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AJNR - American Journal of Neuroradiology

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How Depth of Anesthesia Influences the Blood Oxygenation Level–Dependent Signal from the Visual Cortex of Children

V.L. Marcar^a, U. Schwarz^d, E. Martin^b and T. Loenneker^b,c

^a Department of Neuropsychology, University of Zurich, Zurich, Switzerland
^b the MR-Center, University Children’s Hospital Zurich, Zurich, Switzerland
^c the Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
^d the Department of Anesthesiology, University Children’s Hospital of Eastern Ontario, Ottawa, Ontario, Canada

View larger version (58K): [in a new window]   Fig 1. The figure shows the cortical site of the positive BOLD response (red) and the negative BOLD response (blue) in a single child at the 3 levels of sevoflurane anesthesia. The extent of activation of the positive BOLD response is clearly largest, at 0.75 MAC. The extent of activation of the negative BOLD response can be seen to decline with increasing sevoflurane level.

View larger version (20K): [in a new window]   Fig 2. A, The mean number of activated voxels with a positive BOLD response. B, The mean number of activated voxels with a negative BOLD response at the 3 levels of sevoflurane anesthesia. C, The mean, peak R2* from the positive BOLD. D, The mean, peak R2* from the negative BOLD response at the 3 levels of sevoflurane anesthesia. The error bars indicate the standard error of the mean.

View larger version (21K): [in a new window]   Fig 3. The 2 panels show the frequency distribution of the peak R2* at the 3 levels of sevoflurane anesthesia. Left, the frequency distribution for the positive BOLD response. Right, the frequency distribution of the negative BOLD response. We selected to show the absolute values for each bin, rather than the relative values, to convey to the reader the difference in the number of activated voxels upon which the distribution is based.