Sickle cell anaemia Flashcards
What is sickle cell anaemia?
A disease of RBCs caused by an autosomal recessive single gene defect in the beta chain of haemoglobin (HbA) which results in sickle cell haemoglobin (HbS)
Aetiology of sickle cell anaemia
Inherited condition.
Sickling occurs when RBCs containing sickle Hb become rigid and distorted into a crescent shape.
Pathophysiology of sickle cell anaemia
The polymerisation of sickle Hb in RBCs can be triggered by hypoxia and acidosis.
This causes cells to become rigid and deform into a crescent shape.
These deformed cells may cause vaso-occlusion in the small vessels or they can adhere to vascular endothelium, resulting in intimal hyperplasia in larger vessels and slowing blood flow.
These deformed cells are also prone to haemolysis, which contributes to anaemia.
What are the precipitants of sickle cell anaemia crises?
Acidosis Dehydration Cold temperature Extreme exercise Stress Infections
Signs and symptoms of sickle cell anaemia
Persistent pain in the skeleton, chest and/or abdomen.
Dactylitis- swollen dorsal of hands and feet.
High temp with cough, watery stools, tender abdomen, malaise, chest pain, diarrhoea is suggestive of infection.
Bone pain.
Pneumonia-like syndrome.
Visual floaters
Tachypnoea
Failure to thrive: infants
Pallor
Jaundice
Lethargy
Risk factors of sickle cell anaemia
Parents diagnosed with sickle cell anaemia or they have the sickle cell trait.
Investigations of sickle cell anaemia
DNA-based assays Haemoglobin isoelectric focusing Electrophoresis Peripheral blood smear FBC and reticulocyte count Iron studies
Differentials of sickle cell anaemia
Gout Septic arthritis Connective tissue diseases Avascular necrosis Perthes' disease Acute abdomen Osteomyelitis Trauma
Management of sickle cell anaemia in young children
The main treatment goal is to improve survival by reducing the threat of infections. This can be achieved through: -Early diagnosis -Pneumococcal immunisation -Antibiotic prophylaxis with penicillin -Nutritional counselling
Management of sickle cell anaemia in adults
The main treatment goals are symptom control and management of disease complications.
This can be achieved through:
-Pain management (chronic and acute)
-Pharmacological amelioration of disease severity with the use of hydroxycarbamide.
-Prophylaxis and prompt treatment of infections.
-Prevention and management of acute complications (acute chest syndrome)
-Prevention of stroke
-Prevention and treatment of chronic organ damage (kidney, renal, pulmonary)
-Genetic counselling
Prophylactic treatment in sickle cell anaemia
Hydroxycarbamide- prevents life-threatening neurological events in patients at risk of stroke and reduce the frequency of dactylitis in infants.
L-glutamine- In people who are intolerant to hydroxycarbamide or who continue to have painful events while on hydroxycarbamide
Blood transfusion- Repeated simple transfusion is repeated to maintain HbS below 30%
When should bone marrow transplant be suggested for patients with sickle cell anaemia?
Kids with severe complications of sickle cell anaemia (stroke, recurrent acute chest syndrome) who are unresponsive to first-line therapies
Complications of sickle cell anaemia
Stroke- offer regular blood transfusion Splenic infarct before 2 years of age Poor growth Chronic renal failure Gallstones Retinal disease Iron overload Lung damage: hypoxia- fibrosis- pulmonary HTN
Management of crises in sickle cell anaemia
Prompt generous analgesia e.g. IV opiates
Oxygen by mask if sats < 95%
Fluid resuscitation to lower haematocrit
Start antibiotics if there are signs of sepsis
Exchange transfusion reserved for those with rapid worsening.
Why is surgery a problem for patients with sickle cell disease?
Propensity to Hypoxia:
Pre-existing anaemia
Pre-op dehydration
Anaesthesia
Operative blood loss
Stress of the Surgery predisposes to Sickle Crises:
Fever
Post-op hypoxia
Post-op Infection
These pre-dispose to development of:
Painful Crises
Acute Chest Syndrome
