Anemia 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?
Types of amenia
- Acute = Acute blood loss
-
Chronic
- Nutritional Hemolytic
- Aplastic
- Manifestation of another disease
- Abnormal RBC structure (SS, Thalassemia)
What are the CLINICAL manifestations of amenia
Decreased oxygen carrying capacity and the accompanying decreased tissue oxygen delivery
What defines O2 carrying capacity
Hgb.
Anemia decreases it.
Bonus- What are the B/G coefficients of the common volatile agents?
- N20- 0.47
- Halothane- 2.3
- Enflurane- 1.8
- Isoflurane- 1.4
- Sevoflurane- 0.69
- Desflurane- 0.42
In anemia treatment, what two things must be considered
Treatment of the underlying cause, as well as the state of anemia itself
Calculation of arterial blood oxygen content
CaO2 = (Hgb x 1.39) SaO2 + PaO2 (0.003)
Compensation 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
In anemia, the oxy-hemoglobin dissociation curve…
Shifts to the RIGHT
Methemoglobin resembles a shift to
the LEFT
Curve shifts to the right are seen 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)
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Curve shifts to the left are seen 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)
Suspicion of anemia begins around
Hgb
(<11.5 g/dL in females)
(<12.5 in males)
What is the most effective treatment for anemia
Treating the underlying cause
Bonus- What are the maximum doses for Bupivacaine and Lidocaine?
- Bupivacaine- 2.5mg/kg
- Lidocaine- 4mg/kg (7 with epi)
In managing a pt with chronic anemia, what do we really want to avoid?
Disrupting their compensation methods.
For example, most don’t do well with alkalosis, hypothermia, or decreased CO (propofol)
Will intererfere with O2 delivery
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
- How do volatile agent kinetics change in a patient with anemia?
- In an anemic patient, what often offsets the lower B/G coefficient in regards to inhaled agents
- Lower B/G coefficient
- faster on/off,
- may need less gas
Often offset by:
- Increased CO
- That’s Pharm and Coexisting colliding…
The decision to transfuse is based on:
- The clinical judgment that the oxygen carrying capacity must be increased to prevent oxygen consumtion (VO2) from outstripping oxygen delivery (DO2)
What are the two possible goals of transfusion therapy?
- Increase O2 carrying capacity
- Correct a coagulation disorder
1 unit of RBCs will increase Hct by how much
3-5%
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?
- Microcytic (also hypochromic, right?)
- In adults, depletion of iron stores is caused by chronic blood loss
- GI bleed
- menorrhagia
- cancer
- Most common form of nutritional anemia in children
B12-def. anemia (pernicious)- RBCs are? May result in? Anesthesia considerations?
Macrocytic (Megaloblastic bone marrow morphology)
May result in:
- Bilateral peripheral neuropathy
- Loss of proprioception/vibratory sensation in lower limbs
- Decreased tendon reflexes
- Unsteady gait
- Memory impairment/mental depression
Anesthesia considerations:
- Avoid regional blocks (neuropathys)
- Avoid N2O (binds B12)
- Maintain oxygenation
- Emergency correction for surgery is RBC transfusion
Causes of acquired hemolytic anemias
Immune Hemolysis and Infection
- Drug induced (High dose PCN, alpha- methyldopa)
- Disease induced (malaria, epsteen Barr)
- Sensitization of RBCs (Materna/fetal)
(particals released durring hemolysis can result in DIC and hypersplenism)
Folic acid deficiency anemia- RBCs are? May result in? Anesthesia considerations?
Macrocytic (Megaloblastic bone marrow morphology)
May result in:
- 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
Anesthesia considerations for folic acid def. anemia
- Thorough airway assessment-
- Have an alternative airway plan in place, often have difficult airways
Glucose-6-Phosphate dehydrogenase deficiency What is it? Who does it affect? What should you avoid?
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, Benzos, Meth. Blue) AVOID: hypothermia, acidosis, hyperglycemia, infection
Pyruvate kinase deficiency
Hemolytic anemmia
- Deficiency of glycolic enzyme→ which converts glucose to lactate→ it is the primary pathway to ATP production →
- leads to K+ leak→ results in rigid RBC and accelerated destruction
- 2,3-dpg accumulates, causes right shift
Peri-op risks for hemolytic anemia
- Tissue hypoxia
- Increased infection risk if prior splenectomy
- Increased risk of venous thrombosis
Pre-op planning for hemolytic anemia
- EPO often given for 3 days pre-op
- Hgb acutely less than 8 or chronically less than 6 should be considered for transfusion
- Ensure pre-op hydration, prophylactic RBC transfusions
- Caution with methylene Blue - can increase hemolysis!!!
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Sickle cell anemia patho
- Inherited Single AA defect in the ß-globin chains
- Mutant S hemoglobin →valine substituted for a glutamic acid
- Hgb aggregates and forms polymers when exposed to low O2 concentrations
Sickle cell anemia trait
- Carriers
- 1 normal, 1 abnormal gene
- 40% is S Hgb, 60% is normal
- Usually non-symptomatic,
- about 5% will have hematuria and difficulty concentrating urine.
- No treatment needed.
- 8% of african americans have the trait
SS disease
- Homozygous for SS trait
- 70-98% Hgb S
- Chronic hemolysis, low O2 situations can lead to vaso-occlusive crisis
Pts with SS disease typically display what type of shift in the O-Hgb dissociation curve?
Right shift
Complications associated with SS disease
- Stroke
- heart failure
- MI
- Hepatic/Splenic sequestration
- renal failure
- High rate of peri-op complications
Sickle cell anemia crisis
- Life threatening
- Deoxygenation causes Hgb S to form insoluble globulin polymers
- Acute vaso-occlusive crisis
- Ischemia and organ infarcts
- very painful
- Stroke, renal failure, liver failure, splenic sequestration, PE
Anesthetic concerns for Sickle cell anemia
- Assess for organ damage,
- cardiac dysfunction,
- current infections
- Possible benefit from conservative transfusions preoperatively if having a high risk surg→ decrease Hgb S to less than 30% (diluted with Hgb A)
3 things that must be avoid in Sickle cell anemia
- Hypoxia
- Hypovolemia
- Blood stasis
Periop planning for Sickle cell anemia
- O2
- 12 hours hydration
-
Caution with pre-med
- avoid respiratory depression that can lead to acidosis
- Regional
- AGGRESSIVE pain management
- Strict aseptic technique, must avoid infections
- Avoid tourniquets