A long-term objective is to understand the pathogenesis of neurologic injuries associated with cardiac surgery, cardiopulmonary bypass, and circulatory arrest. Our specific aims are to establish a dose of air which results in moderate to severe neurologic defects in normothermic (37℃) rabbits.

To first establish a dose of air which would cause unequivocal neurologic impairment, anesthetized rabbits received either 0, 50, 100 or 150 microgram l/kg of air into the internal carotid artery(n=5 in each group). One hour later, anesthesia was discontinued and animals were recovered. Animal were neurologically evaluated at 24 hours using a zero(normal) to 97(coma) point scale.

There was a clear relationship between the dose of air injected and the severity of neurologic impairment at 24 hours, p=1.1x10(-7). Rabbits receiving 50 micrograml/kg of air were minimally affected and were difficult to distinguish from controls. In contrast, rabbits receiving 150 micrograml/kg of air were uniformly and unequivocally impaired.

we recommend for future cerebral air embolism studies, 150 microgram l/kg as the optimal dose of air which would reliably produce viable subjects for 24 hours with marked unequivocal, neurologic impairment.