Randomized Trial of Nocturnal Oxygen in Chronic Obstructive Pulmonary Disease

The benefits and drawbacks of home oxygen therapy for COPD: what's next?

INTRODUCTION

Home oxygen therapy is one of the few interventions that can improve survival in patients with chronic obstructive pulmonary disease (COPD) when administered appropriately, although it may cause side effects and be an unnecessary burden for some patients.

AREAS COVERED

This narrative review summarizes the current literature on the assessment of hypoxemia, different types of home oxygen therapy, potential beneficial and adverse effects, and emerging research on home oxygen therapy in COPD. A literature search was performed using MEDLINE and EMBASE up to January 2024, with additional articles being identified through clinical guidelines.

EXPERT OPINION

Hypoxemia is common in patients with more severe COPD. Long-term oxygen therapy is established to prolong survival in patients with chronic severe resting hypoxemia. Conversely, in the absence of chronic severe resting hypoxemia, home oxygen therapy has an unclear or conflicting evidence base, including for palliation of breathlessness, and is generally not recommended. However, beneficial effects in some patients cannot be precluded. Evidence is emerging on the optimal daily duration of oxygen use, the role of high-flow and auto-titrated oxygen therapy, improved informed decision-making, and telemonitoring. Further research is needed to validate novel oxygen delivery systems and monitoring tools and establish long-term effects of ambulatory oxygen therapy in COPD.

Sleep disordered breathing: OSA-COPD overlap

INTRODUCTION

Sleep has important effects on breathing and gas exchange that may have negative consequences in patients with chronic obstructive pulmonary disease (COPD). COPD and obstructive sleep apnea (OSA) are highly prevalent and may coexist, which is referred to as the overlap syndrome.

AREAS COVERED

The probability of OSA-COPD overlap represents the balance of protective and promoting factors such as hyperinflation and fluid retention; thus, different clinical COPD phenotypes influence the likelihood of comorbid OSA. The clinical presentation of OSA-COPD overlap is nonspecific, and the diagnosis requires clinical awareness to identify patients needing overnight studies. Both COPD and OSA are associated with a range of overlapping physiological and biological disturbances including hypoxia and inflammation that contribute to cardiovascular comorbidities. The management of OSA-COPD overlap patients differs from those with COPD alone and the survival of overlap patients treated with positive airway pressure (PAP) is superior to those untreated.

EXPERT OPINION

The recognition of OSA-COPD overlap has important clinical relevance because of its impact on outcomes and management. Management of the overlap should address both sleep quality and disordered gas exchange. PAP therapy has demonstrated reductions in COPD exacerbations, hospitalizations, healthcare costs and mortality in overlap patients.

European Respiratory Society clinical practice guideline on symptom management for adults with serious respiratory illness

Respiratory symptoms are ubiquitous and impair health-related quality of life in people with respiratory disease. This European Respiratory Society (ERS) task force aimed to provide recommendations for symptomatic treatment in people with serious respiratory illness. The ERS task force comprised 16 members, including representatives of people with serious respiratory illness and informal caregivers. Seven questions were formulated, six in the PICO (Population, Intervention, Comparison, Outcome) format, which were addressed with full systematic reviews and evidence assessed using GRADE (Grading of Recommendations Assessment, Development and Evaluation). One question was addressed narratively. An "evidence-to-decision" framework was used to formulate recommendations. To treat symptoms in people with serious respiratory illness, the task force suggests the use of graded exercise therapy (conditional recommendation, low certainty of evidence); and suggests the use of a multicomponent services, handheld fan and breathing techniques (conditional recommendations, very low certainty of evidence). The task force suggests not to use opioids (conditional recommendation, very low certainty of evidence); and suggests either administering or not administering supplemental oxygen therapy (conditional recommendation, low certainty of evidence). The task force suggests that needs assessment tools may be used as part of a comprehensive needs assessment, but do not replace patient-centred care and shared decision making (conditional recommendation, low certainty of evidence). The low certainty of evidence, modest impact of interventions on patient-centred outcomes, and absence of effective strategies to ameliorate cough highlight the need for new approaches to reduce symptoms and enhance wellbeing for individuals who live with serious respiratory illness.

Factors Associated With Change in S3-NIV Score Over Time in People With Chronic Respiratory Failure Treated With Long-Term Home Noninvasive Ventilation

INTRODUCTION

Monitoring changes in symptoms over time during long-term nocturnal home non-invasive ventilation (NIV) using patient-reported outcome measures is crucial. This study aimed to identify factors associated with changes in the S3-NIV total score, its two domains ("respiratory symptoms" and "sleep and NIV-related side effects") and individual item responses.

METHODS

We conducted a retrospective, longitudinal data analysis of a cohort of adults with chronic respiratory failure treated with NIV. Data were obtained from a French homecare provider. Multivariate linear and multinomial ordinal mixed effect models were used to identify factors associated with changes in S3-NIV scores over time.

RESULTS

Median follow-up was 2 years for 2135 participants. Each participant completed a median of five S3-NIV questionnaires; totaling 11,359 analyzed questionnaires. Type of respiratory condition, sex, age and time since NIV initiation were associated with change in S3-NIV score over time. NIV adherence was not associated with total S3-NIV score but high adherence was associated with more severe respiratory symptoms and an improvement in sleep and NIV-related side effects during the follow-up. Intensity of pressure support was associated with a lower total S3-NIV score and more side effects. Face masks and supplemental oxygen were associated with a lower S3-NIV total score.

CONCLUSION

Changes in S3-NIV scores over time are associated with the individual's characteristics and NIV settings. Analysis of the two domains and individual items of the S3-NIV could increase understanding of the difficulties experienced by people on NIV.

Management of Refractory Chronic Obstructive Pulmonary Disease: A Review

Chronic obstructive pulmonary disease (COPD) is a common condition with an estimated prevalence of 12% in adults over the age of 30 years worldwide. COPD is a leading cause of morbidity and mortality globally, with a substantial economic and social burden. There are an estimated 3 million deaths annually due to COPD. However, most of the patients with COPD respond to routine interventions like bronchodilator therapy, assessing supplemental oxygen needs, smoking cessation, vaccinations, and pulmonary rehabilitation. There is a significant number of patients who unfortunately progress to have persistent symptoms despite these interventions. Refractory COPD is not yet formally defined. Patients with severe persistent symptoms or exacerbations despite appropriate care can be considered to have refractory COPD. Managing refractory COPD needs a multidimensional approach. In this review article, we will discuss essential interventions like ensuring adequate inhaler techniques, exploring the need for non-invasive ventilatory support, use of chronic antibiotics and phosphodiesterase inhibitors to advanced therapies like bronchoscopic lung volume reduction surgery, and the upcoming role of anti-IL5 agents in managing patients with refractory COPD. We will also discuss non-pharmacologic interventions like psycho-social support and nutritional support. We will conclude by discussing the palliative care aspect of managing patients with refractory COPD. Through this review article, we aim to better the approach to managing patients with refractory COPD and discuss new upcoming therapies.

Chronic obstructive pulmonary disease (COPD) and COPD-like phenotypes

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. Historically, two COPD phenotypes have been described: chronic bronchitis and emphysema. Although these phenotypes may provide additional characterization of the pathophysiology of the disease, they are not extensive enough to reflect the heterogeneity of COPD and do not provide granular categorization that indicates specific treatment, perhaps with the exception of adding inhaled glucocorticoids (ICS) in patients with chronic bronchitis. In this review, we describe COPD phenotypes that provide prognostication and/or indicate specific treatment. We also describe COPD-like phenotypes that do not necessarily meet the current diagnostic criteria for COPD but provide additional prognostication and may be the targets for future clinical trials.

