Hematology

Question 1

Which of the following is NOT a confirmed benefit of pre-storage leukoreduction?

Answer 1

Leukoreduction is a decrease or complete elimination of donor leukocytes in blood components. This can reduce the risk of febrile transfusion reactions and the risk of viral transmission (e.g. cytomegalovirus). It does not fully protect against bacterial infection and does not prevent graft-versus-host disease

Question 2

Which of the following is LEAST likely true concerning fresh-frozen plasma (FFP) administration for warfarin reversal?

Answer 2

FFP administration acts to correct coagulation factor deficiencies by supplying coagulation factors that are reduced in a patient on warfarin therapy (factors II, VII, IX, X, protein C and protein S). It is indicated in urgent warfarin reversal among other hypocoagulable states. Specific factor concentrates or prothrombin complex concentrates may also be considered.

TrueLearn Insight : After initiation of warfarin, protein C, with a half-life of six hours, there will be a quick decline in the plasma. This causes an initial shift toward clotting which is responsible for the complication of warfarin-induced skin necrosis.

Question 3

A patient with hemophilia A and diverticulitis presents for laparotomy for left sigmoid colectomy for a perforated diverticulum. The patient had a life threatening hemorrhage after a car accident five years ago requiring massive transfusion at that time. What blood product should be considered if intraoperative blood loss, refractory to cryoprecipitate, is encountered?

Answer 3

Hemophilia A patients who do not respond well to exogenous human factor VIII infusion may have developed anti-factor VIII antibodies. The treatment in the case of hemorrhage or surgery in patients with hemophilia A with anti-factor VIII antibodies involves porcine factor VIII, recombinant factor VIIa, or recombinant factor IIa.

Question 4

A patient with septic shock is intubated in the intensive care unit on a norepinephrine drip.  Vital signs and lab data are as follows:
Mean arterial pressure 80 mmHg
Heart rate 70 bpm
SpO2 90%
Central venous pressure 16 mmHg
Cardiac index 1.8 L/min/m^2
SVO2 60%
Hgb 10
Lactate 5.0

Which of the following therapies is LEAST likely to increase peripheral oxygen delivery?

Answer 4

DO2 = CO * CaO2 * 10. Delivery of oxygen in the periphery depends on CO, the amount of O2 bound to Hgb, and the amount of O2 dissolved in plasma. Phenylephrine does not increase cardiac output.

Question 5

Which of the following BEST approximates the maximum allowable blood loss for a 70 kg, 64-year-old male? Assume a starting hematocrit of 42% and a lowest acceptable hematocrit of 30%, with estimated blood volume being 65-70 mL/kg.

Answer 5

The MABL of a patient = [EBV * (starting Hct - target Hct)] / (starting Hct)
Age Group	EBV (mL/kg)
Premature infant	90-105
Full term newborn	80-90
Infant (3 months - 1 year)	70-80
Child 1-12 years	70-75
Adult Female	60-65
Adult Male	65-70

Question 6

Since the year 2000, which of the following is the MOST common cause of mortality from transfusion of blood products in the United States?

Answer 6

The top three causes of death associated with blood product transfusion since the year 2000 in the United States are 1) TRALI, 2) HTRs (non-ABO > ABO), and 3) Infection and TAS.

Question 7

A thromboelastogram is done on a patient with severe post-partum hemorrhage. The isolated abnormal value is a decreased maximum amplitude (MA). Which of the following is the BEST treatment for this patient?

Answer 7

Thromboelastography (TEG) is a point-of-care test that provides information on functional coagulation. An isolated decrease in MA would suggest dysfunctional platelets or thrombocytopenia, which could be corrected with a platelet transfusion.

Question 8

A 73-year-old male is undergoing pulmonary endarterectomy with deep hypothermic cardiac arrest. An arterial blood gas is drawn while the patient’s temperature is 30 °C and run at 37 °C with the following results: pH 7.40, PaO2 80, PaCO2 40.

Compared to these results, which of the following describes how the values would change if temperature-corrected to 30 °C?

Answer 8

Blood pH and the solubilities of gases in blood are inversely related to temperature while the partial pressures of gases are directly related to temperature. Accordingly, when arterial blood gas values are corrected to a colder temperature, PaO2 and PaCO2 decrease while pH increases.

