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Key Points

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  • Control pain aggressively.

  • Search for and treat the precipitants of pain crisis.

  • Complications of sickle cell disease, both typical and atypical, must be aggressively sought after and treated.

  • Have a low threshold for admission when patients may have an occult infection.

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Introduction

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Sickle cell disease (SCD) is an inherited chronic disease found primarily in those of African, Middle Eastern, Indian, or Mediterranean ancestry. SCD is characterized by a defect in the hemoglobin molecule, which normally consists of two pairs of α and β globin. A single amino acid substitution (valine for glutamine) on the β-globin gene results in sickle hemoglobin (Hb S). The mutation that causes the amino acid substitution is inherited as an autosomal recessive trait. Patients with sickle cell trait have one abnormal β-globin gene (heterozygous HbAS), whereas those with SCD have 2 abnormal β-globin genes (homozygous HbSS). During states of biologic stress (eg, low O2 state, infection, dehydration, pregnancy, cold exposure, trauma) the Hb S polymerizes, resulting in deformation (sickling) of the red blood cell (RBC). This sickled RBC has reduced ability to pass through small blood vessels, resulting in vasoocclusion, hemolysis, and end-organ damage. Premature destruction of the sickled RBC results in a shorter than normal life span of the cell.

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Two million people in the United States have sickle cell trait, and 70,000 have sickle cell disease. Although survival has improved dramatically recently, life expectancy of patients with SCD is shorter than average, now just greater than 50 years.

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Most patients with SCD present to the emergency department (ED) with either a painful vasoocclusive crisis or sequela from vaso-occlusion, some of which may be life-threatening. It is the role of the emergency physician to not only control pain but also diagnose and treat potential life threats. Acute sickle cell emergencies can be divided into several classifications: acute pain crisis, acute chest syndrome, infection, neurologic, splenic sequestration, aplastic crisis, hemolytic anemia, and priapism.

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Acute Pain Crisis

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Vaso-occlusive pain crises account for approximately 90% of ED visits. Severe back and extremity pain results from micro-infarction of the bones and joints. Abdominal pain crises result from ischemia to the mesentery, spleen, and liver.

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Acute Chest Syndrome

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Acute chest syndrome is the most common cause of death in patients with SCD. Although it is more common in children, it is more severe in adults. Acute chest syndrome is characterized by fever, chest pain, respiratory symptoms, hypoxia, and an infiltrate seen on chest x-ray (CXR). It is a result of pulmonary ischemia and infarction. Acute chest is frequently a complication of pneumonia. Chlamydia and Mycoplasma are the 2 most common organisms, but viruses, Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae are all potential causes.

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Infection

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Patients with SCD are at increased risk of infection ...

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