Supplemental oxygen therapy in chronic obstructive pulmonary disease: is less is more? How much is too much?

PURPOSE OF REVIEW

Currently available evidence supporting the use of supplemental oxygen therapy (SOT) in chronic obstructive pulmonary disease (COPD) is complex, and data on the mortality reduction associated with SOT usage in patients with severe daytime resting hypoxemia have not been updated since the development of other treatments.

RECENT FINDINGS

No reduction in mortality was found when SOT was used in patients with moderate resting daytime, isolated nocturnal, or exercise-induced hypoxemia. However, some of these patients obtain other significant benefits during SOT, including increased exercise endurance, and a mortality reduction is possible in these 'responders'. The adverse effects of long-term oxygen therapy also need to be considered, such as reduced mobility and social stigma. Furthermore, conservative SOT could improve outcomes in the setting of COPD exacerbations compared with higher concentration oxygen regimens. Compared with usual fixed-dose SOT, automated oxygen administration devices might reduce dyspnea during exercise and COPD exacerbations.

SUMMARY

Current recommendations for SOT need to be revised to focus on patients who respond best and benefit most from this therapy. A conservative approach to SOT can reduce side effects compared with higher concentration oxygen regimens, and automated oxygen administration devices may help to optimize SOT.

Smoking and home oxygen therapy: a review and consensus statement from a multidisciplinary Swedish taskforce

BACKGROUND

Home oxygen therapy (HOT) improves survival in patients with hypoxaemic chronic respiratory disease. Most patients evaluated for HOT are former or active smokers. Oxygen accelerates combustion and smoking may increase the risk of burn injuries and fire hazards; therefore, it is considered a contraindication for HOT in many countries. However, there is variability in the practices and policies regarding this matter. This multidisciplinary Swedish taskforce aimed to review the potential benefits and risks of smoking in relation to HOT, including medical, practical, legal and ethical considerations.

METHODS

The taskforce of the Swedish Respiratory Society comprises 15 members across respiratory medicine, nursing, medical law and ethics. HOT effectiveness and adverse risks related to smoking, as well as practical, legal and ethical considerations, were reviewed, resulting in five general questions and four PICO (population-intervention-comparator-outcome) questions. The strength of each recommendation was rated according to the GRADE (grading of recommendation assessment, development and evaluation) methodology.

RESULTS

General questions about the practical, legal and ethical aspects of HOT were discussed and summarised in the document. The PICO questions resulted in recommendations about assessment, management and follow-up of smoking when considering HOT, if HOT should be offered to people that meet the eligibility criteria but who continue to smoke, if a specific length of time of smoking cessation should be considered before assessing eligibility for HOT, and identification of areas for further research.

CONCLUSIONS

Multiple factors need to be considered in the benefit/risk evaluation of HOT in active smokers. A systematic approach is suggested to guide healthcare professionals in evaluating HOT in relation to smoking.

The Overlap Syndrome: A Combination of Chronic Obstructive Pulmonary Disease and Obstructive Sleep Apnea

Chronic obstructive pulmonary disease (COPD) is a severe lung disease that results in persistent and progressively worsening airflow obstruction due to abnormalities in the airway and alveoli. Obstructive sleep apnea (OSA) is a critical condition characterized by obstructive apneas, hypopneas, and respiratory effort-related arousals. These events occur due to the repetitive collapse of the upper airway during sleep, and it is essential to address this condition. These two conditions, when co-occur, are known as overlap syndrome (OS), which is associated with a higher likelihood of morbidity and mortality compared to either condition alone. Effective management of overlap syndrome is critical to maintain normal oxygen levels during sleep and reduce the incidence of hypoxemia and hypoventilation while improving sleep quality. Positive pressure ventilation is a standard technique used to effectively lower hospitalizations, emergency room visits, moderate and severe exacerbations, and related healthcare expenses in patients diagnosed with COPD and OSA. Despite the lack of literature on overlap syndrome, it is imperative to understand that this condition requires prompt and effective management to prevent further complications. Therefore, this review provides a detailed discussion highlighting the importance of proactive measures to manage overlap syndrome.

Impact of pharmacological and non-pharmacological interventions on mortality in chronic obstructive pulmonary disease (COPD) patients

PURPOSE

This review aimed to summarise evidence about the impact of pharmacological and non-pharmacological interventions on survival in COPD patients.

METHODS

We performed a narrative literature review on the effect of pharmacological and non-pharmacological interventions on survival in COPD patients.

RESULTS

Inhaled therapies are central to reduce symptoms in COPD. In particular, inhaled steroids seem to have the greatest effect on mortality. Despite the anti-inflammatory effects attributed to statins, their benefit in COPD has been shown only in cases of combined cardiovascular diseases. The use of beta-blockers in COPD has not been associated with increased COPD-related mortality and a beneficial effect on all-cause mortality has even been shown in COPD patients with cardiovascular diseases. Influenza and pneumococcal vaccination reduced the occurrence of exacerbations and mortality due to COPD. In addition, long-term oxygen therapy (LTOT) (≥15h/day) in COPD patients with severe hypoxemia had a positive effect on survival. Regarding non-pharmacological interventions, it has been demonstrated that smoking cessation, treatment compliance and nutritional supplementation for underweight patients also have a positive effect on survival. Non-invasive ventilation results were dependent on patient PaCO2 levels. In patients with advanced COPD, further prospective studies are needed to know the effect of bronchoscopic lung volume reduction and lung transplant on COPD survival. Regarding lung transplant, a survival benefit in patients with a pre-transplant BODE score of ≥7 has been shown in retrospective studies.

CONCLUSION

Most of the studies did not evaluate survival as the main criteria and further long-term studies on the global management of COPD are required.

Relationship between nighttime symptoms and clinical features in COPD patients: A cross-sectional multicenter study in China

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that causes breathing difficulties, coughing, and other symptoms. Nighttime symptoms, such as coughing, wheezing, and shortness of breath, can significantly impact the quality of life for people with COPD.

OBJECTIVE

To investigate the relationship between nighttime symptoms and other clinical features in patients with COPD, and identify potential risk factors associated with nighttime symptoms.

METHODS

This cross-sectional study was conducted from October 1, 2022 to November 30, 2022 in 24 hospital outpatient departments in different cities of Hunan Province, China. The COPD Nighttime Symptom Instrument (NiSCI) was used to measure the severity of night time symptoms in COPD patients. Descriptive and inferential statistics were used to express patient socio-demographics and factors influencing nighttime symptoms.

RESULTS

The study included 2219 COPD patients. The results showed that nighttime symptom scores differed significantly based on gender, whether the patient had experienced acute exacerbation in the past year, mMRC and CAT scores, the duration of home oxygen therapy and home non-invasive ventilation (all P < 0.0001). Multiple linear regression analysis revealed that CAT score (P < 0.0001) was significantly associated with nighttime symptom scores.

CONCLUSION

Nighttime symptoms are prevalent in Chinese COPD patients and correlate with disease severity. The assessment and management of nighttime symptoms in COPD patients must take into account gender, CAT and mMRC scores, history of acute exacerbations, and duration of home oxygen therapy and home non-invasive ventilation to enable tailoring of treatment strategies to individual needs.

