Introduction

Blood transfusion begins with collecting whole blood from a donor using a preservative-anticoagulant combination (typically citrate phosphate dextrose or citrate phosphate dextrose adenine-1). The blood is then tested for transfusion-transmitted diseases, separated it into its specific components, and then transfused as clinically indicated. This process is known to have both risks and benefits to the patient, and the decision to transfuse must be based on many variables so that the benefits outweigh the risk.

Subsequently, the process of patient blood management (PBM) was developed to incorporate an evidence-based, interprofessional approach to blood product administration. This process considers the patient's entire (projected) course and aids the clinician in determining if transfusion is indicated versus the use of alternative care pathways to ensure the best possible outcome for the patient.  

Function

Red Blood Cells

The literature strongly supports adhering to a restrictive transfusion strategy (7 g/dL) in hospitalized adult and pediatric intensive care patients who are hemodynamically stable.[1][2] The evidence is not as compelling for patients with cardiovascular disease, but recommendations are to adhere to a restrictive strategy (hemoglobin 8 gm/dL) for patients with preexisting cardiovascular disease. There is insufficient evidence to make recommendations for patients with acute coronary syndrome.

RBC transfusion is indicated in actively bleeding patients. The amount should be based on clinical assessment[3] and, if possible, by laboratory tests to guide targeted therapy. However, in patients with upper gastrointestinal bleeding, patients with a restrictive transfusion strategy may have better outcomes.[4]

Plasma

There is minimal guidance for plasma transfusion. However, plasma is a frequently prescribed intervention, often for mild to moderate elevations in prothrombin time or an international normalized ratio (INR). This continues to occur despite numerous studies that failed to show a relationship between these elevations and the risk of bleeding or that INR has any ability to predict bleeding.[5]

The Cochrane Reviews found no evidence to support plasma transfusions in patients who were not coagulopathic undergoing elective cardiac surgery or critically ill patients.

The British Society of Haematology (BSH) published recommendations in 2018 for various patient groups in the absence of major bleeding.[6][7]

• There is no evidence to support the prophylactic use of plasma in non-bleeding patients with abnormal standard coagulation tests pre-procedure
• The impact of commonly used doses to correct clotting results or to reduce the bleeding risk is very limited, especially when the PT ratio or INR is between 1.5 to 1.9.
• Vitamin K should be administered in patients with prolonged PT that is likely to be due to acquired vitamin K deficiency.

In patients with liver disease, plasma is often transfused to correct a prolonged INR. British Society of Haematology recommends these guidelines: 

• PT and APTT do not reflect the true hemostatic status of patients with advanced liver disease.
• There is no good evidence to endorse the use of prophylactic plasma for correction of abnormal clotting tests in non-bleeding patients prior to interventions such as elective variceal bleeding.
• There is no good evidence to support a role for prophylactic plasma to reduce the risk of bleeding from a percutaneous liver biopsy.
• Prophylactic transfusion of plasma should not be given in low bleeding risk procedures.
• Do not use plasma for volume replacement.

And for sites that have 4-Factor Prothrombin Concentrates such as K-Centra and Bebulin, this should always be the first therapeutic of choice to reverse warfarin emergently.

Cryoprecipitate

There are few data on the use of cryoprecipitate in non-bleeding patients, and it is often used prophylactically but not based on good quality evidence.

The British Society of Haematology[8] recommends:

• There is insufficient evidence on which to base a recommendation about the threshold of fibrinogen to transfuse cryoprecipitate, or the optimal dose, in patients with hypofibrinogenemia undergoing procedures.
• If fibrinogen is <1.0g/L (100 mg/dL) and other factors (i.e., personal/family bleeding history, drug history, bleeding risk associated with planned procedure) indicate a significant bleeding risk before a procedure, a starting dose of two five donor pools of cryoprecipitate [10 individual units] can be considered (but there is no evidence to support this).

Many US sites consider fibrinogen <2.0 g/L (<200 mg/dL) in a bleeding obstetric patient as an indication to transfuse cryoprecipitate.

Platelets

Common guidelines for platelet transfusions include:[9]

1. Prophylaxis against bleeding—PLT count <10,000 mg/dL
2. Neonate—PLT count <50,000 mg/dL
3. Bedside procedure—PLT count <50,000 mg/dL
4. Kidney or liver biopsy—PLT count <50,000 mg/dL
5. Bronchoscopy without biopsy—PLT count <50,000 mg/dL
6. Bronchoscopy with biopsy—PLT count <75,000 mg/dL
7. Intra-/postoperative bleeding—PLT count <50,000 mg/dL
8. Clinical bleeding with dysfunctional PLTs:

PLT count <50,000 mg/dL (medical)

PLT count <100,000 mg/dL (surgical)

1. Neurosurgery—PLT count <100,000 mg/dL

Cell Salvage

The Association of Anaesthetists guidelines make the following transfusion recommendations: Use cell salvage when it can be expected to reduce the likelihood of allogeneic (donor) red cell transfusion and/or severe postoperative anemia. Collection of blood for potential cell salvage (‘collect only’ mode) should be considered for surgical procedures where blood loss may exceed 500 ml (or > 10% of calculated total blood volume) in adult patients or > 8 mL/kg (> 10% of calculated total blood volume) in children weighing > 10 kg.[10]

Whole Blood

There has been increasing interest in using low titer group O whole blood (LTOWB) in military and civilian trauma, and there is evidence to show that it saves lives. [11][12] It has also been used in non-trauma massive hemorrhage cases. LTOWB provides all of the components of blood (RBCs, platelets, and plasma with fibrinogen) and provides a balanced resuscitation addressing oxygen needs and coagulopathy in a single bag of blood. The whole blood has a critical titer of anti-A and anti-B of less than 50 to 200). The transfusion of up to 4 units of whole blood has been shown to be safe.[13]

Issues of Concern

Single studies may have misleading results. Using the Cochrane database of systematic reviews and meta-analyses which summarize and interpret the results of medical research helps minimize the biases of single studies.

Clinical Significance

Adverse events related to transfusion have been well documented. Transfusion-associated circulatory overload (TACO), transfusion-related acute lung injury (TRALI), bacterial contamination, transfusion-associated dyspnea (TAD), allergic mild to severe, hemolytic, febrile, immunosuppression which can lead to increased risk of infection, increased length of stay. These adverse events are dose-dependent. When restrictive strategies have the support of data, it is reasonable to abide by the recommendations.

Enhancing Healthcare Team Outcomes

To decrease known morbidity and mortality risks, transfusion guidelines based on evidence-based data have been developed. Results demonstrate that these guidelines can lead to fewer transfusions, better patient outcomes, and, concomitantly, cost reductions for hospitals. Guidelines alone cannot ensure these benefits, as they must be accompanied by physician education and clinical consideration. Additionally, many transfusion strategies recommend the transfusion of one unit and checking lab values to assess effectiveness. This minimizes the risk of over-transfusion as well as circulatory overload.

Nursing, Allied Health, and Interprofessional Team Interventions

Nurses are a critical partner in transfusions.  They ensure the blood is the right product at the right time for the right reason and, of course, for the right patient. Without these safeguards, patients are at significantly higher risk of a clinically significant adverse event.

Nursing, Allied Health, and Interprofessional Team Monitoring

Nurses must monitor transfusions before, during, and after transfusion to ensure an adverse event is recognized early and the transfusion stopped.