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121 Cards in this Set
- Front
- Back
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The principle defect in herediatry Spherocytosis (HS)
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deficiency in membrane skeletal protiens usually spectrin and ankyrin
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Some symptoms of HS are
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splenomegaly and experience of easy fatiguability in proprotion their chronic anemia.
Also pigment gallstones and should be suspected in biliary colic patients |
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What precipitates a hemolytic crisis in HS
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viral or bacterial infection
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What precipitates aplastic crisis in HS
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parovirus B19 infection
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What are the anesthetic considerations for HS
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Episodic anemia often tirggered by viral or bacterial infection, cholelithiasis must be taken into consideration.
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What is th abnormality in herediatry elliptocytosis
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abnormality in one of the membrane proteins spectrin or glycophorin that makes the erythrocyte less pliable.
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What is the defect in acanthocytosis
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defect in cell membrane structure found in patients with a congenital lack of lipoprotein-B (abetalipoproteinemia).
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What is accumulated in the outer membrane of of the erythrocyte in acanthocytosis?
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cholesterol or sphingomyelin.
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what is the abnormality in paroxysmal nocturnal hemoglobinuria (PNH)
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abnormalites in or reduction of membrane protein known as glycosylphosphatidyl glycan.
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What are patients with PNH at increased risk for?
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venous thrombosis due to activation of coagulation by the dysregulated complement activation
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What are three disorders that affect red cell structure
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Hereditary spherocytosis
hereditary elliptocytosis Paroxysmal Nocturnal hemoglobinuria |
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name the 4 glucose supported metabolic pathways that intracellular Hgb depends on
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Emden meyeroff pathway
phosophogluconate pathway Methoglobin Reductase Pathway Luebering-Rapaport Pathway |
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What is Emden Meyeroff Pathway responsible for
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generation of ATP necessary for membrane function adn the maintenance of cell shape and pliability
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what are the results of defects in the Emden Meyeroff pathway
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increased red cell rigidity and decreased survival which produces hemolytic anemia
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Are there morphologic red cell changes in Emden Meyeroff pathway
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No
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What is th abnormality in herediatry elliptocytosis
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abnormality in one of the membrane proteins spectrin or glycophorin that makes the erythrocyte less pliable.
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What is the defect in acanthocytosis
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defect in cell membrane structure found in patients with a congenital lack of lipoprotein-B (abetalipoproteinemia).
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What is accumulated in the outer membrane of of the erythrocyte in acanthocytosis?
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cholesterol or sphingomyelin.
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what is the abnormality in paroxysmal nocturnal hemoglobinuria (PNH)
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abnormalites in or reduction of membrane protein known as glycosylphosphatidyl glycan.
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What are patients with PNH at increased risk for?
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venous thrombosis due to activation of coagulation by the dysregulated complement activation
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What are three disorders that affect red cell structure
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Hereditary spherocytosis
hereditary elliptocytosis Paroxysmal Nocturnal hemoglobinuria |
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name the 4 glucose supported metabolic pathways that intracellular Hgb depends on
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Emden meyeroff pathway
phosophogluconate pathway Methoglobin Reductase Pathway Luebering-Rapaport Pathway |
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What is Emden Meyeroff Pathway responsible for
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generation of ATP necessary for membrane function adn the maintenance of cell shape and pliability
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what are the results of defects in the Emden Meyeroff pathway
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increased red cell rigidity and decreased survival which produces hemolytic anemia
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Are there morphologic red cell changes in Emden Meyeroff pathway
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No
and this pathway is not subject to hemolytic crisis after exposure to oxidants |
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Non-oxidative anerobic pathway
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Emden Myerhoff pathway
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what does the phosphogluconate pathway do
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counteracts environmental osidants and prevents globin denaturation
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what are the two key enzymes that a person may lack one or both of in phosphogluconate pathway
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G6PDor glutathione reductase
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what does glutthione reductase do?
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protects the red cells from the toxicity of the oxygen it carries
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where are the regional varients of G6PD
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mediterranean southeast asia and chinese territories
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where is G6PD encoded
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X chromosome
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acute Insults that precipitate new or aggravate pre-existing anemias are
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infections drugs or fava bean injestion
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why is methylene blue a concern with G6PD deficiency
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Patient with methoglobinemia adn G6PD deficient can be life threatening.
