Adjustment to Extrauterine Life

1
Adjustment to Extrauterine Life

• Quickly breathe and maintain respirations
• Replace fluid in lungs with air
• Open pulmonary circulation and close fetal shunts
• Allow pulmonary blood flow to increase and blood
  volume to be redistributed
• Provide energy to maintain body temperature and
  support metabolic processes
• Dispose of waste products
• Detoxify substances entering from external
  environment

2
Preparatory Events to Breathing

• In utero lungs filled with fluid
• At birth, air has to take the place of this fluid
• Surfactant is produced by mature lungs prevents
  the alveoli from collapsing with each expiration
• Surfactant also promotes lung compliance, the
  ability of the lung to fill easily with air

3
Onset of Breathing

• Fig 9-1
• Internal factors
• chemical changes occur with clamping of the
  umbilical cord, hypoxia occurs leading to
  acidosis
• External factors
• thermal factors include going from a warm
  environment to the cold exterior
• sensory stimuli include cold, touch, movement,
  light sound
• mechanical stimuli are chest compression as it
  passes through the birth canal recoil as it is
  born

4
Changing from Fluid-filled Lungs to Air-filled
Lungs

• During vaginal birth as the thoracic cage is
  compressed it promotes drainage of fluid from the
  lungs
• As the infant is delivered the thoracic cage
  recoils infant sucks in air to replace the fluid
  that has drained out
• In C-sections this does not occur so infants born
  by this method are more prone to respiratory
  distress
• Other mechanisms are fluid absorbed by the
  lymphatic vessels what is left is removed by the
  pulmonary capillaries

5
SHUNTS CLOSING

• FORAMEN OVALE- the opening between the 2 atrium-
  functionally closes within 1 minute takes 2
  weeks to structurally close permanent closure is
  several months after birth
• DUCTUS ARTERIOSUS-by passes the fetal
  lungs-functionally closes within 15-24 hrs-
  anatomic closing 3-4 wks
• DUCTUS VENOSUS-bypasses the liver reduced blood
  flow immediately anatomically closes within 2
  weeks
• If the infant has a decrease in BP or becomes
  hypoxic these shunts may reopen within the 1st
  few weeks of life

6
THERMOREGULATION

• The ability of the newborn to produce heat and
  maintain a normal body temperature
• CONTROL HEAT LOSS fig 9-3 cold stress
• evaporation wet diapers, hair or clothes
• conduction cold objects, hands, scale,
  stethoscope
• convection drafts, A/C, people moving
  about
• radiation when the infant is near cold
  surfaces such as windows or outside walls
• Fast focus 9-2

7
Nonshivering Thermogenesis

• Newborn cannot shiver like an adult can to
  product heat
• Newborn relies on nonshivering thermogenesis,
  using brown fat stores vasoconstriction in cold
  environments to keep warm see fig 9-5
• BMR also increases