Nagelhout Chapter 22 Flashcards
What is blood component therapy critical for?
Managing hemodynamic disturbances, oxygen delivery, and coagulation, particularly in the perioperative setting.
What is the key focus of blood therapy in anesthesia?
Red Blood Cell (RBC) transfusion to restore intravascular volume and oxygen-carrying capacity.
What are the requirements for proper component therapy?
Recognizing the need for transfusion, performing compatibility testing, obtaining the correct products, and administering and monitoring safely.
Why is accurate blood loss estimation essential?
It guides transfusion decisions.
What is the formula for Estimated Blood Volume (EBV)?
EBV = average blood volume (mL/kg) × body weight (kg)
Typically: 70 mL/kg for adult males, 65 mL/kg for adult females.
What does Maximum Allowable Blood Loss (MABL) determine?
When transfusion may be required.
What is the formula for MABL?
MABL = EBV × (Initial Hct − Lowest Acceptable Hct) / Initial Hct.
How is intraoperative blood loss often estimated?
Visually from sponges, suction, and drapes, but this can be highly inaccurate and subjective.
What are the physiologic signs of significant blood loss?
Tachycardia, hypotension, decreased urine output, decreased oxygen saturation, and diminished cerebral or splanchnic perfusion.
What laboratory and monitoring tools are used in blood therapy?
Hemoglobin (Hgb), Hematocrit (Hct), Platelets, Fibrinogen, Thromboelastography (TEG), Prothrombin time (PT), INR, aPTT, Near-infrared spectroscopy (NIRS), Central/mixed venous oxygen saturation, and Arterial blood gases.
What is the ‘10/30 rule’ in transfusion?
Hgb <10 g/dL, Hct <30% is considered outdated due to evidence showing potential overtransfusion and increased risk of complications.
What should modern transfusion decisions incorporate?
Patient’s clinical condition, hemodynamic status, oxygen delivery and perfusion, and laboratory data.
What have randomized controlled trials shown about restrictive vs. liberal transfusion strategies?
Restrictive strategies (Hgb ~7 g/dL) are as safe as liberal approaches (Hgb ~10 g/dL) in most surgical and critically ill patients.
What are the benefits of restrictive transfusion strategies?
Fewer transfusions and no increase in mortality or complications.
What is an exception to the restrictive transfusion strategy?
Patients with active myocardial ischemia may require a higher transfusion threshold.
When are transfusions rarely indicated according to 2020 guidelines?
When Hgb ≥10 g/dL.
When are transfusions almost always indicated?
When Hgb <6 g/dL, unless contraindicated.
What do newer guidelines recommend for transfusion decisions?
Using multiple physiologic and biochemical parameters, including arterial oxygen content, mixed/central venous oxygen saturation, lactate levels, and signs of myocardial ischemia.
What is the goal of the newer transfusion guidelines?
Avoid both premature and delayed transfusions and consider organ-specific tolerance to anemia.
What does the AABB recommend for transfusion decisions?
Use evidence-based, multifactorial assessment—not just a single hemoglobin value.
What should be considered when determining transfusion timing?
The individual patient’s ability to tolerate anemia, as different organs vary in their oxygen demand and vulnerability to hypoxia.
What is Patient Blood Management (PBM)?
PBM is a strategy developed by the AABB to guide clinical decisions related to blood transfusion.
What is the approach of PBM?
It is a multidisciplinary, multimodal approach that spans the entire perioperative continuum—from preoperative assessment to intraoperative management and postoperative care.
What are the goals of PBM?
- Optimize red blood cell (RBC) production
- Minimize blood loss
- Effectively treat anemia
What are the benefits of PBM?
It ensures patient safety, enhances clinical outcomes, and helps preserve blood supply availability.
What are the key components of PBM in the perioperative period?
- Optimization of RBC Production
- Minimization of Blood Loss
- Treatment of Anemia
What do the Joint Commission and ASA recognize about PBM?
They recognize PBM performance measures as critical to patient safety.
What do ASA Practice Guidelines recommend?
They recommend continuous evaluation for bleeding risks throughout the perioperative period.
Why is early identification and management of conditions important?
It is critical to reducing transfusion requirements and associated risks.
What is erythropoietin?
Erythropoietin is a hormone secreted by the kidneys in response to anemia/hypoxia.
What did a 2019 meta-analysis (Cho et al.) find about erythropoietin?
