Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
pathophysiology of sickling
|
beta gene mutation that leads to amino acid replacement (glu --> val); when Hb dumps o2 and becomes deoxy HbS; becomes reversibly sickled when found in mild hypoxemic environments like microvasculature; if this back and forth goes long enough for an rbc, the membrane can become rigid and irreversibly sickled
|
|
|
what is the most critical relationship for sickling?
|
delay time for sickling versus the transit time throgh hypoxic microvasculature.
|
|
|
what are the manifestations of sickle cell dz?
|
-hemolysis
- irreversibly sickled red cells - organ damage (spleen - cells sickle in the spleen and destroy it; it's the first organ to go) |
|
|
tell me the diff bw these sickle cell dz's:
-SS -SC -Sbeta0 -Sbeta+ |
SS- homozygous mutation - more severe dz
SC - on electrophoresis = 50%S, 50%C...milder course/less anemia S on one chromosome 11 and beta thalassemia on the other gives sickle-beta thalassemia which closely resembles SS, except the MCV is microcytic. Sbeta0- beta thal minor, but you make none of the beta chains (similar course to SS) Sbeta+ - beta thal minor on one chain, sickle on the other...but some beta globulins are produced and this gives your mild dz with enlarged spleen |
|
|
why isn't SC disease manifested until 6 months of age?
|
its masked by HbF until then...HbF inhibits HbS polymerization and with HbF, the mixture of S and F have more solubility
|
|
|
tell me about celular dehydration and what it does to sickle cells
|
Sickle cell diseaes red blood cells are young and have increased activity of the Gardos channel and K-Cl cotransport which act to keep K moving out of the cell taking water with it. The cell dehydrates, the HB S concentration increases and sickling occurs more readily.
|
|
|
tell me about sickle cells and adhesion
|
young red blood cells are more adherent to endothelial cells - this adhesion may account for prolonged transit time in microvasculature --> so that in hypoxic areas, this will increase the delay time for sickling to occur will lead to vasooclusion
|
|
|
tell me about the microvascular effects of sickle cell
|
chronic intravascular hemolysis with poor splenic fxn may lead to inc free hemoglobin levels and scavenging of NO leading to vasoconstriction
|
|
|
why do Saudi's have milder dz?
|
they have higher F levels (epigenetic effects) --> more benign course
|
|
|
how does sickle trait show up in blood smear morphology and CBC? how do you dx (2)?
|
normal CBC, normal peripheral blood smear
dx: screen by solubility test Hb electrophoresis |
|
|
T or F. in SS disease, MCV is normal.
|
T
|
|
what dz is shown?
|
SS- Hb dz (homozygous sickle cell dz)
|
|
|
what do howell-jolly bodies show?
|
evidence of absent splenic fxn (as in SS Hb dz)
|
|
|
how do you make the dx of Hb SS dz? (like which lab tests do you need -- 2)
|
electrophoresis OR HPLC (show HbS as principal Hb)
|
|
|
what does a high flow rate in the circle of willis indicate?
|
that there may be stenosis (smaller lumen) and may mean future stroke in a sickle cell pt ==> bad news
(MCA velocity >170 and greater risk for stroke) |
|
|
what is chest syndrome and how can it be tx'd?
|
The patient present with sickle pain crises then rapidly developed chest pain, fever, dyspnea, and leukocytosis (can't tell b/w pneumonia). Can be ameliorated if you transfuse the patient.
other tx: antibiotics, incentive spirometry, give o2 |
|
|
there is high prevalence of mild ______ HTN in SSD. why is this a cause of concern?
|
pulmonary; this increases mortality rates
|
|
what dz is this?
|
SC Hb disease (fewer sickled cells, these are "fat" sickles, with lots of targeting and very dense spherocytes)
|
|
what dz does this show?
|
SB thal minor
|
|
|
what are causes of death in SS dz pts?
|
multi-organ failure (renal, hepatic, pulmonary HTN)
acute death (during pain crisis, chest syndrome, stroke!!) |
|
|
why are children with SS living longer nowadays
|
they are getting screening birth
|
|
|
when can you use transfusion for a SS dz pt? WHEN DO YOU NOT USE TRANSFUSION?
|
strokes
aplastic crises chest syndrome prior to gen anesthesia complicated pregnancies NOT USED FOR ROUTINE CRISIS |
|
|
which pts get hydroxyurea and how does it help?
|
offered to pts with >3 crises a year
it works by increasing HbF production so that not only is Hb spread out over more cells, F suppresses sickling!! |
