To the Editor:
Weber et. al.1 published data that point-of-care testing guiding hemostatic therapy reduced allogenic blood transfusions in patients undergoing complex cardiac procedures. The authors need to be commended on providing strong evidence of the superiority of “qualitative” over “quantitative” testing. I would like to point out two important considerations that may affect the interpretation and applicability of the results.
Patients in the conventional group received approximately twice the amount of salvaged washed erythrocytes intraoperatively. This indicates that patients in the conventional group had twice the amount of intraoperative blood loss and double the amount of “lost” blood cleared of clotting factors. Using rough approximations and excluding any blood loss through the washing 1.5 l blood loss in the conventional group, versus 760 ml in the point-of-care group (lost Hct 30, retransfused after washing Hct 57),2 could have clearly affected coagulation in the conventional group leading to an increased transfusion requirement.
It is unclear if the cost of unnecessary testing was included in the analysis. Patients were enrolled and randomized preoperatively to start the algorithm with testing for the clopidogrel effect with the Multiplate® (fig. 1C, original article). Then after the release of the aortic cross clamp, the intrinsic and extrinsic coagulation pathways were tested with the ROTEM®. For an MCFFIB = 0 mm fibrinogen (25 mg/kg) was administered before protamine was given. These interventions were done before a patient could show any signs of diffuse bleeding. This cost would reduce the “cost benefit” of the point-of-care testing. Most likely this would not have substantially influenced the cost as shown in a retrospective analysis when point-of-care testing is applied to all cardiac patients.3 But this is important to consider if physicians want to implement the algorithm. There may be substantially less cost savings if only a relatively small number of high-risk, complex, cardiac procedures are being performed in your institution. This also applies if there are only a few patients requiring blood transfusions after cardiac surgery.