Full term neonatal disease Flashcards
How does PPHN cause hypoxemia?
Pulmonary vasculature remains constricted after birth despite clearance of amniotic fluid from lungs and decrease in PVR
Define persistant pulmonary hypertension of the newborn
- Abnormal transition from fetal to extrauterine life
Is persistent pulmonary hypertension a right to left shunt or left to right shunt?
Right to left shunt, blood continues to flow through the ductus arteriosus despite clearance of fluid from the infants lungs
what are the risk factors associated with PPHN?
- Oligohydramnios
- high maternal BMI
- Maternal diabetes
- pre-eclampsia
- smoking
- SSRIs
NSAIDS
What are the proposed etiologies for PPHN?
- repeated intrauterine closure of ductus with redirection of blood flow into the high resistance fetal pulmonary vasculature
- repeated intrauterine hypoxia which stimulates hypertrophy of medial smooth muscle which surround pulmonary arterioles
When does PPHN typically present?
- Full or post term infant
- Dystocia (difficult labor)
How does PPHN present?
- Refractory hypoxemia
- Low APGARS
- Mild respiratory distress to moderate tachypnea
How is PPHN diagnosed?
- Cardiac echocardiogram
- Clear CXR
3 Normal heart
What should you try to rule out before diagnosing PPHN?
- Meconium aspiration
- Congenital heart disease
- Group Be strep PNA
What would indicate the presence of PPHN after reviewing the echocardiogram and CXR?
- Severe hypoxemia
- No parenchymal disease
- Evidence of left to right shunting
What are the 3 categories of PPHN physiology?
- Maladaption
- excessive muscularization
- Hypoplastic vasculature
Describe how PPHN can be caused by maladaption?
structurally normal but abnormally constricted vasculature caused by lung parenchymal disease such as MAS, group b strep or RDS
Describe how excessive muscularization can cause PPHN
normal parenchyma but increased smooth muscle cell thickness and extension of smooth muscle to distal ends of pulmonary vessels
How does hypoplastic vasculature contribute to PPHN?
underdevelopment of the pulmonary vasculature may result in vessels that are small and incapable of carrying the appropriate volume of blood
What IV medications may be used on infants with PPHN?
- Sedatives-fentanyl
- Paralytics - vecuronium
- Magnesium - muscle relaxers
What strategies is employed when mechanically ventilating infants with PPHN?
mild hyperventilation
What respiratory medications can be given to infants with PPHN?
Inhaled Nitric oxide
Flolan
What is the formula for the oxygenation index?
OI = (Paw x FiO2) / PaO2
What is the oxygenation index used for?
Used to measure the disease severity
What is a normal Oxygenation index value?
Normal < 10
What oxygenation index supports the initiation of HFOV or iNO?
> 20
What oxygenation index score supports the initiation of ECMO?
> 40 on conventional ventilation supports ECMO
60 on HFOV supports ECMO
Describe the 20-20-20 rule for initiation of nitric oxide
When OI is 20
Dose 20 ppm
Response if the P/F ration increases by greater than 20 mmhg
What is the 60-60-60 rule for weaning iNO?
When? 60 minutes after demonstrating response if FiO2 is less than 60% and PaO2 is greater than 60 mmHg
What are the risks associated with severe PPHN?
- Inadequate systemic blood pressure
- Cardiac dysfunction
- inability to oxygenate
What is meconium?
meconium is a sterile green tinged bowel content of an infant typically passes within 48 hours of life
What are the risk factors for meconium aspiration?
Post term deliveries
Why do post term deliveries carry and increased risk of MAS?
Fetus passing meconium is thought to be a vagal response due to stress and hypoxia
What physiologic response does meconium aspiration cause?
- Airway inflammation
- Mucus production
- bacterial proliferation
- Surfactant washout
How can the pulmonary vasculature react to MAS?
Pulmonary vasculature may be hyperreactive and vasoconstrict resulting in PPHN
Meconium aspiration can cause something called the ball valve effect. What does this result in?
- Air trapping
- Alveolar hyperinflation
- Air leak syndrome
Describe how MAS may present?
- Green or brown stained amniotic fluid
- Yellow stained skin, nails and umbilical cord
- Difficult delivery
- Depressed at birth
- Low APGARS
- Respiratory distress
- Cyanosis
- Hypoxia
Is endotracheal suctioning an appropriate response to suspected MAS?
research has not been able substantiate improved outcomes in neonates that were endotracheally suctioned vs those who were not
How can MAS be diagnosed?
- Stained amniotic fluid
- respiratory distress at birth
- ruling out other causes such as GBS PNA, PPHN, CHD
- CXR
How does MAS present on a CXR?
heterogenous pulmonary infiltrates in associated with hyperinflated lungs
How can MAS be managed?
- Oxygen
- Mechanical ventilation
- Surfactant administration
- iNO but only if PPHN is present
- ECMO (last resort)
Define congenital diaphragmatic hernia
Condition resulting from inability of the pleura and peritoneal spaces to close during the first trimester of pregnancy leading to the displacement of abdominal organs within the chest cavity
What can result from a congenital diaphragmatic hernia?
Lung hypoplasia and altered pulmonary vascular development
What causes congenital diaphragmatic hernias?
- Cause is unknown
- Multiple potential factors at plays such as genetics, environment and nutrition are suspected
What chromosomal abnormalities is CDH associated with?
Trisomy 13, 18
Turner syndrome
When are most case of CDH found?
at the 2o week anatomy scan
How does CDH present?
- Respiratory distress
- Severe WOB
- Concave abdomen
- decreased breath sounds
- Bowel sounds in abdomen
- low APGARs
How is CDH managed?
- Resuscitation team in delivery room
- orogastric tube to decompress stomach
- intubation
- permissive hypercapnia allow
- ECMO
What are complications associated with CDH?
- Chronic lung disease
- Pulmonary hypertension
- Aspiration risks
- Feeding issues
- Developmental delays
- Re-herniation
