Lecture 10 (labs)-Exam 5 Flashcards

Question

What is the direct and indirect antiglobulin test?

Answer 1

direct-detects antibodies on surface of RBC - add pts RBCs to combs reagent indirect- detects antibodies in the serum- add pts plasma to rbcs then reagent

Answer 2

* **The most common ones - in descending order are cytomegalovirus, or CMV, which can occur once every 100 transfusions, hepatitis B, which occurs about once every 200,000 transfusions, and hepatitis C and HIV, both of which occurs about once every 2 million transfusions.** * These numbers vary quite a bit depending on the healthcare setting because the way blood is screened differs around the world.

Answer 3

The patient experiences risk of exposure based on the amount of donors the product has come from Example: Each unit of red cells exposes the patient to one donor per red cell unit transfused * FFP to approximately 4 to 6 donors per adult dose (of 4 to 6 units FFP) * Adult cryoprecipitate dose of 10 units (in 2 pools of 5 units each in the UK) results in a donor exposure of 10 donors per adult dose.

Answer 4

If a recipient who has blood group O is transfused with non-group O RBCs, the naturally occurring anti-A and anti-B in the recipient's serum binds to their corresponding antigens on the transfused RBCs. **These antibodies fix complement and cause rapid intravascular hemolysis, triggering an acute hemolytic transfusion reaction** that can cause disseminated intravascular coagulation, shock, acute renal failure, and death.

Answer 5

Reactions typically occur due to mismatch or incompatibility of transfused product and the recipient * **Naturally occurring antibodies such as Anti-a and anti-b in the recipient** * **Antibodies made in response to foreign antigens (alloantibodies)**. These are responsible for many reactions including mild allergic, febrile non-hemolytic, acute hemolytic, and anaphylactic * **Antibodies present in the blood donor can also cause reactions and are thought to be involved in transfusion-associated lung injury (TRALI)**

Answer 6

* Range in severity from minor to life-threatening * If the response happens during the transfusion it is termed **“Acute transfusion reactions”** * If the response happens days to weeks later it is termed **“Delayed transfusion reaction”** * Most common signs and symptoms include fever, chills, urticaria, and itching * Most symptoms resolve with little or no treatment, but respiratory distress, high fever, hypotension, and hemoglobinuria indicate a more serious reaction

Answer 7

Immediate discontinuation of transfusion

Answer 8

* Can result in intravascular or extravascular hemolysis, depending on the specific etiology (cause). * Immune-mediated reactions are **often a result of recipient antibodies present to blood donor antigens.** * Non-immune reactions are possible, and occur when red blood cells are damaged

Answer 9

Generally thought to be caused by **cytokines released from blood donor leukocytes (white blood cells).** – can wash WBC’s to reduce this - **leukoreduction**

Answer 10

**Septic**: Caused by bacteria or bacterial byproducts (such as endotoxin) which may contaminate blood.

Answer 11

* **Mild allergic**: Attributed to hypersensitivity to a foreign protein in the donor product. * **Anaphylactic**: A more severe reaction. Sometimes this can occur in a patient with IgA deficiency who makes alloantibodies against IgA and then receives blood products containing IgA.

Answer 12

* **Anaphylactic transfusion reactions are rare but potentially fatal and develop more commonly in patients with IgA deficiency.** * These patients have no IgA and thus form anti-IgA IgG and IgE antibodies that bind to the IgA in the donor's plasma and induce an anaphylaxis reaction. * To avoid such life threatening reactions, patients with known IgA deficiency usually wear a medical alert bracelet/necklace indicating their status.

Answer 13

Occurs when the volume of the transfused component causes hypervolemia (volume overload). * all blood products are packed in fluid, and therefore, a potential complication of transfusions is fluid overload * Higher mortality rate than TRALI due to effect on CV system

Answer 14

* Acute lung injury is due to antibodies in the donor product (human leukocyte antigen or human neutrophil antigen) reacting with antigens in the recipient. * TRALI can start within minutes to 6 hours after blood transfusion

Answer 15

* The first “hit” occurs before the transfusion process, **when any stressor like sepsis, shock, or trauma, causes neutrophils in the blood to be recruited and sequestered in the pulmonary capillaries**. These stressors also cause the neutrophils to be primed, meaning they’re prepared to start an inflammatory response when there's another stressor or a second “hit”. * In TRALI, the second “hit” is the transfusion itself, where antibodies in the donor’s blood activate the primed neutrophils, giving them the signal to start an inflammatory response in the lungs. **Neutrophils then respond by releasing inflammatory mediators like cytokines, proteases, oxidases and reactive oxygen species. This in turn will increase pulmonary capillary permeability, leading to fluid accumulation in the lungs’ interstitium.** As a result, individuals develop noncardiogenic pulmonary edema, which is when the fluid accumulation is not due to cardiac causes like heart failure

