To explore the relationship of obstructive sleep apnea(OSA)with the severity of cardiopulmonary involvement in patients with interstitial lung disease(ILD).

A total of 51 patients with concomitant ILD and OSA treated from February 2010 to December 2019 in Beijing Anzhen Hospital were analyzed of arterial blood gas analysis, BNP, sleeping test, spirometry, echocardiography, etc. The severity and extent of ILD lesions were determined by Warrick scoring algorithm.

In patients with ILD-OSA, the lowest oxygen saturation (LSpO₂) was negatively correlated with tricuspid regurgitation velocity (TRV) (r=-0.415, P=0.028). Oxygen depletion index (ODI) was positively correlated with BNP (rs=0.409, P=0.031). The percentage total sleep time with SpO₂<90% (TST90) was positively correlated with systolic pulmonary artery pressure, TRV and BNP (rs=0.505, P=0.006, rs=0.584, P=0.001, and rs=0.455, P=0.015), and was negatively correlated with lung carbon monoxide diffusion capacity (DL_CO) (rs=-0.458, P=0.028). Logistic regression revealed that TST90 was significantly associated with severe ILD defined by fibrostic Warrick degrees (P=0.036, OR=1.025, 95%CI=1.002-1.049). TST90 1.8% was the best cut-off values for discrimination of severe pulmonary fibrosis, and the area under the curve was 0.719, which resulted in a sensitivity of 89.9% and a specificity of 53.6%.

OSA related intermittent nocturnal hypoxemia was associated with the severity of cardiopulmonary involvement in patients with ILD, and subjects with long desaturation defined by TST90 demonstrated high odds of having severe fibrotic stratification.