Could the combination of bleeding time and platelet function predict the perioperative transfusion requirements in cardiac surgery patients?

Introduction

The reduction in platelet count and function is the most important, unsolved, nonsurgical cause of postoperative bleeding after open heart surgery. On the other hand, the bleeding time (BT), the only comprehensive test to explore primary haemostasis, detects otherwise unknown defects in platelet–vessel wall interactions. The present study was undertaken in order to clarify whether the BT and platelet function tested preoperatively could predict the perioperative transfusion requirements in cardiac surgery patients.

Patients and methods

Sixty-eight patients (54 males/14 females) participated in the study. Thirty-two patients underwent valve(s) replacement (group A) and the remaining underwent coronary artery bypass grafting(s) (group B). The BT determination was performed according to the Mielke technique using Surgicutt devices (ITC, USA). Platelet function was evaluated by the aggregation procedure using four agonists: ADP, arachidonic acid, collagen and ristocetin at a final concentration of 4 × 10^-6 M, 0.5 mg/ml, 0.19 mg/ml and 1.2 mg/ml, respectively.

Results

(1) In the immediate postoperative time, a significant reduction in haemoglobulin levels was observed in both groups compared with that of the preoperative time (13.3%, P < 0.05 for group A and 28.4%, P < 0.01 for group B). No difference existed in haemoglobulin levels between groups postoperatively. (2) Platelet values were slightly different between the groups. A significant decrease in platelet count was observed in both groups postoperatively (28.7%, P < 0.03 for group A and 22.4%, P < 0.05 for group B). (3) The results of BT and platelet activation (performed preoperatively) were similar for patients who underwent valve replacement and patients who underwent coronary artery bypass grafting – although in this group platelet activation with arachidonic acid and ADP was ~11% lower with both agonists. (4) The transfusion requirements were slightly higher for patients in group A, and more patients in group B received no transfusion (one vs four patients).

Conclusion

In patients undergoing cardiac surgery with a negative history of bleeding and early interruption of antiplatelet treatment, the BT and platelet function do not offer much in the setting to predict perioperative bleeding.