CD206+ macrophages are relevant non-invasive imaging biomarkers and therapeutic targets in experimental lung fibrosis.

BACKGROUND: Interstitial lung diseases (ILDs) include a large number of diseases associated with progressive pulmonary fibrosis (PPF), including idiopathic pulmonary fibrosis (IPF). Despite the rarity of each of the fibrotic ILDs individually, they cumulatively affect a considerable number of patients. PPF is characterised by an excessive collagen deposition leading to functional decline. OBJECTIVES: Therapeutic options are limited to nintedanib and pirfenidone which are only able to reduce fibrosis progression. CD206-expressing M2 macrophages are involved in fibrosis progression, and whether they may be relevant therapeutic targets or biomarkers remains an open question. RESULTS: In our study, CD206+ lung macrophages were monitored in bleomycin-induced lung fibrosis in mice by combining flow cytometry, scRNAseq and in vivo molecular imaging using a single photon emission computed tomography (SPECT) radiopharmaceutical, 99mTc-tilmanocept. The antifibrotic effect of the inhibition of M2 macrophage polarisation with a JAK inhibitor, tofacitinib, was assessed in vivo. We demonstrate that CD206-targeted in vivo SPECT imaging with 99mTc-tilmanocept was able to accurately detect and quantify the increase in CD206+ macrophages from early to advanced stages of experimental fibrosis and ex vivo in lung biopsies from patients with IPF. CD206-targeted imaging also specifically detected a decrease in CD206+ lung macrophages on nintedanib and tofacitinib treatment. Importantly, early in vivo imaging of CD206+ macrophages allowed the prediction of experimental lung fibrosis progression as well as nintedanib and tofacitinib efficacy. CONCLUSIONS: These findings indicate that M2 macrophages may be relevant theranostic targets for personalised medicine for patients with PPF.

High risk of lung cancer in surfactant-related gene variant carriers.

BACKGROUND: Several rare surfactant-related gene (SRG) variants associated with interstitial lung disease are suspected to be associated with lung cancer, but data are missing. We aimed to study the epidemiology and phenotype of lung cancer in an international cohort of SRG variant carriers. METHODS: We conducted a cross-sectional study of all adults with SRG variants in the OrphaLung network and compared lung cancer risk with telomere-related gene (TRG) variant carriers. RESULTS: We identified 99 SRG adult variant carriers (SFTPA1 (n=18), SFTPA2 (n=31), SFTPC (n=24), ABCA3 (n=14) and NKX2-1 (n=12)), including 20 (20.2%) with lung cancer (SFTPA1 (n=7), SFTPA2 (n=8), SFTPC (n=3), NKX2-1 (n=2) and ABCA3 (n=0)). Among SRG variant carriers, the odds of lung cancer was associated with age (OR 1.04, 95% CI 1.01-1.08), smoking (OR 20.7, 95% CI 6.60-76.2) and SFTPA1/SFTPA2 variants (OR 3.97, 95% CI 1.39-13.2). Adenocarcinoma was the only histological type reported, with programmed death ligand-1 expression ≥1% in tumour cells in three samples. Cancer staging was localised (I/II) in eight (40%) individuals, locally advanced (III) in two (10%) and metastatic (IV) in 10 (50%). We found no somatic variant eligible for targeted therapy. Seven cancers were surgically removed, 10 received systemic therapy, and three received the best supportive care according to their stage and performance status. The median overall survival was 24 months, with stage I/II cancers showing better survival. We identified 233 TRG variant carriers. The comparative risk (subdistribution hazard ratio) for lung cancer in SRG patients versus TRG patients was 18.1 (95% CI 7.1-44.7). CONCLUSIONS: The high risk of lung cancer among SRG variant carriers suggests specific screening and diagnostic and therapeutic challenges. The benefit of regular computed tomography scan follow-up should be evaluated.

Chronic interstitial lung disease associated with systemic lupus erythematosus: A multicentric study of 89 cases.

