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Assessment of a Non-Invasive Brain Oximeter in a Sheep Model of Acute Brain Injury

Authors Dixon B, Turner R, Christou C

Received 23 October 2019

Accepted for publication 20 November 2019

Published 3 December 2019 Volume 2019:12 Pages 479—487


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 2

Editor who approved publication: Dr Scott Fraser

Video abstract presented by Barry Dixon.

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Barry Dixon,1 Renee Turner,2 Chris Christou3

1Cyban Pty Ltd, Melbourne, VIC, Australia; 2Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia; 3Preclinical Imaging and Research Laboratories, South Australian Health and Medical Research Institute, Adelaide, SA, Australia

Correspondence: Barry Dixon
Cyban Pty Ltd, Melbourne, VIC, Australia
Tel +61 439618815

Introduction: Evidence suggests treatments guided by brain oxygen levels improve patient outcomes following severe traumatic brain injury; however, brain oxygen levels are not routinely monitored as an effective non-invasive method has not been established. We undertook a study, in a sheep model of acute brain injury, to assess a new non-invasive brain oximeter. The monitor uses the principles of pulse oximetry to record a pulse and oxygen levels.
Methods: We studied 8 sheep. An acute increase in intracranial pressure was induced with an injection of blood into the cranial vault. The temporal changes in the brain oximeter, intracranial pressure and cerebral perfusion pressure were recorded. Simultaneous conventional skin pulse oximetry was also recorded to assess the possible influence of skin blood flow on the brain oximeter signal.
Results: At baseline, a pulsatile waveform consistent with the brain circulation was obtained in 7 animals. The baseline brain pulse was quite distinct from the simultaneous conventional skin pulse and similar in shape to a central venous pressure waveform. Injection of blood into the cranial vault triggered an immediate increase in intracranial pressure and fall in cerebral perfusion pressure, by 60-s cerebral perfusion pressure recovered. The brain oximeter oxygen levels demonstrated similar changes with an immediate fall and recovery by 60 s. Periods of high intracranial pressure were also associated with high-frequency oscillations in the brain pulse waveform; there was, however, no change in the conventional skin pulse oximeter pulse waveform.
Conclusion: The brain oximeter detected acute changes in both oxygen levels and the brain pulse waveform following an increase in intracranial pressure levels. The brain oximeter could assist clinicians in the management of acute brain injury.

Keywords: oximetry, traumatic brain injury, brain, sheep

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