Anemia & Blood disorders Flashcards
What are some questions you might want to ask in regards to hematology?
- Have you ever had a blood problem?
- Anemia? Leukemia?
- Any clotting problems?
- Lots of bleeding from cuts, nosebleeds, surgery, dental work?
- Have you ever required a blood transfusion?
- Has a family member/blood relative ever had a serious bleeding condition or clotting problem?
What common medications would make you concerned in terms of possible hematological problems?
- Aspirin/NSAIDS
- Vitamin E,
- Ginseng, Gingko, Garlic, Saw Palmetto.
- How often, how much, and last dose?
Anemia Pathology
- Can be either Acute or Chronic
- Acute = Acute blood loss
- Chronic = Nutritional Hemolytic, Aplastic, Manifestation of another disease, Abnormal RBC structure (Sickle cell, Thalassemia)
-
Disease state related to
- abnormal low concentration of hemoglobin (RBCs)
- Abnormal structure of hemoglobin
-
Clinical manifestation of decreased oxygen carrying capacity and delivery
- Hemoglobin Defines oxygen carrying capacity
- Anemia decreases o2 carrying capacity
- Care must inclued treatment of the underlying disease as well as the state of anemia
- MUST avoid disruption of compensatory mecheanisms
Calculation of arterial blood oxygen content
CaO2 = (Hgb x 1.39) SaO2 + PaO2 (0.003)
- 1.39 = O2 bound to hemoglobin
- SaO2 = saturation of hemoglobin with O2
- PaO2 = arterial partial pressure of oxygen
- 0.003 = dissolved oxygen ml/mmHg/dl
- Normal O2 capacity = 16-20 mL/dL
Compensatory mechanisms for anemia
- Increase CO
- Increase 2,3-DPG
- Increased P50
- Increase plasma volume
- Decreased blood viscosity = increased CO
- Decreased SVR
- Blood shunting to organs with higher extraction ratios
- Kidneys release EPO
- RIGHTWARD shift in ox-hem disassociation curve
Oxyhemoglobin disassociation curve shifts to the right with:
Think of anything that increases metabolism → RBC will want to drop off Oxygen at the tissues
- Increased CO
- Acidosis = Decreased pH
- Increased 2-3 DPG
- Exercise
- Increased temeperature (sepsis)
- Hgb variants with decreased oxygen affinity (Sickle cell)
*
Oxyhemoglobin disassociation curve shifts to the left with:
Think anything that decreases metabolism →tissue does not need as much oxygen
- Decreased CO2
- Alkalosis = Increased pH
- Decreased 2/3 DPG
- Decreased temperature - hypothermia
- High oxygen affinity Hgb variants (Fetal Hgb)
(a leftward shift on someone that is dependent on a rightowrd shift may be a problem - we do this from hyperventilation and decreaseing temperature)
Changes that could interefere with oxygen delivery to the tissues
- Decreased CO
-
LEFTWARD shft in oxy-heme disassociation curve
-
Respiratory alkalosis
- hyperventilation/decreased PaCO2
- Hypothermia
- Abnormal Hgb such as fetal hemoglobin and carboxyhemoglobin
-
Respiratory alkalosis
Anemia Basic Anesthetic management
- Know your pts preoperative Hgb and HCT
- anemia suspected if hemoglobin
- <11.5 g/dl (females); hct <36%
- <12.5 g/dl (males); hct <40%
- anemia suspected if hemoglobin
- Hgb and HCT are RELATIVE measuremants
Treating the underlying cause
Anesthesia management and considerations for chronic anemia
Goal = AVOID disruptions of compensatory mechhanisms that are aimed at maintinging O2 delivery to the tissues!
- Indentify and treat underlying disease if possible
- Maximize O2 delivery- High FiO2
-
Avoid drug induced decreases in CO
- consider etomidate induction
- may want to use high opioid technique
- hydrate/avoid hypovolemia
- AVOID propofol, high amounts of IAs, STP
-
AVOID leftward shifts of the oxyhemoglobin disassociation curve
- no hyperventilation/respiratory alkalosis
- no hypothermia
-
Consder volitile anesthetics may be LESS soluble in plasma
- may have a faster induction, however, often OFFSET by the fact that these patients have and increased CO
Anemia and the decision to transfuse
Goal of transfusion therapy = Increase O2 carrying capacity and/or correct a coagulation disorder
- There is NO tranfusion trigger and the decision to transfuse is based on:
- The clinical judgment that the oxygen carrying capacity MUST be increased to prevent oxygenconsumtion(VO2) from being greater thanoxygendelivery (DO2)
- A drop in Hgb from 15 to 10 = 33% decrease in arterial oxygen content!