BACKGROUND AND OBJECTIVE: Chronic interstitial lung disease (ILD) occurs rarely with systemic lupus erythematosus (SLE) as compared with other connective tissue diseases. This multicentric retrospective study of patients with SLE-ILD from the OrphaLung and French SLE networks during 2005-2020 aimed to describe the characteristics of patients with SLE-ILD and analyse factors associated with prognosis. METHODS: We analysed data for 89 patients with SLE-ILD (82 women, 92.1%) (median age at SLE diagnosis: 35 years [interquartile range 27-47]). All patients met the 2019 EULAR/ACR criteria for the diagnosis of SLE. RESULTS: Forty two (47.2%) patients were positive for anti-ribonuclear protein antibodies and 45 (50.6%) for anti SSA/Ro antibodies. A total of 58 (65.2%) patients had another connective tissue disease: Sjögren's syndrome (n = 33, 37.1%), systemic sclerosis (n = 14, 15.7%), inflammatory myopathy (n = 6, 6.7%), or rheumatoid arthritis (n = 6, 6.7%). ILD was diagnosed along with SLE in 25 (28.1%) patients and at a median of 6 (0-14) years after the SLE diagnosis. The most frequent CT pattern was suggestive of non-specific interstitial pneumonia (n = 41, 46.0%) with or without superimposed organizing pneumonia. After a median follow-up of 86.5 [39.5-161.2] months, 18 (20.2%) patients had died and 6 (6.7%) underwent lung transplantation. The median 5-year and 10-year transplantation-free survival were 96% (92-100) and 87% (78-97). In total, 44 (49.4%) patients showed ILD progression. Cutaneous manifestations and Raynaud's phenomenon were associated with better survival. Only forced vital capacity was significantly associated with survival and ILD progression. CONCLUSION: ILD is a rare manifestation of SLE with good overall prognosis but with possible risk of ILD progression. Patients with SLE-ILD frequently have another connective tissue disease.

Chronic respiratory diseases are predictors of severe outcome in COVID-19 hospitalised patients: a nationwide study.

BACKGROUND: Influenza epidemics were initially considered to be a suitable model for the COVID-19 epidemic, but there is a lack of data concerning patients with chronic respiratory diseases (CRDs), who were supposed to be at risk of severe forms of COVID-19. METHODS: This nationwide retrospective cohort study describes patients with prior lung disease hospitalised for COVID-19 (March-April 2020) or influenza (2018-2019 influenza outbreak). We compared the resulting pulmonary complications, need for intensive care and in-hospital mortality depending on respiratory history and virus. RESULTS: In the 89 530 COVID-19 cases, 16.03% had at least one CRD, which was significantly less frequently than in the 45 819 seasonal influenza patients. Patients suffering from chronic respiratory failure, chronic obstructive pulmonary disease, asthma, cystic fibrosis and pulmonary hypertension were under-represented, contrary to those with lung cancer, sleep apnoea, emphysema and interstitial lung diseases. COVID-19 patients with CRDs developed significantly more ventilator-associated pneumonia and pulmonary embolism than influenza patients. They needed intensive care significantly more often and had a higher mortality rate (except for asthma) when compared with patients with COVID-19 but without CRDs or patients with influenza. CONCLUSIONS: Patients with prior respiratory diseases were globally less likely to be hospitalised for COVID-19 than for influenza, but were at higher risk of developing severe COVID-19 and had a higher mortality rate compared with influenza patients and patients without a history of respiratory illness.

Impact of COVID-19 and lockdowns on pulmonary embolism in hospitalized patients in France: a nationwide study.

