Traditionally, a large blood transfusion refers to the infusion of 10 units of red blood cells (PRBCs) over a 24-hour period. The purpose of large transfusions is to limit complications, limit severe hypoperfusion, and achieve surgical hemostasis. This event reviews the current literature on a large number of transfusion regimens, explores the potential complications of this life-saving intervention, and highlights the role of interprofessional teams in managing patients who need blood products.
Describe indications for large blood transfusions.
Review the complications of massive blood transfusions.
Summarize the institutional scheme of large blood transfusions.
The importance of improving care coordination among interprofessional team members to improve outcomes for patients receiving large transfusions is outlined.
Earn continuing education credits (CME/CE) on this topic.
Traditionally, a large blood transfusion has been defined as the infusion of 10 units of red blood cells (PRBCs) over a 24-hour period. The purpose of large transfusions is to limit complications, limit severe hypoperfusion, and achieve surgical hemostasis. This article reviews the current literature on a large number of transfusion therapies and explores the potential complications of this life-saving intervention
Patients with traumatic injuries, gastrointestinal bleeding, and obstetric haemorrhage may require heavy blood transfusions. Although surgery is the most commonly used application of major transfusion protocols (MTPs), trauma remains the best study category for large blood transfusions. It is estimated that 3 to 5 percent of civilian trauma patients and 10 percent of military trauma patients will receive large blood transfusions. A study at a primary trauma center found that only 1.7 percent of patients received a massive blood transfusion (defined as 10 units in a 24-hour period). Although the incidence of large transfusions is relatively low, patients who require heavy transfusions have higher mortality.
Large transfusions require consideration of multiple physiological parameters such as volume status, tissue oxygenation, management of bleeding and clotting abnormalities, and acid-base balance.
Volume state oxygenation with tissue
When a patient develops hypovolemic shock after acute blood loss, the focus is on expanding the amount of vascular contents and maintaining oxygen delivery to tissues. At baseline, oxygen is delivered to tissues at a rate of about four times the oxygen consumption of the tissues. Therefore, during a large number of blood transfusions, bulk expanders such as crystals can be used to maintain blood pressure and tissue perfusion. However, if the patient is in severe shock, or bleeding continues, blood is eventually needed to maintain an appropriate oxygen delivery rate.
Due to the excess of oxygen in its normal physiological state, the body is able to maintain oxygenation of tissues below normal hemoglobin levels. There is ample evidence to support different hemoglobin "thresholds" at which patients require blood transfusions to maintain adequate oxygen delivery. However, it must be remembered that these transfusion guidelines are not helpful in the occurrence of acute blood loss. Hemoglobin is reported as a concentration. In acute blood loss, the hemoglobin concentration will remain unchanged. Hemoglobin is reduced only after a certain period of time and fluid transfer. Therefore, the hemoglobin "threshold" cannot be used to manage transfusions in acute blood loss settings.
Patients who require a large number of blood transfusions often have acidosis even before the transfusion begins. Persistent hypoperfusion states can lead to acidosis. Once acidosis occurs, it further interferes with blood clotting by reducing the synthesis of coagulation factors. Decreased pH (increased acidosis) is directly related to decreased activity of coagulation cascading components. This leads to delayed and weak formation of fibrin clots, which are destroyed more rapidly by fibrinolytic action.
Many patients with acute, hemorrhagic anemia are also susceptible to hypothermia, which can also lead to coagulopathy. Decreased ambient temperature and volume depletion can predispose these patients to hypothermia. Low temperatures reduce the effect of the coagulation cascade (by reducing the enzyme activity of thrombins) and platelet plaque formation. At 34 ° C, an effect on blood clotting begins, and at 30 ° C, platelet activation is reduced by about 50%.
In patients who may require a large number of blood transfusions, clotting factors are often depleted due to massive bleeding. In addition, due to the dilution of the remaining coagulation components due to capacity expansion, coupled with low temperature and acidosis, it may also lead to coagulopathy and hemostasis changes. A decrease in the ability to stop bleeding leads to further hypothermia and acidosis, forming a positive feedback loop, which leads to further deterioration of the patient's outcome.
