proBNP > 1256 pg/mL (HR = 5.162, 95%-CI = 1.136-23.467, P = 0.018), diffusion capacity for carbon monoxide (DLCO, %pred) (HR = 0.341, 95%-CI = 0.114-1.019, P = 0.043) and higher oxygen use during daytime (HR = 5.236, 95%-CI = 1.489-18.406, P = 0.004) predicted mortality. No independent factor predicting mortality was detected in multivariate analysis.

CONCLUSION

Despite a high long-term NPPV use HRQL worsened. Age, oxygen use at baseline, DLCO (%pred) and NT-proBNP, as a surrogate parameter for PH, were related to long-term survival.

The Effect of Hospital Discharge with Empiric Noninvasive Ventilation on Mortality in Hospitalized Patients with Obesity Hypoventilation Syndrome. An Individual Patient Data Meta-Analysis

Rationale: Hospitalized patients with acute-on-chronic hypercapnic respiratory failure due to obesity hypoventilation syndrome (OHS) have increased short-term mortality. It is unknown whether prescribing empiric positive airway pressure (PAP) at the time of hospital discharge reduces mortality compared with waiting for an outpatient evaluation (i.e., outpatient sleep study and outpatient PAP titration).Objectives: An international, multidisciplinary panel of experts developed clinical practice guidelines on OHS for the American Thoracic Society. The guideline panel asked whether hospitalized adult patients with acute-on-chronic hypercapnic respiratory failure suspected of having OHS, in whom the diagnosis has not yet been made, should be discharged from the hospital with or without empiric PAP treatment until the diagnosis of OHS is either confirmed or ruled out.Methods: A systematic review with individual patient data meta-analyses was performed to inform the guideline panel's recommendation. Grading of Recommendations, Assessment, Development, and Evaluation was used to summarize evidence and appraise quality.Results: The literature search identified 2,994 articles. There were no randomized trials. Ten studies met a priori study selection criteria, including two nonrandomized comparative studies and eight nonrandomized noncomparative studies. Individual patient data on hospitalized patients who survived to hospital discharge were obtained from nine of the studies and included a total of 1,162 patients (1,043 discharged with PAP and 119 discharged without PAP). Empiric noninvasive ventilation was prescribed in 91.5% of patients discharged on PAP, and the remainder received empiric continuous PAP. Discharge with PAP reduced mortality at 3 months (relative risk 0.12, 95% confidence interval 0.05-0.30, risk difference -14.5%). Certainty in the estimated effects was very low.Conclusions: Hospital discharge with PAP reduces mortality following acute-on-chronic hypercapnic respiratory failure in patients with OHS or suspected of having OHS. Well-designed clinical trials are needed to confirm this finding.

Long-term Noninvasive Ventilation in Obesity Hypoventilation Syndrome Without Severe OSA: The Pickwick Randomized Controlled Trial

BACKGROUND

Noninvasive ventilation (NIV) is an effective form of treatment in obesity hypoventilation syndrome (OHS) with severe OSA. However, there is paucity of evidence in patients with OHS without severe OSA phenotype.

RESEARCH QUESTION

Is NIV effective in OHS without severe OSA phenotype?

STUDY DESIGN AND METHODS

In this multicenter, open-label parallel group clinical trial performed at 16 sites in Spain, we randomly assigned 98 stable ambulatory patients with untreated OHS and apnea-hypopnea index < 30 events/h (ie, no severe OSA) to NIV or lifestyle modification (control group) using simple randomization through an electronic database. The primary end point was hospitalization days per year. Secondary end points included other hospital resource utilization, incident cardiovascular events, mortality, respiratory functional tests, BP, quality of life, sleepiness, and other clinical symptoms. Both investigators and patients were aware of the treatment allocation; however, treating physicians from the routine care team were not aware of patients' enrollment in the clinical trial. The study was stopped early in its eighth year because of difficulty identifying patients with OHS without severe OSA. The analysis was performed according to intention-to-treat and per-protocol principles and by adherence subgroups.

