DISTINCTIVE MICROCIRCULATION OF THE BRAIN DURING CEREBRAL PERFUSION BY OBSERVATION WITH A CCD MICROSCOPE

Establishment of safer cerebral protection remains an important issue in reducing cerebral complications during aortic arch repair. Various cerebral perfusion techniques have been used. Recently, the usefulness of retrograde cerebral perfusion (RCP) combined with hypothermia was reported. The authors evaluated the cerebral microcirculation during R CP by direct observation with a charge-coupled device (CCD) microscope . in six craniotomied, anesthetized swine, cardiopulmonary bypass was established by arterial perfusion through the femoral artery and venou s drainage from the right atrium. The authors observed cerebral arteri olae and venulae on the brain surface. Each swine was cooled to a brai n temperature of 20 degrees C. Perfusion was stopped, RCP was initiate d with oxygenated blood through the superior vena cava, and cerebral p erfusion pressure (CPP) was gradually increased. During antegrade cere bral perfusion (ACP), homogeneous vascular flow was observed in all mo dels. During RCP, retrograde vascular flow was generated in four of th e six models, but homogeneous retrograde vascular flow was achieved in arteriolae and venulae in only two models at a CPP of greater than 20 mmHg. It is suggested that homogeneous and effective retrograde perfu sion may not be achieve at a CPP of less than 20 mmHg, and that RCP ca uses uneven microcirculation of the brain with a disadvantageous effec t on cerebral protection when compared with ACP.