Sickle Cell Disease Flashcards
Where do sickle cells sequester?
Sickle cells commonly sequester in the spleen and undergo phagocytosis by the reticular endothelial system. Commonly this leads to splenic congestion and splenomegaly with increased infection risk especially bacteraeia
What is sequestration crisis?
It is caused by pooling of blood in the spleen. Sequestration crisis would present with shock (low blood pressure, raised heart rate) and severe anaemia
What is acute chest syndrome?
Caused by pulmonary infiltrates which will be seen on CXR, presents with pain, fever and respiratory symptoms such as tachypnoea, wheeze and cough
How can patients with sickle cell present
painful masoocclusive crisis, triggered by local hypoxia like cold weather
Acute chest crisis, with tachypnoea, wheeze, and cough, with hypoxia and pulmonary infiltrates on chest X-ray
Poor growth
Iron overload from repeated transfusions
Which type of genotype has milder anaemia?
Patients with Hb SC disease have milder anaemia and suffer fewer crises but are more prone to sickle cell reitnoapthy
What are the blood film findings for sickle cell?
Hyposplenism causing Howell-Jolly bodies
Target cells
Sickle cells
How should acute sickle cell crisis be managed?
High-flow oxygen
IV fluids and analgesia
Top-up transfusions – required in some severe cases
Which medication should be given for chronic management of frequent crisis?
Hydroxycarbamide, increases the levels of foetal haemoglobin (Hb F) in the blood, indications for hydroxycarbamide therapy is three or more moderate-to-severe sickle cell crises
What is sickle cell beta thalassemia?
sickle cell trait and a beta-thalassemia trait, leading to abnormal hemoglobin production and potentially severe anemia, pain, and organ damage.
They will have HBs-Beta
What is HbSC?
Sickle cell disease with haemoglobin C, a normal structural variant of haemoglobin A
How should acute chest syndrome be managed?
Oxygen
Analgesia
Empirical antibiotics
What are patients with sickle cell at risk of?
Cholecystitis due to vaosocclusive crisis in microvasulature of gall bladder
Stroke
Poor growth
Chronic renal disease
Retinal disorders
What is a common complication of splenectomy?
Pneumococcal sepsis due to reduced barrier to encapsulated bacteria
Which conditions precipitate sickliing in sickle cell anaemia?
Hypoxaemia
Acidosis
Dehydration
E.g. infection, sudden changes in temperature, stress, pregnancy
- These are all conditions that favor thetautform of hemoglobin (exposes a hydrophobic patch that allows for aggregation / polymerization
What is aplastic crisis?
Aplastic crisis is a possible feature ofsickle cell diseasethat involvesacute & reversible reticulocytopaenia
Commonly due to Parvovirus B19
Require normal blood transfusions
What is the presentation of sickle cell trait?
Sickle cell trait presents in severe conditions. A complication presents withpainlessgrosshematuriawithnumerousintactRBCson microscopic examination
Renal papillary necrosis (secondary to sickle cell trait)
Often the only symptom insickle cell trait
Why is sickle cell anaemia asymptomatic in new burns?
Fetal haemoglobin (HbF) is high at birth & protects against sickle cell for the first 4-6 months, then HbF ↓ and HbS ↑
Why does the spleen become dysfunctional in sickle cell?
Autosplenectomy Caused by chronic infarction from occlusion of microvasculature with sickled RBC. Immunise patients to protect from encapsulated bacteria & consider prophylactic antibiotics until age 5
Which organisms are sickle cell patients at risk from?
Encapsulated organisms Streptococcus pneumoniae,Haemophilus influenzae,andNeisseria meningiditis
What is the role of the spleen aginast specific bacteria?
The spleen filters blood, including bacteria. Encapsulated bacteria is opsinised, then specialised macrophages phagocytose them. The immune system finds difficulty detecting & destroying them without the spleen, thus making patients susceptible to encapsulated bacteria
What is the vaccination for sickle cell disease?
Vaccination is pneumococcal, Men B and Hib vaccine and influenza ideally 2 weeks before splenectomy.
What is the prophylactic antibiotic for sickle cell?
Prophylactic antibiotics will be Phenoxymethypenicillin
What is a marker on blood test used when investigating response to infection in sickle cell patients?
Reticulocyte count which should be elevated due to chronic anaemia
What is the management of an acute chest crisis?
Antibiotics
Oxygen
IV morphine
-> arises from occlusion of pulmonary microvascualture causing infarction
