In this study, we compared PPG-derived APF and frequency domain features between OSA patients within the best and worst PVT performance quartiles. We found increased APF and higher nocturnal variance of the frequencies in the worst-performing male OSA patients compared to the best-performing patients. However, differences in PPG features diminished in female patients and were not as clearly distinguishable. Step-wise regression analysis revealed that higher APF and t90% are associated with a higher number of lapses in PVT. These results imply that increased APF together with more severe nocturnal hypoxaemia may provide a PSG marker for impaired vigilance in male OSA patients. In addition, findings are in line with previous studies, indicating that female sex and older age are independent risk factors for poor PVT performance.
The frequency content of nocturnal PPG exhibits a clear difference between males in the worst-performing (Q4) and the best-performing (Q1) quartiles based on both lapses and Sample Entropy. APF was found to vary more in both Q4s and have significantly higher values compared to Q1s. Furthermore, in lapses Q4s the increased APF was also observed in the group-median power spectrum together with reduced power of
the peak frequencies.
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