30: 2-year-old male with sickle cell disease

Question 1

Pathophysiology of Sickle Cell Disease (SCD)

Answer 1

• -SCD is a group of disorders characterized by substitution of valine for glutamic acid at the sixth amino acid position of the hemoglobin molecule.
• -This mutation leads to the formation of polymers of hemoglobin when the hemoglobin becomes deoxygenated.
• -These polymers lead to deformation of the rbc into the characteristic “sickle” cells. Sickle cells have increased adherence and block blood flow in the microvasculature, which leads to local tissue hypoxia, pain, and tissue damage.
• -The abnormal hgb induces hemolysis of the rbc leading to chronic anemia with an elevation of the retic count.

Question 2

F

Answer 2

Predominant hemoglobin at birth is hemoglobin F (fetal), so this always appears first in the naming.

Question 3

A

Answer 3

Hemoglobin A is normal adult hemoglobin.

Question 4

FS

Answer 4

FS is the most common hemoglobin pattern causing sickle cell disease.

Question 5

FSA

Answer 5

• -FSA is sickle cell beta thalassemia, meaning one of the globin genes has a mutation for S and the other has a mutation for beta thalassemia (which produces no or little normal hemoglobin).
• -This pattern causes a sickling disorder, although it may behave in a milder fashion than FS (in which both genes have the sickling mutation). From a clinical management standpoint, these patients are treated in the same manner.

Question 6

FSC

Answer 6

• -FSC is sickle cell hemoglobin C disease: one gene has the S mutation and one gene has the mutation for hemoglobin C.
• -This pattern causes a sickling disorder, although it may behave in a milder fashion than FS (in which both genes have the sickling mutation). From a clinical management standpoint, these patients are treated in the same manner.

Question 7

Common Procedures for Young Individuals with SCD: TONSILLECTOMY

Answer 7

Lymphoidal-tissue hypertrophy involving Waldeyer’s ring is common in children with sickle cell disease.

• -Excessive snoring may be observed, as well as obstructive sleep apnea.
• -Some physicians think tonsillar hypertrophy may relate to desaturation of hemoglobin and increase the risk of sickling.
• -Tonsillectomy with adenoidectomy will improve the obstructive apnea for most patients.

Question 8

Common Procedures for Young Individuals with SCD: CHOLECYSTECTOMY

Answer 8

Bilirubin gallstones occur frequently in all patients with hemolytic anemias—including sickle cell disease—the result of increased release of hemoglobin during breakdown of abnormal red blood cells.

Question 9

Risk of Sepsis in Children with SCD

Answer 9

• -The decreased splenic function leads to decreased resistance to infection with encapsulated organisms (Streptococcus pneumoniae, Hib, Neisseria meningitidis).
• -When given to infants with sickling disorders, penicillin significantly decreases the risk of mortality from overwhelming sepsis.
• -Penicillin is usually continued until the child is 5 or 6 years of age; after this age there is little data to support its use except in patients who have had documented sepsis and bacteremia, or who have had their spleens removed.

Question 10

Goals for the Comprehensive Visit for SCD

Answer 10

1. How the family deals with the various complications that can occur.
2. The frequency of painful or other vaso-occlusive problems.
   - -This will give an indication of the need for other, more aggressive interventions such as the use of hydroxyurea.
3. How the family accesses health care.
4. How the family is dealing with a chronic illness.

Question 11

Expected Complications for Children with SCD

Answer 11

• jaundice
• anemia
• stroke
• respiratory problems

Question 12

Immunization Recommendations for Children with SCD

Answer 12

The Haemophilus influenzae type b conjugate vaccine and 13-valent pneumococcal conjugate vaccine (Prevnar 13)-given at 2, 4 and 6 mo-have aided in protection against 2 bacteria that have been major leaders in M&M in children with SCD

Question 13

Impairment of growth is common in children with sickle cell disease. This is probably multifactorial and may be due to any one or combination of the following:

Answer 13

Chronic anemia
Poor nutrition
Painful crises
Endocrine dysfunction 
Poor pulmonary function

Question 14

Important Signs in the Physical Exam in a Patient with SCD

Answer 14

• splenic enlargement
• sclera
• neurologic exam

Question 15

Baseline Hemoglobin in SCD

Answer 15

between 6 and 9 g/dL (60-90 g/L). They accommodate to this level of hemoglobin very well, but the lower the baseline hemoglobin, the more difficult it is for the patient to withstand any acute change.

Question 16

In a child with sickle cell disease, cough and breathing difficulty may indicate:

Answer 16

Acute chest syndrome:

• -Pneumonia
• -Intrapulmonary sickling
• -Pulmonary fat embolism

Question 17

Acute chest syndrome (ACS)

Answer 17

Multilobar infiltrates (more commonly lower and middle lobes)
Effusions
Atelectasis

Question 18

Pericarditis

Answer 18

can present with effusion and infiltrate on chest x-ray.

Question 19

Congestive heart failure (CHF)

Answer 19

Lower lobe infiltrates and cardiomegaly are both consistent with a diagnosis of CHF.

Question 20

Rib infarction

Answer 20

• -While there would not be pulmonary infiltrates, a pleural effusion might happen as a sequela of rib infarction.
• -Also, cardiomegaly and hypoxia would not usually be present (though patients with sickle cell disease may have baseline cardiomegaly).

Question 21

Sepsis

Answer 21

• -Cardiomegaly would be present only if patient was in cardiogenic shock (although, as noted above, patients with sickle cell disease may have cardiomegaly at baseline).
• -New infiltrates would not be a usual finding unless the sepsis leads to acquired/adult respiratory distress syndrome (ARDS).

Question 22

CBC Findings in Stress Response

Answer 22

Patients with sickle cell disease frequently demonstrate an exaggerated leukocytosis and thrombocytosis in response to stress.

Question 23

Atelectasis

Answer 23

Definition:
A collapsed or airless segment of lung due to obstruction with distal collapse of the alveoli.

Risk:
Atelectasis is a serious risk in a child with chest pain. It can exacerbate acute chest syndrome, causing it even to become life-threatening.

Question 24

Indications for RBC transfusion in ACS are not precise, but if a child experiences one of the following, a transfusion of packed red cells is recommended:

Answer 24

A fall in hemoglobin from baseline 
Increasing respiratory rate 
Worsening chest symptoms 
Declining O2 sats
Progressive infiltrates on chest x-ray

Question 25

When to Seek Emergency Care for a Patient with SCD

Answer 25

• fever
• splenic enlargement
• slurred speech
• chest pain
• rapid breathing
• INC pallor
• INC jaundice
• priapism

Question 26

Various infectious agents have been reported in ACS including:

Answer 26

Viruses
Chlamydia
Mycoplasma
Bacteria

Question 27

Differential Diagnosis of Fever, Respiratory Distress, and Chest Pain in Child with SCD

Answer 27

• ACS
• pericarditis
• CHF–Tachypnea is one of the most common signs of CHF in children.
• rib infarction
• sepsis

Question 28

Parvovirus B19 causes aplastic anemia–SCD

Answer 28

especially in children with shortened RBC half-life. A mild anemia associated with parvovirus often goes unnoticed in healthy children. However, in patients with decreased RBC survival, such as sickle-cell patients, anemia can develop very rapidly and severely, along with decreases in the other cell lines (resulting in leukopenia and thrombocytopenia). In the above presentation, the presence of fever in a child with sickle cell disease should also raise concern for significant bacterial infection from encapsulated organisms like pneumococcus. This patient should have a blood culture and be started on empiric antimicrobial therapy pending screen labs and cultures