POS0906 PREVALENCE OF SPECIFIC AND ASSOCIATED MYOSITIS ANTIBODIES IN A COHORT OF PNEUMOLOGICAL PATIENTS: FROM THE DIAGNOSIS OF INTERSTITIAL LUNG DISEASE TO A POSSIBLE DIAGNOSIS OF CONNECTIVE TISSUE DISEASE

Background

Interstitial lung disease (ILD) could be the first and only manifestation of idiopathic inflammatory myopathies (IIMs). Myositis-associated (MAA) or myositis-specific autoantibodies (MSA) are found in 60%-65% of cases [1, 2], but only anti-Jo1 have been included in EULAR 2017 criteria [3].

Objectives

Aim of this work is to evaluate the presence of MSA/MAA in patients with ILD on serum analyzed by line blot (LB) immunoassay, the associated clinical diagnoses and the consistency of these diagnoses with antibody specificity.

Methods

Between march 2017 and march 2021, 267 sera were analyzed for MSA/MAA, 84 (31.4%) of which requested after a pneumological evaluation. The search was performed by LB (EUROLINE, Autoimmune Inflammatory Myopathies 16 Ag Profile). Medical records were analyzed for patients with at least one MSA/MAA and diagnosis divided in: connective tissue disease (CTD), interstitial pneumonia with autoimmune features (IPAF) or only pneumological diagnosis.

Results

A positivity for at least one MSA/MAA was found in 37/84 (44%) patients that had the following pneumological diagnosis: 13 non-specific interstitial pneumonia (NSIP, 35.1%), 10 organizing pneumonia (OP, 27%), 10 usual interstitial pneumonia (UIP, 27%), 1 acute interstitial pneumonia (AIP, 2.7%), 1 lymphoid interstitial pneumonia (LIP, 2.7%), 1 iatrogenic ILD for amiodarone (2.7%) and 1 idiopathic pulmonary artery hypertension (IPAH, 2.7%).

Distribution of antibodies is reported in Table 1. The most frequent autoantibody was anti-Ro52 (13 sera, 35.2%), while anti-Mi2 was the most frequent MSA (10 sera, 32.4%) followed by anti-Jo1 and anti-SRP with 5 (13.5%) positive sera each. In Figure 1 the heat-map represents the frequency of MSA/MAA and their mutual associations. Multiple autoantibodies were found in 17 (46%) sera. More than one MSA was found in 8 (21.6%) sera of patients with the following diagnosis: 4 only pneumological diseases, 3 ASS and 1 IPAF.

Table 1.

Distribution of MSA/MAA and associated autoimmune diseases

Autoantibodies distribution N (%)Sera with a single MSA/MAA (N/positive; %)CTD* (N/positive; %)IPAF (N/positive; %)MSAJo-1 = 5 (13.5)2/5 (40)3/5 (60)0PL7 = 4 (10.8)02/4 (50)1/4 (25)PL12 = 6 (16.2)3/6 (50)3/6 (50)0OJ = 3 (8.1)2/3 (66.6)1/3 (33.3)2/3 (66.6)EJ = 1 (2.7)1/1 (100)1/1 (100)0Mi-2 = 10 (32.4)3/10 (30)2/10 (20)0NXP2 = 1 (2.7)001/1 (100)SRP = 5 (13.5)2/5 (40)2/5 (40)0TIF1gamma = 2 (5.4)01/2 (50)0MAARo-52 = 13 (35.2)3/13 (23)9/13 (69.2)1/13 (7.6)PM/Scl = 6 (18.9)4/6 (66.6)01/6 (16.6)

For some patients there are multiple positive antibodies.

*The following diagnosis were included: antisynthetase syndrome, dermatomyositis, polymyositis and systemic sclerosis.

During the diagnostic work-up, at least one MSA/MAA were detected in 13 patients diagnosed with a CTD (35%), 5 with a IPAF (13%), 19 (51%) only a pneumological diagnosis. Of these 19 patients, 11 (57.9%) had a single autoantibody positivity (8 for a MSA, 3 for a MAA) while 8 (42.1%) had multiple positivity (4 with a MSA plus MAA and 4 with multiple MSA positivity).

