Blood Therapy

Question 1

The patient who requires high-volume transfusion (>10 units packed red blood cells [PRBCs] in 24 hours) experiences an increased mortality rate: …

Answer 1

a 10% increase for every 10 units of blood given. Thus if 50 units o blood are given, there is a 50% mortality rate

Question 2

If typespecific plasma is not available, the plasma of … blood type donors can be given to all individuals, as it does not contain antibodies against the major surface antigens found on RBC

Answer 2

AB-negative

Question 3

Dose, Volume per Unit, Shelf Life Storage and Response of PRBCs

Answer 3

Dose: 1 unit

Volume per Unit: 200–250 mL

Shelf Life: 21–42 days

Storage: 1–6°C

Response:1 g/dL increase

Question 4

Dose, Volume per Unit, Shelf Life Storage and Response of FFP (fresh frozen plasma)

Answer 4

Dose: 10–15 mL/kg

Volume per Unit: 200–300 mL

Shelf Life: Frozen: 1 year; Thaw: 24 hours

Storage: Frozen: <−18°C; Thaw: 1–10°C

Response: 30% of normal coagulation factors

Question 5

Dose, Volume per Unit, Shelf Life Storage and Response of Cryo (Cryoprecipitate)

Answer 5

Dose: 1 unit/5 kg

Volume per Unit: 15–20 mL

Shelf Life: Frozen: 1 year; Thaw: 4 hours

Storage: Frozen: <−18°C; Thaw: 1–10°C

Response: 100 mg/dL increase in fibrinogen

Question 6

Dose, Volume per Unit, Shelf Life Storage and Response of platelets

Answer 6

Dose: 4–6 pooled WB derivative or 1 apheresis unit

Volume per Unit: 200–250 mL

Shelf Life: 5 days

Storage: 20–24°C with gentle agitation

Response: 30–60 × 109 /L increase*

• Uma unidade de concentrado de plaquetas aumenta em cerca de 7 mil plaquetas a concentração sérica delas. Uma aférese de plaquetas equivale à transfusão de, aproximadamente, 6 unidades de plaquetas

Question 7

Whole blood may be preferable to PRBCs when replacing blood losses that exceed …% of the blood volume

Answer 7

30

Question 8

Specific ratios of PRBC transfusions with FFP and platelets have been used in place of whole blood. For example, a ratio of … units PRBC with 1 unit of FFP.
In addition, … platelets for 6 units of RBCs has been recommended in patients with large blood losses and trauma.
Interestingly, despite its wide acceptance in massive resuscitation in trauma patients, these ratios have not been conclusively proven to improve mortality

Answer 8

1.5 (i.e., for every 1.5 units of PRBCs administered, 1 unit of FFP should be given)

1 unit of apheresis (or 6 pooled random donor units)

Question 9

Which blood components are present in the fresh frozen plasma?

Answer 9

All coagulation factors, except platelets, are present in FFP, which explains the use of this component for the treatment of hemorrhage from presumed coagulation factor deficiencies

Question 10

Indications of FFP transfusion

Answer 10

FFP transfusions during surgery are probably not necessary unless the prothrombin time/ international normalized ratio (PT/INR) or activated partial thromboplastin time (aPTT), or both, are at least 1.5 times longer than normal.

More recently, FFP has been given in specific ratios with PRBCs in trauma patients regardless of laboratory values.

Other indications for FFP are an urgent reversal of warfarin and management of heparin resistance (i.e., FFP contains antithrombin III).

Question 11

Which blood components are present in the cryoprecipitate

Answer 11

factor VIII, fibrinogen, fibronectin, von Willebrand factor, and factor XIII

Question 12

Utility of cryoprecipitate

Answer 12

This component is useful for treating hemophilia A (it contains high concentrations of factor VIII in a small volume) or von Willebrand factor deficiency that is unresponsive to desmopressin. Cryoprecipitate can also be used to treat hypofibrinogenemia because it contains more fibrinogen than FFP.