- it is also manifested by a RIGHT shift in the poxthemoglobin disassociation curve
2006 ASA guidelines regurding blood transfusion
- Rarely indicated if Hgb > 10 g/dL
- Almost ALWAYS indicated if Hgb
- If Hgb is 6-10: transfusion is based on the patients risk for complication and inadequate oxygenation
- Use of a transfusion trigger of Hgb is NOT RECOMMENDED
- Where apprropriate use of autologous blood, cell save or acute normovolemic hemodilution and measures to decrease blood loss (deliberate hypotension)
- Indications for transfusion are more liberal for autologous blood than blood from the blood bank
How do you know when to transfuse?
- You calculate the allowable blood loss for your surgical case
- ABL = EBV x (patients Hct - Allowable Hct)
patients Hct
- Know that:
- 1 unit of RBCs will increase Hct 3-5%;
- or it will increase Hgb ~1 g/dL
Nutritional anemias
- Iron deficiency
- Folic acid deficiency
- B12 deficiency
- Chronic illness (infections, cancer, RF, DM, AIDS, connective tissue disorders)
Iron deficiency anemia- RBCs are? Common causes in adults?
- Nutritional Anemia
- Ineffective erythropoesis and Microcytic RBCs
- In adults, depletion of iron stores is caused by chronic blood loss
- GI bleed
- menorrhagia
- cancer
- Most common form of nutritional anemia in infants and children
B12-def. anemia - RBCs are? May result in? Anesthesia considerations?
Macrocytic (Megaloblastic bone marrow morphology)
B12 deficiency may result in pernicious anemia
- Bilateral peripheral neuropathy
- Loss of proprioception/vibratory sensation in lower limbs
- Decreased deep tendon reflexes
- Unsteady gait
- Memory impairment/mental depression
Anesthesia considerations:
- Avoid regional blocks (neuropathys)
- Avoid N2O (binds B12)
- Maintain oxygenation
- Emergency correction for imminent surgery is RBC transfusion
Causes hemolytic anemias
Acquired Hemolytic Anemias
- Drug induced (High dose PCN, alpha- methyldopa)
- Disease/infection induced (malaria, epsteen Barr)
- Sensitization of RBCs (Maternal/fetal)
(particals released durring hemolysis can result in <strong>DIC</strong> and <strong>hypersplenism</strong>)
Hereditary hemolytic anemias
- Hereditary spherocytosis
- Paroxysmal nocturnal hemoglobinuria
- Glucose 6 Phospahete dihydrogenase deficiency
- Pyruvate Kinase Deficiency
Folic acid deficiency anemia- RBCs are? May result in? Anesthesia considerations?
Macrocytic (Megaloblastic bone marrow morphology)
Folic acid deficiency may result in penicious anemia
- Smooth tongue (difficult intubation)
- Hyperpigmentation
- Mental depression
- Peripheral edema
- Liver dysfunction
- Severely ill patient
Anesthesia considerations:
- Thorough airway assessment
- Have an alternative airway plan in place
- often have difficult airways d/t tongue texture!
Glucose-6-Phosphate dehydrogenase deficiency What is it? Who does it affect? What should you avoid?
Disorder affecting RBC metabolism
Form of hemolytic anemia
- Most common enzymopathy; decreased G6PD activity leaves RBCs susceptible to damage by oxidation.
- Cell membranes have increased rigidity of membranes and there is accelrated RBC clearance
- Acute and chronic episodes.