The most frequently diagnosed CTD was ASS with 9 patients (24.3%), followed by 2 polymyositis (5.4%), 1 dermatomyositis (2.7%) and 1 systemic sclerosis (2.7%). Pulmonary involvement in patients with CTD was represented by 9 cases of NSIP (69,3%) and 4 UIP (30,7%).

Conclusion

During the last 4 years about 1/3 of research for MSA/MAA requests to our laboratory had a pneumological indication and MSA/MAA were found in 44% of these patients. In patients with pulmonary involvement and MSA/MAA positivity 35% developed a CTD. Interstitial lung disease could be the first manifestation of a systemic autoimmune disease: research for MSA/MAA and a collaboration between rheumatologist and pneumologist allows a correct diagnostic work-up and therapeutic approach.

References

[1]Betteridge Z, et al. J Autoimmun 2019;101:48-55

[2]Vojinovic T, et al. Clin Rev Allergy Immunol. 2021 Feb;60(1):87-94

[3]Lundberg IE, et al. Ann Rheum Dis 2107;76:1955-1964

Disclosure of Interests

None declared

One-year pulmonary impairment after severe COVID-19: a prospective, multicenter follow-up study

Background

Long-term pulmonary sequelae following hospitalization for SARS-CoV-2 pneumonia is largely unclear. The aim of this study was to identify and characterise pulmonary sequelae caused by SARS-CoV-2 pneumonia at 12-month from discharge.

Methods

In this multicentre, prospective, observational study, patients hospitalised for SARS-CoV-2 pneumonia and without prior diagnosis of structural lung diseases were stratified by maximum ventilatory support (“oxygen only”, “continuous positive airway pressure (CPAP)” and “invasive mechanical ventilation (IMV)”) and followed up at 12 months from discharge. Pulmonary function tests and diffusion capacity for carbon monoxide (DLCO), 6 min walking test, high resolution CT (HRCT) scan, and modified Medical Research Council (mMRC) dyspnea scale were collected.

Results

Out of 287 patients hospitalized with SARS-CoV-2 pneumonia and followed up at 1 year, DLCO impairment, mainly of mild entity and improved with respect to the 6-month follow-up, was observed more frequently in the “oxygen only” and “IMV” group (53% and 49% of patients, respectively), compared to 29% in the “CPAP” group. Abnormalities at chest HRCT were found in 46%, 65% and 80% of cases in the “oxygen only”, “CPAP” and “IMV” group, respectively. Non-fibrotic interstitial lung abnormalities, in particular reticulations and ground-glass attenuation, were the main finding, while honeycombing was found only in 1% of cases. Older patients and those requiring IMV were at higher risk of developing radiological pulmonary sequelae. Dyspnea evaluated through mMRC scale was reported by 35% of patients with no differences between groups, compared to 29% at 6-month follow-up.

Conclusion

DLCO alteration and non-fibrotic interstitial lung abnormalities are common after 1 year from hospitalization due to SARS-CoV-2 pneumonia, particularly in older patients requiring higher ventilatory support. Studies with longer follow-ups are needed.

Nutritional assessment in idiopathic pulmonary fibrosis: a prospective multicentre study

Background

Nutritional status impacts quality of life and prognosis of patients with respiratory diseases, including idiopathic pulmonary fibrosis (IPF). However, there is a lack of studies performing an extensive nutritional assessment of IPF patients. This study aimed to investigate the nutritional status and to identify nutritional phenotypes in a cohort of IPF patients at diagnosis.

Methods

Patients underwent a thorough pulmonary and nutritional evaluation including questionnaires on nutritional status, and physical activity, anthropometry, body impedance, dynamometry, 4-m gait speed and blood tests.

