How is the alveolar-arterial gradient computed in neonates considered for ECMO?

Updated: Dec 21, 2017
  • Author: Edwin Rodriguez-Cruz, MD; Chief Editor: Stuart Berger, MD  more...
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The alveolar-arterial (A-a) gradient of 600-624 mm Hg for 4-12 hours at sea level may be computed as follows (where 47=partial pressure of water vapor):

  • (A-a)(Diffusing capacity [D] of O2 equals atmospheric pressure - 47 - (PaCO2 + PaO2])/FiO2

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