Obesity paradox or hypoxia preconditioning: How obstructive sleep apnea modifies the Obesity-MI relationship

OBJECTIVES

The objective of this study was to evaluate the interaction between obesity and obstructive sleep apnea on acute MI in hospital mortality.

METHODS

This retrospective cohort study utilized Veterans Health Administration data from years 1999-2020. Participants were categorized according to their body mass index (BMI) to non-obese (BMI <30) and obese (BMI ≥30) groups. Clinical obstructive sleep apnea (SA) diagnosis was confirmed using ICD9/10 codes and the study subgroups included non-obese with no obstructive sleep apnea (nOB-nSA), non-Obese with obstructive sleep apnea (nOB-SA), obese with no obstructive sleep apnea (OB-nSA), and obese with obstructive sleep apnea (OB-SA). The primary outcome was odds ratio of in-hospital mortality during the hospitalization with acute MI as the principal diagnosis adjusted for age, gender, race, ethnicity, and Charlson comorbidity index (CCI) with the nOB-nSA group as the comparison group.

RESULTS

Among 72,036 veterans with acute-MI hospitalization, individuals with obesity and obstructive sleep apnea (OB-SA) had the lowest in-hospital mortality rate (1.0%) compared to those without obesity and obstructive sleep apnea (nOB-nSA, 2.8%), with obesity but without obstructive sleep apnea (OB-nSA, 2.4%), and with obesity and obstructive sleep apnea (nOB-SA, 1.4%). The adjusted odds ratio for mortality, compared to nOB-nSA, was 9% higher but not significant in OB-nSA (aOR, 1.09, 95%CI: 0.95, 1.25), 46% lower in OB-nSA (aOR, 0.54, 95%CI: 0.45, 0.66), and 52% lower in OB-SA (aOR, 0.48: 95%CI: 0.41, 0.57).

CONCLUSION

Our data suggest that the association between obesity and improved survival in acute MI is largely driven by the presence of sleep apnea.

Holistic management of patients with progressive pulmonary fibrosis

Progressive pulmonary fibrosis (PF) is a complex interstitial lung disease that impacts substantially on patients' daily lives, requiring personalised and integrated care. We summarise the main needs of patients with PF and their caregivers, and suggest a supportive care approach. Individualised care, education, emotional and psychological support, specialised treatments, and better access to information and resources are necessary. Management should start at diagnosis, be tailored to the patient's needs, and consider end-of-life care. Pharmacological and non-pharmacological interventions should be individualised, including oxygen therapy and pulmonary rehabilitation, with digital healthcare utilised as appropriate. Further research is needed to address technical issues related to oxygen delivery and digital healthcare.

Educational aims

To identify the main needs of patients with PF and their caregivers.To describe the components of a comprehensive approach to a supportive care programme for patients with PF.To identify further areas of research to address technical issues related to the management of patients with PF.

Prognostic value of oxygen inhalation therapy for simple nocturnal hypoxemia in COPD: a meta-analysis

Objective: The effect of oxygen therapy on the prognosis of chronic obstructive pulmonary disease (COPD) with nocturnal hypoxemia (NOD) has been controversial. Therefore, this study systematically evaluated the relevant literature and included it into randomized controlled studies for meta-analysis to evaluate the efficacy and prognosis. Methods: We searched PubMed, EMBASE, web of science, Cochrane, China HowNet and Wanfang database for the literature on the prognosis of COPD patients with simple NOD from the establishment of the database to 30 June 2022. The outcome indicators were death and aggravation of the disease. The efficacy evaluation measures were pulmonary function and arterial blood gas results. The publication bias and heterogeneity of the included studies were evaluated. Results: A total of 621 patients from 5 studies were included in this meta-analysis, and there was no publication bias in the included studies. The total mortality of long-term oxygen therapy (LTOT) in COPD patients with simple NOD in oxygen therapy group (RR = 1.04; 95% CI: 0.81-1.33, p = 0.77), mortality (RR = 0.87; 95% CI: 0.58-1.31, p = 0.50), risk of progression to LTOT events (RR = 1.07; 95% CI: 0.76-1.51, p = 0.71). PaO2 in patients with COPD and simple NOD in oxygen therapy group was higher than that in non-oxygen therapy group (mean difference (MD) = 13.47; 95% CI: 3.49-23.46, p = 0.008), the decrease of PaCO2 level was not statistically significant (MD = -10.05; 95% CI: -26.36-6.27, p = 0.23). Conclusion: Oxygen therapy can improve the prognosis of blood oxygen partial pressure in COPD patients with simple NOD, but oxygen therapy has no significant effect on the survival rate, controlling the progression of the disease to LTOT and reducing the partial pressure of carbon dioxide.

Mental health and quality of life among patients with chronic respiratory failure on domiciliary oxygen: a prospective cohort study from a tertiary care centre in India

OBJECTIVES

The study aims to assess the prevalence of anxiety, depression and the quality of life among patients with chronic respiratory failure and the changes in anxiety and depression scores after initiating domiciliary oxygen.

DESIGN AND SETTING

Prospective, single-centre cohort study conducted in a tertiary care hospital in India.

PARTICIPANTS

Patients of Indian origin with chronic respiratory failure who visited the hospital where domiciliary oxygen is indicated were included in the study. Patients with acute respiratory failure on a mechanical ventilator, haemodynamic instability and already-diagnosed psychiatric conditions were excluded from the study.

INTERVENTIONS

Patients who met the inclusion criteria were assessed at baseline, at 3 and 6 months, for anxiety and depression using the 7-item Generalised Anxiety Disorder questionnaire (GAD-7) and 9-item Patient Health Questionnaire (PHQ-9). Quality of life was evaluated using the WHO Quality of Life-BREF questionnaire.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome is the proportion of patients with chronic respiratory failure having depression and anxiety and assessing the changes in anxiety and depression scores after initiating domiciliary oxygen. The secondary outcome is the change in health-related quality of life (HRQOL) of patients on domiciliary oxygen.

RESULTS

121 patients who met the inclusion criteria were included in the study. Of 102 patients who completed the study, 36.2% (n=37) had anxiety and 44.1% (n=45) had depression at baseline. There is a worsening trend in the mean GAD-7 (p=0.003) and PHQ-9 score (p=0.015) in patients over 6 months while on domiciliary oxygen. HRQOL is poor in all the domains at baseline, and there is a progressive worsening during follow-up while on oxygen.

CONCLUSIONS

The worsening trend in anxiety and depression in patients after initiating domiciliary oxygen may be related to social isolation, restricted mobility, economic issues, addictions and frequency of exacerbations. Screening for psychological problems in these patients at baseline and on follow-ups helps early detection, and prompt intervention could improve the quality of life and survival.

Oxygen Therapy Part 2 - Indications and Toxicity

Oxygen Therapy Part 2: Indications and ToxicityWemple et al. continue their review of oxygen therapy, discussing the acute and chronic indications for oxygen and the delivery of supplemental oxygen (and its potential adverse effects and toxicity).

