35. A 57-year-old diabetic man presents to your office for presurgical evaluation for total hip replacement.
After a thorough history and physical examination, you ask the patient if he has any questions. He says that the orthopedic surgeon told him that there was a possibility he will need blood products during or after the surgery, and the patient is concerned about the risks of contracting a contagious disease from blood products.
Which of the following statements about the risk of infection associated with transfusion is true?
❑ A. Risk of transfusion-associated hepatitis A is higher in pooled products such as factor concentrates than in single-donor products
❑ B. Postdonation screening to identify donors likely to transmit blood-borne infections has produced the biggest decrease in the risk of trans-fusion-transmitted disease
❑ C. Directed donation offers a small but significant reduction in the risk of transfusion-associated infections
❑ D. Currently, there is no postdonation test available for West Nile virus
Key Concept/Objective: To understand the screening process used to reduce transmission of infec-tious diseases through transfusion of blood products
Available prevalence data show that the risk of infectious disease from directed donors is no different from that of first-time donors. Predonation donor screening to identify clini-cal and lifestyle characteristics associated with higher incidences of infection has produced the biggest decrease in the risk of transfusion-transmitted disease. Postdonation testing is essential in identifying donors likely to transmit blood-borne infections who are missed in the initial screening process. Because the viremic phase of hepatitis A lasts about 17 days in humans before signs and symptoms develop, hepatitis A transmission from single-donor products is extremely rare. Pooled products, such as factor concentrates, however, carry a substantially higher risk. Transmission of West Nile virus by blood products has led to new donor questions to eliminate donors at risk for this disease. A nucleic acid–based test for all donated units was introduced in June 2003. (Answer: A—Risk of transfusion-associ-ated hepatitis A is higher in pooled products such as factor concentrates than in single-donor products)
36. A 49-year-old woman is admitted to the hospital with newly diagnosed severe anemia. Her hemoglobin level is 7 g/dl, and she has shortness of breath and fatigue. She denies any obvious source of blood loss, such as menorrhagia or rectal bleeding. On examination, the patient is pale. She is tachycardic, with a pulse of 110 beats/min. Her blood pressure is 105/62 mm Hg. Rectal examination shows heme-positive brown stool. Before you leave the room to write your orders, you explain the risks and benefits of blood product transfusion.
Which of the following statements about blood components is true?
❑ A. Whole blood transfusion would be preferable to red cell transfusion in this patient
❑ B. Leukocyte reduction reduces febrile transfusion reactions
❑ C. Cryoprecipitate consists of albumin and platelets
❑ D. Single-donor platelet transfusions carry a higher risk of blood-borne infection than platelet concentrates
Key Concept/Objective: To understand the components of whole blood
Except for some autologous blood programs that use whole blood rather than packed red cells, use of whole blood has now been almost completely supplanted by therapy employ-ing specific blood components. To prevent transfusion reactions or to delay alloimmu-nization, red cells are further processed by leukocyte reduction or washing to remove plasma proteins. Current filter technology reduces white cell counts to less than 5 × 106 cells per unit, a concentration that is sufficient to reduce febrile transfusion reactions and
delay alloimmunization and platelet refractoriness. With single-donor platelet therapy, there is a reduction in the risk of blood-borne infection and antigen exposure, because the product is from one donor rather than four to six; disadvantages are a longer collection time, greater cost, and often limited supply. Fresh frozen plasma (FFP) that is frozen with-in 8 hours of collection contawith-ins all the procoagulants at normal plasma concentrations.
Cryoprecipitate consists of the cryoproteins recovered from FFP when it is rapidly frozen and then allowed to thaw at 2° to 6° C. These cryoproteins include fibrinogen, factor VIII, von Willebrand factor, factor XIII, and fibronectin. (Answer: B—Leukocyte reduction reduces febrile transfusion reactions)
37. A 58-year-old man with acute myelogenous leukemia received chemotherapy 10 days ago. He now pres-ents to the emergency department with severe fatigue and shortness of breath. He has had no fever.
Results of complete blood count are as follows: white cell count, 800/µl; hemoglobin level, 7.5 g/dl;
platelet count, 43,000/µl.
Which of the following statements regarding indications for transfusion of blood products is true?
❑ A. In patients with acute blood loss, the first treatment goal is transfusion of packed red blood cells
❑ B. Platelet transfusions are contraindicated in autoimmune thrombocy-topenia
❑ C. The prevalence of bleeding increases significantly below a threshold of about 10,000 platelets/µl in otherwise asymptomatic patients
❑ D. In chronically anemic patients, red cell 2,3-diphosphoglycerate pro-duction is decreased to maximize the red blood cells’ oxygen affinity
Key Concept/Objective: To know the indications for transfusion of blood products
The decision whether to use red cells depends on the etiology and duration of the anemia, the rate of change of the anemia, and assessment of the patient’s ability to compensate for the diminished capacity to carry oxygen that results from the decrease in red cell mass.
