PMS III Week 5 - Overview of Blood Products and Transfusion Medicine

What are the four main clinical situations in which blood products are transfused?

Trauma, surgery, anemia, and bleeding or clotting deficiencies.

What are the three major reasons for transfusion?

To restore oxygen-carrying capacity, restore circulating volume, and correct clotting abnormalities.

Which blood product is mainly used to improve oxygen-carrying capacity?

Packed red blood cells (PRBCs).

Which type of product is generally used first for volume resuscitation?

Isotonic crystalloid.

Which products may be needed to correct platelet or coagulation-factor deficiencies?

Platelets, individual clotting factors, fresh frozen plasma (FFP), and/or cryoprecipitate.

Why may a patient with massive hemorrhage need more than PRBCs?

Massive blood loss also depletes platelets and clotting factors, so platelets and plasma-derived products may be required.

What balanced ratio does the lecture recommend for massive transfusion?

A 1:1:1 ratio of PRBCs, plasma, and platelets, given early.

What are the major categories of transfusion products covered in the lecture?

Crystalloid, whole blood, PRBCs, leukocyte-reduced PRBCs, irradiated PRBCs, platelets, FFP, and cryoprecipitate.

Which product is listed but not further explained in the presentation?

Irradiated PRBCs.

What general principle guides blood-product selection?

Choose the component that replaces the specific deficit: red cells for oxygen-carrying capacity, fluid for volume, platelets for platelet deficits, and plasma or cryoprecipitate for coagulation deficits.

Approximately how much blood is in a 70-kg adult?

About 5 liters.

Why are hemoglobin and hematocrit unreliable for evaluating acute blood loss?

They may not immediately reflect the severity of acute whole-blood loss, so they are unreliable early markers of acute hemorrhage.

What is Class I hemorrhage?

Loss of up to 15% of blood volume, or approximately 750 mL; the patient may be asymptomatic.

What is Class II hemorrhage?

Loss of 15% to 30% of blood volume, or approximately 750 to 1,500 mL; tachycardia may occur while blood pressure remains normal.

What is Class III hemorrhage?

Loss of 30% to 40% of blood volume, or approximately 1,500 to 2,000 mL, with tachycardia, tachypnea, oliguria, decreased mentation, and 'hypotnatremia' as written in the lecture.

What is Class IV hemorrhage?

Loss of more than 40% of blood volume; this is life-threatening.

Which hemorrhage class may be asymptomatic?

Class I.

Which hemorrhage class may cause tachycardia with a normal blood pressure?

Class II.

Which hemorrhage class is associated with oliguria and decreased mentation?

Class III.

Which hemorrhage class represents life-threatening blood loss?

Class IV.

How much blood loss corresponds to Class I hemorrhage?

Up to approximately 750 mL.

How much blood loss corresponds to Class II hemorrhage?

Approximately 750 to 1,500 mL.

How much blood loss corresponds to Class III hemorrhage?

Approximately 1,500 to 2,000 mL.

How much blood loss corresponds to Class IV hemorrhage?

More than 40% of circulating blood volume, or more than approximately 2,000 mL in a 70-kg adult.

What important lesson does Class II hemorrhage demonstrate?

A normal blood pressure does not exclude clinically significant hemorrhage because tachycardia may develop before hypotension.

What body systems show dysfunction in Class III hemorrhage?

Cardiovascular, respiratory, renal, and neurologic systems, reflected by tachycardia, tachypnea, oliguria, and decreased mentation.

How is blood loss estimated in the operating room?

By measuring blood in the wound, blood collected in suction containers, and the weight of blood-soaked sponges.

What degree of blood loss may often be replaced with crystalloid alone?

Less than 20% blood loss.

What degree of blood loss often requires PRBC transfusion?

More than 20% blood loss.

What products may be added during larger-volume transfusions?

FFP and possibly platelets.

What does failure to stabilize after initial crystalloid suggest?

More than approximately 15% to 20% blood loss, ongoing blood loss, or both.