Results

90 IPF patients (78.9% males, mean age 72.7 years) were enrolled. The majority of patients were classified as Gender-Age-Physiology Index stage 2 (47, 52.2%) with an inactive lifestyle according to International Physical Activity Questionnaire score (39, 43.3%), and had mean forced vital capacity and diffusing capacity for carbon monoxide 86.5% and 54.2%, respectively. In regards to nutritional phenotypes, the majority of patients were normally nourished (67.8%, 95% CI 58.6–77.7%), followed by non-sarcopenic obese (25.3%, 95% CI 16.1–35.2%), sarcopenic (4.6%, 95% CI 0.0–14.5%) and sarcopenic obese (2.3%, 95% CI 0.0–12.2%). Among the normally nourished, 49.2% showed early signs of nutritional and physical performance alterations, including body mass index ≥30 kg·m⁻² in 4.3%, history of weight loss ≥5% in 11.9%, and reduction of gait speed and hand grip strength in 11.9% and 35.6%, respectively. Low vitamin D values were observed in 56.3% of cases.

Conclusions

IPF patients at diagnosis are mainly normally nourished and obese, but early signs of nutritional and physical performance impairment can already be identified at this stage.

Patients with IPF at diagnosis are mainly normally nourished and obese but early signs of nutritional and physical performance impairment can already be identified. Sarcopenia is identified only in a minority of cases; cachexia has not been observed.https://bit.ly/3kZuRh2

Six-Month Pulmonary Impairment after Severe COVID-19: A Prospective, Multicentre Follow-Up Study

BACKGROUND

Long-term pulmonary sequelae following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia are not yet confirmed; however, preliminary observations suggest a possible relevant clinical, functional, and radiological impairment.

OBJECTIVES

The aim of this study was to identify and characterize pulmonary sequelae caused by SARS-CoV-2 pneumonia at 6-month follow-up.

METHODS

In this multicentre, prospective, observational cohort study, patients hospitalized for SARS-CoV-2 pneumonia and without prior diagnosis of structural lung diseases were stratified by maximum ventilatory support ("oxygen only," "continuous positive airway pressure," and "invasive mechanical ventilation") and followed up at 6 months from discharge. Pulmonary function tests and diffusion capacity for carbon monoxide (DLCO), 6-min walking test, chest X-ray, physical examination, and modified Medical Research Council (mMRC) dyspnoea score were collected.

RESULTS

Between March and June 2020, 312 patients were enrolled (83, 27% women; median interquartile range age 61.1 [53.4, 69.3] years). The parameters that showed the highest rate of impairment were DLCO and chest X-ray, in 46% and 25% of patients, respectively. However, only a minority of patients reported dyspnoea (31%), defined as mMRC ≥1, or showed restrictive ventilatory defects (9%). In the logistic regression model, having asthma as a comorbidity was associated with DLCO impairment at follow-up, while prophylactic heparin administration during hospitalization appeared as a protective factor. The need for invasive ventilatory support during hospitalization was associated with chest imaging abnormalities.

CONCLUSIONS

DLCO and radiological assessment appear to be the most sensitive tools to monitor patients with the coronavirus disease 2019 (COVID-19) during follow-up. Future studies with longer follow-up are warranted to better understand pulmonary sequelae.

Predictive Features and Clinical Presentation of Interstitial Lung Disease in Inflammatory Myositis

Interstitial lung disease (ILD) represents one of the most severe extra-muscular features of idiopathic inflammatory myositis (IIM). We aimed to identify any clinical and serological predictors of ILD in a monocentric cohort of 165 IIM patients.

ILD+ patients were defined as having restrictive impairment in lung function tests and signs of ILD at chest high-resolution computed tomography (HRCT). Available HRCT images were centralized and classified in different ILD patterns: non-specific interstitial pneumonia (NSIP), organizing pneumonia (OP), usual interstitial pneumonia-like (UIP), indeterminate for UIP, and interstitial lung abnormalities (ILA). Lung function test data were recorded at onset, at 1 and 5 years after ILD diagnosis.

