Effects Of Selective Brain Hypothermia On Cerebral Ischemia In Dogs

Object:In this studying ,we constructed canine selective brain hypothermia model through lateral ventricle by perfusing cooling solution , evaluated the effects of its hypothermia on globe brain ischemia using a canine model of transient four artery occlusion, and observed the relation between initiating time of hypothermia and its results. Methods18 dogs were divided randomly into 3 groups, which were that group A was prompt hypothermia group (n=6) ; group B was delayed group ( n=6 ) ;group C was normothermia severed as a contrast group (n=6) .Cerebral blood supply of the three groups was interrupted by clamping their bilateral vertebral arteries and common carotid arteries for half an hour, then the cerebral blood supply were recovered. Constantly perfusing isotonic nitric chloride at 20 degrees into one of their lateral ventricles and draining the solution from the other side, group A was initiated the perfusing promptly at the beginning of blood supply recovery, group B was delayed for 30 minutes after blood supply recovered, and then initiate the perfusion, but group C was never perused. Sustaining perfusing for 4 hours and lowering the brain temperature to the level of mild hypothermia, then the hypothermia perfusion was finished. Whole Brain tissue was extracted byoperation means after 24 hours since the ischemic initiated, some for cerebraltissues dyeing, the residues for water content measurement.ResultsIn group A and B ,it took 30 minutes for the perfusing side to lower their brain temperature to the level of mild hypothermia, the other side needed 45 minutes, while rectal temperature was maintained at above 37° C, As water content among the three groups, there is significantly different. The pathologic changes of hippocampus CA1 area are also different, such as, in the group C there is karyopyknosis and neuron nucleus thick dyed, while in the group B, the phenomenon is fewer, in group A, its pathology is almost normal. ConclusionsThese results demonstrate that our method is useful for carrying out selective brain hypothermia to a mild degree, can relieve neuronal damage by ischemia, and decrease tissue edema .The effects have relation with the initiating time after cerebral ischemic.