Visualisation of cortical pO2 during an epidural mass lesion in rodents

Abstract

Monitoring pbtO2 is a valuable supplemental-procedure for neurocritically ill patients. Here, we utilise an opto-chemical method for measuring cortical pO2 during a reversibly introduced epidural mass lesion in a rat model. The sensor was placed in a cortical window of 17 ventilated Wistar rats. Inflating the balloon device over the contralateral hemisphere increased ICP. Physiological parameters and cortical pO2 were recorded. The ICP increased from 6.2 ± 4.6 to 44.6 ± 12.6 mmHg (p < 0.001). Cortical pO2 over arterioles changed from 28.9 ± 2.1 to 19.0 ± 2.1 mmHg (p < 0.001), over venules from 14.8 ± 1.2 to 9.9 ± 1.5 mmHg (p = 0.002) and over parenchyma from 4.1 ± 0.7 to 2.4 ± 0.8 mmHg respectively (p < 0.001), while basic physiological parameters remained constant (p > 0.05). During baseline, arterial pO2 correlated significantly with cortex arteriole and venole pO2, but not with cortex parenchyma pO2. While ICP was raised, cortical pO2 did not correlate with arterial pO 2. In this model, a moderate epidural mass lesion causes a significant decrease in cortical pO2. Cortex parenchyma pO 2 appeared to be independent from arterial pO2. The correlation of cortex vessel pO2 with arterial pO2 disappeared during the epidural mass lesion. These findings show the capability of the device to elucidate the behaviour of functionally different cortex areas at pathophysiological conditions. © 2012 Springer-Verlag/Wien.