Lippincott's Anesthesia Review: 1001 Questions and Answers

Chapter 5. Fluid Management and Blood Transfusion

Rebecca Kalman and Edward Bittner

    1.   All of the following are signs of dehydration, except

          A.   Progressive metabolic acidosis

          B.   Urinary specific gravity > 1.010

          C.   Urine osmolality < 300 mOsm/kg

          D.   Urine sodium < 10 mEq/L

    2.   Regarding central venous pressure (CVP) monitoring

          A.   Low values of <5 mm Hg may be considered normal in the absence of other signs of hypovolemia

          B.   CVP readings can be interpreted independently of the clinical setting

          C.   CVP monitoring is never indicated in patients with normal cardiac and pulmonary function

          D.   In a patient with right ventricular dysfunction, a CVP of 10 mm Hg should be considered elevated

    3.   In healthy patients, the lactate in lactated Ringer solution

          A.   Causes a lactic acidosis

          B.   Is converted to bicarbonate by the liver

          C.   Is rapidly bound by albumin

          D.   Causes a hyperchloremic metabolic acidosis

    4.   All of the following fluids are generally considered to be isotonic, except

          A.   Lactated Ringer

          B.   Normal saline

          C.   D5 normal saline

          D.   D5¼ normal saline

    5.   All of the following statements regarding dextran solutions are true, except

          A.   Dextran 40 may improve blood flow through the microcirculation

          B.   Dextrans may have antiplatelet effects

          C.   Large-volume infusions of dextrans have been associated with renal failure

          D.   Dextran 40 is a better volume expander than dextran 70

    6.   Which of the following statements is true regarding fluid loss?

          A.   Substantial evaporative losses can be associated with large wounds and are directly proportionate to the surface area exposed

          B.   Internal redistribution of fluids, “third spacing,” cannot cause massive fluid shifts

          C.   Traumatized, inflamed, or infected tissues can only sequester minimal amounts of fluid in the interstitial space

          D.   Cellular dysfunction as a result of hypoxia usually produces a decrease in intracellular fluid volume

    7.   The probability of developing anti-D antibodies after a single exposure to the Rh antigen is

          A.   <1%

          B.   5% to 10%

          C.   50% to 70%

          D.   >80%

    8.   In a conventional crossmatch

          A.   Donor cells are mixed with recipient serum

          B.   Recipient cells are mixed with donor serum

          C.   Donor serum is tested against red cells of known antigenic composition

          D.   None of the above

    9.   A leftward shift of the oxyhemoglobin dissociation curve may be related to

          A.   Low levels of 2,3-DPG in packed red blood cells

          B.   Hypothermia resulting from transfusion of blood

          C.   Both A and B

          D.   None of the above

  10.   Which of the following statements regarding fresh-frozen plasma (FFP) is correct?

          A.   Contains all of the clotting factors except factor VIII

          B.   Should not be used in patients with antithrombin III deficiency

          C.   Carries the same infection risk as a unit of whole blood

          D.   Is contraindicated in the case of isolated-factor deficiencies

  11.   The most common cause of an acute hemolytic transfusion reaction is

          A.   An error during type and screen

          B.   An error during type and crossmatch

          C.   Misidentification of the patient, blood specimen, or transfusion unit

          D.   Defective blood filter

  12.   Evidence for the fact that leukocyte-containing blood products appear to be immunosuppressive includes all of the following, except

