The effect of methylprednisolone pre-treatment on brain damage in dogs during cardiopulmonary bypass. A double blind study.

Brain damage remains a significant cause of post-operative morbidity following open-heart surgical procedures. Though cerebral ischaemia and micro-embolic damage are considered the main causative factors, further understanding of this particular clinical problem has been hampered by the lack of an acceptably sensitive experimental model. Recent development of a biochemical marker model using cerebrospinal fluid levels of creatine kinase enzyme and its B brain specific isoenzyme have been used in the present study designed to investigate the effect of corticosteroid pre-treatment of dogs submitted to 60 minutes of normothermic cardiopulmonary bypass. Identical vials containing methylprednisolone 30 mg/kg body weight or placebo were administered intravenously to the dog before the period of bypass was begun. The cisterna magna was cannulated in order to obtain appropriate cerebrospinal fluid samples. The results indicate a rise in the enzyme and isoenzyme levels in cerebrospinal fluid during the period of perfusion for both total creatine kinase enzyme and its B isoenzyme. Analysis of the results following completion of the study indicated that the levels of enzyme and isoenzyme rise in the steroid treated group were always lower than the levels obtained in the group receiving placebo. Though this difference was consistent it did not achieve statistical significance. Analysis of the distribution of the rise in enzyme levels in the individual dogs in the two groups suggested, however, that the group of dogs receiving methylprednisolone were possibly protected from excessive degrees of enzyme release indicating a possible protective effect of steroid pre-treatment.(ABSTRACT TRUNCATED AT 250 WORDS)