Bedside approach in the diagnosis obstructive sleep apnea using postprandial oximetry testing: A comparative study with polysomnography.

INTRODUCTION: Due to the availability and cost issues in developing countries of polysomnography (PSG), there is a need for outpatient test for an initial assessment of the patients with suspected obstructive sleep apnea (OSA). OBJECTIVES: Epworth sleepiness scale (ESS) is a widely used and best-validated scale for assessing daytime sleepiness, including dozing when sitting quietly after a lunch (no alcohol). This study introduces a novel screen test called postprandial oximetry test (POT) used during daytime. METHODS: This single-center prospective study included 101 patients (80 patients with suspected OSA and 21 patients without OSA suspicion). Berlin Questionnaire was used to determine the score/pretest probability of OSA patients, all chosen randomly. First, all the patients underwent POT in laboratory. Then we performed PSG. After lunch, while sleeping, the patients were monitored for 1 hour with pulse oximetry and standard electroencephalographic system. The oximetry saturation classification events with SpO2 was divided into two groups as normal or mild obstructive sleep apnea syndrome (OSAS), and moderate-to-severe OSAS. Below 90% SpO2 drops in a postprandial oximetry recordings were accepted as moderate-to-severe. RESULTS: The mean lowest oxygen saturation in PSG was 82.34 ± 5.99, while it in POT were 87.42 ± 1.39. A positive correlation was found between POT- and PSG-derived Apnoea-Hypopnoea Index (AHIs). The sensitivity and specificity in postprandial oximetry were 85% and 85.7%, respectively. The accuracy was 0.903 for POT. CONCLUSION: POT may be useful as an outpatient test in the initial assessment of the patients with suspected OSA, serving as a gatekeeper for PSG.

Assessment of the relationship between functional capacity and right ventricular ultrasound tissue characterization by integrated backscatter in patients with isolated mitral stenosis.

AIM: The aim of the present study was to investigate right ventricular (RV) myocardial textural properties in asymptomatic and symptomatic mitral stenosis (MS) patients with normal RV systolic function using integrated backscatter (IBS). METHODS: The study included 40 patients with MS of moderate or severe degree. Patients were classified into 2 groups according to NYHA class (asymptomatic group, NYHA class I, symptomatic group, NYHA class II-III). RV pulsed-wave tissue Doppler imaging (TDI) and IBS analyses were performed in all patients. Isovolumic contraction time (IVCT), systolic wave velocity (S), isovolumic relaxation time (IVRT), early diastolic wave velocity (E), and late diastolic wave velocity (A) were measured by TDI. IBS amplitude (IB) and cyclic variation (CV) of the RV lateral wall in the parasternal long-axis view were measured by IBS. CV was calculated by subtracting systolic IB from diastolic IB. RESULTS: IVRT (54.2 +/- 11.9 ms versus 86.2 +/- 16.2 ms, P < 0.001) and A wave amplitude (10.2 +/- 2.1 cm/s versus 13.6 +/- 1.8 cm/s, P < 0.05) were higher whereas E wave amplitude (11.7 +/- 1.6 cm/s and 10.3 +/- 1.5 cm/s, P < 0.05) and E/A ratio (1.3 +/- 0.3 versus 0.7 +/- 0.1, P < 0.001) were lower in group 2. Symptomatic patients had a lower CV value of RV (9.5 +/- 3.4 dB versus 6.7 +/- 1.9 dB, P = 0.004). There was a positive correlation between CV and E/A (r = 0.964, P < 0.001) CONCLUSION: Symptomatic isolated MS patients had RV echo texture changes and diastolic dysfunction in comparison to asymptomatic ones with similar mitral valve areas in the presence of normal RV systolic function. In isolated MS, both pulsed-wave TDI and IBS may aid in the detection of RV diastolic pathology.