Answer 16

* Bilateral Infiltrates: TRALI often presents with bilateral diffuse pulmonary infiltrates on chest X-ray. These infiltrates typically manifest as patchy or confluent opacities throughout both lungs. * Ground-Glass Appearance: The infiltrates in TRALI may have a ground-glass appearance, meaning they appear hazy or cloudy, resembling ground glass. * Normal Heart Size: Unlike TACO, where heart enlargement may be evident due to fluid overload, TRALI typically does not show cardiomegaly on chest X-ray. * Normal Vascular Structures: TRALI usually does not involve prominent vascular congestion or redistribution seen in conditions like cardiogenic pulmonary edema.

Answer 17

Typically caused by an anamnestic response to a foreign antigen that the patient was previously exposed to (generally by prior transfusion or pregnancy).

Answer 18

Results from **engraftment of donor lymphocytes (commonly found in cellular blood products) into an immunocompromised recipient’s bone marrow. The donor lymphocytes recognize the patient as foreign and react against the recipient’s body**. The patient’s immune system is unable to clear the foreign lymphocytes. This is rare but often fatal.

Answer 19

An individual is either Rh-positive, meaning they have the antigen on their red blood cells, or Rh-negative, meaning it is absent. * **People who are Rh-positive can receive both Rh-negative and Rh-positive blood.** * **Individuals with Rh-negative blood should only receive Rh-negative blood to prevent hemolytic transfusion reactions.**

Answer 20

* Rh+ = presence of Rh protein (**dominant**) * Rh- = absence of the Rh protein (**recessive**)

Answer 21

* Creates IgG antibodies that require prior exposure through transfusion or pregnancy * 15% of North American donors are negative

Answer 22

In **Rh incompatibility, maternal anti-D IgG antibodies** form after maternal exposure to fetal Rh positive blood during birth or pregnancy-related complications. The initial pregnancy is not affected; however, subsequent pregnancies are at risk of **fetal hemolysis** and, in severe cases, **intrauterine hydrops fetalis**, secondary to the passage of **maternal anti-D IgG across the placenta.**

Answer 23

* By ABO antibodies in infants of blood group A or B who are born to group O mothers. * Can also happen with incompatibility of Rh+/Rh-

Answer 24

* This is because the anti-A and anti-B formed in group O individuals tend to be of the IgG type (and therefore can cross the placenta), * Whereas the anti-A and anti-B found in the serum of group B and A individuals, respectively, tends to be of the IgM type. * Although uncommon, cases of HDN have been reported in infants born to mothers with blood group A2 and blood group B.

Answer 25

* HDN tends to be relatively mild in nature mainly because fetal RBCs don't express adult levels of A and B antigens. However, the strength of fetal ABO blood group antigens can vary * Any degree of hemolysis can be detrimental.

Answer 26

* Severe hyperbilirubinemia and jaundice – the babies liver can’t handle the large amount of bilirubin * **Kernicterus** – most severe form of hyperbilirubinemia – build up of bilirubin in the baby’s brain

Answer 27

Rh negative mothers that have not been sensitized, receive injection called **Rh immunoglobin (Rhogam)** which will stop Rh antibodies from reacting to the babies Rh positive cells – **received around 28 weeks of pregnancy** * If the baby is Rh positive, the mother gets a second dose within 72 hours after giving birth

Answer 28

In situations where Rh D negative units are unavailable, Rh D positive units may be given to men and women over reproductive age after they have been determined to lack anti-D antibodies. This practice is known as "Rh compatibility" or "Rh-matched transfusion" **and is based on the understanding that individuals who lack Rh D antigens on their red blood cells (Rh D negative) will not develop antibodies against Rh D antigens upon exposure to Rh D positive blood if they have not previously been sensitized.**

Answer 29

* Rh D Incompatibility: Rh D incompatibility occurs when an Rh D negative individual is exposed to Rh D positive blood, leading to the potential development of anti-D antibodies. This can occur during pregnancy, blood transfusions, or other forms of blood exposure.

Answer 30

Sensitization Risk: Sensitization to Rh D antigens is most concerning for women of childbearing age, as anti-D antibodies can cross the placenta during pregnancy and lead to hemolytic disease of the newborn (HDN) in Rh D positive fetuses of Rh D negative mothers. However, the risk of sensitization decreases significantly after menopause or surgical sterilization in women, and it is negligible in men.

