Physiological determinants of nocturnal arterial oxygenation in patients with obstructive sleep apnea.
ABSTRACT Among patients with similar degrees of obstructive sleep apnea (OSA) there is considerable variability in the degree of associated nocturnal hypoxemia. The factors responsible for this variability have not been clearly defined. Therefore we studied 44 patients with OSA to identify the physiological determinants of nocturnal arterial O2 saturation (SaO2). All patients underwent pulmonary function testing, arterial blood gas analysis, and overnight polysomnography. Mean nocturnal SaO2 ranged from 96 to 66% and apnea-hypopnea index from 11 to 128 per hour of sleep. Several anthropometric, respiratory physiological, and polysomnographic variables that could be expected to influence nocturnal SaO2 were entered into a stepwise multiple linear regression analysis, with mean nocturnal SaO2 as the dependent variable. Three variables [awake supine arterial PO2 (PaO2), expiratory reserve volume, and percentage of sleep time spent in apnea] were found to correlate strongly with mean nocturnal SaO2 (multiple R, 0.854; P less than 0.0001) and accounted for 73% of its variability among patients. Body weight, other lung volumes, and airflow rates influenced awake PaO2 and expiratory reserve volume but had no independent influence on nocturnal SaO2. In a further group of 15 patients with OSA a high correlation was obtained between measured nocturnal SaO2 and that predicted by the model (r = 0.87; P less than 0.001). We conclude that derangements of pulmonary mechanics and awake PaO2 (generally attributable to obesity and diffuse airway obstruction) are of major importance in establishing the severity of nocturnal hypoxemia in patients with OSA.
SourceAvailable from: Ahmed Salem BaHammam[Show abstract] [Hide abstract]
ABSTRACT: To compare the apnea-hypopnea indices (AHIs) derived using three hypopnea definitions published by the American Academy of Sleep Medicine (AASM) and to determine the impact of the new modifications of the definition on AHIs and the diagnosis of obstructive sleep apnea (OSA). The study comprised 100 consecutive patients who were investigated for OSA using overnight diagnostic polysomnography (PSG). The hypopneas were scored in three passes by two certified sleep technologists; in the first pass, the hypopneas were scored using the 2007 AASM "Alternative" (H Alt) criteria. In the second pass, the hypopneas were scored using the 2007 AASM "Recommended" (H Rec) criteria. In the third pass, the hypopneas were scored according to the new AASM "2012" (H 2012) criteria. Agreement analysis of the results obtained using the three scoring criteria was performed using the Bland-Altman plot methodology. The studied group had a mean age of 45.5 ± 12.6 years and a body mass index of 30.2 ± 5.8 kg/m(2). Using the H 2012, H Rec and H Alt criteria, the AHIs were 37.9 ± 27.6, 14.8 ± 22.4 and 29.6 ± 27.0/h, respectively (p < 0.05). The Bland-Altman analysis of the AHI demonstrated that more events were nearly always detected using the H 2012 definition. A significant difference in detecting hypopnea events exists among the H 2012, H Rec and H Alt definitions. The 2007 AASM "Recommended" definition tended to result in lower AHI than the other two definitions.Sleep And Breathing 02/2014; 18(4). DOI:10.1007/s11325-014-0939-3 · 2.87 Impact Factor
Revue des Maladies Respiratoires 03/2014; 31(3):263-94. DOI:10.1016/j.rmr.2013.11.007 · 0.49 Impact Factor
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ABSTRACT: Rationale: Difference in mortality from obstructive sleep apnea (OSA) by sex is an important issue. Visceral fat, a significant risk factor for cardiovascular disease (CVD), was reported to be closely related to OSA. Objectives: To assess the different associations between OSA and visceral fat area (VFA) by sex, which might account for the different prognosis in men and women with OSA. Methods: Participants were 271 men and 100 women consecutively hospitalized for examination of OSA from October 2008 to December 2010. Among the 371 participants, relationships were analyzed between fat areas by computed tomography, comorbidity, polysomnographic data, arterial blood gas, pulmonary function and venous blood data. Multiple regression analyses were performed to identify variables independently associated with VFA and subcutaneous fat area (SFA) for each sex. Measurements and Main Results: Despite similar body mass index (BMI) and waist circumference, men had larger VFA, more severe OSA and more severe dyslipidemia than women. Multiple regression analyses revealed that in men, not only age and BMI but also minimum oxygen saturation (contribution rate (R²) = 4.6%) during sleep, and alveolar-arterial oxygen difference (R² = 7.6%) were independently associated with VFA. Conversely, VFA was only associated with BMI in women. Conclusions: Only in men OSA was independently associated with VFA. The lesser associations between OSA and visceral fat in women might account for OSA's lower impact on CVD or mortality in women.01/2014; DOI:10.1513/AnnalsATS.201306-182OC