Good Morning 99Nicu,

I would be grateful for an educational leg up! Very often a term PPHN is normocarbic yet we struggle with PaO2. What are the underlying factors that allow CO2 clearance but fail to enhance PaO2?

Best wishes

Alistair

Good question!

I guess it is related to the higher solubility of CO2, and that the low pulmonary blood flow is enough for elimination of CO2.

Due to the difference in diffusion capacity across the alveolar membrane fecilitated by the increasing ventilatory effort to maintain PaO2..

I'd say the same as already mentioned:

In different words: CO2 travels about 10 times easier over the alveolar membrane than oxygen.

Low pO2 because the need of oxygen is not met due to low oxygenation in the lungs caused by restricted lung blood flow (hypertension).

In PPHN THERE IS SHUNTING OF PUL BLOOD AT ATRIAL(PFO) AND PULM DUCT LEAD TO SEVERE HYPOXEMIA CAUSE TACHYPNEOA .AS LUNG IS NORMAL PCO2 IS MAINTAINED NORMAL