- Most prevalent in: Blacks, Asians, Mediterranean populations
Anesestetic consideratons:
- AVOID: oxidative drugs (LAs, N2O, Meth. Blue)
- AVOID: hypothermia, acidosis, hyperglycemia, infection
Peri-op risks and concerns for hemolytic anemia
Hemolytic anemia risks:
- Increased tissue hypoxia
- Increased infection risk if prior splenectomy
- Increased risk of venous thrombosis
To offset these risks preop planning should include:
- EPO given for 3 days pre-op
- Consider for transfusion if:
- Hgb acutely < 8 g/dl or
- Hgb chronically 6 g/ dl
- Adequate pre-op hydration and prophylactic RBC transfusions
- Caution with Methylene Blue - can increase hemolysis!!!
Sickle cell anemia patho
Cellular Pathology
- Inherited
- Defects in a Single AA substitution in the ß-globin chains of hgb
- →valine substituted for a glutamic acid
- Hgb aggregates & forms polymers when there is low O2 concentrations
- Hemoglobin S has a shorter life span
- 12-17 days vs 120 days normal
- the sicke cells obstructs and occlude small vessels
Sickle cell trait vs. disease
-
trait = heterozygus carriers (asymptomatic)
- 8% African Americans are Heterozygous carriers (hemoglobin genotype AS
- Usually are asymptomatic & Do NOT need Rx
- 40% of their Hgb is S
- 5% at some time have: hematuria, difficulty concentrating urine, and do not require pre-op transfusions
-
disease = Homozygus (have the disease)
- Hgb S - 70-98%
- Anemia is well-tolerated – pts have compensatory RIGHT shift of oxyhemoglobin dissociation curve to provide adequate O2 delivery to tissues
- These pts have a 30% overall complication rate: stroke, HF, MI, hepatic or splenic sequestration, RF
- Avoid all situations leading to: Hypoxemia, Hypovolemia, Stasis
Explain a Sickle cell crisis
- Life threatening
- Acute vaso-occlusive crisis (Deoxygenation causes Hgb S to form insoluble globulin polymers)
- Ischemia and organ infarcts
- very painful
- Can cause stroke, renal failure, liver failure, splenic sequestration, PE and acute chest syndrome
Periop planning for Sickle cell anemia
- O2
- 12 hours hydration
- Pre-op exchange transfusons (HCT to 30% Hgb S )
-
Caution with pre-med
- avoid respiratory depression that can lead to acidosis
- USE Regional!
- AGGRESSIVE pain management
- Strict aseptic technique, must avoid infections
- Avoid tourniquets
AVOID ALL SITUATIONS LEADING TO
- Hypoxemia
- Hypovolemia
- Stasis
What are the signs and symptoms of acute chest syndrome and how is it managed?
Signs and symptoms of acute chest syndrome due to pumonary vascular occlusion
- Pleuritic chest pain
- dyspnea
- fever
- acute pulmonary HTN
Treatment:
- Transfuse to Hct 30%
- give oxygen
- antibiotics
- inhaled bronchodilators
- aggressive pain management
Thalassemia major
patho and signs and symptoms
- Inability to form alpah or beta-globin hemoglobin chains
Signs and symptoms:
- Hepatosplenomegaly
- Dyspnea &orthopnea
- Infection risk
- CHF, dysrhythmias
- Bone malformations (Overgrown maxillae - difficult intubation!!!)