RESULTS

Forty-nine patients in the NIV group and 49 in the control group were randomized, and 48 patients in each group were analyzed. During a median follow-up of 4.98 years (interquartile range, 2.98-6.62), the mean hospitalization days per year ± SD was 2.60 ± 5.31 in the control group and 2.71 ± 4.52 in the NIV group (adjusted rate ratio, 1.07; 95% CI, 0.44-2.59; P = .882). NIV therapy, in contrast with the control group, produced significant longitudinal improvement in Paco₂, pH, bicarbonate, quality of life (Medical Outcome Survey Short Form 36 physical component), and daytime sleepiness. Moreover, per-protocol analysis showed a statistically significant difference for the time until the first ED visit favoring NIV. In the subgroup with high NIV adherence, the time until the first event of hospital admission, ED visit, and mortality was longer than in the low adherence subgroup. Adverse events were similar between arms.

INTERPRETATION

In stable ambulatory patients with OHS without severe OSA, NIV and lifestyle modification had similar long-term hospitalization days per year. A more intensive program aimed at improving NIV adherence may lead to better outcomes. Larger studies are necessary to better determine the long-term benefit of NIV in this subgroup of OHS.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01405976; URL: www.clinicaltrials.gov.

Cost-effectiveness of positive airway pressure modalities in obesity hypoventilation syndrome with severe obstructive sleep apnoea

BACKGROUND

Obesity hypoventilation syndrome (OHS) is treated with either non-invasive ventilation (NIV) or CPAP, but there are no long-term cost-effectiveness studies comparing the two treatment modalities.

OBJECTIVES

We performed a large, multicentre, randomised, open-label controlled study to determine the comparative long-term cost and effectiveness of NIV versus CPAP in patients with OHS with severe obstructive sleep apnoea (OSA) using hospitalisation days as the primary outcome measure.

METHODS

Hospital resource utilisation and within trial costs were evaluated against the difference in effectiveness based on the primary outcome (hospitalisation days/year, transformed and non-transformed in monetary term). Costs and effectiveness were estimated from a log-normal distribution using a Bayesian approach. A secondary analysis by adherence subgroups was performed.

RESULTS

In total, 363 patients were selected, 215 were randomised and 202 were available for the analysis. The median (IQR) follow-up was 3.01 (2.91-3.14) years for NIV group and 3.00 (2.92-3.17) years for CPAP. The mean (SD) Bayesian estimated hospital days was 2.13 (0.73) for CPAP and 1.89 (0.78) for NIV. The mean (SD) Bayesian estimated cost per patient/year in the NIV arm, excluding hospitalisation costs, was €2075.98 (91.6), which was higher than the cost in the CPAP arm of €1219.06 (52.3); mean difference €857.6 (105.5). CPAP was more cost-effective than NIV (99.5% probability) because longer hospital stay in the CPAP arm was compensated for by its lower costs. Similar findings were observed in the high and low adherence subgroups.

CONCLUSION

CPAP is more cost-effective than NIV; therefore, CPAP should be the preferred treatment for patients with OHS with severe OSA.

TRIAL REGISTRATION NUMBER

NCT01405976.

Is Obesity Hypoventilation Syndrome A Postmenopausal Disorder?

Previous studies have assessed the role of gender and menopause in Obstructive Sleep Apnea (OSA). It is well known that menopause is a major risk factor for OSA. However, analogous studies on obesity Hypoventilation Syndrome (OHS) are limited. Recent studies have suggested that OHS is more prevalent in postmenopausal women. Moreover, women with OHS seem to have excess comorbidities, including hypothyroidism, hypertension, pulmonary hypertension, and diabetes mellitus, compared to men. In the present perspective, we discuss recent data on the prevalence and comorbidities associated with OHS in women, as well as the use of noninvasive ventilation in women with OHS, and try to answer the question, “Is OHS a disorder of postmenopausal women?”

