SAN DIEGO (FRONTLINE MEDICAL NEWS) – Cold stored leukoreduced apheresis platelets in platelet additive solution were effective for controlling bleeding in a small study of patients undergoing complex cardiothoracic surgery, according to findings presented at the annual meeting of the American Association of Blood Banks.

The volume of postoperative bleeding was significantly lower among patients who received cold stored platelets compared with those who received standard room temperature storage platelets. Thromboembolic events did not differ between the two groups, nor did measures of coagulation at varying time points. Platelet counts and blood usage were also similar in the two groups. The study was small, however, and further studies are needed to confirm the findings.

“These patients are undergoing major surgery and are at high risk in every aspect,” said Torunn Oveland Apelseth, MD, PhD, of the Laboratory of Clinical Biochemistry, Haukeland (Norway) University Hospital. “They are at high risk for bleeding, at high risk for thromboembolic events and high blood usage, and there is a need for optimized blood components.”

There has been debate over the use of cold stored platelets, she noted. While storage at 4° C shortens platelet circulation time, some research shows that cold stored platelets have better hemostatic function.

In this study , one patient cohort was transfused with leukoreduced apheresis platelets stored at 4° C in platelet additive solution for up to 7 days under constant agitation, while the other group received platelets stored at standard room temperature. The study endpoints were comparisons between the two groups of postoperative bleeding, total blood usage, and laboratory measures of coagulation and blood cell counts within the first postoperative day. Thromboembolic events in the 28 days after surgery were also evaluated.

The study evaluated 17 patients who received cold stored platelets and 22 who received room temperature storage platelets. Patient demographics for the two groups were similar – as were their international normalized ratios, activated partial thromboplastin times, and fibrinogen levels – before surgery, immediately after heparin reversal, and the morning following the procedure.

Platelet counts and hemoglobin levels also did not significantly differ between groups.

As measured by chest drain output after chest closure, patients who received cold stored platelets had a significantly lower median amount of bleeding in the postoperative period compared with patients given room temperature storage platelets: 576 mL vs. 838 mL. Average chest drain output after chest closure was 594 mL in those who did not receive any transfusions.

Thromboembolic events occurred in 3 patients (18%) who received cold stored platelets and 7 (31%) of those given room temperature storage platelets. The difference was not statistically significant. In addition, blood usage – platelets, red blood cells, and solvent/detergent-treated pooled plasma – was similar for the two cohorts.

“There were also no differences in the number of thromboembolic episodes or length of stay in ICU,” said Dr. Apelseth, who recommended larger studies to explore the use of use of cold stored platelet transfusion in the critical care setting.