Question 9

Which of the following is MOST likely to occur as a result of storage of packed red blood cells?

Answer 9

Storage of PRBCs is associated with a gradual decrease in pH and 2,3-DPG, and an increase in potassium.

Question 10

A 77-year-old male is undergoing a radical prostate resection. In addition to standard monitoring he has an arterial line measuring his stroke volume variation (SVV) and a central venous catheter measuring his SvO2. Three hours after incision the patient’s SvO2 decreases to less than 60% but the SVV remains at 8. Which of the following factors is MOST likely to REDUCE the patient’s SvO2 as measured five minutes after the intervention?

Answer 10

In general, mixed venous oxygen saturation can be INCREASED by increasing cardiac output, hemoglobin concentration, and arterial oxygen saturation. In cases of sepsis or high catabolic states, treating the underlying reason for increased oxygen consumption can also improve mixed venous saturation.

TrueLearn Insight : Central venous oxygen saturation (ScvO2) and mixed venous oxygen saturation (SvO2) are often used interchangeably but there is a subtle difference. ScvO2 is measured in the right heart and receives contributions from the superior and inferior vena cavae and the coronary sinus. A true SvO2 measurement is obtained via pulmonary artery catheter and includes deoxygenated blood from the thebesian venous network. Therefore, because it is a more distal measurement, a true SvO2 can be 5-10% lower than the ScvO2. In practice, ScvO2 is a useful surrogate for SvO2.

Question 11

Which of the following is true after a patient receives hetastarch?

Answer 11

Hetastarch may lead to platelet dysfunction by causing a reduction in the availability of glycoprotein IIb-IIIa on platelets.

TrueLearn Insight : Hextend has smaller hydroxyethyl molecules and thus may not affect coagulation as much as Hespan.

Question 12

Which of the following is an indication for administering factor VIII concentrate?

Answer 12

Factor VIII concentrate is the mainstay of therapy for hemophilia A and 30% of levels are needed for hemostasis.

TrueLearn Insight : Cryoprecipitate contains factor VIII:C, factor VIII:vWF, fibrinogen, factor XIII, and fibronectin.

Question 13

Which of the following MOST likely interferes with acetylcholine release?

Answer 13

Factors that decrease release of acetylcholine:
1) Antibiotics (clindamycin, polymyxin)
2) Magnesium: antagonizes calcium
3) Hypocalcemia
4) Anticonvulsants
5) Diuretics (furosemide)
6) Eaton-Lambert syndrome: inhibits P-type calcium channels
7) Botulinum toxin: inhibits SNARE proteins
Both the botulinum and tetanus toxin inhibit SNARE proteins. However, botulinum toxin acts at the level of the peripheral nerve, and the tetanus toxin acts at the central nervous system.
Botulinum –> inhibits SNARE –> decrease acetylcholine release (peripheral nerve)
Tetanus –> inhibits SNARE –> inhibits GABA neurons (CNS)

Question 14

Transfusion-related immunomodulation, mediated by the presence of leukocytes in non-leukoreduced blood transfusions, is likely to cause a beneficial effect in which of the following?

Answer 14

Transfusion-related immunomodulation (TRIM) is defined as a set of pro-inflammatory and immunosuppressive effects in allogeneic blood recipients. In the pre-cyclosporine era, this was used to enhance renal allograft survival. In the current era, TRIM is speculated to play a role in many areas, and may underlie the known decrease in mortality in cardiac surgery patients not subjected to TRIM by virtue of receiving leukoreduced blood transfusions.

Question 15

Transfusion of which of the following blood products is MOST likely to cause transfusion-associated sepsis?

Answer 15

Transfusion-associated sepsis is the third leading cause of transfusion-related deaths in the United States and is most commonly caused by bacterial infection from contaminated platelets. Unlike other blood products, platelets are stored at room temperature which leads to increased bacterial growth.

Question 16

Which of the following infectious agents has the HIGHEST rate of transmission from blood product transfusion?

Answer 16

The risk of CMV transmission when non–CMV-screened leukoreduced cellular products are administered to CMV negative recipients is less than 1%. The risk of HIV, HCV, and human T-cell lymphotropic virus among all allogeneic donations is currently below 1 per 1,000,000 donations, and that of hepatitis B surface antigen is close to 1 per 300,000 donations.

