Disordered breathing during sleep and exercise in idiopathic pulmonary fibrosis

Lee, R.N.C.; Kelly,
E.; Nolan, G.; Eigenheer, S.; Boylan, D.; Murphy, D.; Dodd, J.; Keane,
M.P.; McNicholas, W.T

An International Journal of Medicine,
April 2015, Vol. 108 Issue: Number 4 p315-315, 1p

Abstract: Background
and objective: 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. Methods: 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 (PtcCO<inf>2</inf>) rose by 2.56 ± 1.59 kPa overnight (P</it> =
0.001), suggesting hypoventilation. Oxygen saturation (SaO<inf>2</inf>)
was lower during sleep than exercise (P</it> < 0.01), and exercise
variables correlated with resting pulmonary function. CCL-18 and CRP
levels were elevated and correlated with PtcCO<inf>2</inf> rise during
sleep (P</it> < 0.05). CCL-18 negatively correlated with diffusion
capacity of carbon monoxide (DLCO), arterial oxygen (PaO<inf>2</inf>)
and mean arterial carbon dioxide (PaCO<inf>2</inf>) (P</it> < 0.05) and
CRP negatively correlated with DLCO, PaO<inf>2</inf>, sleep
SaO<inf>2</inf> and oxygen uptake (VO<inf>2</inf>) during exercise
(P</it> < 0.05).
Conclusions: 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.