gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Radial oxygen gradients on the rat cortex surface

Meeting Abstract

  • J. Warnat - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg
  • M. Galler - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg
  • G. Liebsch - Biocam, Regensburg
  • K.M. Schebesch - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg
  • A. Brawanski - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg
  • C. Woertgen - Klinik und Poliklinik für Neurochirurgie, Universitätsklinikum Regensburg

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocP09-11

DOI: 10.3205/09dgnc351, URN: urn:nbn:de:0183-09dgnc3517

Published: May 20, 2009

© 2009 Warnat et al.
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Outline

Text

Objective: The monitoring of oxygen supply to the brain is a challenge in advanced neuromonitoring of critically injured patients with TBI or SAH. It has been shown that poor neurological outcome is associated with a low ptiO2. Radial oxygen gradients over arterioles are of interest because they characterize the transport of pO2 into the tissue. We examined if these gradients can be detected with a novel optochemical, planar measurement device.

Methods: The system was placed after hemicraniectomy on the cortex of intubated and ventilated Wistar rats (n=7, m=376 ± 33g). The sensor foil was excited with a triggered LED-flash. PO2-dependent luminescence pictures of the sensor were registered with a CCD camera and processed with PC based software (IDL, Creaso). The arterial pO2 was varied by changing the FiO2. Blood gas analysis, RR, heart rate and cortical pO2 were recorded simultaneously. ROIs of 10x50 pixels were placed right angled over a cortical arteriole. Columns of 10 pixels lying parallel to the vessel were averaged to increase the signal to noise ratio.

Results: The mean pO2 of the measured cortex region was 25.7 ± 30.8 mmHg (group 1, paO2<80 mmHg), 42.6 ± 29.6 mmHg (group 2, paO2 80-120 mmHg) and 49.6 ± 28.9 mmHg (group 3, paO2 >120 mmHg). The paCO2 of the groups (33-47 mmHg) was not significantly different. The gradient from the middle to the border of the vessel was 12.0 (group1), 1 6.3 (group 2) and 22.5 (group 3) mmHg/mm. Gradients from the border of the vessel into the parenchyma measured 12.0 (gr.1), 16.3 (gr.2) and 22.5 (gr.3) mmHg/mm respectively. Comparing the three groups, both the mean pO2-values and the gradients were significantly (p<0.01) different.

Conclusions: Despite the small dimensions of the cortex structures, sufficient planar pO2 detections of the arterioles and their surroundings were achieved. Oxygen gradients changed depending on the actual arterial pO2.

This method may be useful for an estimation of the delivery of oxygen into the tissue, especially when the oxygen transport is altered, e.g. by edema, and might applicable for neuromonitoring and laboratory investigations.