Hyperbaric oxygen induces rapid protection against focal cerebral ischemia.
OBJECTIVE
The timing and mechanisms of protection by hyperbaric oxygen (HBO) in cerebral ischemia have only been partially elucidated. We monitored the early in vivo effects of HBO after 2 h transient focal ischemia using repetitive MRI.


METHODS
Wistar rats underwent filament occlusion of the middle cerebral artery (MCAO). 40 min after MCAO, rats were placed in a HBO chamber and breathed either 100% O(2) at 3.0 atmospheres absolute (ata; n = 24) or at 1.0 ata (control; n = 24) for 1 h. Diffusion, perfusion and T2-weighted MR-images were obtained after 15 min and 3, 6 and 24 h of reperfusion. In 6 axial MR slices, volume of abnormal diffusion and T2w signals were measured in the ischemic hemisphere. Furthermore, hemispheric mean apparent diffusion coefficient- (ADC) and T2 values were calculated for statistical analysis.


RESULTS
HBO significantly reduced volume of abnormal DWI signal beginning immediately after reperfusion (control: 92 +/- 28 mm(3); HBO: 64 +/- 17) and lesion size on T2w (control: 375 +/- 91 mm(3); HBO: 225 +/- 39) after 24 h. Correspondingly, mean ADC levels were lower and T2 values higher in the ischemic hemisphere in the control group. HBO reduced histological infarct size at 24 h.


CONCLUSIONS
High-dose intraischemic HBO therapy has an immediate protective on the brain which is superior to normobaric oxygen.
Veltkamp
Roland
R
Department of Neurology, Ruprecht-Karls-University Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. roland_veltkamp@med.uni-heidelberg.de
Siebing
Dirk A
DA
Heiland
Sabine
S
Schoenffeldt-Varas
Philip
P
Veltkamp
Claudia
C
Schwaninger
Markus
M
Schwab
Stefan
S
D000818:Animals; D007839:Functional Laterality / Q000502:physiology; D006931:Hyperbaric Oxygenation; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000517:prevention & control*; D008279:Magnetic Resonance Imaging; D008297:Male; D051381:Rats; D017208:Rats, Wistar