Sickle Clinical Flashcards
1
Q
clinical aspects of sickle cell disease
A
- group of disorders with sickle hemoglobin (HbS) in the homozygous or doubly heterozygous (HbS and HbC) state causes disease
- HbS mutation results in polymerization of HbB upon deoxygenation causing increased RBC destruction and anemia and blockage of capillaries causing pain and/or organ dysfunction
2
Q
frequency and severity
A
- 1/400 african americans have sickle cell disease which is often life threatening
- average life-span close to 50 for females and just over 45 for males
- 30%)
- compare to 1/3000 incidence of CF in US pop
- in real world patient care, racism plays a very large role
3
Q
clinical severity
A
- depends on type of sickle cell disease
- even within a type, great variation in severity
- ~20% of patients have ~80% of complications while the rest have a relatively mild disease
- cause of clinical variability still poorly understood
- likely related to other genotypes-RBC or WBC adhesion
- high WBC may inc risk of disease
- improved ability to predict more sever disease may better guide therapy and decrease morbidity/mortality
4
Q
initial diagnosis: newborn screening
A
- fetal HbF >90% newborns Hg in general
- unaffected by sickle mutation and protects newborn for first 3-4 months
- in past Dx made when complications arose
- some infants died of bacterial sepsis since Dx unknown and fever not managed appropriately
- NB screening in USA allows Dx, education, and prophylactic antibiotics prior to risk of sepsis, decreasing morbidity and mortality
5
Q
native gel
A
- how newborn blood is screen
- Hg with different charges separated
- B6 mutation takes neg Glu to neutral Val-shift in electric migration
6
Q
sickle cell trait
A
- AS
- carrier state in 8-10% of African Americans
- 55-65% HbA, 25-45% HbS
- clinical complications are very rare
- main issue is genetic implications
7
Q
homozygous sickle cell anemia
A
- > 2/3 patients and most form of severe sickle cell disease
- both parents AS- 25% risk
8
Q
Hb SC disease
A
- one parent AS and other AC
- AC found in 2-3% African Americans
- C also defect of beta6 Glu-Lys
- C does not sickle but increases Hb viscosity
- 1/4 patients, milder disease
- 50% S and 50% C, no A
9
Q
sickle cell beta thalassemia
A
- HbS from sickle gene, little or no HbA from ineffective beta thal gene
- 1 parent AS trait, 1 parent thal trait
10
Q
bacterial sepsis
A
- splenic vasooclusion inhibits bacterial clearance
- encapsulated bacteria (pneumococcus) in previously unexposed children require splenic clearance-but can’t do it
- risk begins at 4 months, 15% incidence without penicillin prophylaxis
- frightening complication
- 30-50% mortality
- 2/3 of deaths within 8 hours of 1st symptoms
- most common cause of death <5 years of age
- penicillin prophylaxis, aggressive antibiotic Rx of fever (usually ceftraiaxone), immunization greatly decrease risk
11
Q
painful vaso occlusive episode
A
- most common complication throughout life
- not clear why they are so episodic and unpredictable, usually lasting a few days
- hand foot syndrome often in 1st and 2nd years of life
- episodes can involve almost any area
- pain can be excruciating and often need narcotics
- doses still often inadequate
- morphine patient controlled analgesia best
- respiratory depression and addiction are rare
- supportive care
- pain control, fluids, ensure oxygenation, control fever, transfusion not usually helpful
12
Q
stroke
A
- 10% develop stoke with unilateral weakness
- acute unpredictable onset usually in child
- long term neurologic deficits»_space;death
- RBC transfusions as Rx and prophylaxis
- exchange transfusion acutely
- chronic RBC transfusions to prevent recurrence (without, 70% recur)
- indication for bone marrow transplant
- stroke prevention with transcranial doppler
- high cerebral arterial flow rates predict risk
- prevent 80% of strokes with annual studies ages 2-16 years
13
Q
acute chest syndrome
A
- unique term for acute lung disease in sickle cell
- includes-infection, vasoocclusion, fat embolus
- most common cause of death >5 yrs of age and can cause chronic lung disease in adults
- antibiotics, oxygenation, incentive spirometry, transfusion acutely if more severe and occasionally chronically to prevent recurrance
14
Q
acute splenic sequestration crisis
A
- sudden enlargement of the spleen due to acute vasoocclusion
- occurs in 1st 5 years of life and can rapidly result in hypovolemic shock
- acute treatment involves fluid resuscitation and transfusion
- teaching parents splenic palpation reduces mortality
- listen to the family
15
Q
genetic counseling
A
-obligation to empower parents to make their own decisions
-study both parents-electrophoresis for Hbs and blood count, determine risk of SS, SC, S beta thal
-if at risk, prenatal diagnosis via amnio
-preimplantation genetics
harvest placental cord blood from newborn sibling for safest possible transplant to cure affected sibling
