10. Blood Component Therapy | Clinicians Pocket Reference, 11th Edition

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Blood Banking Procedures

T&S or T&H:

The blood bank types the patient's blood (ABO and Rh), screens for antibodies, and holds the blood. If a rare antibody is found, the physician usually is notified. If it is likely that blood will be needed, the T&S order may be changed to a T&C.

T&C:

The blood bank does a T&S on the patient's blood and matches specific donor units to the patient. The cross-match involves testing the recipient's serum against donor blood cells. A T&C usually takes less than 1 h.

Stat Requests:

The bank sets up blood immediately and usually holds it for 12 h. For routine requests, the blood is set up at a date and time that you specify and usually held for 36 h.

Routine Blood Donation

Voluntary blood donation is the mainstay of the blood system in the United States. Donors usually are > 18 y old, are in good health and afebrile, and weigh > 110 lb (50 kg). Donors are usually limited to 1 unit every 8 wk and 6 donations per year. Patients with a history of hepatitis, HBsAg positivity, insulin-dependent DM, IV drug abuse, heart disease, anemia, or homosexual activity are excluded from routine donation. Patients who may have transmissible diseases are counseled about high-risk behaviors that may put the recipient of the blood at risk. Donor blood is tested for ABO, Rh, antibody screen, HBsAg, anti hepatitis B core antigen, hepatitis C antibody, anti HIV-1 and -2, and anti HTLV-1 and -2.

Autologous Blood Donation

Some patients undergoing elective surgery in which blood may be needed use preadmission autologous blood banking (predeposit phlebotomy). General guidelines for autologous banking include good overall health, HCT > 34%, and arm veins that can accommodate a 16-gauge needle. Patients can usually donate up to 1 unit every 3 7 d until 3 7 d before surgery (individual blood banks have their own specifications), depending on the needs of the planned surgical procedure. Iron supplements (eg, ferrous gluconate 325 mg PO tid) are usually given before and for several months after the donation. The use of erythropoietin in this preoperative setting is being investigated. Units of whole blood can be held for up to 35 d.

Donor-Directed Blood Products

A relative or friend can donate blood for a specific patient. This technique cannot be used in the emergency setting because it takes up to 48 h to process the blood for use.

This system has some drawbacks: Relatives may be unduly pressured to give blood; risk factors that would normally exclude the use of the blood (hepatitis or HIV positivity) become problematic; and the routine donation of blood for emergency transfusion may be adversely affected. These units are usually stored as PRBC and released into the general transfusion pool 8 h after surgery unless otherwise requested.

Irradiated Blood Components

Transfusion-associated graft-versus-host disease (GVHD), a frequently fatal condition, can be minimized through the use of highly selected irradiated blood components. Patients who are at risk of GVHD include recipients of donor-directed units or HLA-matched platelets, fetuses receiving intrauterine transfusions, and selected immunocompromised and bone marrow recipients.

Apheresis

Apheresis procedures are used to collect single-donor platelets (plateletpheresis) or WBC (leukapheresis); the remaining components are returned to the donor. Therapeutic apheresis is the separation and removal of a particular component to achieve a therapeutic effect (eg, erythrocytapheresis to treat polycythemia).

Preoperative Blood Set-Up

Most institutions have established protocols for setting up blood before surgical procedures. A number of units of PRBC or only a T&S may be needed depending on the procedure. Check with the surgeon.

Emergency Transfusions

Non-cross-matched blood is rarely transfused because most blood banks can do a complete cross-match within 1 h. In cases of massive, exsanguinating hemorrhage, type-specific blood (ABO- and Rh-matched only), usually available in 10 min, can be used. If even this delay is too long, type O, Rh-negative PRBC can be used as a last resort. When possible, it is generally preferable to support BP with colloid or crystalloid until properly cross-matched blood is available.

Blood Groups

Table 10 1 gives information on the major blood groups and their relative occurrences. Type O is the "universal donor," and AB+ is the "universal recipient."

