Reliability of automatic detection of AHI during positive airway pressure treatment in obstructive sleep apnea patients: A "real-life study".

INTRODUCTION: Automatic event detection (AED) of residual apnea-hypopnea index (AHI) by ventilators is a current practice in sleep and mechanical ventilation Units but this methodology has not been validated in an unselected population of OSA patients. Aim of the present study was to assess in a "real-life" condition the reliability of AED during PAP therapy by the in-built software compared to full polysomnography during follow-up. METHODS: We enrolled 300 OSA patients (105 F; AHI 45.3 ± 27.8) already on Positive airway pressure (PAP) therapy: 53% of the patients were on CPAP while other modalities were used in the rest of the sample. RESULTS: Overall, the built-in software identified residual obstructive AHI (AHIPAP) > 5, 10 or 15 in 18.7, 8.6 or 4.6% of patients, respectively. By using AHIPAP, 28.4% of patients were wrongly classified as "well controlled" despite a residual AHIPSG>5 (6% considering a residual AHIVENT >15); 7% of patients were classified as not controlled while AHIPSG was <5 (1.4% considering a residual AHIVENT >15). Type of ventilation, ventilator parameters, adherence to treatment and level of baseline or follow-up Epworth Sleepiness Scale score were similar between groups. The sensitivity and positive predicted values were very low. Positive likelihood ratio appears adequate only for residual AHIPAP ≥10, but negative likelihood ratio was inconclusive for all the cut-off considered. DISCUSSION: The results of the present study suggest a more cautious approach in the follow-up of OSA patients, since a protocol based only on AED detection and symptoms assessment may not be accurate especially for AHIPAP<15.

Renal haemodynamics and severity of carotid atherosclerosis in hypertensive patients with and without impaired renal function.

BACKGROUND AND AIM: Renal resistance index (RRI), assessed by Duplex-Doppler sonography, has been classically considered as a mere expression of intrarenal vascular resistance. Recent studies, however, have showed that RRI is also influenced by upstream factors, especially arterial compliance, confirming its possible role as a marker of systemic vascular alterations. Several studies have shown that carotid intima-media thickness (cIMT) and carotid plaques (cP), assessed by ultrasonography, are documented markers of subclinical organ damage as well as expression of progressive atherosclerotic disease, and that they get worse with the progressive deterioration of renal function. The study was aimed to evaluate the relationship between RRI and severity of carotid atherosclerosis in hypertensive subjects with and without impaired renal function. METHODS AND RESULTS: The study population, including 263 hypertensive patients (30-70 years), was split into 3 groups based on cIMT and presence of cP (cIMT ≤ 0.9 mm and no cP; cIMT > 0.9 mm and no cP; cP). All patients were also divided into 2 subgroups (normal renal function; CKD stage I-IV). A stepwise increase in RRI corresponding to the groups of progressive severity of carotid atherosclerosis was observed (respectively 0.61 ± 0.07, 0.65 ± 0.06, 0.68 ± 0.06; p < 0.001). A strong positive correlation was observed between RRI and cIMT in the whole population (r = 0.43; p < 0.001) and in the subgroups with (r = 0.42; p < 0.001) and without (r = 0.39; p < 0.001) CKD. These associations remained statistically significant even after adjustment for various confounding factors. CONCLUSION: Showing a close association between RRI and severity of carotid atherosclerosis, our results strengthen the concept that RRI is a marker of systemic vascular changes.

Absence of an independent association between serum uric acid and left ventricular mass in Caucasian hypertensive women and men.

BACKGROUND AND AIM: Experimentally uric acid may induce cardiomyocyte growth and interstitial fibrosis of the heart. However, clinical studies exploring the relationship between serum uric acid (SUA) and left ventricular (LV) mass yielded conflicting results. The aim of our study was to evaluate the relationships between SUA and LV mass in a large group of Caucasian essential hypertensive subjects. METHODS AND RESULTS: We enrolled 534 hypertensive patients free of cardiovascular complications and without severe renal insufficiency. In all subjects routine blood chemistry, including SUA determination, echocardiographic examination and 24 h ambulatory blood pressure (BP) monitoring were obtained. In the overall population we observed no significant correlation of SUA with LV mass indexed for height(2.7) (LVMH(2.7)) (r = 0.074). When the same relationship was analysed separately in men and women, we found a statistically significant correlation in female gender (r = 0.27; p < 0.001), but not in males (r = -0.042; p = NS). When we grouped the study population in sex-specific tertiles of SUA, an increase in LVMH(2.7) was observed in the highest tertiles in women (44.5 ± 15.6 vs 47.5 ± 16 vs 55.9 ± 22.2 g/m(2.7); p < 0.001), but not in men. The association between SUA and LVMH(2.7) in women lost statistical significance in multiple regression analyses, after adjustment for age, 24 h systolic BP, body mass index, serum creatinine and other potential confounders. CONCLUSIONS: Our findings do not support an independent association between SUA and LV mass in Caucasian men and women with arterial hypertension.