          A.   Preoperative blood transfusions appear to improve graft survival in renal transplant patients

          B.   Recurrence of malignant growths may be more likely in patients who receive a blood transfusion during surgery

          C.   Transfusion of allogeneic leukocytes can activate latent viruses in a recipient

          D.   Blood transfusion may decrease the incidence of serious infection following surgery or trauma

  13.   Bacterial infection due to a contaminated blood product is most likely with transfusion of

          A.   Packed red blood cells

          B.   Fresh-frozen plasma

          C.   Platelets

          D.   Cryoprecipitate

  14.   All of the following qualities are advantages of crystalloid solutions, except

          A.   Nontoxic

          B.   Reaction-free

          C.   Relatively inexpensive

          D.   Have the ability to remain in the intravascular space for a relatively long amount of time

  15.   Administration of large volumes of normal saline can lead to

          A.   A metabolic alkalosis

          B.   A hyperchloremic-induced nongap metabolic acidosis

          C.   An anion gap lactic acidosis

          D.   None of the above

  16.   All of the following solutions contain potassium, except

          A.   Lactated Ringer solution

          B.   PlasmaLyte

          C.   Hespan

          D.   Packed red blood cells

  17.   The storage time for packed red blood cells at temperatures of 1 to 6°C is

          A.   7 to 10 days

          B.   21 to 35 days

          C.   60 to 80 days

          D.   120 days

  18.   Which of the following statements regarding transfusion of packed red blood cells is most correct?

          A.   The hematocrit of 1 unit is usually 30% to 40%

          B.   Transfusion of a single unit will increase an adult’s hemoglobin concentration about 4 g/dL

          C.   May cause clotting if the transfused packed red blood cells are mixed with lactated Ringer solution

          D.   Their principle use as that of a volume expander

  19.   Blood products are tested for all of the following, except

          A.   Hepatitis C

          B.   HIV

          C.   West Nile virus

          D.   Herpes virus

  20.   Regarding assessment of surgical blood loss

          A.   Both surgeons and anesthesiologists tend to underestimate blood loss

          B.   Measurement of blood in the surgical suction container is all that is necessary to estimate blood loss

          C.   The use of irrigating solutions does not complicate assessment of blood loss

          D.   A soaked “lap” pad can hold 10 to 15 mL of blood

  21.   The most common nonhemolytic reaction to transfusion of blood products is

          A.   Allergic

          B.   Febrile

          C.   Anaphylactoid

          D.   Urticarial

  22.   Types of autologous blood transfusion include all of the following, except

          A.   Predeposited donation

          B.   Intraoperative blood salvage

          C.   Normovolemic hemodilution

          D.   Donor-directed transfusion

  23.   A patient with type O blood will have which of the following plasma antibodies?

          A.   Anti-A

          B.   Anti-B

          C.   Both anti-A and anti-B

          D.   None

  24.   After blood is collected, the preservative CPDA-1 is commonly added. This contains all of the following, except

          A.   Citrate

          B.   Phosphate

          C.   Dextrose

          D.   Potassium

  25.   A 51-year-old patient was an unrestrained driver in a motor vehicle crash in which he sustained multiple traumatic injuries. He is on mechanical ventilation, and has received 8 units of packed red blood cells, 4 units of fresh-frozen plasma, and 6 units of platelets. His arterial blood gas reveals a metabolic alkalosis. The most likely explanation for this finding is

          A.   Metabolism of citrate to bicarbonate

          B.   Under-resuscitation

          C.   Continued bleeding

          D.   Hypoventilation

  26.   A 70-year-old patient with chronic renal failure is in the operating room undergoing a kidney transplant. There has been more blood loss than expected, and he has received 6 units of packed red blood cells and 3 units of fresh-frozen plasma. The surgeons still complain that the patient “won’t clot.” All of the following are potential contributors to his coagulopathy, except

          A.   Temperature of 34.9°C

          B.   Uremia

          C.   Dilutional thrombocytopenia

          D.   Fibrinogen level of 250 mg/dL

  27.   The estimated maintenance fluid requirement for a 9-year-old, 35-kg patient is

          A.   50 mL/h

          B.   75 mL/h

          C.   100 mL/h

          D.   20 mL/h

  28.   Which of the following patients is least likely to need calcium supplementation due to citrate-induced hypocalcemia related to blood transfusion?

          A.   A 30-year-old trauma patient receiving massive blood transfusion through a rapid transfuser at a rate of 75 mL/min

          B.   A patient with end-stage liver disease undergoing a complicated open shunt procedure, who is hypothermic and has received greater than 2 blood volumes of transfusion

          C.   A neonate undergoing congenital diaphragmatic hernia repair

          D.   A 50-year-old patient with coronary artery disease undergoing an open femoral popliteal bypass procedure, who has received 3 units of packed red blood cells

  29.   A medical student asks you if “young” blood is better for critically ill patients. Which of the following statements regarding “young” blood is most correct?