ILD was found in 52 IIM patients (31.5%): 46.2% was affected by anti-synthetase syndrome (ARS), 21% by polymyositis (PM), 19% by dermatomyositis (DM), and 13.5% by overlap myositis. Most of ILD+ showed NSIP (31.9%), OP (19%), indeterminate for UIP (19%), and UIP (12.8%) patterns. At multivariate analysis, ILD was predicted by anti-Ro52 (p: 0.0026) and dyspnea (p: 0.015) at IIM onset. Most of ILD onset within is 12 months after IIM. In five cases, ILD occurs after 12 months since IIM diagnosis: these patients more frequently show dry cough and anti-Ku antibodies. Anti-Ro52 + ILD patients showed a significant increase of DLCO at 1 and 5 years of follow-up, compared with anti-Ro52 negative cases.

ILD occurs in about one third of IIM and was predicted by dyspnea at onset and anti-Ro52 antibodies. Anti-Ro52 defines a subgroup of ILD showing a significant improvement of DLCO during follow-up.

This retrospective study has been approved by local ethic committee (ASST-Spedali Civili of Brescia, Italy); protocol number: NP3511

Tocilizumab for the treatment of severe COVID-19 pneumonia with hyperinflammatory syndrome and acute respiratory failure: A single center study of 100 patients in Brescia, Italy

A hyperinflammatory syndrome (HIS) may cause a life-threatening acute respiratory distress syndrome (ARDS) in patients with COVID-19 pneumonia. A prospective series of 100 consecutive patients admitted to the Spedali Civili University Hospital in Brescia (Italy) between March 9th and March 20th with confirmed COVID-19 pneumonia and ARDS requiring ventilatory support was analyzed to determine whether intravenous administration of tocilizumab (TCZ), a monoclonal antibody that targets the interleukin 6 (IL-6) receptor, was associated with improved outcome. Tocilizumab was administered at a dosage of 8 mg/kg by two consecutive intravenous infusions 12 h apart. A third infusion was optional based on clinical response. The outcome measure was an improvement in acute respiratory failure assessed by means of the Brescia COVID Respiratory Severity Score (BCRSS 0 to 8, with higher scores indicating higher severity) at 24-72 h and 10 days after tocilizumab administration. Out of 100 treated patients (88 M, 12 F; median age: 62 years), 43 received TCZ in the intensive care unit (ICU), while 57 in the general ward as no ICU beds were available. Of these 57 patients, 37 (65%) improved and suspended noninvasive ventilation (NIV) (median BCRSS: 1 [IQR 0-2]), 7 (12%) patients remained stable in NIV, and 13 (23%) patients worsened (10 died, 3 were admitted to ICU). Of the 43 patients treated in the ICU, 32 (74%) improved (17 of them were taken off the ventilator and were discharged to the ward), 1 (2%) remained stable (BCRSS: 5) and 10 (24%) died (all of them had BCRSS≥7 before TCZ). Overall at 10 days, the respiratory condition was improved or stabilized in 77 (77%) patients, of whom 61 showed a significant clearing of diffuse bilateral opacities on chest x-ray and 15 were discharged from the hospital. Respiratory condition worsened in 23 (23%) patients, of whom 20 (20%) died. All the patients presented with lymphopenia and high levels of C-reactive protein (CRP), fibrinogen, ferritin and IL-6 indicating a HIS. During the 10-day follow-up, three cases of severe adverse events were recorded: two patients developed septic shock and died, one had gastrointestinal perforation requiring urgent surgery and was alive at day 10. In conclusion, our series showed that COVID-19 pneumonia with ARDS was characterized by HIS. The response to TCZ was rapid, sustained, and associated with significant clinical improvement.

AB0624 PREDICTIVE PARAMETERS FOR DEVELOPMENT OF INTERSTITIAL LUNG DISEASE IN IDIOPATHIC INFLAMMATORY MYOSITIS

Background:

Idiopathic Inflammatory Myositis (IIM) is a group of heterogeneous connective tissue diseases, primarily characterized by chronic muscle inflammation as well as myositis-specific or myositis-associated autoantibodies and a spectrum of different extra-muscular features.

