title: Disordered breathing during sleep and exercise in idiopathic pulmonary fibrosis and the role of biomarkers.
abstract: Idiopathic pulmonary fibrosis (IPF) patients report fatigue, possibly reflecting sleep disturbance, but little is known about sleep-related changes. We compared ventilation and gas exchange during sleep and exercise in a cohort of IPF patients, and evaluated associations with selected biological markers.
  
  
  
  Twenty stable IPF patients (aged 67.9 ± 12.3 [SD]) underwent overnight polysomnography following an acclimatization night. Cardiopulmonary exercise testing was performed and inflammatory markers measured including TNF-α, IL-6, CXCL8, C-C motif ligand 18 (CCL-18) and C-reactive protein (CRP) RESULTS: Nine patients had sleep-disordered breathing (SDB) with an apnea-hypopnea frequency (AHI) ≥ 5/h, but only two had Epworth sleepiness score ≥ 10, thus having an obstructive sleep apnea syndrome. Sleep quality was poor. Transcutaneous carbon dioxide tension (PtcCO2) rose by 2.56 ± 1.59 kPa overnight (P = 0.001), suggesting hypoventilation. Oxygen saturation (SaO2) was lower during sleep than exercise (P < 0.01), and exercise variables correlated with resting pulmonary function. CCL-18 and CRP levels were elevated and correlated with PtcCO2 rise during sleep (P < 0.05). CCL-18 negatively correlated with diffusion capacity of carbon monoxide (DLCO), arterial oxygen (PaO2) and mean arterial carbon dioxide (PaCO2) (P < 0.05) and CRP negatively correlated with DLCO, PaO2, sleep SaO2 and oxygen uptake (VO2) during exercise (P < 0.05).
  
  
  
  IPF patients desaturate more during sleep than exercise; thus, nocturnal pulse oxymetry could be included in clinical assessment. CCL-18 and CRP levels correlate with physiological markers of fibrosis.
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: R N C
authors.initials: RN
authors.lastname: Lee
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: E
authors.initials: E
authors.lastname: Kelly
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: G
authors.initials: G
authors.lastname: Nolan
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: S
authors.initials: S
authors.lastname: Eigenheer
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: D
authors.initials: D
authors.lastname: Boylan
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: D
authors.initials: D
authors.lastname: Murphy
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: J D
authors.initials: JD
authors.lastname: Dodd
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland.
authors.forename: M P
authors.initials: MP
authors.lastname: Keane
authors.affiliation: From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland From the Department of Respiratory Medicine, St. Vincent's University Hospital, School of Medicine and Medical Science, University College Dublin, Department of Radiology, St. Vincent's University Hospital, Dublin, Ireland walter.mcnicholas@ucd.ie.
authors.forename: W T
authors.initials: WT
authors.lastname: McNicholas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001049:Apnea / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D015331:Cohort Studies; D016207:Cytokines / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000097:blood / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D017286:Polysomnography / Q000379:methods; D011659:Pulmonary Gas Exchange / Q000502:physiology; D011788:Quality of Life; D012129:Respiratory Function Tests; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators; D002245:Carbon Dioxide; D010100:Oxygen