Healthy Adults & Patients

Healthy Volunteers Cerebral Autoregulation Studies

In recent years we have completed a large number of studies on healthy adult volunteers with optical instrumentation to investigate the normal brain response to various challenges. We have investigated hypoxia ^[2,7], hyperoxia ^[8,9], hypercapnia ^[6,8,9], hypocapnia ^[9] posture changes ^[10,11] and acetazolamide provocation ^[1].

	Figure 1. A moderate hypoxia study on a healthy adult volunteer. SaO2: arterial saturation TOI: tissue oxygenation FiO2: inspired oxygenation Hbdiff: HbO2-HHb HbT: HbO2+HHb

For more information on some of these studies we advise you also to look at Dr Ilias Tachtsidis PhD thesis.

References

[1] Tachtsidis I., Tisdall M., Delpy D.T., Smith M., Elwell C.E., “Measurement of cerebral tissue oxygenation in young healthy volunteers during acetazolamide provocation: a transcranial Doppler and near-infrared spectroscopy investigation.” Advances in Experimental Medicine and Biology 614, 389-396 (2008). [paper]
[2] Tisdall M.M., Tachtsidis I., Leung T.S., Elwell C.E. and Smith M. “Near infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome oxidase in the healthy human brain during hypoxemia.” Journal of Biomedical Optics, 12(2):024002, (2007) [paper]
[3] Hunt K., Tachtsidis I., Bleasdale-Barr K., Elwell C., Mathias C., Smith M., “Changes in Cerebral Oxygenation and Haemodynamics during Postural Blood Pressure Changes in Patients with Autonomic Failure” Physiological Measurements, 27(9):777-785, (2006). [Detail]
[4] Tachtsidis I., Elwell C.E., Leung T.S, Lee C.W., Smith M., Delpy D.T., “Investigation of cerebral haemodynamics by near infrared spectroscopy in young healthy volunteers reveals posture dependent spontaneous oscillations.” Physiological Measurement, 25(2):437-445, (2004). [Detail]
[5] Tachtsidis I., Tisdall M., Leung T.S., Pritchard C., Smith M., Elwell C.E., “Hyperoxia and hypercapnea increase the concentration of oxidised cytochrome c oxidase in the healthy human adult brain.” Brain 07, Osaka, Japan, (2007). [paper]
[6] Tachtsidis I., Jones H., Oliver C., Delpy D.T., Smith M., Elwell C.E., “Investigation of the changes in cerebral tissue oxygenation measured with near infrared spectroscopy in response to moderate hypercapnia.” Journal of Cerebral Blood Flow & Metabolism, 25, S193, (2005) [paper] [poster]
[7] Tisdall M., Tachtsidis I., Elwell C.E., Smith M., “Changes in concentrations of oxidised cytochrome oxidase measured using both broadband and four wavelength near infrared spectroscopy reflect changes in oxygen delivery during hypoxaemia in healthy volunteers.” in Biomedical Optics 2006 Technical Digest (Optical Society of America, Washington, DC, 2006), ME66, (2006). [paper] [poster]
[8] Tachtsidis I., Tisdall M., Leung T.S., Pritchard C., Smith M., Elwell C.E., “Hyperoxia and hypercapnea increase the concentration of oxidised cytochrome c oxidase in the healthy human adult brain.” Brain 07, Osaka, Japan, (2007). [paper]
[9] Tisdall M., Tachtsidis I., Leung T.S., Elwell C.E., Smith M., “Changes in cerebral tissue oxygen saturation measured by near infrared spectroscopy do not only reflect changes in oxygenation.” J. Neurosurg. Anesthesiol.; 19: 152 (2007). [poster]
[10] Tachtsidis I., Elwell C.E., Leung T.S., Bleasdale-Barr K., Hunt K., Toms N., Smith M., Mathias C.J., Delpy D.T. “Rate of change in cerebral oxygenation and blood pressure in response to passive changes in posture: a comparison between Pure Autonomic Failure patients and Controls.” Advances in Experimental Medicine and Biology, 566:187-193, (2005). [paper]
[11] Tachtsidis I., Elwell C.E., Lee C.W., Leung T.S, Smith M., Delpy D.T. “Spectral characteristics of spontaneous oscillations in cerebral haemodynamics are posture dependent.” Advances in Experimental Medicine and Biology, 540:31-36, (2004) [paper] [poster]