Adaptations of Newborns - Respiratory

24-28 weeks

Pulmonary vascular beds come in contact with alveoli.

Surfactant

 Made up of the phospholipids lecithin & sphingomyelin -

as surfactant increases lungs mature.

Phosphatidyl glycerol (PG)

-Presence of PG suggests lung maturity

-Not present until ~34 weeks

Amniocentesis (during 3^rd trimester)

Diagnostic Assesses L/S ratio (lecithin to sphingomyelin) Ratio of 2:1 and presence of PG indicates low risk for respiratory distress =lungs mature.

Increase surfactant production to speed up lung development

Corticosteroids, Dexamethasone or Betamethsone

2+ weeks

Initiation of breathing

Mechanical events

Chemical stimuli

Thermal stimuli

Sensory stimuli

Mechanical events

the primary mechanical event that initiates respirations is removal of fluid from lungs as the infant’s chest is compressed as the baby passes through the birth canal.  

Identify infant’s that may have less chest compression and therefore increased fluid remaining in lungs following delivery. C section, precipitous delivery 

Then, the first inspiration occurs as the chest recoils.  With each consecutive breath more air remains in the lungs along with the remaining fluid being absorbed via the capillaries and lymphatic systems.    

Chemical stimuli

First breath is also stimulated by an inspiratory gasp triggered by a transitory asphyxia.  This occurs in all newborns to some degree.

During vaginal birth there is normally a: 

Decrease in pH

Decrease in PO2

Increase in PCO2

These changes stimulate the medulla’s respiratory center to increase respirations.

Pressure change at cord clamping 

Thermal stimuli

Cold stimulus at birth – helps to increase respiratory rate

Sensory stimuli

Tactile, auditory, visual – also helps to increase respiratory rate

Complications in the initiation of breathing

Gestational age/Preterm – Decreased lung compliance, decreased surfactant to keep alveoli open, alveoli smaller in size and less in number 

Medications – Nubain or Stadol can cause respiratory depression in newborns, MgSO4, Benzos