Table 10 1 Blood Groups and Guidelines for Transfusion

Type (ABO/Rh)	Occurrences	Can Usually Receive^a Blood From
O+	1 in 3	O (+/ )
O	1 in 15	O ( )
A+	1 in 3	A (+/ ) or O (+/ )
A	1 in 16	A ( ) or O ( )
B+	1 in 12	B (+/ ) or O (+/ )
B	1 in 67	B ( ) or O ( )
AB+	1 in 29	AB, A, B, or O (all + or )
AB	1 in 167	AB, A, B, or O (all )

^aFirst choice is always the identical blood type; other acceptable combinations are shown. An attempt is also made to match Rh status of donor and recipient; Rh can usually be given to an Rh+ recipient safely.

Basic Principles of Blood Component Therapy

Table 10 2 shows common indications for and uses of transfusion products. The following are the basic transfusion principles for adults.

Table 10 2 Blood Bank Products

Product	Description	Common Indications
Whole Blood	No elements removed 1 unit = 450 mL 45 mL (HCT 40%) Contains RBC, WBC, plasma and platelets (WBC & platelets may be nonfunctional) Deficient in factors V & VII	Not for routine use Acute, massive bleeding Open heart surgery Neonatal total exchange
Packed Red Cells (PRBC)	Most plasma, WBC, platelets removed; unit = 250 300 mL. (HCT 75%) 1 unit should raise HCT 3%	Replacement in chronic and acute blood loss, GI bleeding, trauma
Universal Pedi-Packs	250 300 mL divided into 3 bags Contains red cells, some white cells, some plasma and platelets	Transfusion of infants
Leukocyte-Poor (Leukocyte-Reduced) Red Cells	Most WBC removed by filtration to make it less antigenic <5 x 10⁶ WBC, few platelets, minimal plasma 1 unit = 200 250 mL	Potential renal transplant patients Previous febrile transfusion reactions Patients requiring multiple transfusions (leukemia, etc)
Washed RBCs	Like leukocyte-poor red cells, but WBC almost completely removed <5 x 10⁸ WBC, no plasma 1 unit = 300 mL	As for leukocyte-poor red cells, but very expensive and much more purified
Granulocytes, Pheresis	1 unit = 220 mL Some RBC, >1 x 10¹⁰ PMN/unit, Lymphocytes, platelets	See Apheresis
Platelets	1 "pack" should raise count by 5000 8000 "6-pack" means a pool of platelets from 6 units of blood 1 pack = about 50 mL >5 x 10¹⁰ platelets unit, contains RBC, WBC	Decreased production or destruction (aplastic anemia, acute leukemia, postchemo, etc) Counts <5000 10,000 (risk of spontaneous hemorrhage) must transfuse Counts 10,000 30,000 if risk of bleeding (headache, GI losses, contiguous petechiae) or active bleeding Counts <50,000 if life-threatening bleed Prophylactic transfusion >20,000 for minor surgery or >50,000 for major surgery Usually not indicated in ITP or TTP unless life-threatening bleeding or preoperative status
Platelets, Pheresis	>3 x 10¹⁰ platelets/unit 1 unit = 300 mL	See Platelets, may be HLA matched
Platelets, Leukocyte-Reduced	As above, but <5 x 10⁶ WBC/unit	See Platelets, may decrease febrile reactions and CMV transmission, alloimmunization to HLA antigens
Cryoprecipitated Antihemophilic Factor ("Cryo")	Contains factor VIII, factor XIII, von Willebrand factor, and fibrinogen 1 unit = 10 mL	Hemophilia A (factor VIII deficiency), when safer factor VIII concentrate not available; von Willebrand disease, fibrinogen deficiency, fibrin surgical glue
Fresh-Frozen Plasma (FFP)	Contains factors II, VII, IX, X, XI, XII, XIII, and heat-labile V and VII About 1 h to thaw 150 250 mL (400 600 mL if single-donor pheresis)	Emergency reversal of warfarin Massive transfusion (>5 L in adults) Hypoglobulinemia (IV immune globulin preferred) Suspected or documented coagulopathy (congenital or acquired) with active bleeding or before surgery) Clotting factor replacement when concentrate unavailable Not recommended for volume replacement If PT <22 s or PTT <70 s, 1 unit is usually sufficient
Single Donor Plasma	Like FFP, but lacks factors V and VIII About 1 h to thaw; 150 200 mL	No longer routinely used for plasma replacement Stable clotting factor replacement Warfarin reversal, hemophilia B (Christmas disease)
Rho Gam (Rho D immune globulin)	Antibody against Rh factor (volume = 1 mL)	Rh mother with Rh+ baby, within 72 h of delivery, to prevent hemolytic disease of newborn; autoimmune thrombocytopenia
All of the aforementioned items usually require a "clot tube" to be sent for typing. The following products are usually dispensed by most hospital pharmacies and are usually ordered as a medication.
Factor VIII (Purified Antihemophilic Factor)	From pooled plasma, pure factor VIII Increased hepatitis risk	Routine for hemophilia A (factor VIII deficiency)
Factor IX Concentrate (Prothrombin Complex)	Increased hepatitis risk Factors II, VII, IX, and X Equivalent to 2 units of plasma	Active bleeding in Christmas disease (hemophilia B or factor IX deficiency)
Immune Serum Globulin	Precipitate from plasma "gamma globulin"	Immune globulin deficiency Disease prophylaxis (hepatitis A, measles, etc)
5% Albumin or 5% Plasma Protein Fraction	Precipitate from plasma (see Drugs, Chapter 22)	Plasma volume expanders in acute blood loss
25% Albumin	Precipitate from plasma	Hypoalbuminemia, volume expander, burns Draws extravascular fluid into circulation