It showed that preoperative erythropoietin administration significantly reduced the need for allogenic transfusions across various surgeries.
What does thorough preoperative evaluation include?
- Medical history
- Hematologic lab work (Hgb, Hct, coagulation studies)
- Review of inherited/acquired disorders
What management is recommended for anticoagulants preoperatively?
Discontinue warfarin, clopidogrel, aspirin if clinically appropriate and use reversal agents as needed.
When may tranexamic acid be appropriate?
It may be appropriate for surgeries with anticipated high blood loss.
What is Preoperative Autologous Donation (PAD)?
It involves donating the patient’s own blood 48–72 hours before surgery.
What are the advantages of PAD?
- Eliminates risk of transfusion-transmitted infections
- Reduces demand on blood banks
What are the disadvantages of PAD?
- Bacterial contamination risk
- High cost, and up to 50% of donated units are wasted
- Not suitable for patients with certain conditions.
What is Acute Normovolemic Hemodilution (ANH)?
Whole blood is withdrawn immediately before surgery, replaced with crystalloids or colloids, and returned postoperatively.
What is the goal hematocrit for ANH?
The goal hematocrit is approximately 20%.
What are the advantages of ANH?
- Lower intraoperative RBC loss due to dilution
- Collected blood retains platelets and clotting factors
What are the risks associated with ANH?
- Hemodynamic instability due to low hematocrit
- Contraindicated in patients with myocardial ischemia or end-organ dysfunction
What is the effectiveness of ANH?
Effectiveness remains uncertain due to limited high-quality studies.
What is Cell Salvage?
A technique where blood lost during surgery is collected, filtered/washed, and reinfused into the patient.
What are common surgical uses for Cell Salvage?
Cardiothoracic, orthopedic, neurologic, and vascular surgeries.
What are the advantages of Cell Salvage?
Provides autologous RBCs proportional to blood lost, cost-effective, decreases need for allogenic transfusions, acceptable for some Jehovah’s Witnesses.
What do the 2018 Association of Anaesthetists guidelines recommend for Cell Salvage?
Routine use to reduce allogenic transfusions and anemia, 24/7 trained staff and equipment availability, use for blood losses >500 mL, full patient education on risks and benefits, leukocyte-depleting filters during cancer surgery reinfusion.
What are the contraindications for Cell Salvage?
Patients with sepsis or undergoing certain oncologic procedures.
What are potential complications of Cell Salvage?
Electrolyte imbalances, dilutional coagulopathy, disseminated intravascular coagulation (DIC).
What are Directed Donor Transfusions?
Blood donated by a friend or family member specifically for a matched patient.
What is the process for Directed Donor Transfusions?
Ordered by the physician ≥5 days before surgery, meant to reduce disease transmission risk.
What are the limitations of Directed Donor Transfusions?
Units may not be available in time, not all facilities accept this method, lacks strong evidence of superiority over anonymous donations.
What essential testing is required prior to transfusion?
ABO blood typing and Rh antigen testing.
What is a Type & Screen?
Determines ABO type, Rh status, and presence of unexpected antibodies.
What is a Crossmatch?
Simulated transfusion where the patient’s serum is tested against donor blood to check for incompatibility or reactions.
What is the blood type overview for Type O negative?
Universal donor.
What is the blood type overview for Type AB positive?
Universal recipient.
What are the matching rules for blood transfusions?
All blood transfusions must match ABO and Rh compatibility unless in an emergency situation.
What should be done in emergency transfusions when the patient’s blood type is unknown?
Type O, Rh-negative blood is given to females of childbearing age; Type O, Rh-positive can be given to others if no history of prior sensitization.
When can a patient return to their original blood type after an emergency transfusion?
Only after bleeding is controlled and crossmatch confirms compatibility.
What defines ‘massive transfusion’?
Multiple clinical thresholds define ‘massive transfusion,’ including:
- ≥10 units PRBCs in 24 hours
- ≥5 units in 4 hours
- Loss of one blood volume
What is the purpose of Massive Transfusion Protocols (MTPs)?
Developed to coordinate timely, structured delivery of blood products during traumatic hemorrhage or major surgical bleeding.
What are the goals of MTPs?
Provide blood components that replicate whole blood, including:
- Packed Red Blood Cells (PRBCs) – for oxygen delivery
- Fresh Frozen Plasma (FFP) and platelets – for coagulation support
- Address early coagulopathy, especially in trauma.