          A.   Fresher blood has better ability to deliver oxygen to tissues

          B.   Blood from younger donors has lower risk of immunosuppression than blood donated by the elderly

          C.   Older blood has a lower potassium content

          D.   Fresher blood can be transfused more rapidly than older blood

  30.   You are caring for an 18-year-old female trauma patient who was emergently transported to the operating room for control of massive bleeding. Due to the acuteness of the patient’s bleeding, there was no time for blood typing and she has received 3 units of O-negative packed red blood cells. The blood bank notifies you that the patient’s blood type is A-positive. If the patient requires further transfusion, which of the following should be administered?

          A.   A-positive RBCs

          B.   A-negative RBCs

          C.   O-negative RBCs

          D.   RhoGAM

CHAPTER 5 ANSWERS

    1.   C.   When dehydrated, patients with normal renal function will retain sodium and produce a concentrated urine. Urine osmolality is typically greater than 450 mOsm/kg in this setting. Urine sodium will be low, and specific gravity will be high.

    2.   A.   CVP measurements must be evaluated in context of the clinical setting. Factors such as underlying cardiopulmonary disease, patient position, and anatomy can affect the values. A CVP of <5 mm Hg can be normal in a healthy patient without signs of hypovolemia. For surgical cases during which large fluid shifts are expected, placement of a CVP monitor may be indicated. Patients with compromised right ventricular function generally have high CVPs, and thus, a CVP of 10 mm Hg should be considered normal to low depending on the degree of dysfunction.

    3.   B.   In healthy patients the lactate in lactated Ringers solution is rapidly converted to bicarbonate by the liver and does not cause a lactic acidosis. Administration of a large volume of normal saline can cause a hyperchloremic metabolic acidosis. Lactate is not bound by albumin.

    4.   C.   An intravenous solution’s effect on fluid movement depends in part on its tonicity. This term is sometimes used interchangeably with osmolarity, although they are subtly different. Osmolarity is the number of osmoles or moles of solute per liter of solution. Tonicity is the effective osmolality and is equal to the sum of the concentrations of the solutes which have the capacity to exert an osmotic force across the membrane. A solution is isotonic if its tonicity falls within (or near) the normal range for blood serum—from 275 to 295 mOsm/kg. A hypotonic solution has lower osmolarity (<250), and a hypertonic solution has higher osmolarity (>350) (Table 5-1).

Table 5-1 Osmolarity and tonicity of commonly used crystalloid solutions

Fluid

Mosm/L

Tonicity

Lactated Ringers

273

Isotonic

Normal saline

305

Isotonic

D5 normal saline

586

Hypertonic

D5¼ normal saline

355

Isotonic

    5.   D.   While dextran 40 has a molecular weight of 40,000, dextran 70 has a molecular weight of 70,000, and therefore, the latter is broken down more slowly, lasts longer, and is a better volume expander. Dextran 40 appears to improve blood flow through the microcirculation, and all dextrans may have antiplatelet effects. Infusion of large volume of dextran (>20 mL/kg/day) has been associated with renal failure.

    6.   A.   Substantial evaporative losses can be associated with large wounds and are directly proportionate to the surface area exposed. Third spacing can cause massive fluid shifts, and traumatized, inflamed, or infected tissue can sequester large amounts of fluid. Cellular dysfunction as a result of hypoxia usually produces an increase in intracellular fluid volume.

    7.   C.   The Rh blood group is second in importance only to the ABO blood group in the field of transfusion medicine. It has remained of primary importance in obstetrics, being the main cause of hemolytic disease of the newborn. The significance of the Rh blood group is related to the fact that the Rh antigen (D antigen) is highly immunogenic. In the case of the D antigen, individuals who do not produce the D antigen will produce anti-D if they encounter the D antigen when transfused with RBCs (causing a hemolytic transfusion reaction). For this reason, the Rh status is routinely determined in blood donors, transfusion recipients, and mothers-to-be.

    8.   A.   A crossmatch mimics a transfusion, where donor cells are mixed with the recipient’s serum. This has three purposes: (1) confirms ABO/Rh typing, (2) detects recipient antibodies to other blood group systems, and (3) detects antibodies in low titers or those that do not agglutinate easily. Choice C describes an antibody screen.

