In vitro platelet function and post-transfusion platelet recovery of platelets stored in whole blood decline during storage. In this pilot randomized clinical trial we aim to investigate the impact of storage time of whole blood on the effect and safety in treatment of immediate blood loss in patients undergoing complex cardiothoracic surgery. The study is designed as an exploratory superiority study to support feasibility and provide critical guidance for future, more definitive randomized trials. In the study the test group will receive CPD whole blood leukocyte-depleted with a platelet-sparing filter and stored for 15-21 days whereas the control group patients will receive leukocyte-depleted CPD whole blood stored for less than 7 days.

A challenge for implementation of Whole Blood programs in civilian health services has been an uncertainty regarding the impact of storage on the clinical effect of the whole blood transfusion, especially when it comes to platelet function which is essential to hemostasis. In vitro platelet function and post-transfusion platelet recovery decline with increasing storage time of the whole blood.

In this pilot randomized clinical trial we aim to investigate the impact of storage time of whole blood on the effect and safety in treatment of immediate blood loss in patients undergoing complex cardiothoracic surgery. The study is designed as an exploratory superiority study to support feasibility and provide critical guidance for future, more definitive randomized trials. In the study the test group will receive CPD whole blood leukocyte-depleted with a platelet-sparing filter and stored for 15-21 days whereas the control group patients will receive leukocyte-depleted CPD whole blood stored for less than 7 days. A control group receiving standard care (blood component-based transfusion) may be included.

Inclusion Criteria:

1. Patients undergoing cardiothoracic, cardiac, or aortic surgery
2. Patients with complex surgical procedures and expected cardiopulmonary bypass (CPB) time over 120 minutes
3. Patients capable of providing informed consent to participate in the study

Exclusion Criteria:

1. Patients not capable of providing informed consent to participate or who will not provide informed consent
2. Patients with known congenital coagulopathies or hemostatic disorders (von Willebrands Disease, hemophilia etc)
3. Patients with known erythrocyte- or platelet/HLA antibodies
4. Patients with a particular increased surgical risk with expected need of ECMO
5. Patients with preoperative EuroScore II ≥ 30

5. RhD negative patient

The participant and clinical personell ordering and evalutaing the effect of transfusion will be blinded, so will also the investigators performing the statistical evaluation of the results. The project co-workers preparing the whole blood units and perforing laboratory analysis will not be blinded.