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Most common enzyme defect causing congenital hemolytic anemia
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pyruvate kinase deficiency
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pyruvate kinate def is most likely to manifest as what kind of anemia
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chronic
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Severely affected individuals of pyruvate kinase deficiency may manifest what symptoms
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chronic jaundice, pigmented gallstones, and manifest spleenomegally.
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what may eliminate the need for transfusions and improve chronic hemolysis with pyruvate kinase deficiency
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spleenectomy
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what does the methoglobin reductase pathway do
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maintain heme iron in its ferrous state
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What happens with mutation of methoglobin reductase pathway
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inability to couneract oxidation of Hb to methemoglobin the ferric form of Hb what will not transport oxygen.
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What does type II methoglobin reductase cause
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severe cyanosis and mental redardation
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what does type I methoglobin reductase cause
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accumulate small amounts of methoglobin in circulating red cells....
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what is the Leubering rapaport pathway responsible for
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production of 2.3 DPG
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what does the synthetase activity in leubering rapaport pathway do
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results in 2,3 DPG formation
Favors an alkalotic environment |
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what doe the phophotase activity in leubering rapaprot pathway do
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converts 2, 3 DPG to 3-phosphoglycerate returing it to the glycolitic pathway.
favors a acidotic environment |
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what happens when deoxyhb shuttles to oxyhgb
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release CO2 and 2,3 DPG
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what actions are responsible for the sigmoid shape of the oxyhgb curve
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binding of one of the heme groups to oxygen increases the affinity of other groups to oxygen loading.
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what is an example of a single amino acid substitution that results in reduced solubility typically causing precipitation of abnormal Hb
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Hb S Sicle cell disease
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sickle cell disease is a disorder caused by substitution of of
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valine for glutamic acid in the Beta-globin unit
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what happens in the deoxygenation state in sickle cell that causes a confirmational change
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a hydrophobic region is exposed.
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what does extreme deoxygenated states in sickle cell cause
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hydrophobic regions aggragate resulting in distortion of erythrocyte membrane, oxidative damage to membrane, impaired deformability, and short half life.
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homozygous form of HbS disease starts early in life with severe hemolytic anemia and vaso occlusive disease involving....
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marrow spleen kidney, and CNS
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In Sickle cell what is the prime target that causes Loss of concentrating ability an early feature of the disease progressing to CRFin the 3rd to 4th decade of life
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renal medulla
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what is a pneumonia like complication in sickle cell that is characterized by a pulmonary infiltrate involving at least one complete lung segment at at least one of the following;chest pain,fever, wheezing, cough, tachypnea
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acute chest syndrome
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Anesthetic risk factors for complications for sickle cell include
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age, # of hospitalizations/transfusions, evidence of organ damage such as low baseline Oxygen sat, elevated creatinine, cardiac dysfunction, hx of CNS event and current infection.
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what are considered intermediate or high risk operations for sickle cell disease
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intermediate are intraabdominal such as chole, and high risk are intracranial and intrathoracic
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what types of surgeries are considerable risk for sickle cell with more than 70% of patients and sickle cell events in 19% of patients
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hip surgery and hip replacement.
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with sickle cell what is the preop goal for hct
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Hct of 30%
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what are the usual secondary goals for operative conditions in patients with sickle cell
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avoid dehysration, acidosis, and hypothermia during anesthesia tourniquets can increase risk of periop complications.
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what are some post op anesthetic considerations with sickle cell patients
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post op pain can exaccerbate a crisis. acute chest syndrome can develop 2 3 days post op adn demands aggresive focus on oxygenation, adequate analgesia, and frequent blood transfusions to correct anemia and imporve oxygenation.
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What happens in sickle cell C hemoglobin
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causes erythrocyte to lose water via enhances activity of the potassium chloride cotransport system resulting in cellular dehydration that in the homoxygous CC state may produce a mild to moderate hemolytic anemia.