Supplemental oxygen and noninvasive ventilation

The respiratory system attempts to maintain normal levels of oxygen and carbon dioxide. However, airflow limitation, parenchymal abnormalities and dysfunction of the respiratory pump may be compromised in individuals with advanced COPD, eventually leading to respiratory failure, with reduced arterial oxygen tension (hypoxaemia) and/or increased arterial carbon dioxide tension (P aCO2 ; hypercapnia). Hypoxaemia may persist in individuals with severe COPD despite smoking cessation and optimisation of pharmacotherapy. Long-term oxygen therapy (LTOT) can improve survival in those with severe daytime hypoxaemia, whereas those with less severe hypoxaemia may only have improved exercise capacity and dyspnoea. Changes in respiratory physiology that occur during sleep further predispose to hypoxaemia, particularly in individuals with COPD. However, the major cause of hypoxaemia is hypoventilation. Noninvasive ventilation (NIV) may reduce mortality and need for intubation in individuals with COPD and acute hypercapnic respiratory failure. However, NIV may also improve survival and quality of life in individuals with stable, chronic hypercapnia and is now suggested for those with prolonged hypercapnia (e.g. P aCO2 >55 mmHg 2-6 weeks after hospital discharge) when clinically stable and after optimisation of medical therapy including LTOT if indicated. Many questions remain about the optimal mode, settings and goal of NIV therapy.

Diagnosing sleep disordered breathing in patients with chronic pulmonary disease: which test for which patient?

Overnight polysomnography should be the first-line diagnostic test in patients with severe respiratory disease. However, if access to polysomnography is limited, overnight polygraphy can be used as an alternative first-line diagnostic. https://bit.ly/3KlmFED.

Adaptive exhaustion during prolonged intermittent hypoxia causes dysregulated skeletal muscle protein homeostasis

Nocturnal hypoxaemia, which is common in chronic obstructive pulmonary disease (COPD) patients, is associated with skeletal muscle loss or sarcopenia, which contributes to adverse clinical outcomes. In COPD, we have defined this as prolonged intermittent hypoxia (PIH) because the duration of hypoxia in skeletal muscle occurs through the duration of sleep followed by normoxia during the day, in contrast to recurrent brief hypoxic episodes during obstructive sleep apnoea (OSA). Adaptive cellular responses to PIH are not known. Responses to PIH induced by three cycles of 8 h hypoxia followed by 16 h normoxia were compared to those during chronic hypoxia (CH) or normoxia for 72 h in murine C2C12 and human inducible pluripotent stem cell-derived differentiated myotubes. RNA sequencing followed by downstream analyses were complemented by experimental validation of responses that included both unique and shared perturbations in ribosomal and mitochondrial function during PIH and CH. A sarcopenic phenotype characterized by decreased myotube diameter and protein synthesis, and increased phosphorylation of eIF2α (Ser51) by eIF2α kinase, and of GCN-2 (general controlled non-derepressed-2), occurred during both PIH and CH. Mitochondrial oxidative dysfunction, disrupted supercomplex assembly, lower activity of Complexes I, III, IV and V, and reduced intermediary metabolite concentrations occurred during PIH and CH. Decreased mitochondrial fission occurred during CH. Physiological relevance was established in skeletal muscle of mice with COPD that had increased phosphorylation of eIF2α, lower protein synthesis and mitochondrial oxidative dysfunction. Molecular and metabolic responses with PIH suggest an adaptive exhaustion with failure to restore homeostasis during normoxia. KEY POINTS: Sarcopenia or skeletal muscle loss is one of the most frequent complications that contributes to mortality and morbidity in patients with chronic obstructive pulmonary disease (COPD). Unlike chronic hypoxia, prolonged intermittent hypoxia is a frequent, underappreciated and clinically relevant model of hypoxia in patients with COPD. We developed a novel, in vitro myotube model of prolonged intermittent hypoxia with molecular and metabolic perturbations, mitochondrial oxidative dysfunction, and consequent sarcopenic phenotype. In vivo studies in skeletal muscle from a mouse model of COPD shared responses with our myotube model, establishing the pathophysiological relevance of our studies. These data lay the foundation for translational studies in human COPD to target prolonged, nocturnal hypoxaemia to prevent sarcopenia in these patients.

Home oxygen for moderate hypoxaemia in chronic obstructive pulmonary disease: a systematic review and meta-analysis

BACKGROUND

Long-term oxygen therapy (LTOT) improves survival in patients with chronic obstructive pulmonary disease (COPD) and severe hypoxaemia. However, the best method of management of moderate hypoxaemia not qualifying for LTOT (including isolated nocturnal desaturation) is uncertain. We examined the effect of home oxygen (either LTOT or nocturnal oxygen therapy) on overall survival in patients with COPD and moderate hypoxaemia.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, CINHAL, and Web of Science from database inception to Jan 13, 2022, for parallel-group randomised trials of long-term or nocturnal oxygen in patients with COPD and moderate daytime hypoxaemia or isolated nocturnal desaturation, or both. Control groups received usual care or ambient air through sham concentrators (placebo) throughout the study period. The primary outcome of interest was 3-year mortality. Crossover trials and trials of oxygen in severe hypoxaemia were excluded. Two reviewers applied inclusion and exclusion criteria to titles and abstracts and screened the full-text articles and reference lists of relevant studies. Aggregate data were extracted manually in duplicate using structured data collection forms. Methodological quality was assessed using the Cochrane Risk of Bias tool. Random-effects meta-analysis was used to pool individual studies. We considered the minimal clinically important difference for home oxygen to be a relative risk reduction in mortality at 3-year follow-up of 30-40%. The meta-analysis is registered on PROSPERO, CRD42021225372.

FINDINGS

We identified 2192 studies and screened 1447 after removal of duplicates, of which 161 were subjected to full-text screening, and six were identified as being eligible for inclusion. These six randomised trials were published between 1992 and 2020 and the quality of evidence was high. In the primary meta-analysis (five trials; 1002 patients), we found the effect of home oxygen in reducing 3-year mortality to be small or absent (relative risk 0·91 [95% CI 0·72-1·16]; τ² = 0·00), hence the lower limit of the 95% CI did not meet the prespecified minimal clinically important difference.

INTERPRETATION

The results of our meta-analysis suggest that home oxygen probably makes little or no difference to 3-year mortality in patients with COPD and moderate hypoxaemia. The data do not support the widespread use of home oxygen in this patient population.

FUNDING

None.

Chronic obstructive pulmonary disease and obstructive sleep apnoea overlap: co-existence, co-morbidity, or causality?

PURPOSE OF REVIEW

The chronic obstructive pulmonary disease and obstructive sleep apnoea overlap syndrome is associated with higher morbidity and mortality rates than either disease alone. There is evidence of a bidirectional relationship between the two conditions, with the overlap syndrome encompassing a spectrum of clinical phenotypes.

RECENT FINDINGS

This review examines the evidence for the various factors that determine the overlap syndrome, the impact overlap syndrome has on co-morbidities, and implications for diagnosis and treatment.

SUMMARY

The accurate diagnosis of the overlap syndrome is critical given its implications for treatment optimisation and reduction in healthcare utilisation and costs.

2022 Brazilian Thoracic Association recommendations for long-term home oxygen therapy

Some chronic respiratory diseases can cause hypoxemia and, in such cases, long-term home oxygen therapy (LTOT) is indicated as a treatment option primarily to improve patient quality of life and life expectancy. Home oxygen has been used for more than 70 years, and support for LTOT is based on two studies from the 1980s that demonstrated that oxygen use improves survival in patients with COPD. There is evidence that LTOT has other beneficial effects such as improved cognitive function, improved exercise capacity, and reduced hospitalizations. LTOT is indicated in other respiratory diseases that cause hypoxemia, on the basis of the same criteria as those used for COPD. There has been an increase in the use of LTOT, probably because of increased life expectancy and a higher prevalence of chronic respiratory diseases, as well as greater availability of LTOT in the health care system. The first Brazilian Thoracic Association consensus statement on LTOT was published in 2000. Twenty-two years la-ter, we present this updated version. This document is a nonsystematic review of the literature, conducted by pulmonologists who evaluated scientific evidence and international guidelines on LTOT in the various diseases that cause hypoxemia and in specific situations (i.e., exercise, sleep, and air travel). These recommendations, produced with a view to clinical practice, contain several charts with information on indications for LTOT, oxygen sources, accessories, strategies for improved efficiency and effectiveness, and recommendations for the safe use of LTOT, as well as a LTOT prescribing model.

