Fetal Circulation Flashcards
What are the adaptations that must happen at birth?
Cardiovascular adaptation
Pulmonary adaptation
Thermal adaptation
What special features does the fetal cardiovascular system have?
umbilical vein
ductus venosus
foramen ovale
ductus arteriosus
umbilical arteries
What does the umbilical vein do?
Carries oxygenated blood from placenta
What does the ductus venosus do?
What does the foramen ovale do?
What does ductus arteriosus do?
What does the umbilical arteries do?
What is the blood haemoglobin level in the fetus?
20.7 g/dl
What is the blood volume in the fetus?
80-100 ml/kg
When does the ductus arteriosus close?
Within the first few days of birth
What are the adaptations of extrauterine life?
Depends on the interplay between cardiovascular and respiratory system. Initiated within 60 seconds but may not be fully completed for a few week as the separation of the neonate from the placenta results in cessation of blood flow which collapses the umbilical vein and arteries.
What happens to the ductus venosus and the hypogastric arteries after birth?
They will eventually fibrose to become supporting ligaments.
What benefits does delayed cord clamping have?
In term of iron status as well as a more gentle adaptation to extrauterine life
Fetal Breathing Movements
FBMs are episodic and irregular, interspersed with periods of apnea (suspension of breathing)
When are FBMs detectable by ultrasound?
Around 10-11 weeks gestation
Why are FBM important?
FBMs in utero are vital for postnatal lung function. As gestation progresses, FBM increases in strength and frequency. Promotes growth and allows rehearsal of respiratory actions.
Describe lung liquid.
During fetal life the lung develops as a liquid-filled organ. This liquid is produced by the fetal lung and leaves via the trachea from where it is either swallowed or enters the amniotic sac
What is the role of fetal lung liquid?
Plays a crucial role in the growth and development of the fetal lungs by maintaining them in a distended state. It is now recognised that the retention of liquid within the future airways is required to maintain the lungs at an appropriate level of expansion in order to stimulate their growth.
What are the pulmonary adaptations?
Production of surfactant from the 20th week. At term lungs are filled with 100mls of fluid (1/3 is expelled during birth and the rest is carried away by blood and lymphatic vessels).
What does surfactant do?
Reduced surface tension in the alveoli and assists gaseous exchange after birth
What factors stimulate the first breath?
Changes in temp and tactile stimulation. Also surges of steroids and catecholamines associated with labour.
What is the respiratory rate like after birth?
What happens to temp after birth?
Babies are usually born into a cold and wet environment so they usually experience temperature loss
Why do they lose heat so quickly?
The subcutaneous fat layer is thin and provides poor insulation
What to do at birth to help the babies temperature?
close windows switch off fans
warm towels
dry wet skin at birth
skin to skin contact
Breastfeeding
What does the APGAR score stand for?
Appearance
Pulse
Grimace
Activity
Respiration
What are the main things that must occur at birth for a successful transition to neonatal life?
- Conversion of fetal to neonatal circulation
- Initiation of breathing
thermoregulation
What does successful breathing require?
- Adequate maturation of the lungs
- Presence of adequate surfactant
- Neuromuscular control
- Clearance of lung fluid.
What are the other adaptations to extrauterine life?
- Establishment of breastfeeding
- Elimination of waste through kidneys and gastrointestinal (digestive) system
- Communication /development through parent child interactions
