What are the pathophysiologic mechanisms for hypoxemic respiratory failure?

Updated: Apr 07, 2020
  • Author: Ata Murat Kaynar, MD; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM  more...
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The pathophysiologic mechanisms that account for the hypoxemia observed in a wide variety of diseases are V/Q mismatch and shunt. These 2 mechanisms lead to widening of the alveolar-arterial PO2 gradient, which normally is less than 15 mm Hg. They can be differentiated by assessing the response to oxygen supplementation or calculating the shunt fraction after inhalation of 100% oxygen. In most patients with hypoxemic respiratory failure, these 2 mechanisms coexist.

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