Ünal Şahin

Copeptin: a new predictor for severe obstructive sleep apnea.

Introduction Copeptin which is the C-terminal fragment of antidiuretic hormone (ADH), is a biomarker that has been reported to be increased in various cardiovascular disorders, cerebrovascular diseases and associated with prognosis. Patients with obstructive sleep apnea syndrome (OSAS) have a tendency to develop coronary and cerebral atherosclerotic diseases. Objectives The aim of the present study was to study copeptin levels in patients with obstructive sleep apnea and in a control group in order to determine whether copeptin could be used as a biomarker predicting the severity of OSAS and possible complications in this group. Methods A total of 116 patients with OSAS, diagnosed by polysomnography, and 27 controls were included in the study. Blood samples were collected after overnight fasting, and copeptin levels were measured with enzyme-linked immunosorbent assay. Results Copeptin levels were significantly higher in the OSAS group compared to control group (2,156±502; 1,845±500 pg/mL, respectively, P=0.004). Mean copeptin level of the patients having apnea-hypopnea index (AHI) ≥30 was significantly higher than that of the patients having AHI <30 (2,392±415; 2,017±500 pg/mL, respectively, P<0.001). A multivariate regression analysis showed that copeptin level, (hazard ratio: 1.58; 95% confidence interval: 1.09–2.30) was a predictor of severe OSAS (P=0.016). Copeptin levels showed significant positive correlation with AHI (r=0.32; P<0.001), desaturation index (r=0.23; P=0.012), arousal index (r=0.24; P=0.010) and CRP (r=0.26; P=0.011) respectively. Conclusion Copeptin levels are high in OSAS patients and copeptin is a potential marker for identifying patients with a high risk of early cardiovascular complications of OSAS. Copeptin has modest sensitivity (84%) for discriminating severe OSAS patients who are candidates for severe cardiovascular complications.

The relation between retrobulbar blood flow and posterior ocular changes measured using spectral-domain optical coherence tomography in patients with obstructive sleep apnea syndrome

PurposeTo investigate the effect of posterior ocular hemodynamics on the retinal nerve fiber layer (RNFL), choroid thickness (CT) and central macular thickness (CMT) in patients with obstructive sleep apnea syndrome (OSAS) and to reveal the association with glaucomatous optic neuropathy.MethodsThe research was planned as a prospective, randomized study. The ophthalmic, retinal and posterior ciliary artery pulsatile index (PI) and resistive index (RI) were measured by colored Doppler sonography. RNFL thickness, CMT and CT were then measured by spectral-domain optical coherence tomography.ResultsSixty subjects were divided into four groups—mild, moderate and severe OSAS and a control group. There were 16 subjects in the control group, 14 in the mild OSAS group, 15 in the moderate OSAS group and 15 in the severe OSAS group. Ophthalmic artery and central retinal artery PI and RI values of the OSAS patients did not show statistically significant difference than those of the control group, but posterior ciliary artery (PCA) PI and RI values were significantly higher. In addition, mean, superior and inferior RNFL thickness values were significantly lower than those in the control group. Moreover, the glaucoma prevalence of the OSAS patients in this study was 6.8% and all of these patients were in the severe OSAS group.ConclusionPI and RI values of the PCA, which supplies the optic nerve, show a linear increase as the apnea hypoxia index values in OSAS. As the grade of OSAS improves, this situation leads to a more serious ischemic optic neuropathy. Furthermore, the prevalence of glaucoma in this study is found to be higher in the severe OSAS group.

An evaluation of peripheral arterial tonometry for the diagnosis of obstructive sleep apnea

Objective: Peripheral arterial tonometry (PAT) as a portable method of monitoring sleep quality is a relatively recent innovation. The aim was to compare the results of PAT and polysomnography (PSG) and to evaluate the role of PAT in diagnosing obstructive sleep apnea syndrome (OSAS). Methods: This study included adult patients who admitted to ENT clinic with OSAS complaints (excessive daytime sleepiness, snoring, and witnessed apnea), undergone sleep monitorization using PAT system (WatchPAT 200TM; Itamar Medical Ltd., Caesarea, Israel) and had single-blind, level 1 polysomnography at sleep laboratory of Chest Diseases Department. Results: For the two sleep monitoring sessions as conducted at different times: the apnea-hypopnea index (AHI) and respiratory disturbance index (RDI) values were strongly correlated between sessions (r=0.749, r=0.753; p<0.001). The oxygen desaturation index (ODI) values were very strongly correlated (r=0.861; p<0.001). When the AHI scores calculated using PAT for the patients enrolled in the trial were taken into consideration; 89.7% of the patients were correctly diagnosed with OSAS (AHI≥5); for RDI calculated (RDI≥5) using PAT, 100% of OSAS diagnoses were correct; for AHI values calculated with the PAT method, taking 15 as cut-off point, the sensitivity was found to be at an extremely high level of 96.1%. Conclusion: PAT and PSG values were highly correlated. This finding demonstrated that the reproducibility of the results obtained with PAT was also high. This study shows that PAT can be used as a screening test for OSAS and in a group of patients who are highly suspected for OSAS.