Sickle cell disease
Acute Chest Syndrome
Hgb S = valine replaces glutamic acid in 6th position of beta chain (E6V)
Alters shape of cells in certain environments
Hemolysis from brittle RBC’s
Vascular occlusion caused by sickled cells
Hgb SS 0.2% American blacks
A homozygous patient will have hemoglobin SS (HbSS, 80-90%), hemoglobin F (HbF, 2-20%), and hemoglobin A2 (HbA2, 2-4%).
A carrier patient will have HbSS (35-40%) and hemoglobin A (HbA, 60-65%).
The test is not accurate in a patient who has recently received blood transfusions.
Sickle cell trait
Heterozygous expression of sickle hemoglobin
Affects ~10% Black Americans
Hgb S: 35-45% (versus 80-95% in Hgb SS)
Clinically benign (usually)
Splenic infarct w/severe hypoxia
Occasional sudden death
Hgb: usually 5-9 g/dL
Peripheral smear: sickle cells, target cells, Howell-Jolly bodies
Retic count: 5-15%
Leukocytosis & thrombocytosis
ESR: lowered (cells don’t rouleaux)
if abd pain: do LFTs (chronic hemolysis may explain increased indirect hyperbili)
consider type and crossmatch
Perform in patients with respiratory symptoms.
Radiographic findings may initially be normal in patients with acute chest syndrome.
Perform in patients with localized bone tenderness.
Do not differentiate between osteomyelitis and bone infarction in the early stages. Radiographic signs of osteomyelitis may not appear for 8-10 days.
A view of the vertebral column shows typical fish-mouth appearance of vertebrae in patients with sickle cell anemia. This is due to expansion of the bone marrow.
Use in patients with abdominal pain to rule out cholecystitis or an ectopic pregnancy.
Assess liver and spleen size.
Cholelithiasis may occur because gallstones form as a result of chronic hemolytic anemia. Ultrasound is diagnostic. If symptomatic, cholecystectomy is indicated.
Head CT or MRI is used in cases of neurologic crisis.
Bone scans can aid in early differentiation of bone infarction and osteomyelitis.
Hgb electrophoresis (newborn screen): Quantifies different Hgb fractions
Sickle cell prep: Hgb added to buffer w/reducing agent; Turbid ppt forms if >15% Hgb S present
Administer oral hydration if the patient is having a mild episode, is not vomiting, and can tolerate oral fluids.
Administer IV fluids (at least 3-4 L normal saline solution [NSS]). Ensure accurate intake-output measurements by inserting a Foley catheter. Take care not to overload the patient.
While considering the severity of pain and the patient's past response, follow consistent protocols to relieve the patient's pain.
Oxygen supplementation is only beneficial if patient has hypoxia. Intubation and mechanical ventilation may be required in patients in whom cerebrovascular accidents have occurred.
Simple blood transfusion is indicated in patients in aplastic crisis and acute sequestration crisis.
Exchange blood transfusions are indicated in cases of cerebrovascular accidents and acute chest syndrome. They are performed occasionally in patients with acute sequestration crisis or in cases of priapism that do not resolve after adequate hydration and analgesia (ie Priapism).
Exchange transfusion consists of replacing the patient's RBCs by normal donor RBCs, decreasing HbS to less than 30%.
Prevent & treat infections
Immunize!!! (esp. Hib, Pneumococcus)
PCN prophylaxis until age 6yo
Bring to medical attention for T> 38.5
Refer to Sickle cell center
Anticipatory guidance re: splenic
sequestration & exam
Hydroxyurea/Butyrate: Hydroxyurea is a purine analog that stimulates fetal Hgb production, however it can cause leucocytopenia and thrombocytopenia. Causes RBC macrocytosis, which can be monitored to evaluated compliance. Goal MCV is 110-125. It does not prevent stroke. It is used to decrease the number of vaso-occlusive crises, but does not prevent them completely. Do NOT use in pregnancy. With hydroxyurea, mortality is decreased in 50% of adults.
Folic acid should be prescribed to those who are not already taking it.
Discharge patient on oral analgesics for a week. Up to 2 doses of narcotics can be administered in ED over a period of 4-6 hours.
Oral drugs for mild pain include acetaminophen, ibuprofen, aspirin, and codeine. If pain is moderate, oxycodone or methadone can be administered.
Administer parenteral drugs for severe pain. Morphine is the drug of choice, but meperidine with promethazine can be used.
Antibiotics are indicated when an infection is suspected, when body temperature is higher than 38 degrees Celsius, or when a patient has localized bone tenderness. Fever in children is strongly suggestive of infection. It has been found that signs of infection are more accurate in children than in adults.
Common infections include pneumonia, bronchitis, pyelonephritis, cystitis, osteomyelitis, meningitis, and sepsis. Recommended parenteral antibiotics include cephalosporins (eg, ceftriaxone, cefuroxime).
If the patient is discharged home, oral antibiotics (eg, Augmentin, Ceclor) are useful. If the patient has localized bone tenderness, seek antibiotic coverage for S typhimurium and S aureus.
Teach patients to seek medical care in certain situations, including the following:
Persistent fever (>38.3°C)
Chest pain, shortness of breath, nausea, and vomiting
Abdominal pain with nausea and vomiting
Persistent headache not experienced previously
Patients should avoid the following:
Nonprescribed prescription drugs
Cigarettes, marijuana, and cocaine
Seeking help in multiple institutions
Sickle cell disease and pregnancy
Patients who are pregnant and have sickle cell disease are at increased risk for crisis, toxemia, pyelonephritis, thrombophlebitis, and spontaneous abortion compared to the general population.
Prophylactic transfusion with special concern for folic acid replacement have been shown to decrease the incidence of vasoocclusive crisis during pregnancy.
In the past, pregnancy was strongly discouraged, and tubal
ligation often was performed.
CHLA Board Review 2005