Objective To explore the relationship between heart rate variability (HRV) and hypoxia in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).

Methods A total of 165 patients with OSAHS admitted to Zhongshan Hospital (Xiamen Branch), Fudan University from January 2021 to June 2023 were selected and divided into four groups based on the minimum pulse oxygen saturation (SpO₂) at night: non-hypoxic group, mild hypoxic group, moderate hypoxic group and severe hypoxic group. All patients completed the general data collection, polysomnography (PSG) and Holter. One-way analysis of variance was used to compare the general clinical characteristics among different groups with hypoxia. Correlation analysis was used to compare the correlation between HRV and PSG parameters. The multiple linear regression analysis was applied to explore the correlation between HRV and PSG parameters.

Results With the increase of hypoxia, standard deviation of all normal to normal RR intervals (SDNN), standard deviation of all 5-minute RR intervals (SDANN), SDNN during waking and SDNN during sleeping decreased (P < 0.05). Correlation analysis showed that after adjusting the age, there was a relationship between SDNN, SDANN, SDNN during waking and PSG parameters (P < 0.05). The multiple linear regression analysis showed that the age, percentage of sleep time spent with oxygen saturation < 90% (T90), the average SpO₂ and the lowest SpO₂ were correlated with the HRV of OSAHS patients (P < 0.05).

Conclusions HRV shows the ability to identify the individuals with different levels of hypoxia in the OSAHS patients, which may play an independent role in predicting cardiovascular events.