TY - JOUR
T1 - The relationship of daytime hypoxemia and nocturnal hypoxia in obstructive sleep apnea syndrome
AU - Fanfulla, Francesco
AU - Grassi, Mario
AU - Taurino, Anna Eugenia
AU - Lupo, Nadia D Artavilla
AU - Trentin, Rossella
PY - 2008
Y1 - 2008
N2 - Question of the study: Prevalence and determinants of daytime hypoxemia in patients with obstructive sleep apnea (OSA) syndrome are not well established. The aims of this study, conducted in a large series of OSA patients, were to estimate the prevalence of daytime hypoxemia, to assess the reciprocal effects between daytime PaO2 and nocturnal SpO2, and to investigate the direct and indirect role of sleep apnea severity in determining feedback gas exchange abnormalities. Materials and methods: In 456 patients a daytime hypoxemia-nocturnal hypoxia feedback structural equations model was designed. PaO2 adjusted for age (% of predicted), percent sleep time spent with SpO2 90), oxygen desaturation index and the apnea-hypopnea index, were determined as the measures of daytime hypoxemia, nocturnal hypoxia, and sleep apnea severity, respectively, after adjusting for the severity of obesity and lung volumes. Results: The TST 90-PaO2 feed-back structural equations modeling showed that daytime PaO2 was inversely related (P2 per 1 SD of TST90). The severity of OSA (-1.0%) was an indirect determinant of daytime PaO2 via the TST90 pathway. In contrast, daytime PaO2 did not influence (P>0.05) the extent of nocturnal hypoxia. Conclusions: In OSA patients, the extent of nocturnal hypoxia seems to be both a direct determinant and a mediator of the indirect effect of sleep apnea on the development of daytime hypoxemia.
AB - Question of the study: Prevalence and determinants of daytime hypoxemia in patients with obstructive sleep apnea (OSA) syndrome are not well established. The aims of this study, conducted in a large series of OSA patients, were to estimate the prevalence of daytime hypoxemia, to assess the reciprocal effects between daytime PaO2 and nocturnal SpO2, and to investigate the direct and indirect role of sleep apnea severity in determining feedback gas exchange abnormalities. Materials and methods: In 456 patients a daytime hypoxemia-nocturnal hypoxia feedback structural equations model was designed. PaO2 adjusted for age (% of predicted), percent sleep time spent with SpO2 90), oxygen desaturation index and the apnea-hypopnea index, were determined as the measures of daytime hypoxemia, nocturnal hypoxia, and sleep apnea severity, respectively, after adjusting for the severity of obesity and lung volumes. Results: The TST 90-PaO2 feed-back structural equations modeling showed that daytime PaO2 was inversely related (P2 per 1 SD of TST90). The severity of OSA (-1.0%) was an indirect determinant of daytime PaO2 via the TST90 pathway. In contrast, daytime PaO2 did not influence (P>0.05) the extent of nocturnal hypoxia. Conclusions: In OSA patients, the extent of nocturnal hypoxia seems to be both a direct determinant and a mediator of the indirect effect of sleep apnea on the development of daytime hypoxemia.
KW - Hypoxemia
KW - Polysomnography
KW - Respiratory function
KW - Sleep apnea
KW - Structural equation model
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M3 - Article
C2 - 18274273
AN - SCOPUS:41449114180
VL - 31
SP - 249
EP - 255
JO - Sleep
JF - Sleep
SN - 0161-8105
IS - 2
ER -