(1) loss of umbilical circulation to placenta
(2) closure of ductus venosus
(3) closure of the foramen ovale
(4) closure of ductus arteriosus
(5) large increase in pulmonary circulation
(6) increase in RBF from decrease renal vascular resistance
(7) changes in skin blood flow
(1) loss of placental gas exchange
(2) initiation of ventilation of the newborns lung
(3) commencement of pulmonary gas exchange
(4) establishment of FRC
1. First breath -> lungs expand -> pulmonary blood flow increases markedly -> drop in PVR -> bolus of blood to LA + LV -> reversing pressure & closure of foramen ovale.
2. Loss of umbilical circulation (clamping cord) -> increased SVR
3. Closure of ductus venosus
4. Closure of ductus arteriosus
- functional not anatomical due to increased exposure to increased PO2, pH and decreased PCO2 -> inhibiton of prostaglandins E1 & E2 -> vasoconstriction
5. Large increase in pulmonary circulation.
- inflation of lungs drawing blood into thorax
- prostaglandin & NO action
6. Changes in skin blood flow from exposure.
7. Decrease renal vascular resistance -> increase in RBF & GFR.
8. Increased FiO2 shifting oxy-Hb curve to to right -> less fetal Hb & increased 2,3 DPG.
- passage through birth canal compresses the babies chest wall -> expels foetal fluid
- also reabsorbed (lung lymphatics) and replaced with air
- high negative intrathoracic pressure (-50cmH2O) -> breathing comes easier c/o sufactant & establishment of air-liquid interface.
- @ 10min FRC = 20mL/kg
- @ 60min FRC = 30mL/kg
- neonatal alveolar ventilation 120 to 140mL/kg/min (double adults) -> achieved through an increase in RR