Orhan DALKILIÇ, Nesrin SARIMAN, Bekir Sami UYANIK
Experimental Biomedical Research - 2026;9(4):263-274
Aim: To investigate the acute effects of PAP titration on respiratory disturbances, nocturnal oxygenation, and sleep stage organization by comparing diagnostic and titration studies. Methods: Consecutive adults who completed overnight diagnostic PSG followed by attended PAP titration were eligible. Within-patient comparisons included respiratory indices, oxygenation, sleep stages, sleep continuity, arousal burden, snoring, and total sleep time. Additional paired subgroup analyses were performed according to baseline OSA severity and body mass index (BMI). Results: A total of 266 paired sleep studies were analyzed. Mean age was 51.56 +/- 14.04 years; 80.1% were men and 19.9% women. AHI decreased from 45.79 +/- 23.14 to 4.03 +/- 6.24 events/h, AI from 34.40 +/- 22.54 to 1.90 +/- 4.09 events/h, and ODI from 43.32 +/- 23.33 to 3.39 +/- 5.53 events/h (all p < 0.001). Minimum oxygen saturation increased from 74.06 +/- 11.59% to 85.50 +/- 7.42% ( p < 0.001). REM sleep increased from 11.32 +/- 8.90% to 18.13 +/- 9.06% and N3 sleep from 6.23 +/- 7.84% to 11.57 +/- 10.73% (both p < 0.001), with reductions in snoring and arousal index. Total sleep time and PLM index did not change significantly. Respiratory indices improved across all OSA severity and BMI categories, while sleep-stage reorganization was most pronounced in severe OSA and obesity. Conclusions: PAP titration during the first treatment night produced multidimensional physiological improvement beyond respiratory-event suppression. Early response patterns varied by OSA severity and BMI, suggesting that respiratory stabilization and sleep architecture recovery are related but not interchangeable outcomes and supporting assessment beyond residual AHI alone.
