Hypoxaemic reperfusion ameliorates the histopathological changes in the pig brain after a severe global cerebral ischaemic insult

Background and purpose: We have recently shown that hypoxaemic reperfusion, after an ischaemic brain insult, improves neurological outcome and decreas es lipid peroxidation. In the present study, we investigated the effect of hypoxaemic reperfusion on brain histopathological changes. Methods: Sixteen pigs subjected to a 10-min global cerebral ischaemia were either hypoxaemically (PaO2 approximate to 35 mmHg, hypoxaemic reperfusion (HR) group, n = 8) or hyperoxaemically (PaO2 > 300 mmHg, control (C) group, n = 8) reperfused. The brains were removed 24 h after reperfusion and six neuropathological abnormalities were evaluated blindly and scored semi-quan titatively (0: normal to 3: severe injury) on eight representative regions of the brain. The overall cumulative score of the abnormalities and their r egional prevalence, as well as the neurological outcome, were compared betw een the two groups. Results: The neuronal degeneration, assessed in terms of cumulative score ( P = 0.002) and regional prevalence (P = 0.025 to P = 0.041), was lower in t he HR group than in the C group. Spongy degeneration attained statistically significant difference only in cerebellum (P = 0.002) and inflammation onl y in hippocampus (P = 0.046) but the difference in the cumulative score of these abnormalities was not statistically significant. The difference of th e three neurological assessments over time was statistically significant be tween the two groups, i.e. after resuscitation (P = 0.001), at 8 h (P = 0.0 06) and at 24 h (P = 0.001) after reperfusion. Conclusions: Hypoxaemic reperfusion during resuscitation from a severe glob al ischaemic cerebral insult is associated with statistically significantly fewer histopathological changes of the brain than in controls. This is ass ociated with a superior neurological outcome.