Objective To investigate the association between nocturnal hypoxia and systemic inflammatory response in patients with chronic obstructive pulmonary disease.

Methods Seventy moderate to very severe stable COPD patients with an age range of 45-74 years (Average age, 65.41±7.84 years) were included.Patients were divided into nocturnal hypoxia group and non-nocturnal hypoxia group, and lung function, PSG, and inflammatory indicators were performed. The differences of serum IL-6 and IL-8 in each group were compared, the correlation between IL-6 and IL-8 as well as PSG parameters were further evaluated using partial correlation analysis.

Results Twenty-seven patients (38.57%) with nocturnal hypoxia were enrolled.Compared with patients without nocturnal hypoxia, serum IL-6 and IL-8 in the hypoxic group (14.34±2.76 ng/mL and68.49±9.65 ng/mL, respectively) were significantly higher than those in the non-nocturnal hypoxic group (11.79±1.85 ng/mL and61.62±8.47 ng/mL, respectively; P < 0.001). Additionally, after adjustment for BMI and age, serum IL-6 level showed significant positive correlation with TS88 (r=0.651, P=0.041), nevertheless, serum IL-6 level showed significant negative correlation with the lowest SaO₂ and the mean SaO₂ (r=-0.644, P=0.038 and r=-0.780, P=0.018); serum IL-8 level showed significant positive correlations with TS88 (r=0.627, P=0.039), nevertheless, serum IL-6 level showed significant negative correlation with the lowest SaO₂ and the mean SaO₂ (r=-0.659, P=0.026 and r=-0.732, P=0.014).

Conclusions Nocturnal hypoxia generally exists in patients with moderate to very severe stable COPD. Compared with the non-nocturnal hypoxia group, the nocturnal hypoxia group has enhanced systemic inflammatory response, which might be correlated with nocturnal hypoxia.