Nocturnal oxygen desaturation in precapillary pulmonary hypertension

<bold>Purpuse:</bold> to evaluate the frequency of nocturnal oxygen desaturation (NOD) and its relationship with severity of precapillary PH. <bold>Methods:</bold> The study included 25 patients (72% females; 50±2,9 years). PH was confirmed by RHC. All patients underwent overnight cardio-respiratory monitoring. A/H≥15 was found in 3 patients, they were not included in assessment of NOD. 22 patients were allocated to groups according to the presence of NOD, which was defined as SpO₂<90% for at least≥30% of sleep time: group 1 (64%) without NOD and group 2 (28%) with NOD taking approximately 44,0±11,2% of sleep time. <bold>Results:</bold> All 22 patients had precapillary hemodynamic, 86% were classified to PAH Group 1, 13,6%-to PH Group 4. Mean BMI was 30,4±1,9; NTproBNP was 1792,4±974,3 pg/ml; 80% patients had moderate increase of mPAP. There were no significant differences in mean lowest SpO₂ (73,4±4,6 vs 78,0±2,3), ODI (8,0±3,6 vs 6,1±1,6), A/H index (6,7±2,4 vs 11,2±3,0) between the groups (p>0,05). In patients with NOD the following markers of prognosis and RV dysfunction were significantly worse: 6MWT distance (272±18,6 vs 345,8±21,8, p=0,02); PVR (1455,6±340,1 vs 595,9±92,3, p=0,05); RVFI (59,7±10,8 vs 32,6±4,4, p=0,05); RVSWI (28,7±3,8 vs 17,9±2,1, p=0,05); TAPSE (16,1±2,6 vs 23,8±2,0, p=0,04); iLVESV (10,0±1,4 vs 16,7±1,1, p=0,003). NOD inversely correlated with 6MWT (r=-0,43; p=0,05); iLVESV (r=-0,48; p=0,03); TAPSE (r=-0,44; p=0,04) and directly with PVR (r=0,63; p=0,009). <bold>Conclusion:</bold> NOD is highly prevalent in precapillary PH. Established in our study strong relation of NOD with markers of right heart remodelling and disease severity asserts the need of further NOD evaluation as a precapillary PH prognosis marker in large clinical context.