Question 17

An 85-year-old male with atrial fibrillation is brought to the operating room for urgent repair of a hip fracture. The patient had received 6 units of fresh frozen plasma by the primary service prior to arrival in the operating room. A central line is placed for possible vasoactive support and central venous pressure is 2 mm Hg. Post-operatively in the intensive care unit, the patient is hypotensive, tachycardic, and significantly hypoxemic. Central venous pressure is 6 mm Hg. A chest radiograph is obtained, as shown here.

Answer 17

The chest radiograph in TRALI is characterized by bilateral patchy infiltrates without signs of heart failure.

Question 18

A 30-year-old male undergoes an exploratory laparotomy. He receives 4 units of packed red blood cells and 2 units of fresh frozen plasma. Two hours after the surgery, the patient develops hypoxemia and hypotension. A chest radiograph shows bilateral diffuse pulmonary edema and the pulmonary artery wedge pressure is 8 mm Hg. Which of the following is the MOST appropriate management of this patient?

Answer 18

Treatment for TRALI is supportive and starts with intravenous fluids and/or vasopressors. Diuretics and corticosteroids are not recommended.

Question 19

Which of the following is an antibody test with high sensitivity for heparin induced thrombocytopenia?

Answer 19

Detection of antiplatelet factor 4 antibodies is commonly used to diagnose HIT. Antiplatelet factor 4 detection has a high sensitivity for HIT. The serotonin release assay has a high specificity for HIT.

Question 20

A patient presents for emergency surgery with an INR of 5.4. The surgeon states the surgery cannot wait any longer than 4 hours. Which of the following is the MOST APPROPRIATE method to correct this patient’s INR?

Answer 20

Reversal of INR depends on patient circumstances and if immediate reversal is required. Typically, if the patient has life threatening bleeding or requires emergent surgery, PCCs along with vitamin K administration should be given. Patients will respond differently thus frequent monitoring and reevaluation is required. Multiple studies have shown that FFP is unable to correct INR values ranging from 1-1.85.

TrueLearn Insight : There is no evidence to guide practitioners with FFP dosing. The American Society of Anesthesiologists Task Force on Blood Component Therapy recommends 8-15 mL/kg of FFP when the goal of increasing all coagulation factor levels above 30 is needed; however, this is considered controversial since the dose response of FFP is not standard. There are certainly risks associated with FFP transfusion; most notable are transfusion related acute lung injury (TRALI), febrile reactions, allergic reactions, and transfusion associated circulatory overload (TACO).

Question 21

Which of the following is NOT an indication for cryoprecipitate administration?

Answer 21

Cryoprecipitate contains von Willebrand factor (vWF), fibrinogen, fibronectin, factor VIII, and factor XIII.
Indications for Cryoprecipitate

Microvascular bleeding with hypofibrinogenemia *
Bleeding due to uremia that is unresponsive to DDAVP
Factor XIII deficiency
Prophylaxis before surgery or treatment of bleeding with congenital dysfibrinogenemias
Prophylaxis before surgery or treatment of bleeding with Von Willebrand disease **
Prophylaxis before surgery or treatment of bleeding with hemophilia A **
Use in fibrin sealant production

Question 22

Which of the following laboratory tests is used to monitor the anticoagulant response to enoxaparin?

Answer 22

Although not routinely necessary, the anticoagulant effects of enoxaparin can be monitored by measuring factor Xa activity. Unfractionated heparin is monitored using either aPTT or ACT, depending on the clinical situation.

TrueLearn Insight : Treatment of AT3 deficiency includes the administration of AT3 and/or FFP, which includes AT3. This may be useful in the setting of a patient requiring high dose heparinization.

Question 23

Which of the following factors in fresh frozen plasma is the LEAST stable during storage and closely interacts with von Willebrand factor?

Answer 23

Factors V and VIII are the least stable factors in FFP. Factor VIII is produced in the vascular endothelium and sinusoidal cells of the liver. Von Willebrand factor serves as a carrier molecule for factor VIII, which is ultimately activated by IIa. This promotes further coagulation along the clotting cascade.

