The aim is to identify peculiarities of changes in the intensity of lipid peroxidation (LP) processes and the activity of antioxidant defense factors in obstructive sleep breathing disorders (OSBD) of varying severity.
Material and methods. 48 patients were examined complaining about snoring and excessive daytime sleepiness. They were divided into 4 groups. The 1st (control) group consisted of patients without OSBD (n=16), the 2nd – with mild OSBD (n=16), the 3rd – with moderate OSBD (n=8), and the 4th – severe OSBD (n=8). Cardiorespiratory monitoring was performed for OSBD detection; the severity of OSBD was estimated by the apnea/hypopnea index (AHI). The state of lipid peroxidation processes was evaluated by the content of diene conjugates (DC) and malondialdehyde (MDA) in the blood serum, the state of antioxidant protection – by changes in the activity of superoxide dismutase (SOD) and catalase (CAT). Data were considered reliable at a significance level of p <0,05.
Results. In all groups, indicators of saturation of blood oxygen during wakefulness (Bas SpO2) were within the reference values and did not significantly differ. The values of the minimum SpO2 (Min SpO2) during sleep in patients of the 2nd and 3rd groups did not significantly differ between themselves and the values of patients in the control group. In patients of the 4th group, Min SpO2 was lower than in patients of the control and 2nd groups, respectively, by 11,9 (p <0,001) and 8,8% (p=0,002). In the control group, the values of the degree of reduction of SpO2 (∆SpO2) were the smallest. Index ∆SpO2 in the 4th group was higher by 86,9% than in the control (p=0,0001) and 66,6% than in the 2nd group (p=0,002), however, the differences in Δ SpO2 in the control, 2nd and 3rd groups were not significant. The concentration of DC did not significantly differ in the examined groups. The increase in AHI was accompanied by an increase in the concentration of MDA: in patients of the 3rd group, its values were 25,1% higher than in patients of the control group (p=0,007), and 48,4% higher compared to patients of the 2nd group (p=0,005); in patients of the 4th group – by 45,5 (p=0,004) and 72,5% (p=0,003), respectively. In the control group, the maximum values of SOD and CAT activity in serum were observed. In the 2nd group, the activity of CAT and SOD was significantly lower by 13,6 and 13,5%, respectively, than in the control group; in the 3rd group – by 14,7 and 33,7%, respectively; in the 4th group – by 19,4 and 35,9%, respectively.
Conclusion. Hypoxia, increasing with OSBD progression, leads to an increase in the activity of LP processes due to an increase in the concentration of MAD in the blood serum, as well as to a decrease in the activity of antioxidant defense factors SOD and CAT. Performing individual therapeutic measures aimed at preventing the development of episodes of respiratory arrest in sleep and hypoxemia can lead to the normalization of LP processes and the antioxidant defense system.

Keywords: obstructive sleep disturbances, lipid peroxidation, antioxidant defense system