| Red blood cell transfusion in intensive care |
More than half of all patients admitted to intensive care are anemic and 30% of these have an initial Hb < 90 g/L.
Early anemia after admission is mainly caused by hemorrhage, hemodilution, and frequent sampling.
Later, reduced red blood cell production due to inflammation becomes an important factor and 80% of patients have Hb <90 g/L after 7 days. About 80% of these transfusions are given to correct low Hb rather than treat active bleeding. Phlebotomy blood loss can be reduced through the use of blood conservation sampling devices and pediatric blood sample tubes.
Transfusion management has been strongly influenced by the Transfusion Requirements in Critical Care (TRICC) study which randomly assigned patients to a Hb "transfusion trigger" of 100 g/L (liberal) or 70 g/L. (restrictive). There was a trend toward lower mortality in patients randomized to a restrictive policy (30% of whom did not receive transfusions).
This was statistically significant in younger patients (<55 years) and in those who were less severely ill. A restrictive transfusion policy was associated with lower rates of new organ failure and acute respiratory distress syndrome. Randomized trials in pediatric intensive care, cardiac surgery, elderly patients undergoing "high risk" hip surgery, and gastrointestinal bleeding have shown no advantage for a liberal transfusion policy.
A higher transfusion trigger may be beneficial in patients with ischemic stroke, traumatic brain injury with cerebral ischemia, acute coronary syndrome (ACS), or in the early stages of severe sepsis. There is no current evidence to support the use of “fresh” RBCs instead of stored ones in critically ill patients or the routine use of erythropoiesis-stimulating agents.
| Platelet transfusion in intensive care |
Moderate thrombocytopenia (>50×109/L) is common in intensive care patients, often associated with sepsis or disseminated intravascular coagulation (DIC). “Prophylactic” platelet transfusion in non-bleeding patients is not indicated , although this is the most common reason for transfusion identified in clinical audits (followed by “coverage” for invasive procedures). There are no high-quality randomized controlled trials to guide clinical practice and a guideline is currently being developed.
The risk of bleeding in thrombocytopenic patients can be reduced by avoiding or withdrawing antiplatelet agents (e.g., aspirin, clopidogrel, or nonsteroidal anti-inflammatory drugs) and the use of antifibrinolytics such as tranexamic acid.
Table 1 summarizes guidelines based on observational studies and expert opinions.
| Indication | Transfusion threshold or goal |
| Nonbleeding patients without severe sepsis or hemostatic abnormalities | Not indicated |
| Prophylaxis in nonbleeding patients with severe sepsis or hemostatic abnormalities | Threshold 20×109/L |
| DIC with bleeding | Maintain >50×109/L |
| Platelet dysfunction with bleeding not surgically correctable (eg, after cardiopulmonary bypass or strong antiplatelet drugs) | You may bleed despite a normal platelet count. Transfusion of an adult therapeutic dose and repeat according to clinical response |
| Major hemorrhage and massive transfusion | Maintain >75×109/L (>100×109/L if there is polytrauma or trauma to the central nervous system or inside the eye) |
Table 1. Suggested indications for platelet transfusion in adult intensive care.
| Transfusion of plasma components in intensive care |
A study of UK intensive care units showed that 13% of patients received fresh frozen plasma (FFP) transfusions. About 40% of these transfusions were given to nonbleeding patients with normal or only mildly abnormal coagulation tests, and many doses were subtherapeutic. Cryoprecipitate is used as a concentrated source of fibrinogen (fibrinogen concentrate is not yet licensed in the UK for this use). More research is needed to define best practices, but the following pragmatic guidelines are suggested:
> Fresh frozen plasma:
-Indicated for the treatment of bleeding in patients with coagulation disorders due to deficiency of multiple coagulation factors (for example, DIC).
-Minimum dose 12-15 mL/kg (equivalent to four units in an average adult).
-Not indicated for prophylaxis in non-bleeding patients with abnormal coagulation tests.
-Not indicated for the immediate reversal of warfarin ( Prothrombin Complex Concentrate must be used ).
-In liver disease, there is no benefit to PFC transfusions in patients with an INR less than 1.7.
> Cryoprecipitate:
-The adult dose is two combined units (ten donor units: approximately 3 g of fibrinogen).
-Indications include:
- Acute DIC with bleeding and fibrinogen <1.5 g/L
- Severe liver disease with bleeding
- Prophylaxis for surgery when fibrinogen <1.5 g/L
- Hypofibrinogenemia associated with massive transfusion (maintain >1.5 g/L).