Ventilatory neural drive in chronically hypercapnic patients with COPD: effects of sleep and nocturnal noninvasive ventilation

Sleep brings major challenges for the control of ventilation in humans, particularly the regulation of arterial carbon dioxide pressure (P _aCO2 ). In patients with COPD, chronic hypercapnia is associated with increased mortality. Therefore, nocturnal high-level noninvasive positive-pressure ventilation (NIV) is recommended with the intention to reduce P _aCO2 down to normocapnia. However, the long-term physiological consequences of P _aCO2 "correction" on the mechanics of breathing, gas exchange efficiency and resulting symptoms (i.e. dyspnoea) remain poorly understood. Investigating the influence of sleep on the neural drive to breathe and its translation to the mechanical act of breathing is of foremost relevance to create a solid rationale for the use of nocturnal NIV. In this review, we critically discuss the mechanisms by which sleep influences ventilatory neural drive and mechanical consequences in healthy subjects and hypercapnic patients with advanced COPD. We then discuss the available literature on the effects of nocturnal NIV on ventilatory neural drive and respiratory mechanics, highlighting open avenues for further investigation.

Nocturnal nasal high-flow oxygen therapy in elderly patients with concomitant chronic obstructive pulmonary disease and obstructive sleep apnea

Purpose

The coexistence of obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) is known as “overlap syndrome” (OS). Patients with OS are usually older than patients with OSA alone, suffer from more profound oxygen desaturation during the obstructive events often accompanied by sustained nocturnal hypoventilation. Although oxygen-enriched positive airway pressure (PAP) is the treatment of choice in these patients, this therapy is often poorly tolerated particularly by the elderly. The aim of this study was to assess the usefulness of nocturnal oxygen therapy via nasal high flow (NHF-OT) as a possible alternative to PAP in patients with OS.

Methods

Patients > 65 years old with OS and nocturnal respiratory failure (time spent below SaO2 90% (T90) > 30%) had cardio-respiratory monitoring performed at baseline, during NHF-OT, or during conventional oxygen therapy (COT).

Results

A total of 40 patients were enrolled in the study. NHF-OT significantly reduced the apnea–hypopnea index (AHI) in all patients compared to baseline and COT. The mean basal AHI was 25.4 ± 8.6. During COT and NHF-OT, the AHI was 19.4 ± 7 and 5.4 ± 4.6, respectively (P < 0.001) and 19 patients reached an AHI < 5 during NHF-OT. The mean nocturnal SaO2% was 86.2 ± 2.6 at baseline and at equivalent FiO2 it significantly increased to 91.8 ± 2.4 during COT and to 93.9 ± 2.5 during NHF-OT (P < 0.001). The T90% was 48.7 ± 20.1 at baseline, 16.8 ± 11.7 during COT, and 8.8 ± 8.0 during NHF-OT (P < 0.001).

Conclusions

In elderly patients with OS, nocturnal treatment with NHF-OT significantly reduces obstructive episodes and improves oxygenation. As the treatment is generally well tolerated compared to PAP, NHF-OT may be a possible alternative therapy in this subgroup of patients.

Short-Term Oxygen Therapy Outcomes in COPD

Rationale

Short-term oxygen therapy (STOT) is often prescribed to allow patients with chronic obstructive pulmonary disease (COPD) to be discharged safely from hospital following an acute illness. This practice is widely accepted without being based on evidence.

Purpose

Our objective was to describe the characteristics and outcomes of patients with COPD who received STOT.

Patients and Methods

The study was a secondary analysis of the INOX trial, a 4-year randomised trial of nocturnal oxygen in COPD. The trial indicated that nocturnal oxygen has no significant effect on survival or progression to LTOT, allowing our merging of patients who received nocturnal oxygen and those who received placebo into a single cohort to study the predictors and outcomes of STOT regardless of the treatment received during the trial.

Results

Among the 243 participants in the trial, 60 required STOT on at least one occasion during follow-up. Patients requiring STOT had more severe dyspnoea and lung function impairment, and lower PaO₂ at baseline than those who did not. STOT was associated with subsequent LTOT requirement (hazard ratio [HR]: 4.59; 95% confidence interval [CI]: 2.98–7.07) and mortality (HR: 1.93; 95% CI: 1.15–3.24). The association between STOT and mortality was confounded by age, disease severity and comorbidities. Periods of STOT of more than one month and/or repeated prescriptions of STOT increased the probability of progression to LTOT (OR: 5.07; 95% CI: 1.48–18.8).

Conclusion

Following an acute respiratory illness in COPD, persistent hypoxaemia requiring STOT is a marker of disease progression towards the requirement for LTOT.

Sleep Deficiency, Sleep Apnea, and Chronic Lung Disease

With sleep occupying up to one-third of every adult's life, addressing sleep is essential to overall health. Sleep disturbance and deficiency are common in patients with chronic lung diseases and associated with worse clinical outcomes and poor quality of life. A detailed history incorporating nocturnal respiratory symptoms, symptoms of obstructive sleep apnea (OSA) and restless legs syndrome, symptoms of anxiety and depression, and medications is the first step in identifying and addressing the multiple factors often contributing to sleep deficiency in chronic lung disease. Additional research is needed to better understand the relationship between sleep deficiency and the spectrum of chronic lung diseases.

Spanish COPD Guidelines (GesEPOC 2021): Non-pharmacological Treatment Update

In addition to recommendations for pharmacological treatment stratified for risk and phenotype, the new 2021 edition of the Spanish COPD Guidelines (GesEPOC 2021) proposes a personalized approach to treatable traits, defined as a characteristic (clinical, physiological, or biological) that can be identified by diagnostic tests or biomarkers, for which a specific treatment is available. Some treatable traits, such as malnutrition, sedentarism, emphysema or respiratory failure, can be treated with non-pharmacological therapies, and this was not covered in detail in the guidelines. This section of GesEPOC 2021 includes a narrative update with recommendations on dietary treatment, physical activity, respiratory rehabilitation, oxygen therapy, non-invasive ventilation, volume reduction, and lung transplantation. A PICO question with recommendations on the use of supplemental oxygen during exercise in COPD patients without severe hypoxemia is also included.

Sleep-Related Breathing Complaints in Chronic Obstructive Pulmonary Disease

This review presents the normal physiologic changes in ventilation during sleep and how they can be detrimental to chronic obstructive pulmonary disease (COPD). Sleep-related breathing disorders (SRBDs) in COPD lead to higher morbidity and mortality if left unrecognized and untreated. The diagnosis of SRBDs requires a high index of suspicion, as symptoms may overlap with other sleep disorders. Mortality risk is improved when patients with COPD with OSA (overlap syndrome) are treated with positive airway pressure and when long-term nocturnal noninvasive ventilation is started on chronic stable hypercapnic COPD. Treatment of isolated nocturnal oxygen desaturation has not been associated with improved survival.

