Chapter 6: Diseases of Infancy and Childhood

Question 1

When are the following stages defined?

Neonatal

Infancy

Early childhood

Late childhood

Answer 1

Neonate = First four weeks

Infancy: First year

Early childhood: 1-4 years

Late childhood: 5-14 years

Question 2

Prematurity is defined as…

Answer 2

Gestational age < 37 weeks (timed from first day of last menstrual period)

Question 3

What defines low birth weight infants?

What are some causes? How do they categorize?

Answer 3

Weight < 2500g. Appropriate for gestational age or small for gestational age.

Premature birth or intrauterine growth retardation.

Very-low-birth-weight infants: < 1500g. Half of neonatal deaths.

Question 4

What factors predispose to premature birth?

Answer 4

1. Maternal illness
2. Uterine incompetence
3. Fetal disorders
4. Placental abnormalities.

Question 5

What are some complications of premature birth?

How about small for gestational age?

Answer 5

Premature: Respiratory distress, metabolic disturbances (hypoglycemia, hypocalcemia, hyperbilirubinemia), circulation problems (anemia, hypothermia, hypotension), bacterial sepsis.

SGA: Congenital abnormalities, in-utero infections. Perinatal asphyxia, meconium aspiration, necrotizing enterocolitis, pulmonary hemorrhage, birth defects/metabolic diseases.

Question 6

What problem underlies pulmonary immaturity in premature newborns?

Answer 6

Alveoli do not differentiate into type I and type II pneumocytes until late. Lack of surfactant, which reduces surface tension (type II pneumocytes), required to remain open when exhale.

Picture is amniotic fluid retention/aspiration. Air passages contain desquamated squamous cells (squames) and lanugo hair and protein rich amniotic fluid.

Surfactant proteins SP-B and SP-C most important. A and D also have functions.

Question 7

What test assesses the risk of respiratory distress in a neonate?

Answer 7

Amniocehtesis lecithin-to-sphingomyelin ratio above 2:1.

Monitor for appearance of phosphatidylglycerol in amniotic fluid.

Question 8

How is an APGAR score taken?

What does it predict?

Answer 8

APGAR taken at 1 and 5 minutes.

1-minute: Measure of asphyxia, need for ventilation

5-minute: Impending death, neurologic damage.

Measure (all out of 0-2)

Heart rate

Respiratory effort

Muscle tone

Response to catheter in nostril

Color

For infants < 2000g…

9-10: 5% mortality first month

3 or less: 80% mortality first month

Question 9

What are risk factors for neonatal respiratory distress syndrome?

Answer 9

1. Prematurity
2. Neonatal asphyxia
3. Maternal diabetes
4. Delivery by C-section
5. Precipitous delivery
6. Twin pregnancy

Biopsy: Alveoli atelectatic, alveolar ducts lined by fibrin-rich HYALINE MEMBRANES.

Due to surfactant deficiency. Respiratory effort injures alveoli, leak plasma into airspaces, hypoxia and acidosis. Pulmonary arterial vasoconstriction, Right-to-left shunt.

Question 10

A newborn with high APGAR scores begins showing signs of increased respiratory effort a half-hour after birth. The respiratory rate increases over 100 and the baby becomes cyanotic.

Chest radiograph shows “ground glass” granularity and “white out” of the lungs. The baby dies of asphyxia.

Answer 10

Respiratory distress syndrome of the neonate.

Lungs dark red, solid-appearing,a nd airless. Alveoli collapsed. Ducts and bronchioles dilated, contain cellular debris, proteinaceous edema, and erythrocytes.

Biopsy histology shows atelactatic alveoli with dilated alveolar ducts lined by fibrin-rich HYALINE MEMBRANES.

Question 11

What are some complications of neonatal respiratory distress syndrome?

Answer 11

Related to anoxia and acidosis.

Intraventricular cerebral hemorrhage: Dilated, thin-walled veins rupture easily. Anoxic injury?

Persistent patent ductus arteriosus: Pulmonary artery pressure declines after pulmonary disease, higher pressure in aorta reverses blood flow in the ductus. Persistent Left-to-right shunt.

Necrotizing enterocolitis: Ischemia of intestinal mucosa, C. difficile colonization.

Bronchopulmonary dysplasia: Oxygen toxicity? Respiratory distress persists, Right-sided heart failure. Opaque/sponge like lungs.

Question 12

An Rh-negative mother presents in her second pregnancy with antibodies against Rh.

What are you concerned about?

Answer 12

Erythroblastosis Fetalis - hemolytic disease caused by maternal antibodies against fetal erythrocytes.

Occurs during second pregnancy of a Rh negative mother against Rh-postiive fetus.

Question 13

A multiparous women delivers a child (shown in image) that quickly dies after birth. What happened?

Answer 13

Hydrops fetalis, due to severe erythroblastosis fetalis - hemolytic disease caused by maternal antibodies against fetal erythrocytes.

Severe edema due to congestive heart failure caused by severe anemia. Can give Rh-negative cell transfusion. Not jaundiced at birth, but develop progressive hyperbilirubinemia. Hypatosplenomegaly and bile-stained organs, erythroblastic hyperplasia in bones and extramedullary hematopoiesis.

Question 14

A baby presents with severe jaundice. Maternal antibodies to Rh factor are found. What is the disease, and what are complications?

Answer 14

Kernicterus or bilirbuin encephalopathy due to erythroblastosis fetalis - hemolytic disease caused by maternal antibodies

Severe jaundice and bile staining of the brain, especially basal ganglia, pontine nuclei, and dentate nuclei in cerebellum. Neonatal liver deficient in glucuronyl transferse (UGT). Lose startle and athetoid movements.

Exchange transfusions and phototherapy to treat.

Give human anti-D globulin.