Elderly patients undergoing major, orthopedic surgery are at risk of developing postoperative cognitive dysfunction (POCD) or memory impairment following surgery. Transcranial doppler (TCD) monitoring of blood flow to the brain has detected cerebral emboli in 60% of patients following release of the thigh tourniquet during total knee replacement or arthroplasty (TKA). These cerebral embolic events may represent one of the mechanisms responsible for postoperative cognitive problems.