2 Hospital Physician Board Review Manual www.turner-white.com
Management of Acute Chest Syndrome and Other
Pulmonary Complications of Sickle Cell Disease
Amyn Hirani, MD, Sandra Weibel, MD, and Gregory C. Kane, MD, FACP, FCCP
Sickle cell disease (SCD) is an inherited disorder of the hematopoietic system that affects approximately 250 million people globally, making
it one of the most prevalent genetic diseases.
The highest prevalence of SCD is found in Sub-Saharan Africa, South and Central America, Saudi
Arabia, and Mediterranean countries.2–4 In the
United States, the disease occurs at a rate of 1 in
500 births among African Americans and 1 in up to
1400 births among Hispanic Americans.
The sickle-shaped red blood cells that characterize SCD are the result of a single gene mutation
in hemoglobin A that causes the formation of abnormal hemoglobin chains (ie, hemoglobin S) that
polymerize when deoxygenated. These deformed
cells may obstruct blood vessels, causing pain, tissue death, and severe injury in the major organs
in the event of vaso-occlusive crisis. Obstruction
in the blood vessels of the lungs related to the effects of these vaso-occlusive events can cause
lung injury and infarction, a complication known
as acute chest syndrome (ACS).
6 ACS occurs in
approximately 48% of people with SCD, with an incidence rate of 14 episodes per 100 patient-years.
It is a leading cause of morbidity and is the most
common cause of mortality among patients with
VARIANTS OF SCD
The SCD variants result from different hemoglobin gene mutations and differ substantially in terms
of their clinical manifestations. The most common types are homozygous SCD, sickle hemoglobin C disease, and the sickle b thalassemias.
Homozygous SCD occurs when the gene for hemoglobin S, or sickle hemoglobin, is inherited from
both parents. In sickle hemoglobin C disease, the
hemoglobin S gene is inherited from one parent
and the hemoglobin C gene is inherited from the
other. The sickle β thalassemias result from the
inheritance of a hemoglobin S gene and a thalassemia gene. β Thalassemia genes produce
reduced amounts of normal hemoglobin, with the
amount produced varying from patient to patient. In
sickle cell/β0 thalassemia, no normal hemoglobin
is produced, and the clinical manifestations are
comparable to homozygous SCD. In sickle cell/β+
thalassemia, small amounts of normal hemoglobin
are produced, which can mitigate the effects of he-
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