Anemia and coagulopathy 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*1.39)SaO2+PaO2(0.003)
Compensation mechanisms for anemia
Increase CO
Increase 2,3-dpg
Increase plasma volume
Decreased blood viscosity
Decreased SVR
Blood shunting to organs with higher extraction ratios
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
Decreased pH
Hgb variants with decreased oxygen affinity (fetal Hgb)
Increased 2,3-dpg
Increased Temp
Curve shifts to the left are seen with
Increased pH
High oxygen affinity Hgb variants
Decreased 2,3-dpg
Decreased Temp
Suspicion of anemia begins around
Hgb <11.5 for females (Hct 36%)
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.
Anesthesia considerations for chronic anemia
Maximize O2 delivery- high FiO2
Avoid drug induced decrease in CO- consider etomidate induction, high opioid maintenance, hydrate/avoid hypovolemia
Avoid left shifts- no hyperventilation, no hypothermia
How do volatile agent kinetics change in a patient with anemia?
Lower B/G coefficient, faster on/off, may need less gas
In an anemic patient, what often offsets the lower B/G coefficient in regards to inhaled agents
Increased CO (That’s Pharm and Coexisting colliding…)
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-
Macrocytic (Megaloblastic bone marrow)
Bilateral peripheral neuropathy Loss of proprioception/vibratory sensation in lower limbs Decreased tendon reflexes Unsteady gait Memory impairment/mental depression
Anesthesia considerations for pernicious anemia
Avoid regional blocks (neuropathys) Avoid N2O (binds B12) Maintain oxygenation Emergency correction for surgery is RBC transfusion
Folic acid deficiency anemia-
RBCs are?
May result in-
Same are B12
Smooth tongue Hyperpigmentation Mental depression Peripheral edema Liver dysfunction Severely ill patient
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 (hemolytic)- What is it? Who does it affect? What should you avoid?
Most common enzymopathy, leaves RBCs susceptible to oxidation. Acute and chronic episodes. Increased rigidity of RBCs, increased clearance.
Blacks, Asians, Mediterranean populations
Avoid oxidative drugs (LAs, Benzos, Meth. Blue)
Avoid hypothermia, acidosis, hyperglycemia, infection
Pyruvate kinase deficiency (hemolytic)
Deficiency of glycolic enzyme leads to K+ leak, results in rigid RBC and increased clearance.
2,3-dpg accumulates, causes right shift
Peri-op risks for hemolytic anemia
Tissue hypoxia
Increased infection risk if prior splenectomy
Increased thrombosis risk
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 transfusions
Caution with methylene Blue
SS- patho
Inherited
Single AA defect in either the alpha or beta chains
Mutant S hemoglobin likely to form aggregates when exposed to low O2 concentrations
SS 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 AA 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
SS crisis
Life threatening
Deoxygenation leads to Hgb S forming insoluble globulin polymers
Acute vaso-occlusive crisis, organ infarcts, very painful
Anesthetic concerns for SS
Assess for organ damage, cardiac dysfunction, current infections
Possible benefit from conservative preop transfusions with high risk surg
What is the ASA goal for Hct in SS
30%