BACKGROUND: This study assessed the impact of the COVID-19 epidemic on overall hospitalizations for pulmonary embolism (PE) in France in comparison with previous years, and by COVID-19 and non-COVID-19 status. METHODS: Hospitalization data (2017-2020) were extracted from the French National Discharge database (all public and private hospitals). We included all patients older than 18 years hospitalized during the 3 years and extracted PE status and COVID-19 status (from March 2020). Age, sex and risk factors for PE (such as obesity, cancer) were identified. We also extracted transfer to an intensive care unit (ICU) and hospital death. The number of PE and the frequency of death in patients in 2019 and 2020 were described by month and by COVID-19 status. Logistic regressions were performed to identify the role of COVID-19 among other risk factors for PE in hospitalized patients. RESULTS: The overall number of patients hospitalized with PE increased by about 16% in 2020 compared with 2019, and mortality also increased to 10.3% (+ 1.2%). These increases were mostly linked to COVID-19 waves, which were associated with PE hospitalization in COVID-19 patients (PE frequency was 3.7%; 2.8% in non-ICU and 8.8% in ICU). The final PE odds ratio for COVID-19 hospitalized patients was 4 compared with other hospitalized patients in 2020. The analyses of PE in non-COVID-19 patients showed a 2.7% increase in 2020 compared with the previous three years. CONCLUSION: In 2020, the overall number of patients hospitalized with PE in France increased compared to the previous three years despite a considerable decrease in scheduled hospitalizations. Nevertheless, proactive public policy focused on the prevention of PE in all patients should be encouraged.

Management of patients with pulmonary mycobacteriosis in France: a multicenter retrospective cohort study.

BACKGROUND: Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis. METHODS: To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not). RESULTS: 477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors. CONCLUSION: These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

TRIM33 prevents pulmonary fibrosis by impairing TGF-ß1 signalling.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a devastating disease characterised by myofibroblast proliferation and abnormal extracellular matrix accumulation in the lungs. Transforming growth factor (TGF)-ß1 initiates key profibrotic signalling involving the SMAD pathway and the small heat shock protein B5 (HSPB5). Tripartite motif-containing 33 (TRIM33) has been reported to negatively regulate TGF-ß/SMAD signalling, but its role in fibrogenesis remains unknown. The objective of this study was to elucidate the role of TRIM33 in IPF. METHODS: TRIM33 expression was assessed in the lungs of IPF patients and rodent fibrosis models. Bone marrow-derived macrophages (BMDM), primary lung fibroblasts and 3D lung tissue slices were isolated from Trim33-floxed mice and cultured with TGF-ß1 or bleomycin (BLM). Trim33 expression was then suppressed by adenovirus Cre recombinase (AdCre). Pulmonary fibrosis was evaluated in haematopoietic-specific Trim33 knockout mice and in Trim33-floxed mice that received AdCre and BLM intratracheally. RESULTS: TRIM33 was overexpressed in alveolar macrophages and fibroblasts in IPF patients and rodent fibrotic lungs. Trim33 inhibition in BMDM increased TGF-ß1 secretion upon BLM treatment. Haematopoietic-specific Trim33 knockout sensitised mice to BLM-induced fibrosis. In primary lung fibroblasts and 3D lung tissue slices, Trim33 deficiency increased expression of genes downstream of TGF-ß1. In mice, AdCre-Trim33 inhibition worsened BLM-induced fibrosis. In vitro, HSPB5 was able to bind directly to TRIM33, thereby diminishing its protein level and TRIM33/SMAD4 interaction. CONCLUSION: Our results demonstrate a key role of TRIM33 as a negative regulator of lung fibrosis. Since TRIM33 directly associates with HSPB5, which impairs its activity, inhibitors of TRIM33/HSPB5 interaction may be of interest in the treatment of IPF.

Usual interstitial pneumonia in ANCA-associated vasculitis: A poor prognostic factor.