    9.   C.   The level of 2,3-DPG in stored blood is reduced, causing decreased oxygen unloading to the tissues. Hypothermia also causes a leftward shift of the oxyhemoglobin dissociation curve (Fig. 5-1).

images

Figure 5-1.

  10.   C.   FFP is the fluid portion obtained from a single unit of whole blood that is frozen within 6 hours of collection. All coagulation factors, except platelets, are present in FFP, which explains the use of this component in the treatment of hemorrhage. FFP is also indicated in antithrombin III deficiency and isolated-factor deficiencies. A transfusion of FFP carries the same risk of infection as transfusing a whole blood.

  11.   C.   Hemolytic reactions occur when the wrong blood type is administered to a patient. The immediate signs of acute hemolytic transfusion reactions include lumbar and substernal pain, fever, chills, dyspnea, flushing of the skin, and hypotension. The appearance of free hemoglobin in plasma or urine is presumptive evidence of a hemolytic reaction. Acute renal failure reflects precipitation of stromal and lipid contents (not free hemoglobin) of hemolyzed erythrocytes in distal renal tubules. Acute hemolytic transfusion reactions are usually due to ABO blood incompatibility, and the most common cause is misidentification of the patient, blood specimen, or transfusion unit (clerical error).

  12.   D.   Blood transfusion suppresses cell-mediated immunity, which may place surgical patients at risk for postoperative infection. The association with long-term prognosis in cancer surgery is unclear, but there is a suggestion of a correlation between tumor recurrence and blood transfusions. Removing most of the white blood cells from blood and platelets (leukoreduction) reduces the incidence of nonhemolytic febrile transfusion reactions and the transmission of leukocyte-associated viruses. Preoperative blood transfusions appear to improve graft survival in renal transplant patients.

  13.   C.   One of the leading causes of transfusion-related fatalities in the United States is bacterial contamination, which is most likely to occur in platelet concentrates. Platelet-related sepsis can be fatal and occurs as frequently as 1 in 5,000 transfusions. Platelets are stored at 20 to 24°C instead of 4°C, which probably accounts for the greater risk of bacterial growth than with other blood products. Any patient in whom a fever develops within 6 hours of receiving platelet concentrates should be considered to be possibly manifesting platelet-induced sepsis, and empirical antibiotic therapy should be instituted.

  14.   D.   Advantages of crystalloid solutions are that they are nontoxic, reaction-free, and inexpensive. Colloid solutions are composed of large-molecular-weight substances that remain in the intravascular space longer than crystalloids, and typically, the initial volume of distribution is equivalent to the plasma volume. The synthetic colloids and processed albumin have minimal or no risks of infection. Colloids are more expensive than crystalloids, but have fewer risks than blood products.

  15.   B.   Normal saline (0.9% NaCl) is slightly hypertonic and contains more chloride than extracellular fluid. Administration of large volumes of normal saline solution can lead to a hyperchloremic non–anion gap metabolic acidosis. Administration of large amounts of lactated Ringer solution may result in a metabolic alkalosis because of increased bicarbonate production from the metabolism of lactate.

  16.   C.   Hespan is colloid containing starch and saline. All of the other options contain potassium. Many patients with hyperkalemia, including patients with renal failure, routinely receive normal saline because it contains no potassium.

  17.   B.   The storage time (70% viability of transfused erythrocytes 24 hours after transfusion) is 21 to 35 days, depending on the storage medium. Changes that occur in blood during storage reflect the length of storage and the type of preservative used.

  18.   C.   Mixing of packed red blood cells with lactated Ringer solution can cause clotting as the citrate in the blood product can bind with calcium in the lactated Ringer. The other options are all false. The hematocrit of 1 unit of packed red blood cells is 70% to 80%. Transfusion of a single unit will increase an adult’s hemoglobin concentration by about 1 g/dL. The objective in transfusion of packed red blood cells is to increase the blood’s oxygen-carrying capacity. Although transfusion of packed red blood cells increases intravascular fluid volume, they should not be used routinely for this purpose given the risks associated with transfusion.

