HYPERBARIC-OXYGEN AFTER GLOBAL CEREBRAL-ISCHEMIA IN RABBITS REDUCES BRAIN VASCULAR-PERMEABILITY AND BLOOD-FLOW

Background and Purpose Hyperbaric oxygen (HBO) has been advocated as a therapy to improve neurological recovery after ischemia, since HBO ma y improve tissue oxygen delivery. We examined the effect of HBO treatm ent after global cerebral ischemia on early brain injury. Methods Rabb its were subjected to 10 minutes of global cerebral ischemia by cerebr ospinal fluid compression. After 30 minutes of reperfusion, rabbits ei ther were subjected to HBO for 125 minutes and then breathed 100% O-2 at ambient pressure for 90 minutes or breathed 100% O-2 for 215 minute s. At the end of reperfusion and 90 minutes after exposure, brain vasc ular permeability and cerebral blood flow were measured. Somatosensory evoked potentials were monitored throughout the experiment. Results H BO treatment reduced (P<.05) brain vascular permeability by 16% in gra y matter and by 20% in white matter. Cerebral blood flow was lower (P< .05) in the HBO group (40.9+/-1.9 mL/min per 100 g, mean SEM) compared with controls (50.8+/-2.0 mL/min per 100 g). Somatosensory evoked pot ential recovery was similar in the two groups (P>.05). Conclusions HBO administered after global cerebral ischemia promoted blood-brain barr ier integrity. HBO treatment also reduced cerebral blood flow; this ef fect was not associated with a reduction in evoked potential recovery. Since neurological outcome after global cerebral ischemia is generall y poor and treatment options are limited, HBO should be further invest igated as a potential therapy.