What is considered a normal cardiopulmonary transition at birth?

Updated: Sep 03, 2019
  • Author: Kate A Tauber, MD; Chief Editor: Howard S Weber, MD, FSCAI  more...
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A dramatic cardiopulmonary transition occurs at birth, as pulmonary blood flow increases 8- to 10-fold and pulmonary arterial pressure decreases by 50% within 24 hours. This is due to a marked increase in oxygen tension, the establishment of an air-liquid interface, and rhythmic distention of the lungs from breathing. [6, 7] The most critical signals for these transitional changes are mechanical distention of the lungs, a decrease in carbon dioxide tension, and an increase in oxygen tension in the lungs. Endothelial nitric oxide (NO) production in the lungs increases after birth as a result of the increased blood flow and oxygenation. The NO then mediates pulmonary vasodilation via cyclic guanosine monophosphate (cGMP). Cyclic adenosine monophosphate (cAMP) is increased after birth by the arachidonic acid-prostacyclin pathway which promotes smooth muscle cell relaxation.

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