Sickle Cell Vaso-Occlusive Crisis

Sickle cell disease (SCD) occurs when a person inherits two affected beta-globin alleles: usually HbSS, HbSC, HbS/beta-zero thalassaemia, or HbS/beta-plus thalassaemia. Severity differs by genotype and by person, but acute-care principles are similar. Sickle cell trait means one sickle allele; it is a carrier state and does not require sickle-cell-disease crisis care. In SCD, deoxygenated haemoglobin S (HbS) sticks together into long polymers. The red cell becomes rigid and distorted instead of flexible enough to pass through narrow vessels. Rigid cells obstruct small vessels, while haemolysis shortens their lifespan. The result is chronic anaemia plus intermittent tissue ischaemia. A vaso-occlusive episode (VOE), also called a pain crisis, is pain caused by impaired blood flow and inflammation in bone, marrow, muscle, or other tissues. Pain may affect the back, chest, abdomen, arms, legs, or joints. It may be severe despite a calm appearance, normal vital signs, or no obvious injury. Dehydration, infection, hypoxaemia, acidosis, cold exposure, physical stress, and emotional stress can promote sickling. These are contributors, not proof that the patient caused the crisis. A person with an individualized pain...