Show simple item record Mutch, W. Alan C Patel, Sunni R. Shahidi, Ayda M. Kulasekara, Susith I. Fisher, Joseph A. Duffin, James Hudson, Christopher 2013-11-19T14:56:45Z 2013-11-19T14:56:45Z 2013-02
dc.identifier.citation PLoS ONE 8 (2): e57881 en_US
dc.description.abstract Background - Monitoring cerebral saturation is increasingly seen as an aid to management of patients in the operating room and in neurocritical care. How best to manipulate cerebral saturation is not fully known. We examined cerebral saturation with graded changes in carbon dioxide tension while isoxic and with graded changes in oxygen tension while isocapnic. Methodology/Principal Findings - The study was approved by the Research Ethics Board of the University Health Network at the University of Toronto. Thirteen studies were undertaken in healthy adults with cerebral oximetry by near infrared spectroscopy. End-tidal gas concentrations were manipulated using a model-based prospective end-tidal targeting device. End-tidal carbon dioxide was altered ±15 mmHg from baseline in 5 mmHg increments with isoxia (clamped at 110±4 mmHg). End-tidal oxygen was changed to 300, 400, 500, 80, 60 and 50 mmHg under isocapnia (37±2 mmHg). Twelve studies were completed. The end-tidal carbon dioxide versus cerebral saturation fit a linear relationship (R2 = 0.92±0.06). The end-tidal oxygen versus cerebral saturation followed log-linear behaviour and best fit a hyperbolic relationship (R2 = 0.85±0.10). Cerebral saturation was maximized in isoxia at end-tidal carbon dioxide of baseline +15 mmHg (77±3 percent). Cerebral saturation was minimal in isocapnia at an end-tidal oxygen tension of 50 mmHg (61±3 percent). The cerebral saturation during normoxic hypocapnia was equivalent to normocapnic hypoxia of 60 mmHg. Conclusions/Significance - Hypocapnia reduces cerebral saturation to an extent equivalent to moderate hypoxia. en_US
dc.description.sponsorship Internal Funding, Department of Ophthalmology and Vision Sciences en_US
dc.publisher PLoS en_US
dc.subject cerebral saturation en_US
dc.subject neurocritical care en_US
dc.subject Isoxia en_US
dc.subject Isocapnia en_US
dc.subject graded response en_US
dc.title Cerebral oxygen saturation: graded response to carbon dioxide with isoxia and graded response to oxygen with Isocapnia en_US
dc.type Article en_US

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