RBC = red blood cells; WBC = white blood cells; HCT = hematocrit; GI = gastrointestinal; ITP = idiopathic thrombocytopenic purpura; TTP = thrombotic thrombocytopenic purpura; HLA = histocompatibility locus antigen; PT = prothrombin time; PTT = partial thromboplastin time.

Red Cell Transfusions

Acute Blood Loss:

Healthy persons can usually tolerate up to 30% blood loss without transfusion. Patients may manifest tachycardia and mild hypotension without evidence of hypovolemic shock. Start volume replacement (IV fluids, etc).

Hgb > 10 g/dL, transfusion rarely indicated.
Hgb 7 10 g/dL, transfusion based on clinical symptoms, unless patient has severe medical problems (eg, CAD, severe COPD).
Hgb < 7 g/dL, transfusion usually needed.

"Allowable Blood Loss":

Often used to guide acute transfusion in the operating room. Losses less than allowable are usually managed with IV fluid replacement.

Weight in kg x 0.08 = Total blood volume

Total volume x 0.3 = Allowable blood loss (assumes normal Hbg)

Example: A 70-kg adult

Estimated allowable blood loss = 70 x 0.08 = 5.6L or (5600 mL) x 0.3 = 1680 mL

Chronic Anemia:

Common in certain chronic conditions, such as renal failure, rarely managed with blood transfusion; typically managed with pharmacologic therapy (eg, erythropoietin). However, transfusion is generally indicated if Hgb < 6 g/dL or in the face of symptoms due to low hemoglobin.

RBC Transfusion Formula:

As a guide, 1 unit of PRBC raises the HCT 3% (Hgb, 1 g/dL) in the average adult. To roughly determine the volume of whole blood or PRBC needed to raise the HCT to a known amount, use the following formula:

where total blood volume is 70 mL/kg in adults, 80 mL/kg in children. The HCT of PRBC is approximately 70%, and that of whole blood is approximately 40%.

White Cell Transfusions

The use of white cell transfusions is rarely indicated because genetically engineered myeloid growth factors such as GM-CSF (see Chapter 22) are used instead.
Indicated for patients being treated for overwhelming sepsis and severe neutropenia (< 500 PMN/L)

Platelet Transfusions

Indications are in Table 10 2.