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what are anesthetic considerations with Sickle C Hgb
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periop transfusions considerably reduce the incidence of sicle complications in this subset.
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Reduced amounts of Hb A or abscence of Hb A are seen in what hemolytic disease
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hgb sickle-Beta-thalasemia
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What do patients with Hgb sickle beta thalsemia experience
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acute vaso oclusive crisis, acute chest syndrome, and other sickling complications at rates approaching those of Hb SS.
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what do heinz bodies do?
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interact with red blood cell membranes reducing its defromability and favoring its removal by slpenic macrophages.
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what is the anesthetic mgmt concerns with unstable hgb's
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severe bouts treated with transfusion and avoidance of oxidizing agents.
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what are 2 disorders of hgb resulting in reduced or ineffective erythropeisis Macorcytic megoblasitc anemia
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Folate and Vit B12 deficiency
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sustained exposure to what can cause impairment of vitamin B12 activity ... can be found in dental offices or with recreational use
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nitrous oxide
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full blown megoblastic anemia due to folate or vitamin deficiency may result in
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Hb < 8-10, mean cell volume of 110-140, normal retic count, increased levels of lactate dehydrogenase. and bilirubin
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Megoblastic anemia is associated with
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bilat peripheral neuropathy, symmetrical paresthesia's, loss of propioceptive and vibratory sensations esp the lower extremeties, memory impariment and mental depression may be prominent
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what are some anesthetic consideration with folate B12 def
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the preseince of neurologic changes may detract fro selection of regional anesthetic techniques or the use of peripheral nerve blocks.
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what are anesthetic considerations with Sickle C Hgb
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periop transfusions considerably reduce the incidence of sicle complications in this subset.
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Reduced amounts of Hb A or abscence of Hb A are seen in what hemolytic disease
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hgb sickle-Beta-thalasemia
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What do patients with Hgb sickle beta thalsemia experience
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acute vaso oclusive crisis, acute chest syndrome, and other sickling complications at rates approaching those of Hb SS.
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what do heinz bodies do?
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interact with red blood cell membranes reducing its defromability and favoring its removal by slpenic macrophages.
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what is the anesthetic mgmt concerns with unstable hgb's
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severe bouts treated with transfusion and avoidance of oxidizing agents.
even short expossure to nitrous oxied may produce megablastic anemias |
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name two types of microcytic hypochromic anemia
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iron def anemia and the thalasemia's
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In adults what two areas may reflect depletion of iron stores owing to chronic blood loss
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Gi tract and female genital tract.
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what happens in microcytic hypochromic anemia
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RBC's are lost rapidly and the new RBC's that are produced have too little Hb.
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what is treatment for micocytic anemia
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ferrous iron salts orally should be continured for one year favorble repsonses are increase in 2g in 3 weeks or normal level in 6 weeks
recominent erytho may be used for drug induced anemia |
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how is microcytic anemia diagnosed
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abscence of sustainable bone marrow but decreased serum ferrtin concentrations serve as a low cost effective alternative to bone marrow exam
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What region does thalasemia B predominate
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africa and mediteranean
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what region does alpha -thalasemia and Hb E predominate
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southeast asia
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what is the Hbg in thalasemia minor usually
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10-14 at worst
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To survive childhood what is needed for thalasemia major
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long term transfusion therapy
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what do the most severe forms of thalasemia major produce
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1. ineffective eryythropoesis
2. hemolytic anemia 3. hypochromia with microcytosis |
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In thalasemia major what causes damage to red blood cells
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inclusion bodies which are unpaired globins that form and aggregate.
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features of severe thalasemia are
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massive marrow hyperplasia, frontal bossing maxillary overgrowth, stunted growth osteoporosis, extramedullary hematopoesis(hepatomegally) splenomegaly extreme dyspnea and orthopnea, CHF and mental retardation.
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what are some complications with transfusion therapy in thalasemia major
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right sided heart failure, cirrhosis, endocrinapathy require chelation therapy.
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hemoglobins with increase oxygen affinity shift the oxyhgb curve to
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the left. reducing the parital pressure of oxygen to tissues at normal capillary Po2 levels and blood returns to the lungs still saturated.
