ASSOCIATION OF HYPOXIC BURDEN WITH DISEASE SEVERITY IN OBSTRUCTIVE SLEEP APNOEA: A POLYSOMNOGRAPHY-BASED STUDY.

Background: Obstructive sleep apnoea (OSA) is characterized by recurrent upper airway obstruction during sleep, leading to intermittent hypoxaemia and sleep fragmentation. While the apnoea–hypopnoea index (AHI) is the standard metric for grading disease severity, it does not fully capture the physiological impact of nocturnal hypoxia. Oxygen desaturation parameters may better reflect hypoxic burden and associated clinical risk. This study aimed to evaluate the correlation between the degree of oxygen desaturation and the severity of OSA in adults undergoing diagnostic polysomnography. Materials and Methods: This hospital-based cross-sectional study included 92 adult patients with polysomnography-confirmed OSA. All participants underwent full-night, attended, in-laboratory polysomnography. OSA severity was classified using AHI into mild, moderate, and severe categories. Oxygen desaturation parameters analyzed included minimum and mean nocturnal oxygen saturation (SpO2), oxygen desaturation index (ODI), and percentage of total sleep time spent with SpO2 below 90% (T90). Comparisons across severity groups were performed using appropriate parametric or non-parametric tests, and correlations between AHI and desaturation parameters were assessed using correlation coefficients. Results: The mean age of participants was 52.6 ± 10.8 years, with male predominance (72.8%). Severe OSA constituted 40.2% of cases. A progressive worsening of oxygen desaturation was observed with increasing OSA severity. Minimum SpO2 decreased from 86.9% in mild OSA to 74.8% in severe OSA, while ODI increased from 9.6 to 38.7 events/hour (p < 0.001). Time spent with SpO2 < 90% increased significantly across severity categories (p < 0.001). AHI showed strong positive correlations with ODI (r = 0.72) and T90 (r = 0.74), and significant negative correlations with minimum (r = −0.68) and mean SpO2 (r = −0.61) (all p < 0.001). Conclusion: Nocturnal oxygen desaturation parameters correlate strongly with the severity of obstructive sleep apnoea. Incorporating hypoxic burden indices alongside AHI may provide a more comprehensive assessment of disease severity and aid in improved risk stratification and clinical management of patients with OSA. [ABSTRACT FROM AUTHOR]