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Choroidal blood flow variations to gas in healthy young subjects before and after intermittent hypoxia
Author(s) -
KHAYI H,
TONINI M,
TAMISIER R,
GEISER M,
PEPIN JL,
LEVY P,
ROMANET JP,
CHIQUET C
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.581.x
Subject(s) - carbogen , hypoxia (environmental) , intermittent hypoxia , medicine , placebo , anesthesia , inhalation , laser doppler velocimetry , nitric oxide , vasodilation , apnea , blood flow , obstructive sleep apnea , oxygenation , chemistry , pathology , oxygen , alternative medicine , organic chemistry
Purpose To evaluate the effect of 14‐day intermittent hypoxia on the response of the sub‐foveal choroidal blood flow (ChBF) after gas inhalation, in healthy subjects. Recent studies have emphasized the effect of the obstructive sleep apnea (OSA) on CO2 vasodilatation and O2 vasoconstriction. A human model of OSA has been developed in our laboratory with healthy subjects submitting to intermittent hypoxia during 14 consecutive nights. The aim of our study was to determine if these subjects exhibit a dysregulation in ChBF response during and after exposition to intermittent hypoxia. Methods The ChBF was measured before, at the end (D14) and 5 days after the period of exposition to intermittent hypoxia. ChBF was measured using laser Doppler flowmetry (LDF) in 6 healthy young volunteers exposed to night time intermittent hypoxia. We measured the variations in ChBF during 10 minutes of air inhalation (placebo), 100% O2, and carbogen (8% CO2) at each visit Results The ChBF response to carbogen was considered as normal (increase of 11%) before the exposition to intermittent hypoxia, and was reduced at the end (+5%) and after the exposition (+5%). The response to 100% O2 in these subjects was not altered by the exposition to intermittent hypoxia. Using placebo, the ChBF remained unchanged at each visit. The sensitivity of the ChBF measurement was 6 %. Conclusion Healthy subjects exposed to intermittent hypoxia exhibit an altered response of ChBF to carbogen. This CO2 responsiveness could be related to an alteration of the nitric oxide synthase expression.