What factors should be considered when evaluating hemorrhage beyond the hemoglobin level?

Estimated blood volume lost, vital signs, urine output, mental status, ongoing bleeding, and response to crystalloid.

In a normovolemic patient, at what hemoglobin does the lecture generally recommend transfusion?

Hemoglobin below 6 g/dL.

In a normovolemic patient, at what hemoglobin does the lecture recommend not transfusing?

Hemoglobin above 10 g/dL.

What usual post-transfusion hemoglobin goal is listed in the lecture?

Approximately 7 to 9 g/dL.

Where is transfusion for anemia often a clinical issue?

In intensive care units.

What is the lecture's broad hemoglobin decision range?

Generally transfuse below 6 g/dL, generally do not transfuse above 10 g/dL, and usually target about 7 to 9 g/dL.

What does 'normovolemic' imply in the lecture's anemia thresholds?

The patient has adequate circulating volume, so the decision is focused on anemia rather than acute volume replacement.

Does the presentation provide a complete individualized transfusion algorithm for anemia?

No. It provides general hemoglobin thresholds and a usual target range.

What is a crystalloid?

An aqueous solution of mineral salts or other water-soluble molecules.

What are the isotonic crystalloids listed in the lecture?

Normal saline, Lactated Ringer's, and Ringer's acetate.

What is the composition of normal saline?

0.9% sodium chloride.

What components of Lactated Ringer's are listed in the lecture?

Sodium chloride, lactate, potassium, and calcium.

What is generally the first fluid used in volume resuscitation?

Crystalloid.

What is the 3:1 crystalloid replacement rule?

For every 1 liter of blood lost, approximately 3 liters of crystalloid may be needed.

According to the 3:1 rule, how much crystalloid may replace 1 liter of blood loss?

Approximately 3 liters.

According to the 3:1 rule, how much crystalloid may replace 2 liters of blood loss?

Approximately 6 liters.

What initial crystalloid volume does the lecture suggest in acute hemorrhage?

Approximately 2 to 3 liters.

What does persistent hemodynamic instability after 2 to 3 liters of crystalloid suggest?

The patient may have lost more than 15% to 20% of blood volume, may have ongoing blood loss, or both.

What survival advantage does colloid have over crystalloid according to the lecture?

None.

How does colloid compare with crystalloid in cost?

Colloid is more expensive.

Why is crystalloid favored as the initial resuscitation fluid in the lecture?

It is generally the first-line volume replacement fluid, while colloid has no survival advantage and is more expensive.

Why would whole blood theoretically be ideal for replacing blood loss?

It replaces the multiple components lost during whole-blood hemorrhage.

Why is whole blood commonly fractionated into components?

Because of storage limitations.

Into what components is whole blood commonly separated?

PRBCs, platelets, plasma, and other blood components.

Where has fresh whole blood continued to be used?

In combat situations.

What is the main practical limitation of whole blood emphasized in the lecture?

Storage limitations.

What are PRBCs?

Red blood cells prepared by removing most of the plasma and adding a preservative.

How are PRBCs prepared?

Most plasma is removed from whole blood, and a preservative is added.

How much does one unit of PRBCs usually raise hemoglobin?

Approximately 1 g/dL.

How much does one unit of PRBCs usually raise hematocrit?

Approximately 3 percentage points.

How many PRBC units does the lecture state are generally transfused at a time?

Generally two units at a time.

What is the main therapeutic purpose of PRBCs?

To improve oxygen-carrying capacity by replacing red blood cells.

A patient's hemoglobin is 6 g/dL. What would two units of PRBCs be expected to do based on the lecture?

Increase hemoglobin by approximately 2 g/dL, to about 8 g/dL, assuming the expected response.

A patient's hematocrit is 21%. What would one unit of PRBCs be expected to do based on the lecture?

Increase hematocrit by approximately 3 percentage points, to about 24%.

What are leukocyte-reduced PRBCs?

PRBCs filtered to remove most white blood cells and platelets.

