A new semi-invasive method for two dimensional pO2 measurements of cortical structures.
BACKGROUND
Measuring brain oxygenation in patients with TBI or SAH is of major interest. We present a new semi-invasive method for two dimensional measurements of cortical pO2.


METHODS
For this feasibility study, a porphyrin containing sensor foil was placed directly on the cortex of intubated and variably ventilated Wistar rats. The sensor was excited with a light pulse and pictures of the foil's pO2 dependant emissions were captured with a CCD camera. After online data processing, two-dimensional maps of cortex oxygenation were displayed and analyzed using ROIs (here: arteriole, vein, parenchyma) with a display rate of 7 Hz. The size of one single measurement pixel was 0.03 x 0.03 mm2.


RESULTS
The mean pO2 over cortex arterioles was 20.3 +/- 0.69, over veins 17.1 +/- 0.5 and over parenchyma 9.1 +/- 0.6 (mmHg +/- SD). The arterial pO2 showed a good correlation to the pO2 in the ROIs (r = 0.46-0.72, p < 0.0001, n = 198). Comparing groups with different paO2 and paCO2 we found significantly different pO2 values in the ROIs of the cortex.


CONCLUSIONS
This prototype is capable of obtaining cortical pO2 maps with excellent temporal and spatial resolution and provides simultaneous imaging of the cortex structures.
Warnat
Jan
J
Department of Neurosurgery, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany. Jan.Warnat@klinik.uni-regensburg.de
Liebsch
Gregor
G
Stoerr
Eva-Maria
EM
Brawanski
Alexander
A
Woertgen
Chris
C
D000818:Animals; D001158:Arteries / Q000378:metabolism; D001784:Blood Gas Analysis; D002540:Cerebral Cortex / Q000098:blood supply*; D002560:Cerebrovascular Circulation; D007091:Image Processing, Computer-Assisted; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D019904:Polymethyl Methacrylate; D051381:Rats; D017208:Rats, Wistar; D013012:Sorbitol / Q000378:metabolism; D014993:Xylitol / Q000378:metabolism
C073737:Profylin; D013012:Sorbitol; D019904:Polymethyl Methacrylate; D010100:Oxygen; D014993:Xylitol