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

Background: The purpose of this guideline is to optimize evaluation and management of patients with obesity hypoventilation syndrome (OHS).Methods: A multidisciplinary panel identified and prioritized five clinical questions. The panel performed systematic reviews of available studies (up to July 2018) and followed the Grading of Recommendations, Assessment, Development, and Evaluation evidence-to-decision framework to develop recommendations. All panel members discussed and approved the recommendations.Recommendations: After considering the overall very low quality of the evidence, the panel made five conditional recommendations. We suggest that: 1) clinicians use a serum bicarbonate level <27 mmol/L to exclude the diagnosis of OHS in obese patients with sleep-disordered breathing when suspicion for OHS is not very high (<20%) but to measure arterial blood gases in patients strongly suspected of having OHS, 2) stable ambulatory patients with OHS receive positive airway pressure (PAP), 3) continuous positive airway pressure (CPAP) rather than noninvasive ventilation be offered as the first-line treatment to stable ambulatory patients with OHS and coexistent severe obstructive sleep apnea, 4) patients hospitalized with respiratory failure and suspected of having OHS be discharged with noninvasive ventilation until they undergo outpatient diagnostic procedures and PAP titration in the sleep laboratory (ideally within 2-3 mo), and 5) patients with OHS use weight-loss interventions that produce sustained weight loss of 25% to 30% of body weight to achieve resolution of OHS (which is more likely to be obtained with bariatric surgery).Conclusions: Clinicians may use these recommendations, on the basis of the best available evidence, to guide management and improve outcomes among patients with OHS.

Long-term clinical effectiveness of continuous positive airway pressure therapy versus non-invasive ventilation therapy in patients with obesity hypoventilation syndrome: a multicentre, open-label, randomised controlled trial

BACKGROUND

Obesity hypoventilation syndrome is commonly treated with continuous positive airway pressure or non-invasive ventilation during sleep. Non-invasive ventilation is more complex and costly than continuous positive airway pressure but might be advantageous because it provides ventilatory support. To date there have been no long-term trials comparing these treatment modalities. We therefore aimed to determine the long-term comparative effectiveness of both treatment modalities.

METHODS

We did a multicentre, open-label, randomised controlled trial at 16 clinical sites in Spain. We included patients aged 15-80 years with untreated obesity hypoventilation syndrome and an apnoea-hypopnoea index of 30 or more events per h. We randomly assigned patients, using simple randomisation through an electronic database, to receive treatment with either non-invasive ventilation or continuous positive airway pressure. Both investigators and patients were aware of the treatment allocation. The research team was not involved in deciding hospital treatment, duration of treatment in the hospital, and adjustment of medications, as well as adjudicating cardiovascular events or cause of mortality. Treating clinicians from the routine care team were not aware of the treatment allocation. The primary outcome was the number of hospitalisation days per year. The analysis was done according to the intention-to-treat principle. This study is registered with ClinicalTrials.gov, number NCT01405976.

FINDINGS

From May 4, 2009, to March 25, 2013, 100 patients were randomly assigned to the non-invasive ventilation group and 115 to the continuous positive airway pressure group, of which 97 patients in the non-invasive ventilation group and 107 in the continuous positive airway pressure group were included in the analysis. The median follow-up was 5·44 years (IQR 4·45-6·37) for all patients, 5·37 years (4·36-6·32) in the continuous positive airway pressure group, and 5·55 years (4·53-6·50) in the non-invasive ventilation group. The mean hospitalisation days per patient-year were 1·63 (SD 3·74) in the continuous positive airway pressure group and 1·44 (3·07) in the non-invasive ventilation group (adjusted rate ratio 0·78, 95% CI 0·34-1·77; p=0·561). Adverse events were similar between both groups.

INTERPRETATION

In stable patients with obesity hypoventilation syndrome and severe obstructive sleep apnoea, non-invasive ventilation and continuous positive airway pressure have similar long-term effectiveness. Given that continuous positive airway pressure has lower complexity and cost, continuous positive airway pressure might be the preferred first-line positive airway pressure treatment modality until more studies become available.

FUNDING

Instituto de Salud Carlos III, Spanish Respiratory Foundation, and Air Liquide Spain.

Obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS) is defined as a combination of obesity (body mass index ≥30 kg·m-2), daytime hypercapnia (arterial carbon dioxide tension ≥45 mmHg) and sleep disordered breathing, after ruling out other disorders that may cause alveolar hypoventilation. OHS prevalence has been estimated to be ∼0.4% of the adult population. OHS is typically diagnosed during an episode of acute-on-chronic hypercapnic respiratory failure or when symptoms lead to pulmonary or sleep consultation in stable conditions. The diagnosis is firmly established after arterial blood gases and a sleep study. The presence of daytime hypercapnia is explained by several co-existing mechanisms such as obesity-related changes in the respiratory system, alterations in respiratory drive and breathing abnormalities during sleep. The most frequent comorbidities are metabolic and cardiovascular, mainly heart failure, coronary disease and pulmonary hypertension. Both continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) improve clinical symptoms, quality of life, gas exchange, and sleep disordered breathing. CPAP is considered the first-line treatment modality for OHS phenotype with concomitant severe obstructive sleep apnoea, whereas NIV is preferred in the minority of OHS patients with hypoventilation during sleep with no or milder forms of obstructive sleep apnoea (approximately <30% of OHS patients). Acute-on-chronic hypercapnic respiratory failure is habitually treated with NIV. Appropriate management of comorbidities including medications and rehabilitation programmes are key issues for improving prognosis.

Health-related quality of life as predictor for mortality in patients treated with long-term mechanical ventilation

Background

The Severe Respiratory Insufficiency (SRI) questionnaire is a specific measure of health-related quality of life (HRQoL) in patients treated with long-term mechanical ventilation (LTMV). The aim of the present study was to examine whether SRI sum scores and related subscales are associated with mortality in LTMV patients.

Methods

The study included 112 LTMV patients (non-invasive and invasive) from the Norwegian LTMV registry in Western Norway from 2008 with follow-up in August 2014. SRI data were obtained through a postal questionnaire, whereas mortality data were obtained from the Norwegian Cause of Death Registry. The SRI questionnaire contains 49 items and seven subscales added into a summary score (range 0–100) with higher scores indicating a better HRQoL. The association between the SRI score and mortality was estimated as hazard ratios (HRs) with 95% confidence intervals (95% CI) using Cox regression models and HRs were estimated per one unit change in the SRI score.

Results

Of the 112 participating patients in 2008, 52 (46%) had died by August 2014. The mortality rate was the highest in patients with chronic obstructive pulmonary disease (75%), followed by patients with neuromuscular disease (46%), obesity hypoventilation syndrome (31%) and chest wall disease (25%) (p < 0.001). Higher SRI sum scores in 2008 were associated with a lower mortality risk after adjustment for age, education, hours a day on LTMV, time since initiation of LTMV, disease category and comorbidity (HR 0.98, 95% CI: 0.96–0.99). In addition, SRI-Physical Functioning (HR 0.98, 95% CI: 0.96–0.99), SRI-Psychological Well-Being (HR 0.98, 95% CI: 0.97–0.99), and SRI-Social Functioning (HR 0.98, 95% CI: 0.97–0.99) remained significant risk factors for mortality after covariate adjustment. In the subgroup analyses of patient with neuromuscular diseases we found significant inverse associations between some of the SRI subscales and mortality.

Conclusions

SRI score is associated with mortality in LTMV-treated patients. We propose the use of SRI in the daily clinic with repeated measurements as part of individual follow-up. Randomized clinical trials with interventions aimed to improve HRQoL in LTMV patients should consider the SRI questionnaire as the standard HRQoL measurement.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0768-4) contains supplementary material, which is available to authorized users.

Efficacy of bilevel positive airway pressure and continuous positive airway pressure therapy in patients with obesity hypoventilation syndrome: protocol for systematic review and meta-analysis

INTRODUCTION

Obesity hypoventilation syndrome (OHS) is a major respiratory complication caused by severe obesity, being associated with significant morbidity, negative impacts on quality of life and reduced survival if not treated appropriately. Positive airway pressure therapy is the first-line treatment for OHS although the optimal modality remains unclear. The goal of this study is to identify the efficacy of home bilevel positive airway pressure therapy by comparison to continuous positive airway pressure therapy and determine the best strategy for patients with OHS.

METHODS AND ANALYSIS

This study will be conducted following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols 2015 statement. We will search the following databases: PubMed, Web of Science, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL. Ongoing studies will be identified through the ClinicalTrials.gov and WHO International Clinical Trials Registry Platform Search Portal. Grey literature will be recognised through Google Scholar and other search engines. Only randomised controlled trials meeting the eligibility criteria will be included. The risk of bias of the included studies will be evaluated through the Cochrane Collaboration's tool. RevMan V.5.3.5 software will be used for data analysis. The Q statistic and I² index will be used for investigating heterogeneity, and subgroup analysis or sensitivity analysis will be used to explore the source of heterogeneity. In addition, the Grading of Recommendations Assessment, Development and Evaluation system will be used to inspect the quality of evidence.

