Importance of monitoring blood viscosity during cardiopulmonary bypass

Sir,Approximately 500,000 cardiopulmonary bypass (CPB) procedures using extracorporeal circulation are per-formed annually in the United States of America.. For decades, attention has focused on cerebral complications as a source of morbidity and disability post procedures. These deficits include impaired consciousness, seizures, cognitive impairment (memory, attention deficits, lan-guage difficulty) and stroke, all potentially limiting the ability to function independently. The reported inci-dence of neurological complications varies widely from 7 to 61% for transient deficits and 1.6 to 23% for perma-nent deficits.