- Hemothorax
- Spinal compression (No epidurals or spinals)
- Mental Retardation
- Digitalis sensitivity
- Increased RBC production
- Jaundice
- Iron overload
thalassemia
Perioperative risks and concerns
- Difficult airway (maxillary deformities), consider awake fiber optic
-
Complications of iron loading d/t chronic therapy
-
Arrythmias, CHF, Right heart failure, cardiomyopathy
- Get an EKG and ECHO
- also note: VERY sensitive to the effects of digitalis
- Adrenal Insufficiency
- Decreased vasopressor response
- Hemodynamic compromise with induction agents
- if low cardiac reserve use cardiac sparing drugs
- Diabetes → monitor blood glucose
-
Liver Dysfunction→ coagulopathy
- AVOID regional
-
Hepatosplenomegaly
- thrombocytopenia
- increased infection risk
- Hypothyroid and hypoparathyroid
-
Arrythmias, CHF, Right heart failure, cardiomyopathy
Aplastic anemia is caused by
- Bone marrow failure characterized by destruction of rapidly growing cells
- Marrow damage from:
- Drugs (all kinds)
- Radiation
- Chemotherapy
- Infectious diseases
- CBC values extremely low
- Remember: usually see spontaneously bleeding with plt counts of <50-75K; these pts may need pre-op transfusion
- Know the pt’s pre-op medications and therapies. They will typically be on steroids, chemo, Rad tx
Aplastic anemia
perioperative risks and concerns
- Often on immunosuppression
- may need “stress dose” steroids
- Reverse isolation
- Prophylactic antibiotics d/t neutropenia
- Hemorrhage (GI and intercranial)
- LV dysfunction due to high output state
-
Difficulty in cross-matching
- (have had multiple transfusions)
- Co-existing congenital abnormaliities
- (Fanconi anemia - peds- cleft palate and cardiac defects)
Co-existing congenital abnormalities with aplastic anemia
Fanconi anemia in peds
- Cleft lip/palate
- Cardiac defects
aplastic anemia
Induction
- Consider preop transfusion
- Airway Hemorrhage possible with DVL
- Avoid nasal intubation
- Consider Regional if coags allow
- Will have labile hemodynamic response to induction
aplastic anemia
Maintenance
- PEEP will allow for lower FiO2
- Avoid nitrous (immunosupression)
- Maintain normothermia
aplastic anemia
Emergence
- Extubation and post-op perioid are the periods with greatest oxygen demands
- Monitor coagulation status
Methemoglobinemia
What is it?
What casues it?
- Formed when iron in Hgb is oxidized from the ferrous to the ferric state (2+ to 3+)
- LEFT shift = little oxygen delivery to the tissues
- Normal blood level = 1%
- At 30-50% methemoglobinemia there will be signs of oxygen deprivation→BROWN blood
- Over 50% can lead to coma and death
Causes:
- Nitrate poisoning (SNP)
- Toxic drug reactions
- such as from prilocaine (throat spray)
Anesthesia considerations for metHgb
- Makes the pulse ox inaccurate
- MetHgb absorbs red and infrared light equally
- at SaO2 over 85% → true value is underestimated
- at SaO2 under 85%→ true value is overestimated
- MetHgb absorbs red and infrared light equally
(just think the OVER/UNDER RULE!!!)
- Toxic Methemoglobinemia requires emergent treatment
- Oxygen
-
Methylene Blue 1% solution: 1-2 mg/kg over 3-5 minutes
- Mary repeat after 30 minutes
- Clinical Signs of acute blood loss
20% acute blood loss:
- Tachycardia
- Orthostatic hypotension
- CVP changes
40% acute blood loss
- Tachycardia
- (may have EKG chnages d/t change in O2 carrying capacity)
- hypotension
- tachypnea
- oliguria
- acidosis
- restlessness
- diaphoresis
Acute blood loss
Treatment
-
Restore intervascualr volume
- (crystalloids, colloids, blood products)
-
Monitor Labs
-
Coagulation
- CBC (Hgb/HCT, platelets), PT, PTT, INR, fibrinogen
- Calcium and potassium
- ABGs (persistant metabolic acidosis reflects hypovolemia and inadequate oxygen delivery to the tissues)
-
Coagulation
-
Hemodynamic monitoring
- CVP, A-line, +/- PA
- do they have adequate urine output? Hematuria?
Blood loss
Induction, maintinence and Post op
- Induction: Ketamine/Etomidate
-
Maintinence
- May too unstable for ANY Inhaled anesthetics
- trauma cocktail = scopolamine, benzo, opioid mix
- Keep warm
- use pressors sparingly→not treating the problem!
- watch surgical field for non-clotting blood
-
Post-operative
- May need post op ventilation
- Risk for Pulmonary edema and ARDS
Definition massive transfusion
what are consiquences of massive transfusion?
Definition
- More than 10 units PRBCs in 24 hour period
- Replacement of at least one blood volume in 24 hours
- 50% blood volume replacement in 6 hours
Consiquences
- Hypothermia
- Volume overload
- Dilutional coagulopathy
- Decreased 2,3-dpg
- Hyperkalemia
- Citrate toxicity (hypocalcemia)→hypotension
- Tissue hypoperfusion and lactic acidosis
Polycythemia
What is it?