The main indication for a large blood transfusion is any condition that causes acute blood loss and hemodynamic instability. Indications for massive blood transfusions include, but are not limited to, trauma bleeding, obstetric bleeding, surgery, and gastrointestinal bleeding
There are no absolute contraindications to massive blood transfusions.
Collecting the right equipment is an important part of a large number of blood transfusions. Access to blood products is a must. Blood products can be delivered through an external intravenous catheter, a central venous catheter, or an intraosseous catheter. All of these catheters apply the same fluid principle. The flow through the catheter is described by the Hagen-Poiseuille equation. It is proportional to the change in pressure between points and the quadrangle of the radius. It is inversely proportional to the length and viscosity of the catheter. From this equation, we can conclude that the flow rate is directly related to the radius of the catheter, inversely proportional to the length of the catheter. In most patients who receive a large number of blood transfusions, we want to deliver blood products quickly. Therefore, a larger diameter and shorter length of catheters will allow us to achieve higher flow rates, more ideally. Large-bore intravenous catheters (14 to 18 G), central venous catheters, and intraosseous catheters should be collected and inserted into the patient if necessary, keeping in mind that a small number of large-bore peripheral catheters may have a higher flow rate than some central catheters.
Other devices, such as high-speed transfusions and blood heating devices, should also be collected. Materials for frequent laboratory testing of hemoglobin levels, ABG, coagulation, electrolytes, lactate, and thromboelastic maps (TEGs), as well as point-of-care testing equipment(if available), should be collected. In addition, it should be equipped with a monitor for continuous and repeated assessment of body temperature, pulse oximetry, blood pressure, and heart rate.
Massive blood transfusions require coordination between doctors, nurses, laboratory tests, and hospital blood banks. Many healthcare facilities have an alert system, similar to the one used in trauma, informing the necessary personnel that a large blood transfusion may or is occurring.
Healthcare professionals preparing for large blood transfusions should ensure that patients are connected to monitors and that there are sufficient intravenous passages to deliver blood products when they are available. Notifying blood banks will also help avoid delaying the acquisition of more blood products if necessary.
Many institutions have used the knowledge of multi-disciplinary teams to develop programs for large blood transfusions. These agency-specific protocols facilitate the ordering of blood products and the rapid receipt from blood banks. While these regimens vary from institution to institution, in addition to platelets and fresh frozen plasma (FFP), many bulk transfusion regimens focus on providing PRBCs
While not feasible for the average person, strong evidence from medical and military experience suggests that when fresh whole blood is transfused into trauma patients, it produces positive outcomes. This gave rise to the concept of simulating whole blood during a mass transfusion process, through infusion of packaged red blood cells (PRBCs), platelets, and fresh frozen plasma (FFP), which provide coagulation factors. In the case of massive blood transfusions, the optimal ratio of these three ingredients is still controversial. Many experts argue for a ratio of 1:1:1 for FFP, platelets, and PRBC. Platelet and FFP ratios are low, but there is no evidence of inferiority, and the vast majority of mass transfusion protocols in trauma centers target a lower plasma-to-PRBCs ratio (in one MTP study, 80% of trauma centers had a plasma-to-red blood cell ratio greater than 1:2). Results from the use of cryoprecipitation, fibrinogen concentrate, and recombinant VIIIa factor have been mixed.
There is strong evidence from the military that the use of tranexamic acid (TXA) can reduce coagulation disorders and improve survival in war-wounded patients, and further evidence suggests that adding TXA to patients with civilian bleeding trauma can reduce deaths. TXA works by inhibiting fibrinolysis or the breakdown of blood clots. Given its good safety and overwhelmingly positive results, it has been incorporated into many bulk transfusion regimens
Mean arterial pressure (MAP) is 60 to 65 mm Hg
Hemoglobin 7 to 9 g/dL
The INR is less than 1.5
Fibrinogen is greater than 1.5 to 2 g/L
Platelets greater than 50 times 10/L
pH 7.35 to 7.45
Core temperature above 35 C
Potential complications of massive blood transfusions include metabolic alkalosis, hypocalcemia, hypothermia, and hyperkalemia. When transfusions exceed 5 units, more than 50% of patients develop nonfatal complications.
