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Chapter 42 Sickle Cell Disease 597

bystander effect of destruction of recipient blood (not just donor serum opsonizing activity. Even before the anatomic autoinfarction
blood) can result in unanticipated worsening of anemia to levels of the spleen in patients with sickle cell anemia, defective splenic
145
below that seen before transfusion. In addition to the manifesta- function is demonstrable by Howell-Jolly bodies on the peripheral
tions of a delayed hemolytic transfusion reaction as listed, patients blood smear, visible “pits” on the surface of RBCs, and abnormal
150
may develop acute congestive heart failure, acute renal failure, or results of radionuclide spleen scanning. Specific syndromes exhibit-
acute chest syndrome (accompanied by vasoocclusive pain crisis). ing greater rates of hemolysis cause loss of splenic function at earlier
Subsequent transfusions may further exacerbate the anemia. ages—sickle cell anemia earlier than Hb SC disease earlier than sickle
+
Resolution of severe anemia may only occur after withholding cell–β -thalassemia.
further transfusions with subsequent reticulocyte count recovery. Infectious complications of SCD are a major cause of morbidity
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Corticosteroids at high doses (e.g., intravenous methylprednisolone and mortality even with current vaccination and prophylactic
500 mg/day for 2–3 days) should be considered if the anemia is life antibiotic regimens. The infections caused by particular organisms
threatening or if further transfusion is deemed necessary to save the are shown in Table 42.8, and the specific organisms affecting different
patient’s life. Intravenous immunoglobulin can also be considered, target organs are shown in Table 42.9. By 5 years of age, almost all
with proper attention paid to avoiding iatrogenic fluid overload. patients are functionally asplenic, contributing to infectious suscep-
Approaches to minimizing this complication include transfusing tibility. Historically, pneumococcal sepsis has been the predominant
extended-matched (see Basic Management and Disease Modifica- cause of death in those younger than 20 years of age. 152
tion), phenotypically compatible blood. 76–78 This syndrome may or
may not recur with further transfusions after a recovery period. 146 Evaluation
The most critical aspect of infectious illness in SCD is the evaluation
Hyperhemolytic Crisis and treatment of febrile children. Routine evaluation includes a
Hyperhemolytic crisis is the sudden exacerbation of anemia with physical examination, a CBC, blood and urine cultures, a lumbar
increased reticulocytosis and bilirubin level. If suspected, the approach puncture if meningitis is suspected, and chest radiography to evaluate
to management should first be to look for an underlying etiology, for pneumonia. Results of the CBC are compared with baseline
which may be one of the events listed earlier: aplastic crisis (during values. A left shift in the differential count suggests bacterial
the recovery phase when the reticulocyte count may not be decreased), infection.
sequestration crisis, delayed hemolytic transfusion reaction, or auto-
immune hemolysis. Another possible cause is glucose-6-phosphate Penicillin Prophylaxis and Pneumonia Vaccination
dehydrogenase deficiency. 147 Data and recommendations regarding penicillin prophylaxis and
pneumonia vaccination are discussed under Basic Management and
Erythropoietin Deficiency Disease Modification.
This entity is discussed under Basic Management and Disease
Modification. Streptococcus Pneumoniae, Haemophilus Influenzae,
Atypical Mycobacteria, and Acute Febrile Illness
Nutritional Deficiencies: Folate, Iron, or Vitamin Streptococcus pneumoniae bacteremia is accompanied by leukocytosis,
B 12 Deficiency a left shift, aplastic crisis, sometimes disseminated intravascular
151
This entity is discussed under Basic Management and Disease coagulation, and a 20% to 50% mortality rate. Although concerns
Modification. about S. pneumoniae sepsis are largely for young children, this com-
153
plication also occurs in adults, often with devastating results. S.
Hypothyroidism pneumoniae is the major cause of meningitis in infants and young
148
Iron overload in SCD can result in hypothyroidism. Therefore children with SCD, and it occurs in the setting of bacteremia.
hypothyroidism is another etiology to consider in a patient with SCD The second most common organism responsible for bacteremia
with an otherwise unexplained decrease in Hb below baseline. in these children, H. influenzae type b, accounts for 10% to 25% of
episodes. H. influenzae bacteremia affects older children and is less
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fulminant than S. pneumoniae bacteremia, but it may be fatal.
Conjugated H. influenzae type b vaccines produce excellent anti-
Infections body responses in children with SCD and are now administered
in early infancy (http://www.cdc.gov/vaccines/recs/schedules/child-
Immune Deficit schedule.htm).
The propensity of children with SCD to contract S. pneumoniae Owing to the high mortality rate of bacteremia, hospitalization,
149
infection is related to impaired splenic function and diminished blood and cerebrospinal fluid cultures, and parenteral antibiotics have
TABLE Organ-Related Infection in Sickle Cell Disease
42.9
Primary Sites of Most Common
Infection Pathogen(s) Other Pathogens Pathophysiology Prevention Management
Septicemia Streptococcus Haemophilus influenza type b Defective splenic Vaccines a Empiric intravenous
pneumonia Escherichia coli function; deficiency of Prophylactic penicillin antibiotics for fever
Salmonella spp. opsonic antibody
Meningitis S. pneumoniae Same as for septicemia
Osteomyelitis and Salmonella spp. E. coli – Surgical drainage,
septic arthritis S. pneumonia Proteus spp. intravenous antibiotics
Staphylococcus aureus
Pneumonia Mycoplasma Chlamydia pneumoniae Vaccines a See pulmonary and therapy
pneumoniae S. pneumoniae sections for management
Respiratory viruses of acute chest syndrome.
a Against Streptococcus pneumoniae and Haemophilus influenzae type b.
Data from Buchanan GR, Glader BE: Benign course of extreme hyperbilirubinemia in sickle cell anemia: Analysis of six cases. J Pediatr 91:21, 1977.