The effect of nocturnal hypoxemia on metabolic disorders in patients with stable chronic obstructive pulmonary disease

Background. Сhronic obstructive pulmonary disease (COPD) is a heterogeneous disease with different etiologies. As lung function declines and the disease progresses, patients are at increased risk of long-term nocturnal hypoxemia (NH) with consequent tissue hypoxia. It is supposed that tissue hypoxia with NH plays a key role in a number of pathologic processes with the development of metabolic disorders.

Аim. Тo investigate the relationship between NH and metabolic disorders in stable COPD patients.

Materials and methods. A cross-sectional observational study included 106 stable COPD patients managed at a respiratory medical center between 2019 and 2024 who completed ambulatory computerized somnography, pulmonary function testing, questionnaire and laboratory screening. NH was defined according to a time to saturation under 90% (T90) index >10%. Based on the absence/presence of NH, patients were classified into groups of patients with NH (NH+) and without NH (NH-). Factors that affect NH were identified using univariate analysis and logistic regression models.

Results. The group of COPD patients with NH+ was represented by men (92.9%) with a mean age of 59.9±10.9 years, with an increased body mass index (32,14 [21.04–35.96] kg/m²); with moderate-to-severe impairment of forced expiratory volume in 1st second (FEV1) (56.19±21.17% of predicted); with decreased lung diffusing capacity for carbon monoxide (60.61±21.36% of predicted). NH+ patients compared to the NH- group had a statistically significant increase in: insulin resistance index – HOMA-IR (3.6 [3.01; 4.21] vs 2.46 [1.85; 2.88]; p<0.05); low-density lipoprotein – LDL-C (3.16 [2.83; 3.62] vs 2.49 [2.23; 2.88]; p<0.05); triglycerides (1.89 [1.70; 2.03] vs 1.58 [1.45; 1.7]; p<0.05). At the same time, high-density lipoprotein – HDL-C had a statistically significant decrease (1.00 [0.92; 1.09] vs 1.14 [1.04; 1.22]; p<0.05). Univariate regression analysis based on clinical and laboratory data showed a statistically significant association with NH for the following parameters: age (OR 1.06, 95% CI [1.02–1.12]; p=0.011), COPD Assessment Test (CAT) score (OR 1.48, 95% CI [1.10–2.00]; p=0.009), FEV1 (% of predicted) (OR 0.96, 95% CI [0.93–0.99]; p=0.015), HDL-C levels (OR 1.02, 95% CI [1.00–1.04]; p=0.034).

Conclusion. COPD patients with NH have statistically significant correlations of metabolic disorders with NH that has effect on clinical characteristics and functional disturbances. The established correlations are useful to take into consideration in current algorithms of therapy of stable COPD patients.