ETHICS AND DISSEMINATION

Ethics approval is not required because this study contains no primary data collected from humans. This systematic review and meta-analysis will be submitted to a peer-reviewed journal for publication.

PROSPERO REGISTRATION NUMBER

CRD42017078369.

Patterns of use, survival and prognostic factors in patients receiving home mechanical ventilation in Western Australia: A single centre historical cohort study

Home mechanical ventilation (HMV) is used in a wide range of disorders associated with chronic hypoventilation. We describe the patterns of use, survival and predictors of death in Western Australia. We identified 240 consecutive patients (60% male; mean age 58 years and body mass index 31 kg m^-2) referred for HMV between 2005 and 2010. The patients were grouped into four categories: motor neurone disorders (MND; 39%), pulmonary disease (PULM; 25%, mainly chronic obstructive pulmonary disease), non-MND neuromuscular and chest wall disorders (NMCW; 21%) and the obesity hypoventilation syndrome (OHS; 15%). On average, the patients had moderate ventilatory impairment (forced vital capacity: 51%predicted), sleep apnoea (apnoea-hypopnea index: 25 events h^-1), sleep-related hypoventilation (transcutaneous carbon dioxide rise of 20 mmHg) and daytime hypercarbia (PCO₂: 54 mmHg). Median durations of survival from HMV initiation were 1.0, 4.2, 9.9 and >11.5 years for MND, PULM, NMCW and OHS, respectively. Independent predictors of death varied between primary indications for HMV; the predictors included (a) age in all groups except for MND (hazard ratios (HRs) 1.03-1.10); (b) cardiovascular disease (HR: 2.35, 95% confidence interval (CI): 1.08-5.10) in MND; (c) obesity (HR: 0.28, 95% CI: 0.13-0.62) and oxygen therapy (HR: 0.33, 95% CI: 0.14-0.79) in PULM; and (d) forced expiratory volume in 1 s (%predicted; HR: 0.93, 95% CI: 0.88-1.00) in OHS.

Home Mechanical Ventilation: An Overview

Prevalence studies have shown heterogeneous use of home mechanical ventilation in different conditions, with a marked increase in uptake especially in users of noninvasive ventilation. Although randomized controlled trials have examined noninvasive ventilation in acute exacerbations of chronic obstructive pulmonary disease, for weaning from invasive ventilation and for postextubation respiratory failure, the evidence base for long-term noninvasive ventilation and comparisons with invasive ventilation are less well developed. The combination of noninvasive ventilation and cough-assist devices has reduced the indications for tracheotomy ventilation in some situations (e.g., Duchenne muscular dystrophy, spinal muscular atrophy, myopathies, and amyotrophic lateral sclerosis) and has also prolonged survival. Several excellent overviews have been written on the history of home mechanical ventilation and its evolution from negative pressure to positive pressure techniques, including a systematic review of outcomes. This review, instead, will cover recent trials, trends in the field, outcomes, and safety. Because the greatest growth has been in home noninvasive ventilation, this will be the main focus of this article.

Prevention and care of respiratory failure in obese patients

With the increase in the global prevalence of obesity, there is a parallel rise in the proportion of obese patients admitted to intensive care units, referred for major surgery or requiring long-term non-invasive ventilation (NIV) at home for chronic respiratory failure. We describe the physiological effect of obesity on the respiratory system mainly in terms of respiratory mechanics, respiratory drive, and patency of the upper airways. Particular attention is given to the prevention and the clinical management of respiratory failure in obese patients with a main focus on invasive and NIV in intensive care during the perioperative period and long-term use of NIV on return home. We also address other aspects of care of obese patients, including antibiotic dosing and catheter-related infections.

Nutrition and Exercise Rehabilitation in Obesity hypoventilation syndrome (NERO): a pilot randomised controlled trial

Background

Respiratory management of obesity hypoventilation syndrome (OHS) focusses on the control of sleep-disordered breathing rather than the treatment of obesity. Currently, there are no data from randomised trials of weight loss targeted rehabilitation programmes for patients with OHS.