What cells are removed by leukocyte reduction?

Most white blood cells and platelets.

What transfusion reaction is reduced by leukocyte-reduced PRBCs?

Febrile nonhemolytic transfusion reactions.

What additional benefit of leukocyte reduction is listed?

Minimization of viral transmission.

What is the status of leukocyte-reduced PRBCs in the United States and other Western countries?

They are generally the standard blood product used.

Why do leukocyte-reduced products lower febrile reaction risk?

They remove most donor leukocytes and reduce leukocyte-associated cytokines and immune stimulation described in the lecture.

How are platelets generally collected?

By apheresis.

What are the three broad indications for platelet transfusion?

Thrombocytopenia, nonfunctioning platelets, and massive blood-loss transfusion.

What platelet threshold is listed for an asymptomatic patient?

Less than 10,000/µL.

What platelet threshold is listed for a coagulation disorder or minor bleeding?

Less than 15,000/µL.

What platelet threshold is listed for major bleeding?

Less than 20,000/µL.

What platelet threshold is listed before an invasive procedure or general surgery?

Less than 50,000/µL.

What platelet threshold is listed for neurologic or cardiac surgery?

Less than 100,000/µL.

Which platelet transfusion threshold is the lowest in the lecture?

Less than 10,000/µL in an asymptomatic patient.

Which platelet transfusion threshold is the highest in the lecture?

Less than 100,000/µL for neurologic or cardiac surgery.

Why is a higher platelet count required for neurologic or cardiac surgery?

The lecture lists a more conservative threshold of 100,000/µL for these high-risk procedures.

A stable asymptomatic patient has a platelet count of 8,000/µL. What does the lecture suggest?

Platelet transfusion is indicated because the count is below 10,000/µL.

A patient with minor bleeding has a platelet count of 14,000/µL. What does the lecture suggest?

Platelet transfusion is indicated because the count is below 15,000/µL.

A patient with major bleeding has a platelet count of 18,000/µL. What does the lecture suggest?

Platelet transfusion is indicated because the count is below 20,000/µL.

A patient scheduled for general surgery has a platelet count of 45,000/µL. What does the lecture suggest?

Platelet transfusion is indicated because the count is below 50,000/µL.

A patient scheduled for neurosurgery has a platelet count of 90,000/µL. What does the lecture suggest?

Platelet transfusion is indicated because the count is below 100,000/µL.

What examples of nonfunctioning platelets are listed?

von Willebrand disorder, uremia, and medication-related platelet dysfunction.

Are platelet transfusion indications clearly defined in patients with nonfunctioning platelets?

No. The lecture states that indications are less clear.

Why can platelet count alone be insufficient in platelet dysfunction?

The platelet number may be adequate even though the platelets do not function normally.

Why are platelets included in massive transfusion?

Massive blood loss depletes and dilutes platelets, so platelet replacement is needed along with PRBCs and plasma.

What two dimensions guide platelet transfusion decisions?

The platelet count and the clinical setting, including bleeding severity and planned procedure.

What is fresh frozen plasma?

Plasma obtained and frozen after red blood cells and platelets are removed.

What does FFP contain?

Coagulation factors and fibrinogen.

What is the main purpose of FFP?

Replacement of multiple coagulation factors.

Does FFP primarily increase oxygen-carrying capacity?

No. PRBCs increase oxygen-carrying capacity; FFP replaces coagulation factors.

What is one indication for FFP when no specific factor product is available?

Correction of a coagulation defect for which no specific factor is available.

What conditions are listed as examples of bleeding with multiple coagulation defects?

Liver failure and disseminated intravascular coagulation (DIC).

Why may FFP be needed during massive transfusion?

To replace coagulation factors lost or diluted during major hemorrhage and large-volume transfusion.

Is warfarin over-anticoagulation listed as an indication for FFP?

Yes, but the lecture notes that PCC is now used more commonly.

Which product is used more commonly than FFP for warfarin reversal?

Prothrombin complex concentrate (PCC).