What are best practices for MTPs?
Early activation of MTPs improves outcomes. Overuse may cause:
- Wastage of blood products
- Increased transfusion-related risks.
What is critical for the initiation and monitoring of MTPs?
Timely activation is critical to avoid delays in life-saving treatment. Prediction scores like Assessment of Blood Consumption (ABC) and Trauma-Associated Severe Hemorrhage Score help determine when to initiate MTPs.
What are the initial recommendations for blood product ratios?
Initial recommendations (2014):
- Plasma to RBC ratio of 1:1 or 1:2
- 1 apheresis unit or donor platelet pool per every 6 units of RBCs.
What recent recommendations have been made for MTPs?
Recent recommendations include use of:
- Calcium chloride
- Cryoprecipitate
- Tranexamic acid (enhances clot formation).
What are potential complications of MTPs?
Potential complications include:
- Coagulopathy
- Hypothermia
- Storage-related complications
- Immunosuppression and infection
- Transfusion-associated lung injuries.
What is required for the MTP decision process?
Requires interdisciplinary coordination (anesthesia, surgery, blood bank). Must establish clear protocols for when to start or discontinue MTP.
What is the fractionation of whole blood used for?
Allows administration of targeted components:
- PRBCs for anemia or tissue hypoxia
- FFP for anticoagulation reversal
- Platelets for thrombocytopenia
- Cryoprecipitate for hypofibrinogenemia.
What is the clinical use of MTPs?
Individualized therapy reduces unnecessary transfusions. Supports better hemostasis and oxygenation in bleeding patients.
What are Packed Red Blood Cells (PRBCs) used for?
Primary treatment to improve hemoglobin levels and oxygen-carrying capacity.
What is the volume and hematocrit of each unit of PRBCs?
Each unit:
- ~300 mL total volume
- ~65% hematocrit
- Increases Hgb by ~1 g/dL and Hct by 2–3%.
What are the dosing recommendations for PRBCs?
Adults: 1 mL per 2 mL of blood loss.
Pediatrics: 10–15 mL/kg.
Infants: 15 mL/kg due to higher blood volume per kg.
What is the role of platelets in MTPs?
Essential for hemostasis. Indicated in:
- Platelet dysfunction
- Thrombocytopenia.
How are platelets available?
Available as: Platelet concentrates from whole blood or apheresis units. Platelets may be derived from pooled donations (6–10 donors via centrifuge) or from single-donor apheresis.
What is the expected increase in platelet count from one unit of platelet concentrate?
One unit of platelet concentrate is expected to increase platelet count by ~5–10 × 10⁹/L in adults.
What is the recommended dose for platelets?
Recommended dose: 1 unit per 10 kg body weight.
What are the indications for platelet transfusion?
Indications:
- Platelet count <10 × 10⁹/L in non-bleeding stable patients (to prevent spontaneous bleeding).
- Platelet count <50 × 10⁹/L in actively bleeding patients.
What is Fresh Frozen Plasma (FFP)?
FFP contains all coagulation factors; each unit = 200–250 mL.
How is Fresh Frozen Plasma (FFP) prepared and stored?
Prepared from whole blood/apheresis and stored for up to 1 year when frozen at -18°C to -30°C within 8 hours.
What happens to factors V and VIII after thawing FFP?
Factors V and VIII decline if unused after 24 hours.
What are the indications for using Fresh Frozen Plasma (FFP)?
Indications include urgent reversal of warfarin, known factor deficiencies, elevated PT/PTT with microvascular bleeding, and massive transfusion–related coagulopathy.
What is the dosage for Fresh Frozen Plasma (FFP)?
10–20 mL/kg raises factor levels by 20–30%.
What is Cryoprecipitate rich in?
Cryoprecipitate is rich in Factor VIII, fibrinogen (~200 mg), fibronectin, and von Willebrand factor.
How is Cryoprecipitate produced?
Produced by centrifuging thawed FFP at 4°C.
What is the effect of 1 unit of Cryoprecipitate per 10 kg body weight?
Increases fibrinogen by ~50 mg/dL.
What are the indications for using Cryoprecipitate?
Indications include von Willebrand disease (if unresponsive to DDAVP), fibrinogen <80–100 mg/dL during massive transfusion with active bleeding, and congenital fibrinogen deficiencies.
What are storage lesions in blood?
Storage lesions refer to structural and functional deterioration over time, including ↓ ATP and 2,3-DPG levels, ↑ potassium levels, and membrane changes affecting cell viability.