Intervention

A 3-month multimodal hybrid inpatient–outpatient motivation, exercise and nutrition rehabilitation programme, in addition to non invasive ventilation (NIV), would result in greater per cent weight loss compared with standard care.

Methods

A single-centre pilot randomised controlled trial allocated patients to either standard care or standard care plus rehabilitation. Primary outcome was per cent weight loss at 12 months with secondary exploratory outcomes of weight loss, exercise capacity and health-related quality of life (HRQOL) at the end of the rehabilitation programme to assess the intervention effect.

Results

Thirty-seven patients (11 male, 59.8±12.7 years) with a body mass index of 51.1±7.7 kg/m2 were randomised. At 12 months, there was no between-group difference in per cent weight loss (mean difference −5.9% (95% CI −14.4% to 2.7%; p=0.17)). At 3 months, there was a greater per cent weight loss (mean difference −5% (95% CI −8.3% to −1.4%; p=0.007)), increased exercise capacity (6 min walk test 60 m (95% CI 29.5 to 214.5) vs 20 m (95% CI 11.5 to 81.3); p=0.036) and HRQL (mean difference SF-36 general health score (10 (95% CI 5 to 21.3) vs 0 (95% CI −5 to 10); p=0.02)) in the rehabilitation group.

Conclusion

In patients with OHS, a 3-month comprehensive rehabilitation programme, in addition to NIV, resulted in improved weight loss, exercise capacity and QOL at the end of the rehabilitation period, but these effects were not demonstrated at 12 months, in part, due to the limited retention of patients at 12 months.

Trial registration number

Pre-results; NCT01483716.

Obesity Hypoventilation Syndrome: Choosing the Appropriate Treatment of a Heterogeneous Disorder

The obesity hypoventilation syndrome (OHS) is associated with significant morbidity and increased mortality compared with simple obesity and eucapnic obstructive sleep apnea. Accurate diagnosis and commencement of early and appropriate management is fundamental in reducing the significant personal and societal burdens this disorder poses. Sleep disordered breathing is a major contributor to the developmental of sleep and awake hypercapnia, which characterizes OHS, and is effectively addressed through the use of positive airway pressure (PAP) therapy. This article reviews the current evidence supporting different modes of PAP currently used in managing these individuals.

Comorbidities and Subgroups of Patients Surviving Severe Acute Hypercapnic Respiratory Failure in the Intensive Care Unit

RATIONALE

No methodical assessment of the lung, cardiac, and sleep function of patients surviving an acute hypercapnic respiratory failure episode requiring admission to the intensive care unit (ICU) has been reported in the literature.

OBJECTIVES

To prospectively investigate the prevalence and impact of comorbidities in patients treated by mechanical ventilator support (invasive or noninvasive) for acute hypercapnic respiratory failure in the ICU.

METHODS

Seventy-eight consecutive patients admitted for an episode of acute hypercapnic respiratory failure underwent an assessment of lung, cardiac, and sleep function by pulmonary function tests, transthoracic echocardiography, and polysomnography 3 months after ICU discharge.

MEASUREMENTS AND MAIN RESULTS

Sixty-seven percent (52 of 78) of patients exhibited chronic obstructive pulmonary disease (COPD), although only 19 had been previously diagnosed. Patients without COPD were primarily obese. Prevalence of severe obstructive sleep apnea was 51% (95% confidence interval, 34-69) in patients with COPD and 81% (95% confidence interval, 54-96) in patients without COPD. Previously undiagnosed cardiac dysfunction with preserved ejection fraction was highly prevalent (44%), as was hypertension (67%). More than half of the population demonstrated at least three major comorbidities known to precipitate acute hypercapnic respiratory failure. Multimorbidity was associated with longer time to hospital discharge. Hospital readmission or death occurred in 46% of patients over an average of 3.5 months after discharge.

CONCLUSIONS

Severe hypercapnic respiratory failure requiring ICU admission resulted primarily from COPD or obesity. Major comorbidities are highly prevalent in both cases and most often ignored. Surviving acute hypercapnic respiratory failure should be an opportunity to systematically evaluate lung, heart, and sleep functions to improve poor outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT 02111876).

