The influence of cannulation technique on blood flow to the brain in rats undergoing cardiopulmonary bypass: a...

Recently, there has been an increase in the use of rat models of cardiopulmonary bypass (CPB) for research purposes. Much of this work has focused on cerebral injury associated with CPB. Many of these studies employ a peripheral cannulation approach, often utilizing the caudal artery and internal or external jugular vein. The aim of the present study was to establish whether there is any alteration in blood flow to the brain associated with the use of different cannulation routes. Twenty-four adult male Sprague Dawley rats were allocated to one of three study groups: Group 1- caudal artery return, Group 2 -open-chest aortic return, and Group 3- nonbypass control group. Colored microspheres were injected into all animals at four time points (postinduction, initiation of bypass, midbypass, and end bypass). After the termination of each experiment, the brains were excised, the tissue was digested, the microspheres were harvested, and the global blood flow to the brain was assessed using the reference flow method. There was a significant reduction in blood flow to the brain between both bypass groups and the control group. Additionally, cerebral blood flow was significantly lower in the caudal return group than in the aortic return group. There is a significant drop in blood flow to the brain associated with the initiation and continuation of CPB when compared to non-CPB controls. These results also confirm a considerable cerebral hypoperfusion associated with the peripheral cannulation technique, and suggest that peripheral bypass may exaggerate the influence CPB has on cerebral injury. This technique must therefore be employed with caution.