The Use of Blood Components in Trauma Medicine- An Outline

Introduction

Reducing patient suffering and death is a key objective of any medical practice. The decision to transfuse a patient can be a difficult one. Patient resuscitation with trauma and shock (an acute medical condition) is the responsibility of emergency physicians, surgeons, and anesthesiologists. These doctors have to manage life-threatening blood loss and the underlying pathology at the same time. In such situations, they might have to make complex decisions. Therefore, a good understanding of the shock mechanism and the implications of treatment strategies is essential to achieve a favorable outcome. In some surgical procedures, there is a potential for unexpected blood loss during surgery. Therefore, the transfusion of the accurate blood component is the main focus of attention for critical care doctors.

What Is the Importance of Blood Components in Trauma Medicine?

Significant blood loss can overcome body mechanisms, that is, oxygen supply and tissue perfusion (blood delivery to tissue), and lead to hemorrhagic shock. Trauma victims constitute a majority of such patients. The principal reason for death among young patients is traumatic injury. An estimated five million deaths occur worldwide yearly, among which about 20 percent are preventable.

Immediate blood loss following trauma triggers a series of body responses involving multiple organs and organ systems (heart, lungs, kidneys, and endocrine system). A fall in blood pressure is one of the first responses following blood loss. Persistent blood loss also leads to decreased oxygen delivery to the cells and tissues. As a result, it leads to anaerobic (without oxygen) metabolism and cell death. Cell death further causes a release of inflammatory mediators into the circulation. Lack of sufficient energy reserves leads to acidosis (increased blood acidity), coagulopathy (excessive bleeding or clotting), and hypothermia (low body temperature). If the blood loss is controlled, the outcome of shock is influenced by fluid resuscitation, the cellular response of individual organs, and the balance of inflammatory mediators in the following days.

What Are the Various Blood Components in Trauma Medicine?

The decision to transfuse blood and blood components should be taken after adequate knowledge of the clinical symptoms, rate, and extent of blood loss. Further, the emergency physician must note pertinent factors such as cardiac function and the need for surgery. The end goal of blood transfusion is to restore volume and oxygen-carrying capacity. The type of component to be transfused depends on assessing the patient’s clinical status.

1. Whole-Blood: Whole blood consists of plasma, red blood cells (RBCs), white blood cells (WBCs), and platelets. Most patients receiving transfusions do not require whole blood. With the introduction of blood components in trauma medicine, whole-blood use has become obsolete. It is because it lacks clotting factors and has high potassium, ammonia, and hydrogen ions. Although it provides increased blood volume with adequate oxygen-carrying capacity, there can be volume overload.

2. Packed Red Blood Cells: Packed red blood cells (PRBCs) are prepared by extracting plasma from whole blood. Since the central disease mechanism of hemorrhagic (hemorrhage is blood loss) shock is the failure of oxygen delivery, timely infusion of RBCs is the most important component of resuscitation. One must note that blood loss of more than 25 to 30 percent requires PRBC transfusion. Further, ensuring a ready supply of type ‘O’ blood (universal donor) can be life-saving in such patients.

3. Platelets: The decision to transfuse platelets is based on the cause of thrombocytopenia (decreased platelet count), active bleeding, and the need for surgery. Generally, when the platelet count is below 10000, platelets are transfused beforehand to prevent spontaneous blood loss (as platelets aid in blood clot formation). In such patients, the count should be maintained above 50000 (the normal range is 150,000 to 450,000 platelets per microliter of blood). Also, platelet therapy should be guided by monitoring the post-transfusion platelet count.

4. Fresh Frozen Plasma: Fresh frozen plasma (FFP; the liquid portion of the whole blood) is indicated for clotting factor deficiency and abnormal clotting tests in trauma patients. In the presence of massive blood loss or coagulopathy, one unit of FFP is given for every four to five units of infused RBCs. FFP is indicated for blood volume expansion in trauma and rapid bleeding to prevent coagulopathy. The timing of plasma transfusion is also crucial. If correction is required before surgery, it should be given immediately for maximum benefit.

5. Cryoprecipitate: Cryoprecipitate is a frozen product obtained from plasma. It is rich in factor VIII, von Willebrand factor, and fibrinogen (blood clotting factors). If FFP is used for massive transfusion, cryoprecipitate may not be required unless the fibrinogen level falls below 100 milligrams per deciliter. Although it can increase the clotting factor concentration, the advantages of cryoprecipitate in high concentration in the massively bleeding trauma patient are unclear.

What Are the Special Circumstances That Require Blood Components in Trauma Medicine?

An urgent need for transfusion in a patient requiring immediate surgical intervention may prevent the usual testing protocol. Blood transfusion requires the cross-matching of a test sample. However, in emergency transfusion, there is no time for the same. Therefore, group ‘O’ Rh-negative PRBCs can be transfused in such a case.

Massive transfusion is defined as a transfusion of more than the patient’s blood volume. Further, it is referred to as a transfusion of more than ten units of blood within 24 hours. The need for massive transfusions arises due to acute blood loss in trauma patients. Although blood loss of less than 20 percent of the total blood volume is tolerated, blood loss nearing 40 percent can change the vital signs. Furthermore, a loss of more than 40 percent may lead to frank hemorrhagic shock, circulatory system failure, and cardiac arrest. Therefore, priority should be given to blood volume and oxygen-carrying capacity. Other parameters that require monitoring are clotting factors and serum electrolyte levels. Hence, blood and blood product administration is a central feature for patients with hemorrhagic shock after trauma.

Conclusion

The initial revival of a patient with hemorrhagic shock should be based on the identification and correction of the source of bleeding. The rate of administration of blood and its components should support tissue perfusion. Early use of blood component therapy in trauma patients can help to preserve oxygen delivery and clotting parameters. Reviving a severely traumatized patient with crystalloids, colloids, and blood products is a common transfusion practice in trauma patients. Although blood is the ideal resuscitation agent, its use has limitations. Despite the stringent blood component screening with sensitive techniques, there is no ‘zero risk’ transfusion. Hence, it does not warrant the indiscriminate or prophylactic use of blood products. Further, there are concerns such as component availability, cost, transfusion reactions, infections, shelf life, and even religious prohibitions against the transfusion of blood components.