Fetal development/Post natal complications Flashcards
What problems would you expect in a premature infant 24 weeks of gestation?
- RDS or BPD; lack surfactant to keep alveoli open for gas exchange and potential for lung damage
- Hypotension: PDA may stay open = abnormal blood flow between aorta and pulmonary artery
- Intraventricular hemorrhage: brain is literally fragile
- Apnea of prematurity (hypoxia caused by immature resp control center)
What are factors that could affect fetal development?
- Fetal lung fluid
- Teratogens
- Maternal-fetal gas exchange
- Amniotic fluid
Why is fetal lung fluid important to fetal development?
Promotes growth, maturation, and functional development of lung structures.
- Fetus breathe liquid than transition to air
What happens if babes fail to transition to air or fetal fluid remains in the airway?
- Failure to transition to air could mean and lack of fetal fluid during development which could cause pulmonary hypoplasia
- Failure to clear liquid during transition leads to TTNB
What develops at each stage of fetal development?
- Embryonic: trachea + major bronchi
- Pseudo glandular: Conducting airways/tracheobronchial tree
- Canalicular: Vascular bed + framework of acinus
- Saccular: Terminal airways/saccule framework and maturation of surfactant
- Alveolar: Alveoli are developed
What weeks do each of the phases of development occur?
- Embryonic: 0-6
- Pseudo glandular: 6-16
- Canalicular: 17-26
- Saccular: 26-36
- Alveolar: 36-40
What week are fetus viable?
24-26 bc enough proliferation of immature surfactant is created
- aka gas exchange can occur (not great)
- surfactant appears at 20 weeks
Factors that affect fetal development
- Teratogens
- Fetal lung fluid
- Maternal fetal gas exchange
- Amniotic fluid
What could happen if fetal development is halted during the embryonic phase
- Choanal atresia
- Pulmonary hypoplasia
- Congenital diaphragmatic hernia
What happens if cilia dysfunction/impairment occurs during development
Impairs mucous transport increasing risk of infection
- Cilia development begins in week 13
Maternal-fetal gas exchange route/develpment?
- Placenta (poor)
- Chorionic villi
- Umbilical cord
What is the limiting factor in maternal-fetal gas exchange that leads to fetal hypoxia?
Any factor that decreases uterine or fetal blood flow
3 sections of umbilical cord?
- 2 umbilical arteries
- 1 umbilical vein
- Wharton jelly (cushion)
Umbilical cord vs Umbilical vein blood flow/content?
Opposite of adults
- 2 Umbilical arteries carry deoxygenated blood to the placenta for reoxygenation
- 1 umbilical vein carries oxygenated blood to the fetus
Why is persistent fetal circulation (PRF) problematic?
Failure to transition after birth has the risk of hypoxia and worsening oxygen deprivation.
- Alveoli and blood vessels are underdeveloped meaning they cannot oxygenate or ventilate
- Can lead to pulmonary hypertension
Why is pulmonary hypertension a problem?
Increased PVR can strain the heart (RV) reducing overall oxygenation meaning hypoxia
When does brown fat develop?
Week 26; and continues until 3-5 weeks after birth
What is the physiological response for heat preservation by babes if they cannot support themselves mechanically (shivering) or chemically (brown fat)?
Peripheral Vasoconstriction to prevent blood from reaching the skin where heat loss occurs
What are signs of hypothermia/cold stress?
- Peripheral vasoconstriction
- tachypnea
- mottled skin
What is the L/S ratio indicative of?
Lung maturation
- Acquired via amniotic fluid via amniocentesis
In a fetus, are right or left sided heart pressures higher?
- why?
Right bc of hypoxic pulmonary vasoconstriction secondary to low PO2 values with nonaerated lungs
In a fetus, are right or left sided heart pressures lower?
- why?
Left in fetus bc of low resistance from the placenta
Transition to neonatal circulation occurs because of what 3 factors?
- Clamping of the umbilical cord
- Initiation of the first breath
- Closure of fetal shunts
Pulmonary vasodilators for neos?
iNO and oxygen are the big ones.
- Sildenafil is also used for ppHn/high PVR
