Does cardiopulmonary bypass affect the procalcitonin level?

Introduction

Cardiopulmonary bypass (CPB) causes an inflammatory response with clinical and biological changes. This systemic inflammatory response syndrome (SIRS) is a result of several stimuli such as exposure of blood to non-physiological surfaces, surgical trauma, myocardial ischaemia-reperfusion and endotoxin release. Because of this response, conventional clinical and biological signs may be misled in the diagnosis of postoperative complications, particularly infection. Procalcitonin (PCT) is useful as a marker of infection. Further studies suggested that PCT is an early, sensitive and specific indicator of infection but recent investigations showed increases in other conditions associated with systemic inflammation, such as severe trauma, burns and heat stroke. The aim of this study was to determine the normal profile of PCT during preoperative, peroperative and postoperative (PO) periods in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

Methods

We have measured serum PCT levels in 91 patients undergoing elective cardiac surgery with CPB. PCT levels were measured after induction of anaesthesia (baseline), after CPB and PO days 1, 2, 3 and 4. The demographic data of all patients, cross-clamping and bypass times, inotropic medication or intra-aortic balloon pump (IABP) needs were recorded. Repeated-measures analysis of variance was used for statistical analyses.

Results

Baseline PCT levels were measured before the operation (< 0.05 ng/dl) and all increased at the end of the CPB. The increase in serum PCT levels had a peak on the first postoperative day (P < 0.001) (Fig. 1). PCT levels were higher in some patients whose cross-clamping and total bypass times were longer than others or they needed inotropic agents or IABP. Repeated variant analyses showed that there was a closed relationship between the PCT levels and cross-clamp and total bypass times, need of inotropic medications and IABP (Fig. 2).

Figure 1

The procalcitonin (PCT) levels and distribution of measurement times: A, baseline; B, after cardiopulmonary bypass; C, postoperative (PO) day 1; D, PO day 2; E, PO day 3; and F, PO day 4.

Figure 2

Procalcitonin (PCT) levels in patients with and without intra-aortic balloon pump (IABP).

Conclusion

Although PCT is a useful marker of infection, it can be affected from many factors (CPB itself, prolonged operation, cross-clamping and bypass time, inotropic agent and IABP need, etc.) during CPB. So PCT alone is not enough to decide for infection in the early postoperative period in cardiac surgery patients.