Question 13

Most common causes of transfusion related fatalities in the EUA (2015 - 2019)

Answer 13

1- Transfusion associated circulatory overload (34%)

2- Transfusion related acute lung injury (23%)

3- Hemolitic transfusion reaction non ABO (14%)

4- Infection (13%)

5- Hemolíticas transfusion reaction ABO (7%)

Question 14

Describe TRALI

Answer 14

TRALI is acute lung injury that occurs within 6 hours after transfusion of a blood product, especially FFP. It can be further subdivided into type 1 or type 2 depending on the preexistence of acute respiratory distress syndrome (ARDS) in the preceding 12 hours. It is characterized by dyspnea and arterial hypoxemia secondary to noncardiogenic pulmonary edema; it is a diagnosis of exclusion. Immediate actions to take when TRALI is suspected include (1) stopping the transfusion; (2) supporting the patient’s vital signs, especially oxygenation; (3) obtaining a complete blood count and chest radiograph; and (4) notifying the blood bank of possible TRALI so that other associated units can be quarantined

Question 15

Describe the transfusion related immunomodulation

Answer 15

Blood transfusion, especially PRBCs, suppresses lymphocyte function likely via arginase, which, when combined with other effects produced by surgical trauma, may place patients at risk for postoperative infection. Conversely, patients who receive blood transfusions may have more extensive disease and a poorer prognosis independent of the administration of blood. As such, the role of blood transfusions in postoperative infections is difficult to ascertain.

Question 16

Which are the metabolic abnormalities that can be associated with transfusions?

Answer 16

Hydrogen Ions
The addition of most preservatives promptly increases the hydrogen ion content of stored blood. Continued metabolic function of erythrocytes results in additional production of hydrogen ions, with the pH of stored blood being as low as 6,7. Despite these changes, metabolic acidosis in recipients caused by the transfusion of blood products, even with rapid infusion of large volumes of stored blood, does not occur. If there is an acidosis, in all likelihood, it arises from tissue hypoxia and not from the blood product itself.

Potassium
The potassium content of stored blood increases progres- sively with the duration of storage, but even massive transfusions rarely increase plasma potassium concentrations. Failure of plasma potassium concentrations to increase most likely reflects the small amount of potas- sium actually present in 1 unit of stored blood. It is estimated that 1 unit of PRBCs contains 5 to 6 mEq of potassium. Despite this relatively low amount, caution should be exercised when transfusing a large volume in patients with impaired renal function

2,3-Diphosphoglycerate
Storage of blood is associated with a progressive decrease in concentrations of 2,3-DPG in erythrocytes, which results in increased affinity of hemoglobin for oxygen (decreased P50 values). Conceivably, this increased affinity could make less oxygen available for tissues and jeop- ardize tissue oxygen delivery

Citrate
Citrate metabolism to bicarbonate may contribute to met- abolic alkalosis, whereas binding of calcium by citrate could result in hypocalcemia. Indeed, metabolic alkalosis rather than metabolic acidosis can follow within hours of massive blood transfusions. Severe hypocalcemia as a result of citrate binding of calcium is rare because of mobilization of calcium stores from bone and the ability of the liver to rapidly metabolize citrate to bicarbonate. Supplemental calcium may be needed when (1) the rate of blood infusion is more rapid than 50 mL/min, (2) hypothermia or liver disease interferes with the metabolism of citrate, or (3) the patient is a neonate. Patients undergoing liver transplantation are the most likely to experience citrate intoxication, and these patients may require calcium administration during a massive transfusion of stored blood

Question 17

Describe the febrile reactions associated with transfusions

Answer 17

Febrile reactions are the most common adverse non-hemolytic response to the transfusion of blood, and they accompany 0.5% to 1% of transfusions. The most likely explanation for febrile reactions is an interaction between recipient antibodies and antigens present on the leukocytes or platelets of the donor. The patient’s temperature rarely increases to above 38°C, and the condition is treated by slowing the infusion and administering antipyretics. Severe febrile reactions accompanied by chills and shivering may require discontinuation of the blood transfusion. Today, most blood is leukoreduced at the time of separation into its components.