Metabolic alkalosis and hypocalcemia are caused by sodium citrate and citric acid, which are added to blood products to prevent clotting. With the metabolism of citrate, a total of 23 milligram equivalents of bicarbonate can be produced per unit of blood. If the kidneys are unable to excrete excess bicarbonate, this can lead to metabolic alkalosis. In addition, alkalosis can lead to hypokalemia because hydrogen ions are transported out of cells through H+/K+ transporters to compensate for alkalosis. Citrate can also bind to free calcium, resulting in significant free hypocalcemia. It usually does not affect calcium that binds to albumin. Severe hypocalcemia can lead to paresthesias and arrhythmias.
Transfusion of blood products can also lead to hypothermia. Blood products are stored at 4 degrees Celsius. Rapid infusion of cold blood can lead to a decrease in core body temperature. Considering that this population is already susceptible to low temperatures, which can further worsen blood clotting disease, many rapid infusion sets also have heaters to reduce the risk of low temperatures occurring during large blood transfusions. Hyperkalemia is also a possible complication because the potassium content in the blood increases during long-term storage. This usually only occurs when blood products are stored for a long time and are infused at high speed through a central channel.
In addition, traditional complications of blood transfusions, particularly transfusion-related acute lung injury (TRALI) and transfusion-related circulatory overload (TACO), can occur with high transfusions. Although the pathogenesis of TRALI is poorly understood, the incidence of TRALI increases with the increase in the number of blood products. Rapid onset of hypoxemia indicates the occurrence of TRALI within 6 hours of a blood transfusion. Clinically, patients are very similar to those with Acute Respiratory Distress Syndrome (ARDS), with PaP2/FiO2 below 300 mmHg, chest x-rays showing bilateral infiltrates, and no signs of systolic heart failure. Excessive blood transfusions can also be seen in TACO.
A large number of blood transfusions are an important measure to save the lives of a large number of patients with acute blood loss. Massive blood transfusions have been used in many clinical settings, including obstetrics, gastroenterology, trauma and operating theatres. Although the etiology of bleeding is different in all cases, the principle of mass transfusion is the same. However, large blood transfusions can have serious complications and should be reserved for patients with hemodynamic instability as a bridge to eventual treatment.
Today, all healthcare workers should be very familiar with the medical institution's policy of conducting examinations and cross-examinations before blood transfusions. This is mandatory and applies to laboratory technicians who prepare blood, nurses who receive blood from blood banks, and nurses who transfuse blood; in short, all members of an interprofessional medical team. The aim is to prevent adverse reactions to the blood. All patients must be educated about potential adverse effects prior to administration. In addition, the nurse must tell the patient to notify her or him if she or she develops a fever, headache, rash, or difficulty breathing. Nurses should also be aware that 10-15% of patients receiving blood develop a non-hemolytic febrile reaction, so good clinical judgment is required when to continue and when to stop transfusion. If an adverse reaction occurs, the nurse should immediately stop the blood transfusion, call the doctor, and send the blood back to the laboratory along with all the tubes. Be careful at every step, as complications of blood transfusions do have the potential to cause patient death. That is why an interprofessional approach is necessary so that this strategy is used only when necessary and is optimally managed when used [Level 5]
In general, when large blood transfusions are made, especially in traumatic situations, the likelihood of complications is high. Some studies have shown that 20-30 units of blood should not be exceeded to avoid complications. Overall, most studies have shown that this transfusion does not lead to patient survival, but in fact, it is associated with many adverse events. (V Class)