Increased alveolar nitric oxide concentration is related to nocturnal oxygen desaturation in obstructive sleep apnoea.

PURPOSE: To assess distal/alveolar inflammation in patients with suggestive symptoms of obstructive sleep apnoea (OSA) using exhaled nitric oxide (NO) measured by two-compartment model (2-CM) after correction for axial NO back-diffusion (trumpet model). METHODS: Ninety five patients suspected for OSA prospectively underwent pulmonary function test, overnight polysomnography (PSG), and exhaled NO measurement. Patients with apnoea-hypopnoea index (AHI) < 5/hour were included in non-OSA group. Exhaled NO was repeatedly measured after PSG in 21 OSA patients and 8 non-OSA subjects. RESULTS: Alveolar NO concentration (C(ANO)) was significantly higher in OSA patients (n = 71; 4.07 ± 1.7 ppb) as compared with non-OSA subjects (n = 24; 2.24 ± 1.06 ppb; p < 0.0001) whilst maximal bronchial NO flux (J'awNO) and fractional exhaled NO (F(ENO)) did not differ between the two groups. C(ANO) was strongly associated to AHI (r = 0.701; p < 0.0001) and to recording time with SaO2 < 90% (ST-90%; r = 0.659; p < 0.0001) in OSA patients but not in non-OSA persons. The area under ROC curve for screening patients with OSA and significant nocturnal oxygen desaturation (ST-90% > 1%) was 0.865 ± 0.036 (95% IC, 0.793-0.937; p < 0.0001). C(ANO) at 4.5 ppb could detect these patients with specificity of 94% and sensitivity of 46%. Increase of C(ANO) measured after PSG was significantly related to oxygen desaturation index (ST-90%) in OSA patients. CONCLUSIONS: Increased alveolar NO concentration was related to the severity of nocturnal oxygen desaturation in patients with OSA, linking the distal airway inflammation to intermittent hypoxia. (250 words).

Cardiovascular comorbidities in obstructive sleep apnoea according to age: a sleep clinic population study.

PURPOSE: To describe the features of obstructive sleep apnoea (OSA) and its association with arterial hypertension (HT), coronary artery disease (CAD), and arrhythmias in elderly (≥65 years) versus younger patients. METHODS: All adult patients referred to our Sleep Research Unit for suspected OSA were included and underwent a thorough medical examination and an in-laboratory polysomnography. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) as mild [5-15/h), moderate [15-30/h), and severe (≥30/h). RESULTS: Elderly patients (n = 136) and really old patients (>75 years) had higher prevalence of OSA (89 %) and severe OSA (36.8 %) as compared to younger patients (n = 439; 79.5 and 27.6 %, respectively, p < 0.05). In patients with OSA, the elderly group had a poorer sleep quality and more severe nocturnal oxygen desaturation than the younger group. Elderly patients presented higher percentages of HT (47.8 %), CAD (19.8 %), and arrhythmias (16.2 %) as compared to younger patients (p < 0.01). The odds ratio (OR) for HT increased with OSA severity from 1.0 to 1.65 (95 % confidence interval 0.83-3.27), 1.0 to 2.5 (95 % CI 1.25-5.00), and 1.0 to 3.77 (1.95-7.29) in younger patients, but not in elderly ones where the OR increased from 1.0 to 0.6 (0.17-2.04), 1.0 to 1.14 (0.34-3.82), and 1.0 to 1.46 (0.46-4.63), respectively. CONCLUSION: Stronger relation of HT and OSA severity in younger patients should encourage us to screen OSA in these patients at very young age. Increased OSA severity without obesity in very old patients needs to be confirmed and further studied.