Platelet Transfusion Formula:

Platelets are often transfused at a dose of 1 unit/10 kg of body weight. After administration of 1 unit of multiple-donor platelets, the count should rise 5000 8000/mm³ within 1 h of transfusion and 4500 mm³ within 24 h. Under normal circumstances, stored platelets that are transfused survive in vivo 6 8 d after infusion. Clinical factors (eg, DIC, alloimmunization) can significantly shorten this time. To standardize the corrected platelet count to an individual patient, use the corrected count increment (CCI). Measure the platelet count immediately before and 1 h after platelet infusion. If the correction is less than expected, do a work-up to determine the possible cause (eg, antibodies, splenomegaly). Many institutions use platelet pheresis units. One platelet pheresis unit has enough platelets to raise the count 6000 8000/mm³. Using a single unit has the advantage of exposing the patient to only one donor versus possibly six to eight donors. This practice limits exposure to different HLA antigens, reducing the risk of antiplatelet antibody production, and also reduces the risk of infection transmission.

Blood Bank Products

Table 10 2 shows products used in blood component therapy and gives recommendations for use of these products.

Transfusion Procedures

1. Draw a clot tube (red top), and sign the lab slips to verify that the sample came from the correct patient. Identify the patient by referring to the ID bracelet and asking the patient to state, if able, his or her name. Place the patient's name, hospital number, date, and your signature on the tube label. Prestamped labels are not accepted by most blood banks.

2. Obtain the patient's informed consent by discussing the reasons for the transfusion and the potential risks and benefits of it. Follow hospital procedure regarding the need for the patient to sign a specific consent form. At most hospitals, chart documentation is usually all that is necessary.

3. When the blood products become available, ensure good venous access for the transfusion (18-gauge needle or larger is preferred for adults).

4. Verify the information on the request slip and blood bag with another person, such as a nurse, and with the patient's ID bracelet. Many hospitals have defined protocols for this procedure; check your institutional guidelines.

5. Mix blood products to be transfused with isotonic (0.9%) NS only. Using hypotonic products such as D₅W can result in hemolysis of the blood in the tubing. Lactated Ringer solution should not be used because the calcium can chelate the anticoagulant citrate.

6. Infuse red cells through a special filter. Specific leukocyte reduction filters can be used in highly specific circumstances (history of febrile transfusion reactions, need to reduce potential CMV transmission, need to reduce risk of alloimmunization to WBC antigens).

7. When transfusing large volumes of PRBC (> 10 units), monitor coagulation, Mg²⁺, Ca²⁺, and lactate levels. It also usually is necessary to transfuse platelets and FFP. Calcium replacement is sometimes needed because the preservative used in the blood is a calcium binder, and hypocalcemia can occur after large amounts of blood are transfused. For massive transfusions (usually > 50 mL/min in adults and 15 mL/min in children), warm the blood to prevent hypothermia and cardiac arrhythmia.

Transfusion Reactions

1. Acute intravascular hemolysis (1/240,000 760,000 units transfused) More than 85% of adverse hemolytic reactions involving the transfusion of RBC result from clerical error. Usually caused by ABO-incompatible transfusion. Can result in renal failure.

2. Nonhemolytic febrile reaction (~2 3/100 units transfused) Usually mild, fever, chills, rigors, mild dyspnea. Due to a reaction to donor white cells (HLA) and more common in patients who have received multiple transfusions or delivered several children.

3. Mild allergic reaction (~1/100 units transfused) Urticaria or pruritus can be caused by sensitization to plasma proteins in transfusion product.

4. Anaphylactic reaction (1/150,000 units transfused) Acute hypotension, hives, abdominal pain and respiratory distress; seen mostly in IgA-deficient recipients.

5. Sepsis (< 1/500,000 RBC units transfused, 1/12,000 platelet units transfused) Usually caused by transfusion of a bacterially infected transfusion product, with platelet transfusions having the greatest risk. Escherichia coli, Pseudomonas, Serratia, Salmonella, and Yersinia are the more commonly implicated bacteria.

6. Acute lung injury (1/10,000 units transfused) Fever, chills, and life-threatening respiratory failure; probably induced by antibodies from donor against recipient white cells.

7. Volume overload (1/100 units transfused) Usually due to excess volume infusion; can exacerbate CHF.

Detection of Transfusion Reaction

1. Spin an HCT to look for a pink plasma layer (indicates hemolysis).

2. Order serum for free Hgb and haptoglobin (haptoglobin decreases with a reaction) and urine for hemosiderin levels. Obtain a stat CBC to determine the presence of schistocytes, suggesting a transfusion reaction.

