This study will investigate the effects of Leukocyte reduced cold-stored platelet transfusions used in treatment of immediate postoperative blood loss in patients undergoing thoracic surgery in combination with extracorporal circulation. Today platelet concentrates are stored at 22 degrees C .

This is a prospective, randomized, unblinded, non-inferiority two-arm study. Aim of study is to compare platelet function in bleeding patients transfused with leukoreduced platelet concentrates stored cold (4 degrees C) and in room temperature (22 degrees C). Storage time for RCT platelet concentrates are up to 7 days. Patients with expected time on extracorporal circulation more than 120 minutes and/or medical platelet inhibitors will be included.

Platelet function will be assessed by use of Multiplate Aggregometry, Thromboelastography (TEG) and/or Thromboelastometry (ROTEM). In addition post operative bleeding, and adverse events will be recorded.

After completion of recruitment of patients to RCT study of platelet stored cold for up to 7 days, a follow up prospective observational study of platelets stored cold for up to 14 days is performed.

Additonal information 2019, May 03: This trial was registered on Clinical Trials.gov with an original plan to use non-inferiority testing of between-group differences in platelet function. Due to lack of evidence needed to set acceptable tolerance margins for the non-inferiority testing, independent reviewers with expertise in clinical trial design recommended they be replaced by standard tests of superiority, commensurate with the early phase of the trial. Further, post-operative chest tube drainage was chosen as the primary outcome to better present the pilot study's focus on the control of clinically significant bleeding.

This is a prospective, randomized, unblinded, non-inferiority two-arm study were Arm 1 patients will receive Leukocyte reduced cold-stored platelet concentrates and Arm 2 patients will receive leukoreduced room-temperature-stored (22 degrees C) platelet concentrates. Patients with expected time on extracorporal circulation more than 120 minutes and/or medical platelet inhibitors will be included.

The number of patients included is set to 20 patients in each arm, as there is not sufficient information available in the literature to conduct power calculations. The hypothesis is that cold stored platelets are not inferior to room temperature platelet concentrates.

Baseline patient data and information on intervention and post operative recovery will be collected from the Medical journals together with information on transfusion episodes and Blood Components. Blood samples will be retrieved from study participants at specific intervals: baseline, immediately after surgery, at arrival at ICU, before and after (every) platelet transfusion episode, 24 hours post operation, and if indicated, during hospital stay. Blood samples will be investigated for platelet function, coagulation parameters, hematologic parameters, and other risk factors for adverse events. If transfusion reactions occur, additional test of patient and the Blood Component(s) transfused will be performed. Samples will be collected and stored in the biobank for cytokines, complement and allergy analysis.

After completion of recruitment of patients to RCT study of platelet concentrates stored cold for up to 7 days, a follow up prospective observational study of platelets stored cold for up to 14 days is performed.

Additonal information 2019, May 03: This trial was registered on Clinical Trials.gov with an original plan to use non-inferiority testing of between-group differences in platelet function. Due to lack of evidence needed to set acceptable tolerance margins for the non-inferiority testing, independent reviewers with expertise in clinical trial design recommended they be replaced by standard tests of superiority, commensurate with the early phase of the trial. Further, post-operative chest tube drainage was chosen as the primary outcome to better present the pilot study's focus on the control of clinically significant bleeding.

Inclusion Criteria:

• Patients undergoing urgent/semiurgent thoracic surgery
• Expected long extracorporal time (>120 minutes) and/or use of dual platelet inhibition drugs
• Patients likely to require platelet transfusion
• Patients capable of providing informed consent

Exclusion Criteria:

• Patients who will not provide informed consent
• Patients with congenital coagulopathies or hemostatic disorders (von willebrands disease, hemophilia etc)