Anemia and Blood Transfusions

Anemia and Blood Transfusions

1. Anemia and Blood Transfusions

2. Blood Loss Anemia- a decrease in the oxygen carrying capacity of blood Normal reference ranges Males: hgb 14-18 g/dL Females: hgb 12-16 g/dL ICU-Related Anemia Anemia of chronic disease- inflammation inhibits erythropoietin release from the kidneys, reduced marrow response to erythropoietin, iron sequestration in macrophages, and increased destruction of RBCs Phlebotomy- minimize lab testing to only what is necessary

3. Equations

4. Testing Type and Screen (ABO-Rh typing and antibody screen) ABO-Rh typing Recipient RBCs tested with anti-A, B, and Rh antibodies Antibody screen Recipient serum + type O RBCs mixed to check for presence of A or B antibodies. No agglutination = negative screen If antibody screen is positive the serum is tested further Type and Crossmatch Tests recipient serum + donor cells for recipient antibodies to donor This reserves specific blood products for your patient, so use when it is very likely you will transfuse Timing of tests dependent on institution. If you suspect you will need to give blood products, obtain type and screen immediately.

5. Universal Donors & Recipients Donor Recipient O* universal O, A, B, AB A A, AB B B, AB AB AB Donor Recipient O O A A, O B B, O AB* universal O, A, B, AB *In an emergency without a known blood type, the universal donor of red blood cells is O (–) because it is devoid of A, B, and Rh antigens on its surface and won’t trigger a hemolytic transfusion reaction Compatibility for PRBCs Compatibility for FFP

6. Packed Red Blood Cells ( pRBCs ) Definition, Use, & Storage Single donor; volume 250-300 ml with Hct ~70% 1 unit pRBCs increases adult Hgb ~1 g/dl or Hct ~3% 10 ml/kg PRBC increases Hct 10% Always run with a bag of normal saline (do NOT use lactated ringers due to theoretical clot formation from calcium) Often stored with CPDA (lasts 35 days): Citrate (anticoagulant)- also binds iCa , phosphate (buffer), dextrose (energy source), adenosine (precursor to ATP synthesis) Indications (ASA Guidelines) Hgb/ Hct < 6/24 in young, healthy patients Usually unnecessary when H/H is 10/30 At Hgb 6-10 g/dl, the decision to transfuse is based on: Ongoing indications of organ ischemia Potential or ongoing blood loss Volume status Risk factors for complications of inadequate O2 (example: myocardial ischemia)

7. Platelets Definition, Use, & Storage Platelet Concentrate (PC) Platelets from one donated unit, volume = 50-70 ml; increase plt ~5000- 10,000 “6-pack” = 6 pooled PCs; rarely used anymore Apheresis Unit Platelets From a single donor; volume = 200-400 ml; increase plt ~50,000 Can give ABO-incompatible platelets, Rh tested only Stored at room temperature for 5 days Indications (ASA Guidelines) Rarely when plt > 100,000 Usually when plt < 50,000 (spontaneous bleed at < 20K) in the presence of excessive bleeding With platelet dysfunction (e.g. cardiopulmonary bypass, plt inhibitors)

8. Fresh Frozen Plasma Definition, Use, & Storage Fluid portion from whole blood Contains all coagulation factors (except platelets) 1 unit increases clotting factors 2-3% Use ABO-compatible; Rh-incompatible is OK Stored frozen; takes 30 min to thaw; use within 24 hrs of thawing Indications (ASA Guidelines) Urgent reversal of warfarin Correction of known factor deficiency Correction of excessive microvascular bleeding with INR>2 During massive transfusion (before lab results available) Heparin resistance (i.e. antithrombin III deficiency) in patients requiring heparinization

9. Cryoprecipitate Definition Fraction of plasma that precipitates when FFP is thawed Contains Factors VIII, XIII, I (fibrinogen), and vWF 1 unit contains ~5X more fibrinogen than 1 unit FFP Use within 4-6 hours after thawed if want to replace Factor VIII Indications (ASA Guidelines) Rarely when fibrinogen >150 mg/dl When fibrinogen <100mg/dl with microvascular bleeding During massive transfusion when fibrinogen level not available Bleeding patients with von Willebrand Disease Congenital fibrinogen deficiency