The most frequent organ involment in IIM is Interstitial Lung Disease (ILD), occurring in 5-80% of different IIMs cases and considered the hallmark of morbidity and mortality in patients with IIMs.

Objectives:

To retrospectively assess the predictive factors for development of ILD in IIM patients

Methods:

We retrospectively analyzed the prevalence of ILD in a single-center cohort of 165 IIM patients. Patient data was collected from clinical charts. ILD was diagnosed by chest X-ray scan and chest CT scan. All chest CT and chest X-ray scans available and performed at our hospital were consequently re-evaluated by our expert pneumologist for uniform evaluation.

Results:

Myositis-related ILD (M-ILD) was found in 52 IIM patients (31.5%): 46.15% was affected by anti-synthetase syndrome (ARS), 21.15% by polymyositis (PM), 19.23% by dermatomyositis (DM) and 13.46% by overlap myositis. The pulmonary involvement was characterized by Non-specific interstitial pneumonia (NSIP) (30.6%), Unusual Interstitial Pneumonia (UIP) (38.77%), Bronchiolitis Obliterans with Organizing Pneumonia (BOOP) (20.4%), overlap NSIP/BOOP (4.1%) and Undetermined/Unspecific pattern (6.12%). Eighty four percent of M-ILD consisted of non-smokers and 69.23% presented with dyspnea at onset.

ILD was diagnosed in 90.38% of patients within the first year of IIM diagnosis (early onset ILD) and was associated with dyspnea and/or cough in 70.2% and 17% respectively. On the other hand, late onset ILD presented mostly with dyspnea and/or cough in 60% of cases and was significantly associated with anti-Ku antobodies.

At onset ILD was significantly associated with: ARS (p<0.0001; OR:12.98), anti-Jo-1 (p<0.0001; OR:6.1), anti-Ro (p=0.038; OR:2.2), mechanic’s hands (p<0.0001; OR:10.41), arthritis (p=0.01; OR:2.58), polyarthritis (p=0.001; OR:4.578), dyspnea (p<0.0001; OR:9.66), and high levels of CPK (p=0.0001) and GOT (p=0.0146). By contrast, the following features: DM (p=0.012; OR:0.36), facial rash (p=0.003; OR:0.31), anti-NXP-2 (p=0.019; OR<0.0001), anti-PL-12 (p=0,03; OR<0.0001) and myositis (p<0.0001; OR:0.173) present at onset were less frequently associated with M-ILD.

At multivariate analysis M-ILD was predicted by anti-Ro (p=0.0448), polyarthritis (p=0.0093) and dyspnea (p=0.0001) at onset. On the other hand, patients presenting myositis (p=0.0383) and facial rash (p=0.0398) at onset were less likely to developed M-ILD.

Conclusion:

ILD occurs in about one third of patients with IIM, mostly affected by ARS. The presence of anti-Ro antibodies as well as polyarthritis and dyspnea at onset predict the development of ILD.

Disclosure of Interests:

None declared

The role of bronchial epithelial cells in the pathogenesis of COPD in Z-alpha-1 antitrypsin deficiency

BACKGROUND

Alpha-1 antitrypsin is the main inhibitor of neutrophil elastase in the lung. Although it is principally synthesized by hepatocytes, alpha-1 antitrypsin is also secreted by bronchial epithelial cells. Gene mutations can lead to alpha-1 antitrypsin deficiency, with the Z variant being the most clinically relevant due to its propensity to polymerize. The ability of bronchial epithelial cells to produce Z-variant protein and its polymers is unknown.