Problem?
Increased Hct and high RBC mass → caused by:
- dehydration
- Excess RBC production (polycythemia vera)
- Chronic hypoxia
Increased blood viscosity poses risk for:
- Thrombosis leading to CAD, pulm HTN, CNS disorders
- Hct > 55% is problematic
Hemophilia A
Anesthesia considerations
- Factor VIII (8 deficiency)
-
Increased PTT NORMAL PT
- Severe→ (VIII 1%) childhood diagnosis → spontaneous hemorrhages; joints, muscles, organs
- Moderate→ (VIII1-5%)high bleeding risk in surgery→ Have less joint bleeding problems
- Mild→ (VIII = 6-30%)→adultdiagnosis→bleeding risk inMAJOR surgery
-
Anesthesia considerations:
- Pre-op factor VIII →start at 100% then mintain at >50%
- IV: 50-60 U/kg loading then 25-30 U/kg q8-12 hours
- E1/2 = 12 hours
- May need for two weeks post op.
- DDAVP is also effective at correcting for surg
Hemophilia B- Severe, moderate, mild
Congenital Factor IX deficiency
Increased PTT normal PT
- Severe (factor IX 1%)→ severe bleeding
- Moderate(factor IX = 1-5%)
- Mild (factor IX = 5-40%)
Anesthesia Considerations
- GIVE factor IX prior to surgery!!!
- 7000 Units (70kg) = 100 U/kg
- Half life is 18-24 hours, so 50% of original dose needs to be given every 12-24 hours to keep levels about 50%.
- Treatment can result in increased thromboembolic events
von Wilibrand disease
Anesthesia considerations
Von Wilibrand Disease
- Dysfunctional platelets (NORMAL plt count)
- prolonged Bleeding time (>10 minutes)
- Increased PTT
-
Bleed from mucus membranes
- epistaxis, bruising, menorrhagia, gingival and GI bleeding
Anesthesia Considerations
- Avoid messing with the nose (intubation/trumpets)
-
Desmopressin (DDAVP) IV or intranasal
- IV: 0.3mcg/kg in 30-50ml NS over 10-20 minutes
- Intrnasal = 300mcg divided between each nostril
- (can produce tachycardia and hypotension)
- Cryo for severe bleeding or surgical prophylaxis
Compare Labs and Treatment
Hemophelia A, Hemophelia B and von Wilibrand disease
Platelet Dysfunction
Causes and Treatment
Drugs
-
Asprin/NSAIDS
- Inhibits aggregation for life of the platelet
- bleeding time = 2-3x longer within 3 hours of ingestion
- 72 hours = returns to normal
- Aggregation inhibited up to 10 days
- Antibiotics
- Interferes with platelet adhesion and activation
- Biggest impact on critically ill
-
Volume expanders
- dextran = platelet inhibition
- hespan = dilutional thrombocytopenis
Other Factors
- Hypothermia
- Acidosis (pH
- Uremea and liver disease
Treatment
- vWF in Cryo
- Desmopressin DDVAP
- Platelet transfusion
Thrombocytopenia
what is it?
signs and symptoms
goals and treatment
- Low platelet count
- approximately 1/3 of platelets sequestered in spleen
- Signs:
- Petechial rash
- nose bleeds
- GI bleeds
- bruising
- Need >50,000 for major surg
- A six pack of platelets should increase platelets by about 50,000
Most common intra-op coagulopathy
- Dilutional thrombocytopenia or coagulopathy
- occurs when blood loss replaced with crystalloid, colloid or PRBCs
- dilution of platelets and clotting factors
- occurs with massive transfusion (more than 10 units)
- Surgical hemorrhage also causes fibrinogen release from hepatic stores
Acquired defects in platelet production
- Radiation
- Chemo
- Toxic chemicals
- Thiazides,
- ETOH,
- estrogen
- Cancer
- Viral hepatitis
- B12/folate deficiency
Tests of Coagulation
Lab Values
Clotting factors
DIC
What is it?
what is it associated with?
Clinical symptoms?