[Obstructive sleep apnea syndrome. Diagnostic strategies in various clinical settings]

Obstructive Sleep Apnea Syndrome (OSAS) is a common disease, whose prevalence and expression may vary depending on the associated pathology, age or gender. Thus, the prevalence of OSAS is up to 80% in case of refractory hypertension. This led up to individualize clinical presentation of clusters, although currently, the individualization of these different phenotypes did not conduct to a specific care or predict different evolution. Offering the best strategy for the right patient remains an important objective. However, the frequent association of OSAS and various metabolic diseases, and thus induced cardiovascular risk factors, is to be considered in the therapeutic care and judgment of the response to established treatments. By acting on all components in pathological cause in these patients with OSAS, a combined support will thus permit optimal beneficial effect.

The Effect of Supplemental Oxygen in Obesity Hypoventilation Syndrome

STUDY OBJECTIVES

Low flow supplemental oxygen is commonly prescribed to patients with obesity hypoventilation syndrome (OHS). However, there is a paucity of data regarding its efficacy and safety. The objective of this study was to assess the medium-term treatment efficacy of adding supplemental oxygen therapy to commonly prescribed treatment modalities in OHS.

METHODS

In this post hoc analysis of a previous randomized controlled trial, we studied 302 sequentially screened OHS patients who were randomly assigned to noninvasive ventilation, continuous positive airway pressure, or lifestyle modification. Outcomes at 2 mo included arterial blood gases, symptoms, quality of life, blood pressure, polysomnography, spirometry, 6-min walk distance, and hospital resource utilization. Statistical analysis comparing patients with and without oxygen therapy in the three treatment groups was performed using an intention-to-treat analysis.

RESULTS

In the noninvasive ventilation group, supplemental oxygen reduced systolic blood pressure although this could be also explained by a reduction in body weight experienced in this group. In the continuous positive airway pressure group, supplemental oxygen increased the frequency of morning confusion. In the lifestyle modification group, supplemental oxygen increased compensatory metabolic alkalosis and decreased the apnea-hypopnea index during sleep. Oxygen therapy was not associated with an increase in hospital resource utilization in any of the groups.

CONCLUSIONS

After 2 mo of follow-up, chronic oxygen therapy produced marginal changes that were insufficient to consider it, globally, as beneficial or deleterious. Because supplemental oxygen therapy did not increase hospital resource utilization, we recommend prescribing oxygen therapy to patients with OHS who meet criteria with close monitoring. Long-term studies examining outcomes such as incident cardiovascular morbidity and mortality are necessary.

CLINICAL TRIALS REGISTRATION

Clinicaltrial.gov, ID: NCT01405976.

Obesity might be a good prognosis factor for COPD patients using domiciliary noninvasive mechanical ventilation

Cachexia is known to be a deteriorating factor for survival of patients with chronic obstructive pulmonary disease (COPD), but data related to obesity are limited. We observed that obese patients with COPD prescribed long-term noninvasive mechanical ventilation (NIMV) had better survival rate compared to nonobese patients. Therefore, we conducted a retrospective observational cohort study. Archives of Thoracic Diseases Training Hospital were sought between 2008 and 2013. All the subjects were prescribed domiciliary NIMV for chronic respiratory failure secondary to COPD. Subjects were grouped according to their body mass index (BMI). The first group consisted of subjects with BMI between 20 and 30 kg/m², and the second group consisted of subjects with BMI >30 kg/m². Data obtained at the first month’s visit for the following parameters were recorded: age, sex, comorbid diseases, smoking history, pulmonary function test, 6-minute walk test (6-MWT), and arterial blood gas analysis. Hospital admissions were recorded before and after the domiciliary NIMV usage. Mortality rate was searched from the electronic database. Overall, 118 subjects were enrolled. Thirty-eight subjects had BMI between 20 and 30 kg/m², while 80 subjects had BMI >30 kg/m². The mean age was 65.8±9.4 years, and 81% were male. The median follow-up time was 26 months and mortality rates were 32% and 34% for obese and nonobese subjects (P=0.67). Improvement in 6-MWT was protective against mortality. In conclusion, survival of obese patients with COPD using domiciliary NIMV was found to be better than those of nonobese patients, and the improvement in 6-MWT in such patients was found to be related to a better survival.

