Pyrexia after cardiac surgery: natural history and association with infection

Pyrexia is common after major surgery, and infection is often an important consideration. To investigate the natural history and association with infection, we performed a prospective observational study. From November 2000 to January 2001, we studied 219 patients undergoing cardiac surgery screening daily for wound, respiratory, urinary tract, and other infections. Pyrexia was defined as temperature above 37.5°C. Of 219 patients, 7 intraoperative deaths occurred and 1 patient was excluded because of preoperative endocarditis, leaving 211. The mean age (SD) was 64 (10) years, consisting of 172 male patients (81.5%). The proportion pyrexial on days 1, 2, and 5 was 30.0%, 25.8%, and 10.3%, respectively. More patients undergoing urgent or emergency procedures (17.7% versus 7.8%; P = .03) subsequently developed pyrexia. However, there were no differences in wound infection (3.4% versus 8.3%; P = .13), positive cultures for respiratory (14.7% versus 11.4%; P = .16), urinary tract (5.2% versus 2.0%; P = .09), or other infection (8.6% versus 7.3%; P = .71) in patients experiencing postoperative pyrexia compared with those who did not. Pyrexia is common after cardiac surgery and resolves in the majority of patients by day 5. Because there is no association between early pyrexia and infection, diagnosis of early postoperative infection by pyrexia alone is insufficient and is better established by clinical assessment with microbiological evidence.