Effect of Nocturnal Oxygen on Blood Pressure Response to Altitude Exposure in COPD - Data from a Randomized Placebo-Controlled Cross-Over Trial

Purpose

Patients with chronic obstructive pulmonary disease (COPD) are particularly vulnerable to hypoxia-induced autonomic dysregulation. Hypoxemia is marked during sleep. In COPD, altitude exposure is associated with an increase in blood pressure (BP) and a decrease in baroreflex-sensitivity (BRS). Whether nocturnal oxygen therapy (NOT) may mitigate these cardiovascular autonomic changes in COPD at altitude is unknown.

Materials and Methods

In a randomized placebo-controlled cross-over trial, 32 patients with moderate-to-severe COPD living <800 m were subsequently allocated to NOT and placebo during acute exposure to altitude. Measurements were done at low altitude at 490 m and during two stays at 2048 m on NOT (3 L/min) and placebo (3 L/min, ambient air) via nasal cannula. Allocation and intervention sequences were randomized. Outcomes of interest were BP, BRS (from beat-to-beat BP measurement), BP variability (BPV), and heart rate.

Results

About 23/32 patients finished the trial per protocol (mean (SD) age 66 (5) y, FEV₁ 62 (14) % predicted) and 9/32 experienced altitude-related illnesses (8 vs 1, p < 0.05 placebo vs NOT). NOT significantly mitigated the altitude-induced increase in systolic BP compared to placebo (Δ median −5.8 [95% CI −22.2 to −1.4] mmHg, p = 0.05) but not diastolic BP (−3.5 [95% CI −12.6 to 3.0] mmHg; p = 0.21) or BPV. BRS at altitude was significantly higher in NOT than in placebo (1.7 [95% CI 0.3 to 3.4] ms/mmHg, p = 0.02).

Conclusion

NOT may protect from hypoxia-induced autonomic dysregulation upon altitude exposure in COPD and thus protect from a relevant increase in BP and decrease in BRS. NOT may provide cardiovascular benefits in COPD during conditions of increased hypoxemia and may be considered in COPD travelling to altitude.

The effect of Huashibaidu formula on the blood oxygen saturation status of severe COVID-19: A retrospective cohort study

BACKGROUND

Huashibaidu Formula (HSBD) for the COVID-19 treatment has been supported by the China's Diagnosis and Treatment Protocol for Novel Coronavirus Pneumonia. However, it is not clear whether HSBD can improve blood oxygen saturation and when it should be used with conventional therapies.

PURPOSE

To access the effect of HSBD combined with conventional treatment on blood oxygen saturation of COVID-19 patients.

METHODS

A single-center retrospective cohort study was conducted to collect the confirmed severe COVID-19 patients' information, treated by the National Traditional Chinese Medicine Medical Team at the Jinyintan hospital between January 24 and March 31, 2020. According to whether HSBD was used during hospitalization, participants were separated into the conventional treatment group and the HSBD group (HSBD and conventional treatment). The primary observation indicators included the time for relieving blood oxygen saturation and the improvement ratio of blood oxygen saturation in each group.

RESULTS

Of 111 patients with severe COVID-19, 53.2% (59/111) received HSBD, and 46.8% (52/111) only received conventional treatment, respectively. No statistically significant difference was found in image, clinical symptoms, and past medical history between the two groups (p > 0.05). Notably, the median time for relieving blood oxygen saturation in the conventional treatment group was 11 days (IQR, 8-14.25), while that in the HSBD group was only 6 days (IQR, 3.25-10.75), which was significantly shortened by 4.09 days (95%CI, 2.07-6.13; p= 0.0001), compared with the conventional treatment group. After repeated measurement design analysis, the main effect within times (p< 0.001) and the main effect were significantly different under the oxygen saturation dimension between two groups (p= 0.004). However, time and group interaction were observed no significant difference (p= 0.094). After 14 days of treatment, the improvement ratio of the HSBD group over the conventional treatment group was 1.20 (95%CI, 0.89-1.61).

CONCLUSION

For severe COVID-19 patients, the HSBD has a tendency to shorten the time for relieving blood oxygen saturation. After taking a course of HSBD, the effect can be more obvious.

Lack of Medical Criteria for Long-Term Oxygen Therapy Usage According to International Guidance in Outpatients With Chronic Hypoxemia

Background

Benefits of long-term oxygen therapy (LTOT) have been observed in hypoxemic respiratory patients. Reports have shown the lack of observance among healthcare professionals of LTOT. Thus, this study aimed to determine the demographic characteristics and observance of the medical indication of LTOT according to the international guidelines.

Methodology

A cross-sectional study was conducted on patients who attended the Medical Unit in Aguascalientes, Mexico to re-evaluate the need for LTOT. Data are presented as mean ± standard deviation. Statistical analyses were performed using the chi-square test or unpaired t-tests. P-values of <0.05 were considered statistically significant.

Results

From 813 outpatients attended to re-evaluate whether they met the medical criteria to use LTOT, 93 outpatients were excluded, and the remaining 714 outpatients were enrolled. The mean age of the patients was 70.0 ± 15.1 years, with a female gender predominance (59.1 %). The mean PaO₂ level in room air was 7.9 ± 2.3 kPa. Hemoglobin and hematocrit levels were 14.9 ± 4.1 g/dL and 44.7 ± 8.4%, respectively. The mean levels of PaO₂ were higher in female patients (8.1 ± 2.5 kPa vs. 7.6 ± 1.9 kPa; p = 0.01). The most common diagnosis was chronic obstructive pulmonary disorder (60.5%). Moreover, the specialty that most indicated the use of LTOT was pulmonology (57.8%); however, 36.8% of patients who used LTOT did not have any criteria according to international guidelines.

Conclusions

Although a significant percentage of patients do not use LTOT correctly, the most important finding is that the medical indication of LTOT by physicians is not always correct, leading to an excessive prescription of oxygen.

Oximetry neither to prescribe long-term oxygen therapy nor to screen for severe hypoxaemia

Background and objective

Transcutaneous pulse oximetry saturation (S_pO2) is widely used to diagnose severe hypoxaemia and to prescribe long-term oxygen therapy (LTOT) in COPD. This practice is not based on evidence. The primary objective of this study was to determine the accuracy (false positive and false negative rates) of oximetry for prescribing LTOT or for screening for severe hypoxaemia in patients with COPD.

Methods

In a cross-sectional study, we correlated arterial oxygen saturation (S_aO2) and S_pO2 in patients with COPD and moderate hypoxaemia (n=240) and calculated the false positive and false negative rates of S_aO2 at the threshold of ≤88% to identify severe hypoxaemia (arterial oxygen tension (P_aO2) ≤55 mmHg or P_aO2 <60 mmHg) in 452 patients with COPD with moderate or severe hypoxaemia.

Results

The correlation between S_aO2 and S_pO2 was only moderate (intra-class coefficient of correlation: 0.43; 95% confidence interval: 0.32–0.53). LTOT would be denied in 40% of truly hypoxaemic patients on the basis of a S_aO2 >88% (i.e., false negative result). Conversely, LTOT would be prescribed on the basis of a S_aO2 ≤88% in 2% of patients who would not qualify for LTOT (i.e., false positive result). Using a screening threshold of ≤92%, 5% of severely hypoxaemic patients would not be referred for further evaluation.

Conclusions

Several patients who qualify for LTOT would be denied treatment using a prescription threshold of saturation ≤88% or a screening threshold of ≤92%. Prescription of LTOT should be based on P_aO2 measurement.