What did a large observational study find about RBCs stored >14 days?
Associated with higher postoperative complications and reduced short- and long-term survival.
What was historically preferred as a carrier fluid for blood transfusions?
Normal saline (NS) was preferred due to concerns that calcium in Ringer’s Lactate (LR) might cause clotting.
What does newer evidence show about Ringer’s Lactate (LR) and blood transfusions?
At rapid infusion rates or if blood is infused within 60 minutes, LR does not increase clot formation compared to NS.
What are the classifications of complications from blood transfusions?
Complications are classified as acute (within 24 hours) and delayed (days to years later).
What increases the risk of complications during blood transfusions?
The risk increases with the volume transfused.
What are the most common reactions to blood transfusions?
Febrile non-hemolytic and allergic reactions are the most common.
What are some immune-mediated reactions to blood transfusions?
Include febrile reactions, allergic reactions, acute and delayed hemolytic reactions, transfusion-related acute lung injury (TRALI), and transfusion-associated circulatory overload (TACO).
What is the risk of viral and bacterial transmission in transfusions?
Extremely rare due to improved testing and screening.
How does storage time affect bacterial contamination risk?
Bacterial contamination risk increases with storage time—especially platelets, which are stored at room temperature for up to 5 days.
What is a special concern regarding platelet contamination?
Platelet contamination is a special concern due to storage conditions.
What causes an acute hemolytic reaction?
Caused by ABO incompatibility due to clerical or crossmatch error.
What immune response is involved in acute hemolytic reactions?
Complement-mediated immune response destroys donor RBCs.
What are potential severe outcomes of an acute hemolytic reaction?
Can lead to DIC, shock, renal failure, and death.
What are the symptoms of an acute hemolytic reaction?
Fever, chills, back pain, dyspnea, hemoglobinuria, bleeding—may be masked under general anesthesia.
What is the treatment for an acute hemolytic reaction?
Stop transfusion, administer NS, and support hemodynamics. May need FFP, platelets, cryoprecipitate.
What characterizes a delayed hemolytic reaction?
More common, milder, and gradual RBC breakdown.
What are the symptoms of a delayed hemolytic reaction?
Jaundice, ↓Hgb, hemoglobinuria, often asymptomatic.
In which patients are delayed hemolytic reactions common?
Common in obstetric patients or previously transfused individuals.
What was the leading cause of transfusion-related death before 2016?
Transfusion-Related Acute Lung Injury (TRALI).
What is the incidence of TRALI in the general population?
Approximately 0.1% general; up to 5–8% in critically ill.
What causes TRALI?
Caused by donor plasma antibodies triggering leukocyte activation and noncardiogenic pulmonary edema.
When does TRALI typically occur after transfusion?
Occurs within 6 hours of transfusion.
What are the symptoms of TRALI?
Hypoxemia, ARDS, fever, hypotension, ↑airway pressures.
How can TRALI be distinguished from TACO?
TRALI causes hypotension, TACO causes hypertension.
What is the treatment for TRALI?
Stop transfusion, provide ventilatory and hemodynamic support.
What is the leading cause of transfusion-related death since 2016?
Transfusion-Associated Circulatory Overload (TACO).
What causes TACO?
Due to fluid overload, especially in patients with cardiac or renal disease.
What is the incidence of TACO?
1–4%; higher in ICU and elderly patients.
When does TACO typically onset after transfusion?
Onset: 6–12 hours post-transfusion.
What are the symptoms of TACO?
Hypertension, respiratory distress, hypoxia, JVD, rales/wheezing.
How can severe cases of TACO be mistaken for TRALI?
Severe cases may mimic TRALI but usually have hypertension.
What is the treatment for TACO?
Stop transfusion, support respiration/circulation, diuresis, and oxygen therapy.
What triggers allergic reactions in transfusions?
Triggered by donor plasma proteins reacting with recipient IgE.
Can allergic reactions occur without previous transfusion?
Yes, can occur without previous transfusion.
What are the typical symptoms of mild allergic reactions?
Urticaria, erythema—typically mild and treated with diphenhydramine.
What can severe allergic reactions lead to in IgA-deficient patients?
Exposure can lead to anaphylaxis (bronchospasm, hypotension, dyspnea).
What is the treatment for known IgA-deficient patients?
Washed blood products for known IgA-deficient patients.