METHODS

Experiments using a conformation-specific antibody were carried out on M- and Z-variant-transfected 16HBE cells and on bronchial biopsies and ex vivo bronchial epithelial cells from Z and M homozygous patients. In addition, the effect of an inflammatory stimulus on Z-variant polymer formation, elicited by Oncostatin M, was investigated. Comparisons of groups were performed using t-test or ANOVA. Non-normally distributed data were assessed by Mann-Whitney U test or the Kruskal-Wallis test, where appropriate. A P value of < 0.05 was considered to be significant.

RESULTS

Alpha-1 antitrypsin polymers were found at a higher concentration in the culture medium of ex vivo bronchial epithelial cells from Z-variant homozygotes, compared with M-variant homozygotes (P < 0.01), and detected in the bronchial epithelial cells and submucosa of patient biopsies. Oncostatin M significantly increased the expression of alpha-1 antitrypsin mRNA and protein (P < 0.05), and the presence of Z-variant polymers in ex vivo cells (P < 0.01).

CONCLUSIONS

Polymers of Z-alpha-1 antitrypsin form in bronchial epithelial cells, suggesting that these cells may be involved in the pathogenesis of lung emphysema and in bronchial epithelial cell dysfunction.

Central airways remodeling in COPD patients

BACKGROUND

The contribution to airflow obstruction by the remodeling of the peripheral airways in chronic obstructive pulmonary disease (COPD) patients has been well documented, but less is known about the role played by the large airways. Few studies have investigated the presence of histopathological changes due to remodeling in the large airways of COPD patients.

OBJECTIVES

The aim of this study was to verify the presence of airway remodeling in the central airways of COPD patients, quantifying the airway smooth muscle (ASM) area and the extracellular matrix (ECM) protein deposition, both in the subepithelial region and in the ASM, and to verify the possible contribution to airflow obstruction by the above mentioned histopathological changes.

METHODS

Biopsies of segmental bronchi spurs were performed in COPD patients and control smoker subjects and immunostained for collagen type I, versican, decorin, biglycan, and alpha-smooth muscle actin. ECM protein deposition was measured at both subepithelial, and ASM layers.

RESULTS

The staining for collagen I and versican was greater in the subepithelial layer of COPD patients than in control subjects. An inverse correlation was found between collagen I in the subepithelial layer and both forced expiratory volume in 1 second and ratio between forced expiratory volume in 1 second and forced vital capacity. A statistically significant increase of the ASM area was observed in the central airways of COPD patients versus controls.

CONCLUSION

These findings indicate that airway remodeling also affects the large airways in COPD patients who have greater deposition of ECM proteins in the subepithelial layer and a larger smooth muscle area than control smoker subjects. These changes may contribute to chronic airflow obstruction in COPD patients.

Lung function decline in COPD

The landmark study of Fletcher and Peto on the natural history of tobacco smoke-related chronic airflow obstruction suggested that decline in the forced expiratory volume in the first second (FEV(1)) in chronic obstructive pulmonary disease (COPD) is slow at the beginning, becoming faster with more advanced disease. The present authors reviewed spirometric data of COPD patients included in the placebo arms of recent clinical trials to assess the lung function decline of each stage, defined according to the severity of airflow obstruction as proposed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. In large COPD populations the mean rate of FEV(1) decline in GOLD stages II and III is between 47 and 79 mL/year and 56 and 59 mL/year, respectively, and lower than 35 mL/year in GOLD stage IV. Few data on FEV(1) decline are available for GOLD stage I. Hence, the loss of lung function, assessed as expiratory airflow reduction, seems more accelerated and therefore more relevant in the initial phases of COPD. To have an impact on the natural history of COPD, it is logical to look at the effects of treatment in the earlier stages.