BACKGROUND: Progressive fibrosing interstitial lung disease (ILD) is rarely associated with antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). This study focused on the outcomes of ILD patients with associated AAV (AAV-ILD). METHODS: AAV-ILD (cases: microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA) with ILD) were compared to AAV patients without ILD (controls). ILD was defined as a usual interstitial pneumonia (UIP) or non-specific interstitial pneumonia (NSIP) pattern. Two controls were matched to each case for age (>or ≤65 years), ANCA status (PR3-or MPO-positive) and creatininemia (≥or <150 µmol/L). RESULTS: Sixty-two cases (89% MPO-ANCA+) were included. Median age at AAV diagnosis was 66 years. ILD (63% UIP), was diagnosed before (52%) or simultaneously (39%) with AAV. Cases versus 124 controls less frequently had systemic vasculitis symptoms. One-, 3- and 5-year overall survival rates, respectively, were: 96.7%, 80% and 66% for cases versus 93.5%, 89.6% and 83.8% for controls (p = 0.008). Multivariate analyses retained age >65 years (hazard ratio (HR) 4.54; p < 0.001), alveolar haemorrhage (HR 2.25; p = 0.019) and UIP (HR 2.73; p = 0.002), but not immunosuppressant use, as factors independently associated with shorter survival. CONCLUSION: For AAV-ILD patients, only UIP was associated with poorer prognosis. Immunosuppressants did not improve the AAV-ILD prognosis. But in analogy to idiopathic pulmonary fibrosis, anti-fibrosing agents might be useful and should be assessed in AAV-ILD patients with a UIP pattern.

Monitoring of noninvasive ventilation: comparative analysis of different strategies.

BACKGROUND: Noninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO2). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO2) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy. METHODS: This retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO2, TcPCO2 and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO2), B (nocturnal SpO2 + TcPCO2) and C (TcPCO2 + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal). RESULTS: NIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia. CONCLUSION: Monitoring ABG and nocturnal SpO2 is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO2 seems to represent the best strategy to detect poor NIV efficacy. Trial registration Institutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges).

Pathogenesis of fibrosis in interstitial lung disease.

PURPOSE OF REVIEW: Pulmonary fibrosis is a chronic and progressive lung disease involving unclear pathological mechanisms. The present review presents and discusses the major and recent advances in our knowledge of the pathogenesis of lung fibrosis. RECENT FINDINGS: The past months have deepened our understanding on the cellular actors of fibrosis with a better characterization of the abnormal lung epithelial cells observed during lung fibrosis. Better insight has been gained into fibroblast biology and the role of immune cells during fibrosis. Mechanistically, senescence appears as a key driver of the fibrotic process. Extracellular vesicles have been discovered as participating in the impaired cellular cross-talk during fibrosis and deeper understanding has been made on developmental signaling in lung fibrosis. SUMMARY: This review emphasizes the contribution of different cell types and mechanisms during pulmonary fibrosis, highlights new insights for identification of potential therapeutic strategies, and underlines where future research is needed to answer remaining open questions.

CXCL10 could drive longer duration of mechanical ventilation during COVID-19 ARDS.

BACKGROUND: COVID-19-related ARDS has unique features when compared with ARDS from other origins, suggesting a distinctive inflammatory pathogenesis. Data regarding the host response within the lung are sparse. The objective is to compare alveolar and systemic inflammation response patterns, mitochondrial alarmin release, and outcomes according to ARDS etiology (i.e., COVID-19 vs. non-COVID-19). METHODS: Bronchoalveolar lavage fluid and plasma were obtained from 7 control, 7 non-COVID-19 ARDS, and 14 COVID-19 ARDS patients. Clinical data, plasma, and epithelial lining fluid (ELF) concentrations of 45 inflammatory mediators and cell-free mitochondrial DNA were measured and compared. RESULTS: COVID-19 ARDS patients required mechanical ventilation (MV) for significantly longer, even after adjustment for potential confounders. There was a trend toward higher concentrations of plasma CCL5, CXCL2, CXCL10, CD40 ligand, IL-10, and GM-CSF, and ELF concentrations of CXCL1, CXCL10, granzyme B, TRAIL, and EGF in the COVID-19 ARDS group compared with the non-COVID-19 ARDS group. Plasma and ELF CXCL10 concentrations were independently associated with the number of ventilator-free days, without correlation between ELF CXCL-10 and viral load. Mitochondrial DNA plasma and ELF concentrations were elevated in all ARDS patients, with no differences between the two groups. ELF concentrations of mitochondrial DNA were correlated with alveolar cell counts, as well as IL-8 and IL-1ß concentrations. CONCLUSION: CXCL10 could be one key mediator involved in the dysregulated immune response. It should be evaluated as a candidate biomarker that may predict the duration of MV in COVID-19 ARDS patients. Targeting the CXCL10-CXCR3 axis could also be considered as a new therapeutic approach. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03955887.