Answer 31

Pre-transfusion Testing: Before administering Rh D positive blood to an Rh D negative individual, pre-transfusion testing is performed to determine if the recipient has pre-existing anti-D antibodies. If no antibodies are detected, the risk of sensitization is considered minimal, especially in men and women over reproductive age.

Answer 32

* Blood products are transfused through IV tubing with filters * The line is primed first to help keep clots from forming in the IV line * 2 providers verify blood products before administering and patients must be monitored for possible reactions * Each unit should be transfused within 2-4 hours

Answer 33

* Current indications for whole blood transfusion are **generally very few** * The US military buddy transfusion system is the most widespread system of whole blood transfusion * **Sometimes in the trauma bay at civilian settings** * May lead to complications such as volume overload

Answer 34

* in the middle of the last century, blood was collected in glass bottles, which depleted platelets in storage * **Introduced plastic bags which revolutionized blood storage – also found to be gas permeable, which is essential for storing functional platelets**

Answer 35

* Platelets are a scarce resource, partly because of their short shelf life of 5 days. Stored at room temperature – increases some infectious risk * Platelet concentrations can be prepared from whole blood or by apheresis

Answer 36

* Recommended dosing for an adult is 6 units of pooled random donor platelets or one apheresis unit * Volume is **350-400mL** * **Each unit of RDP will raise platelet count 5-10k – standard 6 pack will therefore raise count by 30-60k**

Answer 37

Platelet transfusion is mainly indicated to treat or prevent bleeding in patients with thrombocytopenia or platelet function disorder Platelet transfusion threshold in bleeding patients * < 50,000 in severe bleeding, including Dic * <30,000 when bleeding, not life threatening, or considered not severe * <100,000 for bleeding in multiple trauma patients or patients with intracranial bleeding

Answer 38

* To prevent spontaneous bleeding – transfuse at less than 10,000 * Before neurosurgery <100,000 * Before major surgery <50,000

Answer 39

* Thrombotic thrombocytopenia purpura (TTP) – due to the increased risk of thrombosis * HIT (heparin induced thrombocytopenia) is another condition where platelet transfusion may increase the risk of thrombosis – would only transfuse for pre-procedure or surgery

Answer 40

* **Indicated for the deficiency of coagulation factors with abnormal coagulation tests in the presence of active bleeding** * For the reversal of warfarin in the presence of active bleeding * May not be tolerated in patients with liver disease as patients may not tolerate the infusion volumes necessary to achieve adequate hemostatic levels of coagulation factors

Answer 41

* **Fresh frozen plasma is the fluid portion of a unit of whole blood frozen in a designated time frame, usually within 8 hours** * Contains all coagulation factors except platelets-> **Fibrinogen, albumin , protein C, protein s, antithrombin, tissue factor pathway inhibitor** * Standard dose will raise factor levels by approximately 20% * Each unit contains approximately **250mL of fluid**

Answer 42

* Is stored at -30 Celsius and must be thawed in a water bath at 30-37 Celsius over **20-30min** in a FDA cleared device * **Must be administered immediately after thawing, can be stored again at 1-6 degree Celsius for up to 5 days** * Should not be used if left at room temperature for more than 4 hours

Answer 43

If not used within 24 hours, should be discarded * Once thawed the activity of clotting factors, particularly factor V and factor VIII decline gradually Comes in units, use a weight based dosing of 10-20 mL/kg of recipient weight * Each unit of FFP contains approximately 200-250mL

Answer 44

would require 700mL – divided by 250mL = 2.8 units ## Footnote typical dosing 4-6 units

Answer 45

May need to be re-administered after 6-8 hours if there is ongoing bleeding due to the short half-life of factor VII (2-6 hours)

Answer 46

direct thrombin inhibitors, direct factor Xa inhibitors

Answer 47

* Composed of fibrinogen, von Willebrand factor, and factors 8 and 13 * Kept frozen for up to 36 months * After thawing it should be infused as soon as possible though it can be stored at ambient temperature for up to 4 hours

Answer 48

* One unit of Cryo is **15-20 mL** in volume and contains 150-250 mg of fibrinogen. Cryo is generally transfused in pools of **10 units**, which should increase an adult recipient's fibrinogen level by 50-100 mg/dL * Cryoprecipitate delivers a high dose of fibrinogen in a small fluid volume, compared with therapeutic doses of FFP, so cryoprecipitate may be considered as initial treatment when fibrinogen replacement in a small volume is desirable for example to minimize the risk of TACO