10. Transfusion-Related Infections *Bacterial contamination is most common with platelets due to their storage in dextrose at room temperature, pRBCs are less common cause due to their storage at 4˚C, but Yersinia is the most likely organism

11. Transfusion Reactions *Whenever you suspect a transfusion reaction, STOP THE TRANSFUSION IMMEDIATELY, alert team and blood bank Febrile Non-Hemolytic Reaction Due to recipient reaction to residual donor WBCs or platelets Benign; occurs with 0.5-1% of transfusions Treatment: Tylenol, Benadryl, slow transfusion, prevention by giving a patient leukoreduced blood Anaphylactic Reaction Occurs within minutes; life-threatening Usually associated with IgA deficiency because they have IgA antibodies Signs/Symptoms: shock, angioedema, ARDS Treatment: Stop blood Give fluids, antihistamines, and epinephrine In a patient with known IgA deficiency, get washed blood (it reduces the amount of plasma proteins and immunoglobins)

12. Transfusion Reactions Acute Hemolytic Reaction Due to ABO incompatibility Symptoms: fever, chills, flank pain; watch for unexplained tachycardia and hypotension, diffuse oozing and brown urine; monitor for ARF and DIC Treatment: Stop Blood products Maintain alkaline UOP (bicarbonate, mannitol, Lasix/crystalloid) Supportive care Delayed Hemolytic Reaction Due to antibodies (not anti-A or anti-B) to antigens on donor RBCs More insidious, develops on day 2-21

13. TRALI vs. TACO Both can present with dyspnea, hypoxemia, and pulmonary edema after blood transfusion TRALI (Transfusion-Related Acute Lung Injury) Incidence: 1 in 1120, Mortality 5-10% Due to plasma-containing products (platelets and FFP > pRBCs) - usually donor origin antibodies to leukocytes Diagnosis of exclusion: first rule out sepsis, volume overload, and cardiogenic pulmonary edema Treatment: supportive care, similar to ARDS (O2, mechanical ventilation, volume), NO diuresis TACO- (Transfusion-Associated Circulatory Overload) Due to volume overload in the setting of rapid and/or large volume blood transfusion Treatment: diuresis and supportive care

14. Massive Transfusion Massive Transfusion Definition : Acute administration of greater than 1 blood volume (~10 units) in 24 hours Each hospital has their own Massive Transfusion Guideline (MTG)- generally, a MTG bucket will contain roughly 6 pRBCs , 4 FFP, and 1 unit of platelets. Consequences Hypothermia: Blood products are stored cold - use a fluid warmer! Coagulopathy: Dilutional thrombocytopenia and coagulopathies Citrate Toxicity Citrate is in CPDA storage solution as a Ca2+ chelator Massive transfusion can cause an acute hypocalcemia Binds magnesium as well causing hypomagnesemia Acid-Base Abnormalities: At 21 days, stored blood has pH < 7.0, mostly due to CO2 production Hyperkalemia: K+ moves out of pRBCs during storage If EKG changes occur, stop transfusion and treat hyperkalemia. Impaired O2-Carrying Capacity: 2,3-DPG decreases in stored blood, causing a left-shifted O2-Hb dissociation curve

15. References ASA Task Force on Perioperative Blood Transfusion and Adjuvant Therapies. 2006. Practice guidelines for perioperative Adjuvant Therapies. 2006. Practice guidelines for perioperative blood transfusion and adjuvant therapies. Anesthesiology, 105: 198-208. Stanford Anesthesia Cognitive Aid Group*. Emergency Manual: Cognitive aids for perioperative clinical events. See http://emergencymanual.stanford.edu for latest version. Creative Commons BY-NC-ND. 2013 (creative commons.org/licenses/by-nc-nd/3.0/legalcode). *Core contributors in random order: Howard SK, Chu LK, GoldhaberFiebert SN, Gaba DM, Harrison TK. Goodnough LT. 2003. Risks of blood transfusion. Crit Care Med, 31: S678-86. Morgan GE, Mikhail MS, and Murray MJ. Clinical Anesthesiology, 4th ed. New York: McGraw-Hill Companies, Inc., 2006. Marino, P. Marino’s the ICU book, 4 th Edition. Philadelphia: Wolters Kluwer/Lippincott, Williams, & Wilkins, 2014.