  19.   D.   The incidence of infection from blood transfusions has markedly decreased. Although many factors account for the marked decreased incidence of transmission of infectious agents via blood transfusion, the most important one is improved methods for testing of donor blood. Currently, hepatitis C, HIV, and West Nile virus are tested by nucleic acid technology.

  20.   A.   Both surgeons and anesthesiologists tend to underestimate blood loss. Measurement of blood in the surgical suction container is only one component of estimating blood loss. Blood lost in sponges, “lap” pads, and occult bleeding under the drapes must be accounted for. The use of irrigating solutions often complicates the assessment of blood loss. A soaked “lap” pad can hold up to 100 to 150 mL of blood.

  21.   B.   Febrile reactions are the most common adverse nonhemolytic reaction and occur with 0.5% to 1% of transfusions. The most likely cause is an interaction between the recipient’s antibodies and the antigen present on the leukocytes of platelets of the donor. The patient’s temperature rarely increases 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.

  22.   D.   A directed (or designated) blood donation is one in which a patient selects his/her own blood donor(s) for an anticipated, nonemergency transfusion. The donor is typically a friend or relative to the patient. Patients undergoing elective procedures with a high probability of blood transfusion can donate their own blood 4 to 5 weeks prior to surgery, and this is referred to as a predeposited donation. Blood salvage refers to the collection of shed blood intraoperatively, which is then concentrated, washed, and transfused back to the patient. For normovolemic hemodilution, blood is removed just prior to surgery and replaced with crystalloid or colloid. The blood is stored for up to 6 hours, and then be given back to the patient after blood loss.

  23.   C.   Routine typing of blood is performed to identify the antigens (A, B, Rh) on the membranes of erythrocytes. Naturally-occurring antibodies (anti-B, anti-A) are formed whenever erythrocyte membranes lack A or B antigens (or both). These antibodies are capable of causing rapid intravascular destruction of erythrocytes that contain the corresponding antigens.

  24.   D.   CPDA-1 is the most commonly added preservative added to blood products. It contains citrate as an anticoagulant, phosphate as a buffer, dextrose as a red blood cell energy source, and adenine needed for the maintenance of red cell ATP levels. The potassium found in blood comes from the breakdown of red blood cells.

  25.   A.   The citrate in the blood preservative is metabolized to bicarbonate by the liver and can cause a metabolic alkalosis following a large-volume transfusion. Under-resuscitation and bleeding are likely to cause a metabolic acidosis, whereas hypoventilation causes a respiratory acidosis.

  26.   D.   Hypothermia, uremia, and dilution from massive transfusion are all potential reasons for coagulopathy in this patient. A fibrinogen greater than 150 mg/dL should be adequate for clotting.

  27.   B.   According to the “4-2-1 rule,” 75 mL/h would be the maintenance rate. This is calculated as 40 + 20 + 15 = 75 mL/h (Table 5-2).

Table 5-2 Formula for calculation of maintenance fluid requirement

Weight up to 10 kg

4 mL/kg/h

11–20 kg

Add 2 mL/kg/h

21 kg and above

Add 1 mL/kg/h

  28.   D.   Hypocalcemia as a result of citrate binding of calcium is rare because of mobilization of calcium stores from the bone, and the ability of the liver to rapidly metabolize citrate to bicarbonate. Therefore, arbitrary administration of calcium in the absence of objective evidence of hypocalcemia is not indicated. 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.

  29.   A.   Fresher blood (<5 days of storage) has been recommended for critically ill patients in an effort to improve the delivery of oxygen (2,3-diphosphoglycerate concentrations are better maintained with fresher blood). More recently, some evidence suggests that administration of younger blood (i.e., stored <14 days) is associated with better outcomes including decreased mortality rate and fewer postoperative complications, especially with major surgery.

  30.   C.   In an emergency situation that requires transfusion before type and compatibility testing can be performed, O-negative packed red blood cells may be administered. Even if the patient’s blood type becomes known and available, after 2 units of type O-negative packed red blood cells have been transfused, subsequent transfusions should continue with O-negative blood. RhoGAM is not indicated since the patient’s blood type is Rh+.