Noncardiac surgery brain injury: etiologic factors and prevention

EXCERPT: During total joint arthroplasty, showers of bony spicules, marrow fat, and clot are carried by venous blood to the lungs, creating conditions not unlike those present in patients who have suffered traumatic long bone fractures. There is recent evidence that, like the fat embolism syndrome (FES), which often has a component of neurologic dysfunction, total joint arthroplasty and femoral nailing are associated with intraoperative brain embolization as determined by transcranial Doppler ultrasonography, and magnetic resonance brain imaging. Although there are good data demonstrating that intraoperative brain embolization occurs during total joint arthroplasties, the makeup and, even more importantly, the clinical significance of these emboli remain speculative. Brain microemboli resulting from cardiac surgery occur by the millions and may cause focal ischemia resulting in significant neurologic dysfunction. Our studies suggest that the major source of these microemboli is lipid droplets of the patient's fat that drip into the blood in the surgical field. This lipid-laden blood is aspirated and then returned to the patient via the cardiopulmonary bypass (CPB) apparatus. Our investigations have focused on the causes (microemboli), consequences (brain damage), and strategies for elimination of brain lipid microemboli resulting from salvaged blood collected during surgery.