[Selective cerebral hypothermia following cardiac arrest in the cat]

The aim of the present study was to introduce a new method of external selective brain cooling in cats. By means of this device, which mainly consisted of a head-sized, closely fitting copper basin, it was possible to reduce brain temperature rapidly. The resultant difference between core and cerebral temperatures amounted to mean values of about 10 degrees C after a 20-min cooling period. Ventricular fibrillation lasting for 15 min was induced in 23 healthy adult cats by internal cardiac electrical overpacing and followed by cardiopulmonary resuscitation (CPR). In several animals (n = 8) CPR efforts failed completely or they died without any indication of sufficient spontaneous circulation. In the initial postischemic period the remaining animals stayed normothermic and served as controls (n = 7) or received external brain cooling (n = 8), which was started simultaneously with CPR and continued for 30 min. During a survival time of 4 h cardiocirculatory function was stabilized pharmacologically and artificial respiration was performed, followed by transcardiac perfusion fixation. After removal from the skull, the brains were processed for histopathological evaluation of ischemic neuronal damage by light microscopy and morphometry. The clinical data obtained indicate that the described method provides a means for efficient heat exchange from within the intracranial space. Rapid, selective brain cooling could be achieved without any critical reduction of the core temperature and therefore, cardiac arrhythmias, a usual consequence of generalized hypothermia, could be avoided. The histopathological evaluation of ischemic neuronal damage showed a significantly higher percentage of unaffected cells in some areas of the cerebral cortex in animals treated with postischemic cerebral hypothermia than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)