Neonatology Flashcards
• Suspect transient tachypnea of the newborn (TTN) if:
o Late pre-term or term infant after caesarean delivery without labor
o Chest radiograph showing bilateral perihilar linear streaking secondary to engorged vessels
• Suspect respiratory distress syndrome (RDS) if:
o Preterm infant (with greater risk in decreasing gestational age)
o Infant born to a diabetic mother
o Chest radiography showing diffuse, granular, ground-glass appearance with air bronchograms and low lung volume
• Suspect persistent pulmonary hypertension if:
o Infant with history of bacterial infection, poor intrauterine growth, and non-reassuring fetal heart rate patterns
o Chest radiography can show clear lung fields with decreased pulmonary vascularity
o Management for suspected persistent pulmonary hypertension should include the following:
- Echocardiogram to differentiate between primary cardiac disease and Primary Pulmonary Hypertension
- Oxygen initially administered at high concentrations to reverse pulmonary vasoconstriction
- Circulatory support with fluids and vasopressors to reduce right-to-left shunting
- In severe cases, using vasodilators such as nitric oxide can reduce pulmonary vascular resistance
• Suspect early-onset pneumonia if:
o Lethargy, apnea, tachycardia, poor perfusion
o Chest radiograph findings of bilateral alveolar densities with air bronchograms
• Requirements for the transition from fetal to neonatal life
o Replacement of alveolar fluid with air
o Onset of regular breathing
o Increase in pulmonary blood flow
• Secondary to increased systemic vascular resistance and decreased pulmonary vascular resistance
Definition and causes of central cyanosis
o Results when the deoxygenated hemoglobin in the blood exceeds 5 gm/dL. Causes include:
• Alveolar hyperventilation
• Ventilation-perfusion mismatch
• Right to left shunt
• Diffusion impairment
• Abnormal hemoglobin with decreased oxygen affinity
Definition and causes of peripheral cyanosis
o Systemic arterial oxygen tension is normal, but increased oxygen extraction causes a wide systemic arteriovenous oxygen difference, resulting in increased deoxygenated blood on the venous side.
• The primary life threatening causes of cyanosis in children include:
o Respiratory dysfunction • Decreased inspired oxygen • Upper airway obstruction • Impairment of chest wall or lung expansion • Intrinsic lung disease o Circulatory dysfunction • Congenital heart disease • Pulmonary edema • Pulmonary hypertension • Pulmonary embolism • Pulmonary hemorrhage • Shock o Methemoglobinemia
what is considered post-term?
GA >42 weeks
what are the most common complications of patients born post-term?
• Macrosomia:
o Most common presentation
o Fetal weight and head circumference continue to increase
o Increased risk of birth injury due to their large size
• Fetal growth restriction:
o Can also occur due to a poorly functioning placenta that cannot provide adequate nutrition
o Will present as a long, thin, small for gestational age infant with dry, peeling skin
• Perinatal mortality is thought to increase in post-term infants due to the following reasons:
o Feto-placental insufficiency
o Asphyxia (with and without meconium)
o Intrauterine infection
• Neonatal complications in post-term infants include:
o Shoulder dystocia o Neurologic birth injury o Meconium aspiration o Persistent pulmonary hypertension o Perinatal asphyxia
What is the optimal intervention to prevent post-term births?
Induction of labor at 41 weeks gestation
o When this is not possible, neonatal management consists of screening and treating the complications associated with prolonged pregnancy
What is the definition of pre-term infant?
GA <37 weeks
• Preterm infants are more likely to have the following complications:
- Hypothermia
- Hypoglycemia
- Respiratory distress
- Apnea
- Hyperbilirubinemia
- Feeding difficulties
what’s the cause of hypothermia in pre-term babies?
- Occurs because they have less white adipose tissue for insulation and cannot generate heat as well from brown adipose tissue.
- They also have a larger surface area/weight ratio and lose heat more quickly.
what’s the cause of hypoglycemia in pre-term babies?
• Because of an inadequate response to the loss of maternal glucose supply after birth.
What is the cause of respiratory distress in pre-term babies?
- Because of lung immaturity (lung development of the terminal sacs occurs around 34-36 weeks).
- Infants may also miss the surfactant surge that occurs around 34 weeks.
What is the cause of apnea in pre-term babies?
- Because of immature respiratory control.
- Apnea of prematurity is a disorder that reflects the transition of intermittent breathing in the placenta to continuous breathing postnatally.
