Cognitive impairment after cardiac surgery: Confounding factors and recommendations for improved practice

Abstract

Impaired cognition following cardiac surgery is a common complication. Estimates of the incidence of postoperative cognitive decline/dysfunction (POCD) vary from 20 % to 70 % of patients in the week after cardiac surgery to 10-40 % by 6 weeks. It has become evident that differences in research design have contributed significantly to these differing estimates of POCD and that greater consistency will be achieved if future studies utilize appropriate control groups. Recent studies have shown that many patients have cognitive impairment prior to undergoing cardiac surgery and furthermore that some of the POCD is associated with surgical procedures in general, rather than with cardiac surgery in particular. The domains of language, concentration, and motor control are commonly affected during the first week after cardiac surgery, and memory and executive function can also be affected. Some individuals are more vulnerable than others. In the future it might be possible to identify these individuals prior to surgery with computer-based cognitive tests and measures of emotional state, so that the factors involved can be managed and the risk of POCD can be reduced.