Effects on small airway obstruction of long-term treatments with beclomethasone/formoterol hydrofluoroalkane (metered-dose inhaler) versus fluticasone/salmeterol (dry-powder inhaler) in asthma: a preliminary study

New formulations of extrafine particles of long-acting beta-2 agonists plus inhaled corticosteroids (LABA + ICS) have been shown to reach peripheral regions of the lung. The aim of the study was to assess the effect on small airway obstruction of long-term treatments with two different LABA + ICS formulations in asthma. Ten subjects with moderate persistent asthma were enrolled. After a 4-week washout period they were treated in a randomized crossover design for 24 weeks with formoterol, 12 micrograms, and beclomethasone, 200 micrograms, hydrofluoroalkane (HFA; by metered-dose inhaler) b.i.d. (FB) or salmeterol, 50 micrograms, and fluticasone, 250 micrograms (by dry-powder inhaler), b.i.d. (SF). At baseline and at the end of each period subjects underwent an Asthma Control Test (ACT) and Pulmonary Function Testing. The N(2) phase III slope and closing volume (CV) during single-breath washout test and difference between the maximal expiratory flow rates with air and heliox at isovolume corresponding to 50% [Delta(heliox-air)MEF(50%)] were measured to assess changes on peripheral airways function. Two subjects dropped out and eight completed the study. After SF and FB, forced expiratory volume at 1 second (FEV(1); p < 0.01) and FEV(1)/forced vital capacity (FVC; p < 0.01 for SF and p < 0.05 for FB) increased when compared with baseline. Although both FB and SF treatments slightly increased delta(heliox-air)MEF(50% isovolume) versus baseline, only after FB the N(2) phase III slope and CV decreased from 1.61 ± 0.61%/L to 1.35 ± 0.49 N(2)%/L (p = 0.054) and from 0.98 ± 0.56 L to 0.88 ± 0.58 L (p < 0.05), respectively. ACT score raised from 19 ± 5 (baseline) to 23 ± 1 after FB (p < 0.02) and 23 ± 2 after SF (p < 0.05). When compared with baseline and in contrast to SF (50/250 micrograms b.i.d.), FB HFA (12/200 micrograms b.i.d.) significantly improved functional parameters reflecting small airway obstruction in asthmatic patients. Registered in the public trial registry at www.ClinicalTrials.gov identifier: NCT01255579.

Predictors of nocturnal oxyhemoglobin desaturation in COPD

It would be useful to detect predictors of marked nocturnal oxyhemoglobin desaturation (NOD) among COPD patients, who do not have respiratory failure when awake and sleep apnea (SA). Stable COPD patients with awake Pa(O2) ≥ 60 mmHg and Pa(CO2) ≤ 45 mmHg underwent cardio-respiratory polysomnography to exclude SA and to assess NOD. The patients that spent more than 30% of night time with Sp(O2) < 90%, were defined desaturators (D), and the others non desaturators (ND). Pulmonary function testing was performed to determine lung volumes, maximal flow rates, lung diffusion capacity for carbon monoxide and maximal inspiratory and expiratory pressure (P(Imax) and P(Emax)). Negative expiratory pressure test was performed to assess tidal expiratory flow limitation. Supine pharyngometry was performed to determine upper airway size, shuttle walking test to assess exercise desaturation. Twenty-one patients were included in the study (18 male, age 66.0±7.2 years, Body Mass Index 25.9±4.4 kg/m(2), FEV(1) 47.2±16.4% pred., Pa(O2) 74.7±6.9 mmHg, Pa(CO2) 40.3±3.4 mmHg): 10 were D and 11 ND. Significant differences between the two groups were found in diurnal Pa(CO2) (D: 42.4±3.0 vs. ND: 38.3±2.6mmHg; p<0.01), diurnal Sp(O2) (D: 94.0±1.5 vs. ND: 95.9±0.9%; p<0.01), inspiratory capacity (IC) (D: 69.6±11.9 vs. ND: 87.0±17.7% pred.; p<0.05), and oro-pharyngeal junction area (OPJ) (D: 0.8±0.2 vs. ND: 1.2±0.3 cm(2); p<0.01). Among parameters related to marked NOD at the univariate analysis, [Formula: see text] and OPJ remained as independent predictors after stepwise multiple regression analysis. These findings indicate that previously unrecognized factors such as smaller upper airway caliber and lung dynamic hyperinflation are associated with marked NOD in stable COPD patients without daytime respiratory failure and SA.