Although transcutaneous pulse oximetry is widely used to diagnose severe hypoxaemia and prescribe long-term oxygen therapy in COPD, up to 40% of patients who qualify for this therapy would be denied treatment using the saturation threshold of ≤88%https://bit.ly/3jolWU5

Utility and outcomes among Indigenous and non-Indigenous patients requiring domiciliary oxygen therapy in the regional and rural Australian population

OBJECTIVE

To evaluate the utility and outcomes for Indigenous and non-Indigenous patients requiring domiciliary oxygen therapy.

DESIGN

Retrospective study.

SETTING

Patients residing in the regional and rural Top End Health Service region of the Northern Territory of Australia.

PARTICIPANTS

Indigenous and non-Indigenous patients prescribed domiciliary oxygen therapy between 2018 and 2020.

INTERVENTIONS

Demographics and clinical indication for domiciliary oxygen therapy and mortality were analysed.

MAIN OUTCOME MEASURES

Differences between Indigenous patients requiring domiciliary oxygen therapy in comparison with their non-Indigenous counterparts.

RESULTS

Of the 199 study participants, the majority were male (51%), non-Indigenous (77%) and urban residents (72%). Overall chronic obstructive pulmonary disease was the most common indication for domiciliary oxygen therapy (51%) followed by palliative intent (22%). Indigenous patients were significantly younger (61 vs 73 years), with a higher proportion of males (62% vs 45%, P = .039) and remote residents (62% vs 8%, P < .001). Among Indigenous patients, a significantly greater proportion of domiciliary oxygen therapy was indicated for chronic obstructive pulmonary disease and bronchiectasis (16% vs 1%, P < .001). Among non-Indigenous patients, malignancies were a more common indication for domiciliary oxygen therapy. A similar proportion of Indigenous and non-Indigenous patients were prescribed domiciliary oxygen therapy for palliative intent (31% and 20%, P = .108); however, the underlying diagnosis differed significantly, with a greater proportion of chronic obstructive pulmonary disease among Indigenous patients (43% vs 13%, P = .030) and malignancy among the non-Indigenous patients (73% vs 43%, P = .050). Mortality and length of survival were not significantly different by Indigenous status. Linear regression showed longer survival with domiciliary oxygen therapy for chronic obstructive pulmonary disease.

CONCLUSION

Indigenous Australian patients living in remote communities will likely derive the same benefits and outcomes of domiciliary oxygen therapy as non-Indigenous peers.

A review of therapies for the overlap syndrome of obstructive sleep apnea and chronic obstructive pulmonary disease

Obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are common chronic diseases. These two noncommunicable diseases (NCDs) are prevalent among approximately 10% of the general population. Approximately 1% of the population is affected by the co-existence of both conditions, known as the overlap syndrome (OS). OS patients suffer from greater degrees of nocturnal oxygen desaturation and cardiovascular consequences than those with either condition in isolation. Besides OS, patients with COPD may suffer from a spectrum of sleep-related breathing disorders, including hypoventilation and central sleep apnea. The article provides an overview of the pathogenesis, associated risk factors, prevalence, and management of sleep-related breathing disorders in COPD. It examines respiratory changes during sleep caused by COPD and OSA. It elaborates upon the factors that link the two conditions together to lead to OS. It also discusses the clinical evaluation and diagnosis of these patients. Subsequently, it reviews the pathophysiological basis and the current evidence for three potential therapies: positive airway pressure therapy [including continuous positive airway pressure (CPAP) and bilevel positive airway pressure], oxygen therapy, and pharmacological therapy. It also proposes a phenotypic approach toward the diagnosis and treatment of OS and the entire spectrum of sleep-related breathing disorders in COPD. It concludes with the current evidence gaps and future areas of research in the management of OS.

Experimental Setting for Applying Mechanical Stimuli to Study the Endothelial Response of Ex Vivo Vessels under Realistic Pathophysiological Environments

This paper describes the design, construction and testing of an experimental setting, making it possible to study the endothelium under different pathophysiological conditions. This novel experimental approach allows the application of the following stimuli to an ex vivo vessel in a physiological bath: (a) a realistic intravascular pressure waveform defined by the user; (b) shear stress in the endothelial layer since, in addition to the pressure waveform, the flow through the vessel can be independently controlled by the user; (c) conditions of hypo/hyperoxia and hypo/hypercapnia in an intravascular circulating medium. These stimuli can be applied alone or in different combinations to study possible synergistic or antagonistic effects. The setting performance is illustrated by a proof of concept in an ex vivo rabbit aorta. The experimental setting is easy to build by using very low-cost materials widely available. Online Supplement files provide all the technical information (e.g., circuits, codes, 3D printer drivers) following an open-source hardware approach for free replication.

Effect of Nocturnal Oxygen Therapy on Daytime Pulmonary Hemodynamics in Patients With Chronic Obstructive Pulmonary Disease Traveling to Altitude: A Randomized Controlled Trial

Introduction

We investigated whether nocturnal oxygen therapy (NOT) mitigates the increase of pulmonary artery pressure in patients during daytime with chronic obstructive pulmonary disease (COPD) traveling to altitude.

Methods

Patients with COPD living below 800 m underwent examinations at 490 m and during two sojourns at 2,048 m (with a washout period of 2 weeks < 800 m between altitude sojourns). During nights at altitude, patients received either NOT (3 L/min) or placebo (ambient air 3 L/min) via nasal cannula according to a randomized crossover design. The main outcomes were the tricuspid regurgitation pressure gradient (TRPG) measured by echocardiography on the second day at altitude (under ambient air) and various other echocardiographic measures of the right and left heart function. Patients fulfilling predefined safety criteria were withdrawn from the study.

Results

Twenty-three COPD patients [70% Global Initiative for Chronic Obstructive Lung Disease (GOLD) II/30% GOLD III, mean ± SD age 66 ± 5 years, FEV₁ 54% ± 13% predicted] were included in the per-protocol analysis. TRPG significantly increased when patients traveled to altitude (from low altitude 21.7 ± 5.2 mmHg to 2,048 m placebo 27.4 ± 7.3 mmHg and 2,048 m NOT 27.8 ± 8.3 mmHg) difference between interventions (mean difference 0.4 mmHg, 95% CI −2.1 to 3.0, p = 0.736). The tricuspid annular plane systolic excursion was significantly higher after NOT vs. placebo [2.6 ± 0.6 vs. 2.3 ± 0.4 cm, mean difference (95% confidence interval) 0.3 (0.1 − 0.5) cm, p = 0.005]. During visits to 2,048 m until 24 h after descent, eight patients (26%) using placebo and one (4%) using NOT had to be withdrawn because of altitude-related adverse health effects (p < 0.001).

Conclusion

In lowlanders with COPD remaining free of clinically relevant altitude-related adverse health effects, changes in daytime pulmonary hemodynamics during a stay at high altitude were trivial and not modified by NOT.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT02150590.

Alpha1-antitrypsin Disease, Treatment and Role for Lung Volume Reduction Surgery

Chronic obstructive pulmonary usually is subcategorized into 2 groups: chronic bronchitis and emphysema. The main cause of chronic bronchitis and emphysema is smoking; however, alpha1-antitrypsin also has been seen to cause emphysema in patients who are deficient. As symptoms and lung function decline, treatment modalities, such as lung volume reduction surgery, have been used in individuals with chronic obstructive pulmonary disease and upper lobe predominant emphysema. This article analyzes multiple published series where lung volume reduction surgery has been used in individuals with alpha1-antitrypsin deficiency and their overall outcomes.