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what is the net result of Hgb with increased oxygen affinity
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at normal Hct levels a mild tissue hypoxia results triggering increased erythropoeitin production leading to polycythemia.
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preop exchange tranfusion and careful avoidance of hemoconcentration both pre and introperatively may be required in patients with Hct levels greater than....
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55-60%
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what are some anesthetic considerations of treating patients with Hbg with increased O2 affinity
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modest decreases in Hct are potentially dangerous. also very high Hct's may compromise tissure perfusion and induce hypercoaguability.
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what is a condition in which Hgb has a decreased oxygen affinity
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methamoglobonemia
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what happens in methamoglobinemias
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iron is oxidzed to ferric 3+ state. Deoxygenation ordinarily returns the electron to the iron but methoglobin forms if the electron is not returned.
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methomoglobinemia shifts the curve to the
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left due to its higher oxygen affinity delivers little oxygen to the tissues.
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with methomoglobnemia when do patients begin to display symptoms
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at 30-50% if Hgb get oxygen deprivation at above 50% coma and death ensue.
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what can methomoglobinemias arise from
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globin chain mutations favoring methoglobin, impairment of methomoglobin reductase adn toxic exposure to sustances that oxidize normal Hb iron at a rate that exceeds the capacity of normal reducing mechanisms.
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what color does methomoglobin have that does not change when exposed to oxygen
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brownish blue and gives pt's a cyanotic appearance. independent of thier PO2.
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how are methomoglobinemias treated
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1-2mg/kg of meth blue as a 1% solution in saline infused over 3 to 5 minutes and may be repeated in 30 minutes if needed.
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what about patients that are G6PD deficient and methomoglobinemia
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may need exchange transfusions if severely affected.
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what are some anesthetic considerations with methoglobinemias?
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avoidance of oxidizing agents, measurement of methemoglobin levels and PH may be required for the rare patient at risk of developing severe degrees of methemoglobinemia (>30%)
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name some disorders of red cell production
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fanconi anemia, and polycythemia
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what is fanconi anemia
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an autosomal recessive disorder severe pancytopenia usually in the first two decades of life and progresses to acute leukemia
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what population is fanconi anemia high in
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western socieities
white south africans 1 in 80. |
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what is fanconi associated with
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progressive marrow failure, multiple physical defects, chromostomal abnormalities and cancer predisposition.
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what drug has been associated with severe aplastic anemia
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chloraphenicol and is irreversible
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what other things can cause marrow damage
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viral hepatitis, miliary tuberculosis, epstein barr, HIV ruebella, Parvovirus B19,
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tissue oxygen delivery is maximal at a Hct of
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33-36%
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when is polycythemia symptoms noticable
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when Hct exceeds 50%
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what can cause polycythemia
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acute decrease in plasma volume such as with preop fasting,
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what are the clinical signs of polycythemia when hct is 50% or more
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headaches and easy fatigueability
Increase risk of thrombi |
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what are the criteria for diagnosis of polycythemia
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elevated Hct or RBC normal arterial oxygenation and splenomagaly
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when does PV most likely appear
And what is usually the presenting symptom? |
6th or 7th decade
thrombosis esp cerebral thrombosis |
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what do patients regularly require with PV
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phlebotomy to hct 45 for men to 40% for women.
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what are surgical patients at increase risk for with PV
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bleeding diathesis (von willebrands) and thrombosis
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what is secondary polycythemia
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increase in RBC normal physicoligical response to hypoxia ... living at a high elevation.
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what can cause secondary polycythemia
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high altititude, congenital heart disease, extremely low cardiac output, pulmonary disease, pickwickian syndrome,
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what shift does seconary pv cause
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left
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what are the antesthetic considerations with secondary pv
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oxygen therapy, preop phlebotomy, periopertive hypercoagubility and potential bleeding diathesis.
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what are the causes of 2nd PV due to increased erythropoeitin production
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renal disease and erythropoetin tumors
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what are the anesthetic considerations wtih 2nd PV due to increased erytho production
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preop phlebotomy, periop hyperocoag and potential bleeding diatheses
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