Non-invasive ventilation in obesity hypoventilation syndrome without severe obstructive sleep apnoea

Background

Non-invasive ventilation (NIV) is an effective form of treatment in patients with obesity hypoventilation syndrome (OHS) who have concomitant severe obstructive sleep apnoea (OSA). However, there is a paucity of evidence on the efficacy of NIV in patients with OHS without severe OSA. We performed a multicentre randomised clinical trial to determine the comparative efficacy of NIV versus lifestyle modification (control group) using daytime arterial carbon dioxide tension (PaCO₂) as the main outcome measure.

Methods

Between May 2009 and December 2014 we sequentially screened patients with OHS without severe OSA. Participants were randomised to NIV versus lifestyle modification and were followed for 2 months. Arterial blood gas parameters, clinical symptoms, health-related quality of life assessments, polysomnography, spirometry, 6-min walk distance test, blood pressure measurements and healthcare resource utilisation were evaluated. Statistical analysis was performed using intention-to-treat analysis.

Results

A total of 365 patients were screened of whom 58 were excluded. Severe OSA was present in 221 and the remaining 86 patients without severe OSA were randomised. NIV led to a significantly larger improvement in PaCO₂ of −6 (95% CI −7.7 to −4.2) mm Hg versus −2.8 (95% CI −4.3 to −1.3) mm Hg, (p<0.001) and serum bicarbonate of −3.4 (95% CI −4.5 to −2.3) versus −1 (95% CI −1.7 to −0.2 95% CI)  mmol/L (p<0.001). PaCO₂ change adjusted for NIV compliance did not further improve the inter-group statistical significance. Sleepiness, some health-related quality of life assessments and polysomnographic parameters improved significantly more with NIV than with lifestyle modification. Additionally, there was a tendency towards lower healthcare resource utilisation in the NIV group.

Conclusions

NIV is more effective than lifestyle modification in improving daytime PaCO₂, sleepiness and polysomnographic parameters. Long-term prospective studies are necessary to determine whether NIV reduces healthcare resource utilisation, cardiovascular events and mortality.

Trial registration number

NCT01405976; results.

Drugs influencing acid base balance and bicarbonate concentration readings

Serum bicarbonate dosage is sensitive to pharmacological interferences. However, elevated bicarbonate concentration reflects chronic hypoventilation and has been proposed as a simple marker for screening patients with Obesity Hypoventilation Syndrome (OHS), a currently underdiagnosed multimorbid and high mortality disease. We provide a practical overview of the different drugs acting on the acid-base equilibrium to aid clinicians to interpret bicarbonate concentration readings. Little is known about the chronic impact of the usual doses of these drugs on serum bicarbonate concentration and further studies are needed. It is essential to take into account drugs that could interfere with this parameter to avoid misinterpretation of serum bicarbonate levels.

Obesity Hypoventilation Syndrome: Weighing in on Therapy Options

Obesity hypoventilation syndrome is becoming an increasingly encountered condition both in respiratory outpatient clinics and in hospitalized patients. The health consequences and social disadvantages of obesity hypoventilation syndrome are significant. Unfortunately, the diagnosis and institution of appropriate therapy is commonly delayed when the syndrome is not recognized or misdiagnosed. Positive airway pressure therapy remains the mainstay of treatment and is effective in controlling sleep-disordered breathing and improving awake blood gases in the majority of individuals. Evidence supporting one mode of therapy over another is limited. Both continuous and bilevel therapy modes can successfully improve daytime gas exchange, with adherence to therapy an important modifiable factor in the response to treatment. Despite adherence to therapy, these individuals continue to experience excess mortality primarily due to cardiovascular events compared with those with eucapnic sleep apnea using CPAP. This difference likely arises from ongoing systemic inflammation secondary to the morbidly obese state. The need for a comprehensive approach to managing nutrition, weight, and physical activity in addition to reversal of sleep-disordered breathing is now widely recognized. Future studies need to evaluate the impact of a more aggressive and comprehensive treatment plan beyond managing sleep-disordered breathing. The impact of early identification and treatment of sleep-disordered breathing on the development and reversal of cardiometabolic dysfunction also requires further attention.