Increasing burden of noninfectious lung disease in persons living with HIV: a 7-year study using the French nationwide hospital administrative database.

An overall reduction in the incidence of AIDS and a change in the spectrum of lung disease have been noticed in persons living with HIV (PLHIV). Our aim was to provide an epidemiological update regarding the prevalence of lung diseases in PLHIV hospitalised in France.We analysed the prevalence of lung disease in PLHIV hospitalised in France from 2007 to 2013, from the French nationwide hospital medical information database, and assessed the association between HIV and incident noninfectious disease over 4 years of follow-up.A total of 52 091 PLHIV were hospitalised in France between 2007 and 2013. Among PLHIV hospitalised with lung disease, noninfectious lung diseases increased significantly from 45.6% to 54.7% between 2007 and 2013, whereas the proportion of patients with at least one infectious lung disease decreased significantly. In 2010, 10 067 prevalent hospitalised PLHIV were compared with 8 244 682 hospitalised non-PLHIV. In 30-49-year-old patients, HIV infection was associated with chronic obstructive pulmonary disease (COPD), chronic respiratory failure, emphysema, lung fibrosis and pulmonary arterial hypertension (PAH) even after adjustment for smoking.The emergence of noninfectious lung disease, in particular COPD, emphysema, lung fibrosis, PAH and chronic respiratory disease, in PLHIV would justify mass screening in this population.

Halo Sign and Eosinophilia: What Is Your Diagnosis?

Blood eosinophilia associated with transient and migrating nodules with a halo sign on chest computed tomography scan should suggest larva migrans related to toxocariasis or ascaris suum.

Pleural inhibition of the caspase-1/IL-1ß pathway diminishes profibrotic lung toxicity of bleomycin.

BACKGROUND: Idiopathic and toxic pulmonary fibrosis are severe diseases starting classically in the subpleural area of the lung. It has recently been suggested that pleural mesothelial cells acquire a myofibroblast phenotype under fibrotic conditions induced by TGF-ß1 or bleomycin. The importance and role of inflammation in fibrogenesis are still controversial. In this work, we explored the role of IL-1ß/caspase-1 signaling in bleomycin lung toxicity and in pleural mesothelial cell transformation. METHODS: C57BL/6 mice were intravenously injected with either bleomycin or nigericin or NaCl as control. In vitro, the Met5A cell line was used as a model of human pleural mesothelial cells. RESULTS: Intravenous injections of bleomycin induced lung fibrosis with histologically-proven peripheral distribution, collagen accumulation in the pleural and subpleural area, and overexpression of markers of myofibroblast transformation of pleural cells which migrated into the lung. These events were associated with an inflammatory process with an increase in neutrophil recruitment in pleural lavage fluid and increased caspase-1 activity. TGF-ß1 was also overexpressed in pleural lavage fluid and was produced by pleural cells following intravenous bleomycin. In this model, local pleural inhibition of IL-1ß with the IL-1ß inhibitor anakinra diminished TGF-ß1 and collagen accumulation. In vitro, caspase-1 inhibition interfered with Met5A cell transformation into the myofibroblast-like phenotype induced by bleomycin or TGF-ß1. Moreover, nigericin, a caspase-1 activator, triggered transformation of Met5A cells and its intra-pleural delivery induced fibrogenesis in mice. CONCLUSIONS: We demonstrated, after intravenous bleomycin injection in mice, the role of the pleura and highlighted the key role of IL-1ß/caspase-1 axis in this fibrogenesis process.

