Abstract
Local cerebral oxygénation can be monitored continuously using an intraparenchymal Clark-type
PO2 sensitive catheter. Measured values of brain tissue p02 (Pbr02) not only depend on the clinically interesting balance between oxygen offer and demand, but also on catheter properties and
characteristics of the probe tissue interface. Microdamage surrounding p02-sensitive needles, inserted into various tissues, has been reported; we evaluated histologie changes at the probe tissue
interface after insertion of p()2 probes, suitable for clinical use, in the rat brain. The effect of insertion of the probe itself (mechanical damage), the application of micropotential during the measurements, and the effect of time was evaluated using digital image analysis of H&E-stained histológica! slices. Surrounding the probe tract, a zone of edema with an average radius of 126.8 /im was
seen; microhemorrhages with an average surface area of 56.2 X 103 fim2 were observed in nearly
all cases. The area of edema and the presence of microhemorrhages were not influenced by performed measurements or by time. Intraventricular blood was observed in 10 of 19 rats studied. Measured low Pbr02 values were related to the presence of a microhemorrhage in either probe tract or
ventricles. Tissue damage due to the measurements is negligible, and the amount of edema itself
does not influence the accuracy or response time of the p02 probe. Low Pbr02 readings, however,
could be caused by local microhemorrhages, undetectable on CT or MRI.
PO2 sensitive catheter. Measured values of brain tissue p02 (Pbr02) not only depend on the clinically interesting balance between oxygen offer and demand, but also on catheter properties and
characteristics of the probe tissue interface. Microdamage surrounding p02-sensitive needles, inserted into various tissues, has been reported; we evaluated histologie changes at the probe tissue
interface after insertion of p()2 probes, suitable for clinical use, in the rat brain. The effect of insertion of the probe itself (mechanical damage), the application of micropotential during the measurements, and the effect of time was evaluated using digital image analysis of H&E-stained histológica! slices. Surrounding the probe tract, a zone of edema with an average radius of 126.8 /im was
seen; microhemorrhages with an average surface area of 56.2 X 103 fim2 were observed in nearly
all cases. The area of edema and the presence of microhemorrhages were not influenced by performed measurements or by time. Intraventricular blood was observed in 10 of 19 rats studied. Measured low Pbr02 values were related to the presence of a microhemorrhage in either probe tract or
ventricles. Tissue damage due to the measurements is negligible, and the amount of edema itself
does not influence the accuracy or response time of the p02 probe. Low Pbr02 readings, however,
could be caused by local microhemorrhages, undetectable on CT or MRI.
| Original language | English |
|---|---|
| Pages (from-to) | 813-824 |
| Journal | Journal of Neurotrauma |
| Volume | 15 |
| Issue number | 10 |
| Publication status | Published - 1998 |