Copyright ©ERS Journals Ltd 2002 doi: 10.1183/09031936.02.00265702
Some factors affecting cerebral tissue saturation during obstructive sleep apnoea1 Dept of Thoracic Medicine and 2 Dept of Research and Development, University College London Hospitals, London, UK. 3 Dept of Pulmonary and Critical Care Medicine, Pulmonary Centre Vienna, Otto-Wagner-Spital, Vienna, Austria CORRESPONDENCE: S.G. Spiro, Dept of Thoracic Medicine, Middlesex Hospital, Mortimer Street, London, WIN 8AA. Fax: 44 2076375809. E-mail: s.spiro@academic.uclh.nthames.nhs.uk Keywords: near-infrared spectroscopy, obstructive sleep apnoea
Received: July 31, 2001
Measurement of cerebral tissue saturation during obstructive sleep apnoea (OSA) may provide additional information to conventional peripheral oxygen saturation.
Thirteen subjects with OSA (mean apnoea/hypopnoea index 65.7±27.9) were monitored using full polysomnography and monitoring of near-infrared cerebral tissue oxygenation index (TOI). One-thousand and thirty-six apnoeas and hypopnoeas were analysed, in terms of duration, sleep stage, arterial oxygen saturation (Sa,O2) dip, minimum Sa,O2, TOI dip and minimum TOI. Cerebral TOI is a measure of cerebral tissue saturation of haemoglobin with oxygen, calculated using near-infrared spatially resolved spectroscopy, which has been shown to have a high specificity for intracranial changes.
Decreases in cerebral oxygenation were observed during apnoeas and hypopnoeas. Baseline TOI ranged from 50.173.0% and mean apnoea/hypopnoea related TOI dips ranged from 1.436.85%. Mean Sa,O2 dips varied from 3.821.7%. In regression analysis, factors significantly predicting the magnitude of the TOI dip were Sa,O2 dip, minimum Sa,O2, apnoea duration and rapid eye movement sleep stage. The effect of apnoea duration and sleep stage remained significant after Sa,O2 was included in the regression equation.
Near-infrared spectroscopy provides a noninvasive technique for monitoring cerebral tissue saturation during obstructive sleep apnoea.
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