TrueLearn Insight : Fresh frozen plasma does not carry a significant quantity of viable leukocytes so there is minimal risk for graft vs. host disease or cytomegalovirus (CMV) transmission. It carries the same infectious risk as whole blood aside from CMV transmission.

Question 24

The administration of fresh frozen plasma in a patient on warfarin is MOST appropriate in which of the following scenarios?

Answer 24

FFP for reversal of warfarin may be used if surgery is urgent and INR is significantly elevated; However, PCC has become the agent of choice over FFP. Vitamin K should be used for elective procedures including procedures that can be delayed for 24 hours.

TrueLearn Insight : Unfortunately, there are no current definitive guidelines for when to transfuse FFP based on an INR value. The American Society of Anesthesiologist’s practice parameter on plasma components states that most patients can form clots if INR < 2.5. The actual determination of INR for transfusion is based on the individual patient, the risks of transfusion, and the risks of bleeding during the procedure.

Question 25

A thromboelastogram is performed in a patient during a liver transplant for end-stage liver disease. The maximum amplitude is found to be significantly decreased. Which of the following is the BEST diagnosis for this patient?

Answer 25

Thromboelastography is a graphic evaluation of clotting function that provides numerical measurements. Decreased maximum amplitude values primarily provide evidence of quantitative (thrombocytopenia) and/or qualitative platelet dysfunction or, to a lesser extent, inadequate fibrinogen. The best treatment is the administration of platelets.

Question 26

Which of the following would point to a diagnosis of transfusion related acute lung injury (TRALI) versus of other types of transfusion reactions?

Answer 26

Transfusion related acute lung injury (TRALI) is a clinical syndrome which occurs within six hours of a blood transfusion. Leukopenia can be used to help diagnose TRALI and occurs because leukocytes are depleted following binding in the pulmonary vasculature to HLA in the donor transfusion.

Question 27

A 63-year-male with atrial fibrillation presents to the Emergency Department with abdominal pain. He appears hemodynamically stable and his INR is 1.6. He is diagnosed with nephrolithiasis and the urology team would like to perform a cystoscopy on him in two days. Which of the following would be INAPPROPRIATE in the management of this patient?

Answer 27

Fresh frozen plasma should be avoided in the following situations:

• Use to correct mildly elevated INR (< 1.8) without signs of bleeding
• Use to correct a vitamin K deficiency that could be corrected with vitamin K
• Use as a primary volume expander (absolute contraindication)
• Use to correct a factor deficiency when recombinant factor replacement is available

TrueLearn Insight : Prothrombin complex concentrates (PCC) are an alternative option for coagulopathy relating to vitamin K-dependent coagulation factors.

Question 28

Which of the following does NOT increase the risk for citrate toxicity?

Answer 28

Citrate toxicity occurs when a patient receives any blood product that uses citrate as an anticoagulant. Citrate toxicity is highest during fresh frozen plasma administration; however, it can occur with any blood transfusion and is more common in pediatric patient populations, those with significant liver disease, those undergoing liver transplantation, in patients who are hyperventilated, or if a patient is cooled.

TrueLearn Insight : Fresh frozen plasma is prepared from whole blood collection or through apheresis. Fresh frozen plasma is collected in citrate-containing anticoagulation solution, frozen within 8 hours of collection, and can be stored for up to 1 year at –30 °C. Fresh frozen plasma contains all clotting factors, fibrinogen, plasma proteins (particularly albumin), electrolytes, physiologic anticoagulants (protein C, protein S, antithrombin), and added anticoagulants (citrate).

Question 29

Which situation is MOST concerning for metformin-associated lactic acidosis?

Answer 29

Metformin may be continued perioperatively except in cases of acute renal failure or in situations in which the risk of renal insufficiency is high. Contrast dye is a risk factor for renal nephropathy, and urine output and creatinine should be monitored after the dye is given. The risk of MALA is so low that the benefits of maintaining glucose control without hypoglycemia is reason to continue metformin perioperatively. It should be stopped if renal insufficiency develops.

TrueLearn Insight : Metformin may be continued through the perioperative period.

Question 30

While performing your preoperative evaluation of a 13-year-old female for scoliosis surgery, it is noted that she has no blood products available. The surgeon then asks for a type and crossmatch. Which of the following is NOT a component of a traditional type and crossmatch?