Answer 49

A blood gas can be performed on blood obtained from anywhere in the circulatory system (artery, vein, capillary) An ABG is specifically arterial blood * Provides information on **oxygenation** and ventilation status, as well as **acid-base balance** Obtained through arterial puncture, usually the radial artery * **Must complete a modified Allens test prior to draw**

Answer 50

* Must record what amount of oxygen the patient is on at time of test * Sample should be placed on ice and analyzed as soon as possible

Answer 51

* Your lungs and your kidneys do much of the work to keep your acid-base balance normal. * Oxygen saturation (O2Sat). This measures how much oxygen your red blood cells are carrying * Partial pressure of oxygen (PaO2). This measures the pressure of oxygen that's dissolved in your blood. It helps show how well oxygen moves from your lungs to your bloodstream.

Answer 52

* Partial pressure of carbon dioxide (PaCO2). This measures the amount of carbon dioxide in your blood. It also shows how easily carbon dioxide can move out of your body. * Acid-base balance (pH level). This measures the acidity of your blood. Too much acid is called acidosis. Too much base (alkaline) is called alkalosis. These conditions are symptoms of other problems that upset the acid-base balance in your body. * Bicarbonate (HCO3)- is calculated using the measured values of pH and PaCO2 to determine the amount of the basic compound made from CO2

Answer 53

* Metabolic acidosis – pH<7.35, respiratory CO2 normal, bicarb low (<24mEq/L), split into anion and non anion gap * Metabolic alkalosis – pH >7.45, respiratory CO2 normal, bicarb level high * Respiratory acidosis – pH <7.35, CO2 elevated >45, elevated HCO3 (bicarb) * Respiratory alkalosis – pH >7.45, respiratory CO2 <35

Answer 54

Respiratory acidosis is a state in which there is usually a failure of ventilation and an accumulation of carbon dioxide. The primary disturbance of elevated arterial PCO2 is the decreased ratio of arterial bicarbonate to arterial PCO2, which leads to a lowering of the pH. In the presence of alveolar hypoventilation, 2 features commonly are seen are respiratory acidosis and hypercapnia. To compensate for the disturbance in the balance between carbon dioxide and bicarbonate (HCO3-), the kidneys begin to excrete more acid in the forms of hydrogen and ammonium and reabsorb more base in the form of bicarbonate

Answer 55

Example: hyperventilation (blowing off CO2) due to fever, pain, or anxiety

Answer 56

* pH is in the normal range, so use 7.40 as a cutoff point, in which case it is < 7.40, and acidosis is present. * The elevated PaCO2 indicates respiratory acidosis, and the elevated HCO3 indicates a metabolic alkalosis. * The value consistent with the pH is PaCO2. Therefore, this is a primary respiratory acidosis. The acid-base that is inconsistent with the pH is the elevated HCO3, indicating a metabolic alkalosis, so there is compensation signifying a non-acute primary disorder because it takes days for metabolic compensation to be effective. * Last, the decreased PaO2 indicates an abnormality with oxygenation. However, a history and physical will help delineate the severity and urgency of required interventions, if any

Answer 57

* pH is in the normal range. Using 7.40 as a cutoff point, it is >7.40, so alkalemia is present. * The decreased PaCO2 indicates a respiratory alkalosis, and the HCO3 is normal but on the low end of normal. * The value consistent with the pH is PaCO2. Therefore, this is a primary respiratory alkalosis. The HCO3 is in the normal range and, thus, not inconsistent with the pH, so there is a lack of compensation. * Last, the PaO2 is within the normal range, so there is no abnormality in oxygenation.

Answer 58

Measured using a pulmonary artery catheter

Answer 59

As a diagnostic, derangement in venous oxygen saturation can ascertain the underlying etiology. The oxygen consumption by the tissues by the whole body (VO2) is usually independent of oxygen delivery (DO2). This is because a decrease in DO2 is compensated by an increase in VO2, thereby preventing tissue hypoxia. However, when a 'critical' DO2 is reached, and no further oxygen can be extracted, tissue hypoxia and lactic acidosis sets in. These changes are reflected in venous oximetry and must be interpreted correctly in conjunction with other hemodynamic parameters (CO, arterial oxygen content).

Answer 60

The cardiovascular response to an increase in oxygen requirement and VO2 is an increase in arterial oxygen content or an increase in CO. When these compensatory mechanisms fail to occur, and DO2 drops, a decrease in SvO2 is seen. SvO2 also drops if the compensatory mechanisms are insufficient to meet the metabolic demands of the tissues. SvO2 can drop to as low as 30-50% before tissue oxygen extraction is exhausted, and there is an onset of anaerobic metabolism