DIFFERENTIAL AGE EFFECTS OF MEAN ARTERIAL-PRESSURE AND REWARMING ON COGNITIVE DYSFUNCTION AFTER CARDIAC-SURGERY

Central nervous system dysfunction is a common consequence of otherwis e uncomplicated cardiac surgery. Many mechanisms have been postulated for the cognitive dysfunction that is part of these neurologic sequela e. The purpose of our investigation was to evaluate the effects of mea n arterial pressure (MAP) during cardiopulmonary bypass (CPB) and the rate of rewarming on cognitive decline after cardiac surgery. Two hund red thirty-seven patients completed preoperative and predischarge neur opsychologic testing. MAP and temperature were recorded at 1-min inter vals using an automated anesthesia record keeper. MAP area less than 5 0 mm Hg (time and degree of hypotension), as well as the maximal rewar ming rate, were determined for each patient. Multivariable linear regr ession revealed that the rate of rewarming and MAP were unrelated to c ognitive decline. However, interactions significantly associated with cognitive decline were found between age and MAP area less than 50 mm Hg on one measure, and between age and rewarming rate in another, iden tifying susceptibility of the elderly to these factors. Although MAP a nd rewarming were not the primary determinates of cognitive decline in this surgical population, hypotension and rapid rewarming contributed significantly to cognitive dysfunction in the elderly.