Studying cerebral hemodynamics and metabolism using simultaneous near-infrared spectroscopy and transcranial Doppler ultrasound: a hyperventilation and caffeine study

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dc.contributor.authorYang, Runze
dc.contributor.authorBrugniaux, Julien
dc.contributor.authorDhaliwal, Harinder
dc.contributor.authorBeaudin, Andrew
dc.contributor.authorEliasziw, Misha
dc.contributor.authorPoulin, Marc
dc.contributor.authorDunn, Jeff F.
dc.date.accessioned2016-03-23T19:39:03Z
dc.date.available2016-03-23T19:39:03Z
dc.date.issued2015-03-25
dc.description.abstractCaffeine is one of the most widely consumed psycho-stimulants in the world, yet little is known about its effects on brain oxygenation and metabolism. Using a double-blind, placebo-controlled, randomized cross-over study design, we combined transcranial Doppler ultrasound (TCD) and near-infrared spectroscopy (NIRS) to study caffeine's effect on middle cerebral artery peak blood flow velocity (Vp), brain tissue oxygenation (StO2), total hemoglobin (tHb), and cerebral oxygen metabolism (CMRO2) in five subjects. Hyperventilation-induced hypocapnia served as a control to verify the sensitivity of our measurements. During hypocapnia (~16 mmHg below resting values), Vp decreased by 40.0 ± 2.4% (95% CI, P < 0.001), while StO2 and tHb decreased by 2.9 ± 0.3% and 2.6 ± 0.4%, respectively (P = 0.003 and P = 0.002, respectively). CMRO2, calculated using the Fick equation, was reduced by 29.3 ± 9% compared to the isocapnic-euoxia baseline (P < 0.001). In the pharmacological experiments, there was a significant decrease in Vp, StO2, and tHb after ingestion of 200 mg of caffeine compared with placebo. There was no significant difference in CMRO2 between caffeine and placebo. Both showed a CMRO2 decline compared to baseline showing the importance of a placebo control. In conclusion, this study showed that profound hypocapnia impairs cerebral oxidative metabolism. We provide new insight into the effects of caffeine on cerebral hemodynamics. Moreover, this study showed that multimodal NIRS/TCD is an excellent tool for studying brain hemodynamic responses to pharmacological interventions and physiological challenges.en_US
dc.description.grantingagencyAlberta Innovates Health Solutions; National Science and Engineering Research Council of Canada; Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada and Hotchkiss Brain Instituteen_US
dc.description.refereedYesen_US
dc.identifier.citationYang, R., J. Brugniaux, H. Dhaliwal, A. E. Beaudin, M. Eliasziw, M. J. Poulin and J. F. Dunn. (2015). Studying cerebral hemodynamics and metabolism using simultaneous near-infrared spectroscopy and transcranial Doppler ultrasound: a hyperventilation and caffeine study. Physiol Rep. 3(4).en_US
dc.identifier.doi10.14814/phy2.12378
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/33535
dc.identifier.issn2051-817X
dc.identifier.urihttp://hdl.handle.net/1880/51121
dc.language.isoenen_US
dc.publisherWiley-Blackwell on behalf of The Physiological Society and the American Physiological Societyen_US
dc.publisher.departmentRadiologygoen_US
dc.publisher.facultyMedicineen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.publisher.urlhttp://onlinelibrary.wiley.com/en_US
dc.relation.ispartofseriesPhysiological Reports;
dc.subjectbrainen_US
dc.subjectnear-infrared spectroscopyen_US
dc.subjecttranscranial Doppler ultrasounden_US
dc.titleStudying cerebral hemodynamics and metabolism using simultaneous near-infrared spectroscopy and transcranial Doppler ultrasound: a hyperventilation and caffeine studyen_US
dc.typejournal article
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