The goal of this clinical trial is to compare the effectiveness of unseparated whole blood (referred to as Low-Titer Group O Whole Blood) and the separate components of whole blood (including red cells, plasma, platelets, and cryoprecipitate) in critically injured patients who require large-volume blood transfusions.

Trauma is one of the leading causes of death in the United States, and disproportionately affects the young, killing those who might otherwise have lived long and productive lives. Injuries account for more years of potential life lost before age 75 than any other cause. Hemorrhage remains the most common cause of preventable death after injury, and blood transfusion is an essential part of treatment. Modern blood banking practices separate donated whole blood into components. The current standard of care in trauma transfusion is the balanced administration of equal numbers of units of blood components (packed red blood cells, plasma, and platelets), effectively attempting to reconstitute whole blood. A renewed approach to blood transfusion therapy in trauma is to use whole blood from the outset, which has not been separated. Compared with component therapy, whole blood offers several potential advantages, but there are only a small number of, mostly observational, studies comparing whole blood and component therapy, and they are very heterogeneous.

The TROOP trial will include injured adults with hemorrhagic shock anticipated to require massive blood transfusions, who will be randomized to receive either whole blood (LTOWB) or blood components. This will allow a direct comparison to see if one type of transfusion is more strongly associated with improved clinical outcomes over the other.

The knowledge gained from this clinical trial will transform the way in which massively bleeding trauma patients are transfused. The trial is exceedingly well positioned to improve mortality from trauma and reduce the number of preventable deaths resulting from hemorrhagic shock.

Inclusion Criteria:

1. Adult trauma patient (estimated age > 15 or weight > 50 kg, if age unknown)

2. Patient taken to trauma center directly from scene

3. Commencement of blood transfusion (PRBC, plasma or LTOWB), in pre-hospital or in-hospital setting

4. Activation of site-specific Massive Hemorrhage Protocol or Massive Transfusion Protocol

5. Traumatic injury with at least one of the following:

   1. Confirmed or suspected acute major bleeding
   2. Assessment of Blood Consumption (ABC) Score ≥2

Exclusion Criteria:

1. Patients who have received, prehospital or in-hospital more than two units of LTOWB; the equivalent in components (two units of packed red blood cells and two units of plasma); or a combination of the two (more than one unit of LTOWB, one unit of packed cells, and one unit of plasma). Most trauma centers hold two units of either packed red blood cells (with two units of plasma) or two units of LTOWB in the emergency department. This stock is used to initiate transfusion, while the massive hemorrhage protocol is activated from the blood bank.
2. Patients transferred from another hospital
3. Children <15 years (in most communities, patients aged 15-18 years are treated at adult trauma centers, and patients in this age group frequently suffer life-threatening injuries, and will therefore be included)
4. Known prisoners, defined as individuals involuntarily confined or detained in a penal institution (including juvenile detention, involuntary psychiatric commitment, or court-ordered residential substance abuse treatment)
5. Moribund patients expected to die within 1 hour
6. Patients who required an ED thoracotomy or received more than 5 consecutive minutes of cardiopulmonary resuscitation (prior to receiving randomized blood products)
7. Patients with known "do not resuscitate" orders prior to randomization
8. Patients who refuse the administration of blood products
9. Individuals with a research "opt out" bracelet.
10. Greater than 20% total body surface area (TBSA) burns
11. Suspected inhalation injury victims
12. Patients who are obviously pregnant on clinical examination or known to be pregnant as provided by the subject or legally authorized representative

Care providers will be blinded to assignment until the point of randomization, which is when the cooler is opened, in the trauma bay, to remove blood products for transfusion.