Machine learning for nocturnal diagnosis of chronic obstructive pulmonary disease using digital oximetry biomarkers

Objective.Chronic obstructive pulmonary disease (COPD) is a highly prevalent chronic condition. COPD is a major cause of morbidity, mortality and healthcare costs globally. Spirometry is the gold standard test for a definitive diagnosis and severity grading of COPD. However, a large proportion of individuals with COPD are undiagnosed and untreated. Given the high prevalence of COPD and its clinical importance, it is critical to develop new algorithms to identify undiagnosed COPD. This is particularly true in specific disease groups in which the presence of concomitant COPD increases overall morbidity/mortality such as those with sleep-disordered breathing. To our knowledge, no research has looked at the feasibility of automated COPD diagnosis using a data-driven analysis of the nocturnal continuous oximetry time series. We hypothesize that patients with COPD will exert certain patterns and/or dynamics of their overnight oximetry time series that are unique to this condition and that may be captured using a data-driven approach.Approach.We introduce a novel approach to nocturnal COPD diagnosis using 44 oximetry digital biomarkers and five demographic features and assess its performance in a population sample at risk of sleep-disordered breathing. A total ofn=350 unique patients' polysomnography (PSG) recordings were used. A random forest (RF) classifier was trained using these features and evaluated using nested cross-validation.Main results.The RF classifier obtainedF1 = 0.86 ± 0.02 and AUROC = 0.93 ± 0.02 on the test sets. A total of 8 COPD individuals out of 70 were misclassified. No severe cases (GOLD 3-4) were misdiagnosed. Including additional non-oximetry derived PSG biomarkers resulted in minimal performance increase.Significance.We demonstrated for the first time, the feasibility of COPD diagnosis from nocturnal oximetry time series for a population sample at risk of sleep-disordered breathing. We also highlighted what set of digital oximetry biomarkers best reflect how COPD manifests overnight. The results motivate that overnight single channel oximetry can be a valuable modality for COPD diagnosis, in a population sample at risk of sleep-disordered breathing. Further data is needed to validate this approach on other population samples.

Nocturnal hypoxaemia in interstitial lung disease: a systematic review

BACKGROUND

Patients with interstitial lung disease (ILD) are at risk of developing nocturnal hypoxaemia due to ventilatory restriction and impaired gas exchange that worsen with supine posture and reduced ventilatory drive during sleep. This systematic review synthesised literature on the diagnostic evaluation, epidemiology, associations, management and prognosis of nocturnal hypoxaemia in ILD.

METHODS

Ovid MEDLINE, Embase and CENTRAL databases were searched for eligible studies. Meta-analyses with subgroup analyses were conducted, where possible.

RESULTS

Fifty-three studies were included (total participant number=2590). The most common definition for clinically significant nocturnal hypoxaemia was ≥10% of total sleep time with oxyhaemoglobin saturation <90%, with pooled prevalence of 37%. There were no significant differences in pooled prevalence according to ILD subtype and comorbid obstructive sleep apnoea status. Study heterogeneity precluded meta-analysis of associations and prognosis. Diffusing capacity for carbon monoxide (DLCO) and echocardiographic features for pulmonary hypertension were consistently associated with nocturnal hypoxaemia. There were inconsistent associations between nocturnal hypoxaemia with ILD subtype and severity. Multivariable analyses in most studies demonstrated significant associations of nocturnal hypoxaemia with survival. Two small short-term intervention studies demonstrated that supplemental oxygen of 1-3 L/min corrected nocturnal hypoxaemia, with improved heart rate control during in-laboratory observation and increased serum antioxidant levels after 1 month of therapy.

CONCLUSION

Nocturnal hypoxaemia is common, associated with DLCO impairment and markers suggestive of pulmonary hypertension, and a potential prognostic factor in patients in ILD. There is a need to establish a consensus definition of nocturnal hypoxaemia and evaluate long-term effects of nocturnal supplemental oxygen in ILD.

[Oxygen Therapy in Lung Transplantation Candidates - A Single Center Retrospective Analysis of 807 Patients]

BACKGROUND

 Long-term oxygen treatment (LTOT) is frequently used in patients with advanced pulmonary diseases and respiratory failure. Oxygen treatment influences donor lung allocation for patients and is associated with increased mortality. This study investigates oxygen therapy in lung transplantation candidates.

METHODS

 A retrospective study at a large German transplantation centre between 09/2011 and 01/2019 was performed. Data regarding oxygen therapy was analyzed and LTOT-indication verified by titrated blood gas analysis. The study period splits into 2 periods before and after the introduction of oxygen titration (3rd quarter of 2015). Univariate and multivariate analysis for the endpoint "admission to waiting list" was performed.

RESULTS

 807 patients were included in the analysis, 396 in the first and 411 patients in the second period. Of those 293 patients (36.3 %) were transplanted. Six hundred thirty (78 %) patients stated using oxygen for more than 12 hours per day. After implementing oxygen titration in period 2, in 212 (57 %) of 372 patients LTOT indication could be confirmed. Titrated oxygen flow was lower in period 2 (0.5 l/min [IQR 0.0 - 2.0] versus 2 l/min [IQR 0.5 - 3.0]). In multivariate analysis oxygen flow was associated with admission to waiting list as an independent variable.

CONCLUSION

 Patients referred to lung transplantation use oxygen therapy in the vast majority. Indication for LTOT should be carefully reassessed in candidates. Confirmed LTOT-indication seems to be associated with the likelihood for admission to the waiting list for lung transplantation and could therefore be a selection criterium in the future.

Nocturnal Hypoxemia and CT Determined Pulmonary Artery Enlargement in Smokers

Background: Pulmonary artery enlargement (PAE) detected using chest computed tomography (CT) is associated with poor outcomes in chronic obstructive pulmonary disease (COPD). It is unknown whether nocturnal hypoxemia occurring in smokers, with or without COPD, obstructive sleep apnoea (OSA) or their overlap, may be associated with PAE assessed by chest CT. Methods: We analysed data from two prospective cohort studies that enrolled 284 smokers in lung cancer screening programs and completing baseline home sleep studies and chest CT scans. Main pulmonary artery diameter (PAD) and the ratio of the PAD to that of the aorta (PA:Ao ratio) were measured. PAE was defined as a PAD ≥ 29 mm in men and ≥27 mm in women or as a PA:Ao ratio > 0.9. We evaluated the association of PAE with baseline characteristics using multivariate logistic models. Results: PAE prevalence was 27% as defined by PAD measurements and 11.6% by the PA:Ao ratio. A body mass index ≥ 30 kg/m² (OR 2.01; 95%CI 1.06–3.78), lower % predicted of forced expiratory volume in one second (FEV₁) (OR 1.03; 95%CI 1.02–1.05) and higher % of sleep time with O₂ saturation < 90% (T90) (OR 1.02; 95%CI 1.00–1.03), were associated with PAE as determined by PAD. However, only T90 remained significantly associated with PAE as defined by the PA:Ao ratio (OR 1.02; 95%CI 1.01–1.03). In the subset group without OSA, only T90 remains associated with PAE, whether defined by PAD measurement (OR 1.02; 95%CI 1.01–1.03) or PA:Ao ratio (OR 1.04; 95%CI 1.01–1.07). Conclusions: In smokers with or without COPD, nocturnal hypoxemia was associated with PAE independently of OSA coexistence.