• Sickle cell disease (SCD) and its variants - genetic disorders resulting from the presence of a mutated form of Hb, HbS.
• most common form of SCD = homozygous HbS disease (HbSS), an autosomal recessive disorder

Pre-empting factors which may promote erythrocyte sickling (and vaso-occlusive crises) include:

• Hypoxemia is the strongest stimulus for sickling (deoxygenated hemoglobin S is less soluble).
• Acidosis
• Dehydration
• Infection and inflammation
• Fever
• Stasis of blood (e.g., reduced cardiac output)

1. fever

• consider veno-occlusive disease, acute chest syndrome, osteomyelitis, local or systemic infection
• vaso-occlusive crisis
• assume this is the cause of any painful presentations

2. acute chest syndrome

• life-threatening lung infarction
• assume if hypoxia + chest pain

3. acute splenic sequestration

• typically occurs in infants
• associated with increased spleen size
• fall in Hb by >20 g/L, thrombocytopenia but normal or increased reticulocytes

4. aplastic crisis

• fall in Hb as well as reticulocytes <1%
• triggered by parvovirus infection

5. stroke
6. priapism

• stuttering (2-4h duration and may be recurrent)
• severe (>4 hours and may lead to permanent impotence)

Priorities:

1. Analgesia - requires aggressive pain Mx
2. oxygenation
3. rehydration - ECF (N saline)
4. may need transfusion
5. may need antibiotics
6. avoid thrombolytics in stroke
7. priapism may require surgical intervention

Emedicine: Sickle Cell 2020
https://litfl.com/sickle-cell-crisis/
https://emcrit.org/ibcc/sickle-chest/