Pharmacological management of IPF.

Idiopathic pulmonary fibrosis (IPF) is a deadly disease with a median survival of approximately three years in historical cohorts. Despite increased knowledge of disease pathophysiology and selection of more targeted therapy, main clinical trials yielded negative results. However, two agents, pirfenidone and nintedanib, were recently shown to be effective in IPF and received marketing authorization worldwide. Both drugs significantly reduce functional decline and disease progression with an acceptable safety profile. Yet, none of these drugs actually improves or even stabilizes the disease or the symptoms perceived by the patient. Several other treatments and combinations are currently tested, and many more are ready for clinical trials. Their completion is critical for achieving the ultimate goal of curing patients with IPF.

Haemoptysis in adults: a 5-year study using the French nationwide hospital administrative database.

Haemoptysis is a serious symptom with various aetiologies. Our aim was to define the aetiologies, outcomes and associations with lung cancer in the entire population of a high-income country.This retrospective multicentre study was based on the French nationwide hospital medical information database collected over 5 years (2008-2012). We analysed haemoptysis incidence, aetiologies, geographical and seasonal distribution and mortality. We studied recurrence, association with lung cancer and mortality in a 3-year follow-up analysis.Each year, ~15 000 adult patients (mean age 62 years, male/female ratio 2/1) were admitted for haemoptysis or had haemoptysis as a complication of their hospital stay, representing 0.2% of all hospitalised patients. Haemoptysis was cryptogenic in 50% of cases. The main aetiologies were respiratory infections (22%), lung cancer (17.4%), bronchiectasis (6.8%), pulmonary oedema (4.2%), anticoagulants (3.5%), tuberculosis (2.7%), pulmonary embolism (2.6%) and aspergillosis (1.1%). Among incident cases, the 3-year recurrence rate was 16.3%. Of the initial cryptogenic haemoptysis patients, 4% were diagnosed with lung cancer within 3 years. Mortality rates during the first stay and at 1 and 3 years were 9.2%, 21.6% and 27%, respectively.This is the first epidemiological study analysing haemoptysis and its outcomes in an entire population. Haemoptysis is a life-threatening symptom unveiling potentially life-threatening underlying conditions.

Residual upper airway obstruction during nocturnal noninvasive ventilation despite high positive expiratory pressure. Impact of oronasal mask to nasal mask switch.

BACKGROUND: Nasal mask (NM) and oronasal masks (OM) can be used to provide noninvasive ventilation (NIV). Recent studies suggested that OM is the most used interface and that there is no difference in efficacy or in tolerance between OM and NM for chronic use. However, studies focusing on video laryngoscopy underlined the impact of OM in residual upper airway obstruction (UAO) under NIV. We sought to assess the real-life practice of switching from OM to NM when UAO events persist despite high EPAP levels. METHODS: In an open-label single center prospective cohort study, data from files and full night polysomnography on NM and OM were collected for patients wearing OM and presenting an UAO index ≥15/h despite an EPAP level ≥ 10 cmH20. RESULTS: Forty-four patients were included in the study. In 31 patients (74 %), switching to a NM reduced UAOi to ≥10/h. Interestingly, 92 % of these patients still had NM at 3 to 12 months of follow-up. Switching to a NM was also associated with a trend in paCO2 reduction and significant improvements in Epworth, sleep quality and NIV compliance. Successful interface switching was significantly associated with female gender, and a trend was observed in non-smokers. CONCLUSION: As for CPAP, switching to a NM improved NIV efficacy in a selected group of patients presenting residual UAO events despite high EPAP levels. Additionally, this switch has an impact on compliance and subjective sleepiness. Thus, in patients with persisting UAO on OM, switching to a NM could be a first-line intervention before considering further investigation such as polygraphy or video laryngoscopy. We also derive an algorithm for mask allocation and adaptation in acute and chronic NIV use.