Answer 30

Blood type and screen involve determining the recipient’s ABO status (mixing recipient red cells with anti-A, anti-B, and anti-AB antibodies), Rh status (mixing recipient red cells with anti-D antibodies), and screening for unexpected antibody status (mixing recipient serum with known surface antigens on commercially supplied type O RBCs). Crossmatching involves mixing recipient serum with donor red blood cells to examine for any incompatibilities that were not screened out as well as setting aside the desired number of blood products for potential transfusion. Crossmatched blood that is set aside will not be used for other patients during a set period of time.

TrueLearn Insight : The “type and screen” has been shown to be a safe and cost-effective preoperative substitute for the “type and crossmatch” when the likelihood of transfusion is low, and the antibody screen is negative.

Question 31

Two weeks prior to major surgery, a patient with multiple blood antibodies undergoes phlebotomy to store one unit of blood. Which of the following is the MOST COMMON complication following an autologous blood transfusion?

Answer 31

Infection resulting from improper storage is the most common risk associated with autologous blood transfusion. Hemolytic and non-hemolytic transfusion reactions are extremely rare in this setting as autologous blood does not contain non-self antigens.

Question 32

Which of the following dietary supplements has NOT been shown to interfere with platelet function?

Answer 32

Garlic, ginger, gingko, and vitamin E have all been shown to interfere with platelet function.

Question 33

A 68-year-old, 70-kg (155-lb) man has received 8 units of packed red blood cells, 4 units of fresh frozen plasma, and 7 L of crystalloid during the resuscitation phase of a ruptured aortic aneurysm repair. A decision is made to give 10 units of pooled cryoprecipitate. How much fibrinogen is this patient expected to receive from the cryoprecipitate infusion?

Answer 33

Cryoprecipitate contains about 200 mg of product in each unit. Ten units of cryoprecipitate will typically raise a 70-kg (155-lb) patient’s fibrinogen by 70 mg/dL.

Question 34

Patients with IgA deficiency who receive blood transfusions are at INCREASED RISK for which of the following?

Answer 34

IgA deficient patients are at risk for anaphylactic response to IgA antigens in donor blood, as they may have anti-IgA antibodies from prior blood exposure or pregnancy. To avoid this reaction, these patients should receive washed red blood cells or blood from IgA deficient donors.

Question 35

Which of the following is NOT an indication for the administration of fresh frozen plasma?

Answer 35

Fresh frozen plasma is not indicated for plasma volume expansion. Please see the table above for indications for FFP transfusion.

Question 36

Which of the following is TRUE regarding the P50 in relation to the oxygen-hemoglobin dissociation curve?

Answer 36

P50 is normally ~27 mm Hg and corresponds to the PO2 at which 50% of Hgb is saturated at normal physiologic pH and temperature. A left shift (due to hypothermia, alkalosis, decreased DPG) causes a decreased P50 and an increased Hgb affinity for oxygen. A right shift (due to hyperthermia, acidosis, increased DPG) causes an increased P50 and a decreased Hgb affinity for oxygen, meaning more offloading of oxygen.

Question 37

A 56-year-old man in the post-anesthesia care unit receives a blood transfusion following a partial liver resection for a hepatic adenoma. Thirty minutes after starting the transfusion, he becomes febrile to 38.4 °C. He is otherwise asymptomatic and has a negative direct antiglobulin test. What is the MOST likely mechanism of this reaction?

Answer 37

Non-hemolytic febrile transfusion reaction is the most common blood reaction. Non-hemolytic reaction is defined as a temperature increase of >1 °C without concurrent hemolysis. A non-hemolytic febrile transfusion reaction occurs because recipient antibodies cause lysis of donor leukocytes found in the red cell transfusion product.

TrueLearn Insight : Febrile transfusions reactions are relatively common in multi-transfused and multiparous patients.

Question 38

You are caring for a patient who needs an intra-operative blood transfusion due to ongoing hemorrhage. The patient has intermittent hypotension but still responds to intravenous fluid boluses. Lab results show that the patient has a positive antibody screen and no compatible units are available. Which of the following is the MOST reasonable management of the patient?