3. If acute hemolysis is suspected, request a DIC screen (PT, PTT, fibrinogen, and fibrin degradation products).

Treatment of Transfusion Reactions

1. Stop the blood product immediately, and notify the blood bank.

2. Keep the IV line open with NS, and monitor the patient's vital signs and urine output carefully.

3. Save the blood bag, and have the lab verify the T&C. Verify that the proper patient received the proper transfusion. Redraw blood samples for the blood bank.

4. Treat the patient using the following guidelines and clinical judgment:

Nonhemolytic febrile reaction: Use antipyretics and continue transfusion monitoring. Use leukocyte-washed transfusion products in the future.
Mild allergic reaction: After giving diphenhydramine (25 50 mg IM/PO/IV) resume the transfusion only if the patient improves promptly.
Anaphylactic reaction: Terminate transfusion, monitor closely, give antihistamines (diphenhydramine 25 50 mg IM/PO/IV), corticosteroids (methylprednisolone 125 mg IV, 2 mg/kg pediatric IV), epinephrine (1:1000 0.3 0.5 mL SQ adults, 0.1 mL/kg pediatric), and pressors as needed. Premedicate (antihistamines, steroids) for future transfusions; use only leukocyte-washed red cells.
Acute lung injury: Provide ventilatory support as needed; use only leukocyte-washed red cells for future transfusions.
Sepsis: Culture the transfusion product and the patient; treat empirically by monitoring and administering pressors and antibiotics (third- or fourth-generation cephalosporin or piperacillin/tazobactam along with an aminoglycoside) until cultures are returned.
Volume overload: Use a slow rate of infusion with selective use of diuretics.
Acute intravascular hemolysis: Prevent acute renal failure. Place a Foley catheter, monitor urine output closely, and maintain brisk diuresis with plain D₅W, mannitol (1 2 g/kg IV), furosemide (20 40 mg IV), and/or dopamine (2 10 mcg/kg/min IV) as needed. Alkalize the urine with bicarbonate and pressure support (fluids, vasopressors). Monitor for DIC. Request renal and hematologic consults.

Transfusion-Associated Infectious Disease Risk

For perspective, selected comparative mortality odds ratios are: stroke 1/1,700; pregnancy 1/4,350 1/10,000; MVA 1/6,700; anesthesia 1/7,000 1/339,450; oral contraceptive use 1/50,000; flood 1/455,000; lightning strike 1/10,000,000. (Transfusion 2005;45:254 264; http://www.pathology.unc.edu/labs/textfiles/tms_risk.htm [Accessed May 30, 2006])

Hepatitis

One case of posttransfusion hepatitis B occurs for every 205,000 488,000 units transfused; the incidence of hepatitis C is 1/1,8000,000 units transfused. Anicteric hepatitis is more common than hepatitis with jaundice. Donor screening has greatly reduced hepatitis risk. Pooled factor products (concentrates of factor VIII) are associated with the greatest risk; albumin and globulins carry no risk of hepatitis.

HIV

The incidence of transfusion-related HIV infection is 1/2,3000,000 units. Antibody testing is routinely performed on the donor's blood; a positive antibody test means that the donor may have HIV infection; a confirmatory Western blot is necessary. Do a follow-up test on any donor found to be HIV-positive, because false-positives can occur. There is a delay of approximately 22 d between HIV exposure and the development of HIV antibodies. Risk of HIV transmission exists even when HIV-negative donor blood is used. Use of molecular detection decreases the time between infection and detection from 22 d to 11 d.

CMV

The prevalence of CMV infection among donors is very high (approaching 100% in many series). CMV infection represents a major clinical risk mostly for immunocompromised recipients and neonates. Leukocyte filters can reduce the risk of transmission.

HTLV-I, -II

Very rare (1/514,000 2,993,000 units transfused). Use of leukocyte filters can further decrease risk of transmission.

Bacteria, Parasites, and Other Viruses

Sepsis caused by bacteria is rare (see Transfusion Reactions). Parasites are very rarely transmitted (< 1/1,000,000 units) for yersiniosis, malaria, babesiosis, and Chagas disease, but careful donor screening is necessary, especially in endemic regions. West Nile virus cases are limited but have been reported.