Labs
Treatmetn
DIC = diseminated intravascular coagulation
-
Classified as a Consumptive coagulopathy
- Bleeding, microemboli, consumption of platelet and clotting factors, fibrin deposits and impaired fibrin degredation
-
Associated with:
- sepsis, trauma, cancer, immune disorders
- OB complications, vascular disorders
- Clinical symptoms d/t thrombosis and bleeding:
- microemboli accumulation in the pulmonary system
- organ damage
-
No single lab test diagnostic
- Rapid decrease in PLT to
- Prolonged PT/PTT
- Presence of split fibrin degridation products
- Normal Fibrinogen levels
- Low plasma Antithrombin III
- Treamtment = manage casue and coagualtion process
- PLT, FFP, Fibrinogen, Antithrombin III
- Heparin (Blocks thrombin and faciltates hemostasis)
- Hemodynamic and respiratory support
Vitamin K deficiency
- Vitamin K is needed for formation of factors
- II, VII, IX, X
-
Causes:
- Malnutrition/malabsorbtion
- Antibiotic induced elimination of intestinal flora
- Liver Disease/obstrucyive jaundice
-
Lab profile:
- Prolonged PT, NORMAL PTT
-
Treatment:
- Vitamin K (takes 6-24 hours for effect)
- FFP for acute bleeding
Hypercoagulability Disorder
Causes
Anesthesia considerations
Causes of Hypercoaguability disorders
- Malignancies, Pregnancies, Oral contraceptives
- Lupus, Nephrotic syndrome
Anesthesia considerations
- Prevent thrombus, PE, DVT, blood clots
- Early ambulation
- SubQ heparin
- Compression devices
- ASA
- IVC filter
- Regional anesthesia is beneficial, but contraindicated if pt on LMWH
What is long-term anticoagulation therapy used for
Long term anticoagulation used for:
- A-fib, Venous thrombosis and heart valves
- Hereditary hypercoagulable states
- Cancer
(Threapy poses a problem at the time of surgery → MUST evaluate the risk of thrombosis with the risk of bleeding)
Antiplatelet therapy is indicated periop for what conditions? Which meds are commonly used?
Antiplatelet therapy indicated for:
- Pts at high risk for CVA, MI, vascular thrombosis complications
Medication used
- ASA, PDE inhibitors, ADP receptor antagonists
Warfarin
Anesthesia considerations
-
Mechanism
- Competes with vitamin K →inhibits formation of vitamin K dependent clotting factors
- factor II, VII, IX, and X
- Lab tests: PT/INR
- Reversal: Vitamin K, FFP, 4 factor PCCs
-
Holding Warfarin prior to surgery:
- At least 5 days
- check INR ONE day preop,
- if > 1.8→ give 1 mg vitamin K subQ
-
If they are high risk and cannot go without anticoagualtion
- Start heparin 3 days after stopping warfarin
- Stop heparin 6 hours prior to surg
- surgery can be safely performed if INR
- (regional??? I wouldn’t)
Heparin
Anesthesia connsiderations
Mechanism
- INDIRECTLY inhibits thrombin and Xa by binding to antithrombin III
Lab tests: PTT or ACT
Reversal: Protamine
Complication: HIT (thromboembolic complication)
What is P50
- the partial pressure at which 50% of hemoglobin is saturated
- Usually around 26-28%
- A right shift needs a higher partial pressure to sarurate 50% (left shift = lower PP)
Relative partial pressures and oxygen saturation
At 40 mmHg 70% of hemoglobin will be saturated
At 60 mmHg 90% of hemoglobin will be saturated
Explain the steep part of the oxyhemoglobin disassociation curve
- there is a rapid unloading of O2 in response to a small change in the partial pressure of O2
Treatment for acute blood loss
-
Restore intervascualr volume first!!!
- Colloid
- crystalloid
- Blood products (O2 carrying capacity)
-
Monitor coagulation
- (blood loss decreases clotting factors)
- PT, PTT, INR, CBC, PLT
- If you see oozing in the surgical field CHECK FIBRINOGEN!!!
- Monitor serum calcium and potassium levels
- citrate binds to calcium
- blood products have high potassium and will have a higher contenct as the cells degrade
- Hypotension? may need some calcium!
- ABGs
- persistent metabolic acidosis reflects reflects hypovolemia and decreased oxygen delivery to the tissues