Answer 38

Having a positive type and screen can result in prolonged crossmatching times depending on the antibodies present. This can result in no compatible blood units being available for transfusion or several hour crossmatch times with the possibility of compatible units being at another facility. A patient should not be denied a life saving transfusion if a screen is determined to be positive and the clinician should consult with the pathologist regarding the safest units to transfuse in those circumstances.

Question 39

Which of the following is an effect of blood product leukoreduction?

Answer 39

Leukoreduction is the process of depleting donor blood products of leukocytes in an effort to reduce immunosuppression associated with blood product transfusion. Confirmed benefits of leukoreduction include decreased transmission of CMV, decreased inflammatory response, decreased febrile reactions to packed red blood cell (PRBC) transfusions, and reduced inflammatory mediator accumulation during storage.

Question 40

A 47-year-old patient is accidentally transfused an ABO-incompatible unit of packed red blood cells. Which of the following laboratory findings will MOST likely be seen?

Answer 40

Transfusion of an ABO-incompatible unit of packed red blood cells (PRBCs) results in an acute hemolytic transfusion reaction (AHTR). The increased free hemoglobin load is metabolized to bilirubin and both indirect (unconjugated) and direct (conjugated) bilirubin levels are elevated.

Question 41

A 14-year-old female is about to undergo corrective scoliosis surgery. She is otherwise healthy with a preoperative hemoglobin of 14 g/dL. The surgeon is suggesting acute normovolemic hemodilution as a strategy for this case. Which of the following is NOT a physiologic effect of this approach?

Answer 41

When hemodilution occurs the blood viscosity will decrease. The decreased blood viscosity will decrease peripheral vascular resistance. Cardiac output raises to compensate for the anemia. The increase in cardiac output and decrease in peripheral vascular resistance causes an increase in regional blood flow. However, even with increases in regional blood flow and cardiac output, there is no increase in oxygen delivery.

Question 42

Which of the following is the MOST likely reason for low-grade fevers following packed red blood cell transfusion?

Answer 42

Simple febrile reactions to blood product administration are usually due to antibodies that the host has formed against HLAs present on donor leukocytes. The febrile period is usually mild, short-lived, and can be treated with acetaminophen.

Question 43

A positive direct antiglobulin test MOST LIKELY confirms which of the following transfusion reactions?

Answer 43

Acute hemolytic transfusion reaction carries significant morbidity and mortality. Laboratory testing includes evidence of hemolysis with a positive direct antiglobulin test. Cessation of the transfused unit is most important, as severity of reaction is proportional to amount of blood transfused.

Question 44

A 36-year-old male with no past medical history presents after a gun shot wound to the abdomen. Vital signs are blood pressure 80/40 mmHg, heart rate 120 bpm, and a respiratory rate of 30 per minute. Throughout the course of resuscitation, 10 units of packed red blood cells are given. Which of the following derangements is MOST LIKELY to occur given the large amounts of blood products given?

Answer 44

Transfusion of large amounts of blood products can lead to several physiological and metabolic derangements including hypocalcemia, hyperkalemia, metabolic alkalosis, and hypothermia. Hypocalcemia is common and should be anticipated.

Question 45

A 55-year-old male becomes hypotensive following transfusion of multiple units of packed red blood cells, fresh frozen plasma, and platelets during orthotopic liver transplantation. Flattened T waves and prolonged QT intervals are noted on ECG. Which of the following therapeutic measures would be MOST appropriate at this time?

Answer 45

Citrate is found in blood storage preservatives where it acts as an anticoagulant. Once transfused, large amounts of citrate reversibly bind (chelate) ionized calcium which may lead to hypocalcemia in the setting of rapid transfusion and liver dysfunction. This leads to hypotension, narrow pulse pressure, increased LVEDP, prolonged QT interval, narrowed QRS, and flattened T waves. Supplemental calcium administration is appropriate in this setting. Unlike CPDA, the anticoagulant EDTA is not commonly used clinically since it irreversibly binds calcium.

TrueLearn Insight : CPDA-1 anticoagulant allows PRBC and whole blood storage for up to 35 days

          - Citrate is the anticoagulant (binds calcium necessary for clot formation)
          - Phosphate is incorporated for cellular function and ATP production
          - Dextrose is the nutrition source for glycolysis
          - Adenine is incorporated for ATP production