Restoration of intravascular volume, usually with crystalloid, ensures adequate perfusion of peripheral tissue and is the first treatment goal for a patient with acute blood loss. In general, the decision to transfuse platelets rests on the answers to two questions: (1) Is the thrombocytopenia the result of underproduction or increased consumption of platelets?
and (2) Do the existing platelets function normally? Thrombocytopenia can result from decreased production caused by marrow hypoplasia or from increased consumption caused by conditions such as idiopathic thrombocytopenic purpura (ITP). Studies have shown that the prevalence of bleeding increases significantly below a threshold of about 10,000 platelets/µl in otherwise asymptomatic patients. Transfusion is appropriate in a bleeding patient whose platelet count is adequate but whose platelets are nonfunctional as a result of medications such as aspirin or nonsteroidal anti-inflammatory drugs or as a result of bypass surgery. Proper investigation of the causes of thrombocytopenia will iden-tify clinical situations in which platelets should be withheld because they contribute to evolution of the illness. These disorders include thrombotic microangiopathies such as thrombotic thrombocytopenic purpura, hemolytic-uremic syndrome, and the HELLP syn-drome (hemolysis, elevated liver enzymes, and a low platelet count). Platelet transfusions will not help patients with autoimmune thrombocytopenia (e.g., ITP), but they also will not harm them. (Answer: C—The prevalence of bleeding increases significantly below a threshold of about 10,000 platelets/µl in otherwise asymptomatic patients)
38. A 33-year-old white man presents with an exacerbation of Crohn disease, which is manifested by bright-red blood from the rectum; abdominal pain; and anemia. You begin therapy for exacerbation of Crohn disease, and you also order the transfusion of 2 units of red blood cells. Approximately 30 minutes after the first unit of red cells is begun, the nurse calls and says the patient has a fever and “doesn’t feel well.”
Which of the following statements regarding transfusion complications is true?
❑ A. Immediate hemolytic reactions are the result of an anamnestic response to an antigen to which the recipient is already sensitized
❑ B. Delayed hemolytic reactions occur during primary sensitization and can be as severe as immediate hemolytic reactions
❑ C. Until the cause of the hemolytic transfusion reaction is identified, the patient may only receive type O red cells or AB plasma
❑ D. Fever without signs of hemolysis can be managed with acetamino-phen; no further laboratory workup is necessary
Key Concept/Objective: To understand the potential complications of transfusions
Hemolytic transfusion reactions are classified as immediate or delayed, depending on their pathophysiology. Immediate hemolytic reactions are the result of a preexisting antibody in the recipient that was not detected during pretransfusion testing. Delayed hemolytic reactions are the result of an anamnestic response to an antigen to which the recipient is already sensitized. Clinical evidence of hemolysis is likely to be more severe in immediate hemolytic reactions and may include back pain, pain along the vein into which the blood is being transfused, changes in vital signs, evidence of acute renal failure, and signs of developing disseminated intravascular coagulation. Until the antibody causing the immune hemolysis is identified, only type O red cells and AB plasma should be used.
Febrile reactions are characterized by the development of fever during transfusion or with-in 5 hours after transfusion. The differential diagnosis for a patient undergowith-ing a non-hemolytic febrile transfusion reaction should always include unrecognized sepsis. When febrile reaction is suspected, immediate management consists of discontinuing the trans-fusion, obtaining appropriate cultures, and returning the product to the blood bank.
(Answer: C—Until the cause of the hemolytic transfusion reaction is identified, the patient may only receive type O red cells or AB plasma)
39. A 65-year-old man presents to you for preoperative workup before undergoing aortic valve replacement for aortic regurgitation (indicated because of progressive left ventricular dysfunction, as revealed on echocardiogram) and coronary artery bypass surgery. He is interested in autologous blood donation. He has had chronic stable angina for the past 2 years, which is brought on by maximal exertion; his angi-na has remained unchanged for 1 year. For the past 2 days he has had increased urgency for uriangi-nation and dysuria. On physical examination, he has a 2/4 diastolic murmur and suprapubic tenderness; oth-erwise, his examination is normal.
What absolute contraindication to autologous blood donation does this man have?
❑ A. Angina
❑ B. Aortic regurgitation
❑ C. Active bacterial infection
❑ D. Age older than 60 years
Key Concept/Objective: To know the absolute contraindications to autologous blood donation
This patient appears to have a UTI, so he cannot donate blood until that is resolved. Active bacterial infection is one of the three absolute contraindications to autologous blood dona-tion; the other two are tight aortic stenosis and unstable angina. Although this man’s sta-ble angina might temper one’s willingness to recommend autologous blood donation (especially because the risk of disease transmission in donated blood is low enough to make potential clerical error in the transfusion of autologous blood more of a concern), it is not an absolute contraindication, nor is aortic regurgitation or his age. (Answer: C—Active bacterial infection)
40. A 25-year-old woman who is 28 weeks pregnant is brought to the emergency department after an auto-mobile collision. She complains of abdominal pain; her blood pressure is 85/60; and her pulse is 130.
Normal fetal heart activity is found on fetal monitoring. Abdominal ultrasound reveals free fluid in the peritoneum.
Which of the following is the appropriate transfusion therapy for this patient?
❑ A. Whole blood
❑ B. Packed red cells
❑ C. Irradiated red cells
❑ D. Leukocyte-reduced red cells
Key Concept/Objective: To know the appropriate choice for transfusion of red cells in a pregnant woman
This question highlights the concern about transmission of cytomegalovirus (CMV) dur-ing pregnancy. Whole blood, packed red cells, and irradiated red cells all carry the risk of CMV transmission. Blood from a CMV-negative donor is another choice, but because the prevalence of CMV infection varies widely from region to region in the United States, it is not always available. Use of cellular blood components that contain fewer than 5 × 106 leukocytes is effective in preventing the transmission of CMV. (Answer: D—Leukocyte-reduced red cells)
41. A 22-year-old man with hemophilia A is going to have impacted molars extracted. He has a history of prolonged bleeding after minor surgeries.
Which of the following is the most appropriate transfusion therapy for this patient during his den-tal procedure?
❑ A. Cryoprecipitate
❑ B. Factor VIII concentrate
❑ C. Fresh frozen plasma
❑ D. Platelets
Key Concept/Objective: To know the most appropriate transfusion support therapy for a patient with hemophilia A who is undergoing surgery in which there is a possibility of major bleeding
Factor VIII concentrate is the most appropriate of the choices because its means of