What is the cause of hyperbilirubinemia in pre-term babies?
- Because of the immature hepatic bilirubin conjugation pathways
- The risk for kernicterus is also increased because of the relative immaturity of the blood-brain barrier compared to term infants
What is the cause of feeding difficulties in pre-term babies?
- Because of immature oro-buccal coordination and swallowing mechanisms.
- Breast-feeding is still the best feeding method but requires closer monitoring.
What is hyperbilirubinemia?
• Hyperbilirubinemia is normally defined as an elevated total serum bilirubin (TB) > 5 mg/dL; however, in infants ≥ 35 weeks gestation a TB in the 95th percentile on the hour-specific Bhutani monogram is a more appropriate definition.
What is physiologic Jaundice?
• Physiologic jaundice is a nonpathologic indirect hyperbilirubinemia that peaks between days 3 and 5, and is never present before 24 hours of age.
How common is physiologic jaundice? What causes it?
• Extremely common and occurs due to several physiological changes that take place at birth:
Increased production: a high neonatal hematocrit and shorter life span of fetal red cells leads to large red cell turnover, with higher levels of bilirubin production;
Decreased clearance: a latent deficiency of the enzyme uridine diphosphogluconurate glucuronosyltransferase (UGT1A1) that conjugates bilirubin to make it water-soluble;
An increase in enterohepatic circulation.
What is breast milk jaundice?
o Nonpathologic indirect hyperbilirubinemia that presents 3 to 5 days after birth and peaks within two weeks.
What is breast feeding jaundice?
o Pathologic indirect hyperbilirubinemia that typically occurs during the first week of life as lactation failure leads to inadequate intake with resultant unrepleted fluid loss and significant hypovolemia. (not to be confused with breast milk jaundice)
What causes of pathologic indirect hyperbilirubinemia?
- Isoimmune hemolytic anemias: ABO and Rh incompatibility
- Breast feeding failure
What is significant about ABO and Rh incompatibility?
o Can lead to an indirect hyperbilirubinemia with a positive direct Coombs’ test
• A direct Coombs’ test is positive for the presence of maternal antibody on the surface of neonatal red blood cells.
What is ABO incompatibility?
o ABO incompatibility occurs when a type O mother with a fetus of a different blood type produces small amounts of weakly-reacting anti-AB IgG which cross the placenta and result in an isoimmune hemolytic anemia.
• It is the most common cause of pathologic unconjugated hyperbilirubinemia.
• Note that unlike Rh incompatibility, prior maternal antigen sensitization is not required for ABO incompatibility.
What is Rh incompatibility?
o Rh incompatibility occurs when a previously sensitized Rh-negative mother with an Rh-positive fetus produces anti-Rh IgG that cross the placenta and produce a robust isoimmune hemolytic process with a significant unconjugated hyperbilirubinemia.
What does the following suggest?: Indirect hyperbilirubinemia in a neonate with a negative Coombs’ test and central venous hematocrit ≥ 70%
Polycythemia
What does the following suggest?: Indirect hyperbilirubinemia in a neonate with a negative Coombs’ test, increased reticulocyte count, and normal smear
prenatal hemorrhage/blood loss.
What should be done first for a neonate with indirect hyperbilirubinemia and a negative Coomb’s test?
Should be evaluated with hematocrit, reticulocyte count, and smear.
What does the following suggest?: Indirect Hyperbilirubinemia in a neonate with a negative Coombs’ test, increased reticulocyte count, and abnormal smear
- Non-immune hemolysis
- Inherited red cell membrane defects (e.g. spherocytosis)
- Red cell enzymatic defects (glucose-6-phosphate dehydrogenase, pyruvate kinase)
- Or Thalassemia/hemoglobinopathy.
What does the following suggest?: Indirect hyperbilirubinemia in a neonate with a negative Coombs’ test, normal reticulocyte count, and normal smear
- Peri-/postnatal extravascular blood loss
- Bacterial sepsis
- Or Drug reaction
What’s important to know about Direct hyperbilirubinemia? What causes it?
• Direct hyperbilirubinemia is always pathologic in the neonate, and may be attributable to: o Biliary atresia o Hepatitis o Infection o Inborn errors of metabolism
What is kernicterus?
• When the indirect fraction of bilirubin exceeds 25-30 mg/dL, unconjugated bilirubin begins to deposit in the basal ganglia, pons, cerebellum, and hippocampus, causing acute bilirubin encephalopathy. The resultant yellowing of these tissues is known as kernicterus.
