The value of procalcitonin as an infection marker in cardiac surgery

Cardiopulmonary bypass generally leads to an unspecific increase of inflammatory parameters after cardiac operations. Increased Procalcitonin (PCT)-levels in serum, particularly after contamination with bacterial endotoxines, can be used as a marker for specific infections. The objective of this prospective study was to evaluate the course of PCT after cardiac surgery for the differential diagnosis of infections/unspecific inflammatory reactions, compared to routine infection parameters.

Serum PCT levels were measured in 400 routine cardiosurgical patients preoperatively and at 1., 2., 4. and 6. postoperative days with a luminescence immunoassay. PCT-values were compared to the patient's clinical infection status, body temperature, leukocyte count and C-reactive protein (CRP).

364 patients had an infection-free postoperative course, 27 patients developed infections. All of these patients showed elevated infection parameters at 1-2. postoperative days. In patients without infection, these parameters decreased after 2. postoperative day. Patients predisposed to an infection had continuously high temperature, leukocytes, CRP and PCT until 4.postoperative day with leukocytes and CRP decreasing after 4.postoperative day. PCT however showed a divergent course with a second increase in these patients between 4.-6. postop day (p<0.001). At this time, no clinical sign of an infection was evident. The increase of PCT was independent of infection type, but most apparent in bacteriemia/sepsis.

Based on its different course from other parameters in infection development between 4.-6. days, PCT can probably be used as a predictive marker in bacterial infections after cardiac surgery. The cost of the used immunoassay however will set the limits for a routine application.