Newly Published
Editorial Views  |   June 2019
The Unappreciated Role of Carbon Dioxide in Ventilation/Perfusion Matching
Author Notes
  • From Pulmonary, Critical Care and Sleep Medicine, University of Washington, Veterans Affairs Puget Sound Health Care System, Seattle, Washington.
  • Accepted for publication April 10, 2019.
    Accepted for publication April 10, 2019.×
  • Correspondence: Address correspondence to Dr. Swenson: eswenson@uw.edu
Article Information
Editorial Views / Respiratory System
Editorial Views   |   June 2019
The Unappreciated Role of Carbon Dioxide in Ventilation/Perfusion Matching
Anesthesiology Newly Published on June 12, 2019. doi:10.1097/ALN.0000000000002791
Anesthesiology Newly Published on June 12, 2019. doi:10.1097/ALN.0000000000002791
Ventilation/perfusion ratio VA/Q matching is fundamental to efficient gas exchange, and its disruption or augmentation in disease, during surgery, and with certain drugs is important in the practice of anesthesiology, pulmonology, and critical care medicine. The role of hypoxic pulmonary vasoconstriction is very well known to most physicians and is considered primarily responsible for the effective matching of regional ventilation and perfusion. Hypoxic pulmonary vasoconstriction diverts blood flow from poorly or nonventilated lung regions to better ventilated areas and was first demonstrated in the late 1940s in animals and humans.1  While hypoxic pulmonary vasoconstriction is due to the decrease in alveolar oxygen occurring in underventilated units and initiating vasoconstriction, an increase in carbon dioxide also occurs concurrently and is equally potent in this regard, as von Euler and Liljestrand2  recognized in their seminal study. Although hypercapnia clearly magnifies the strength of hypoxic pulmonary vasoconstriction, hypercapnic vasoconstriction occurs in the normoxic healthy lung as well,3  where the evidence for any role of hypoxic pulmonary vasoconstriction has been questioned.4  Given the importance of matching regional perfusion to ventilation, it should not be surprising that nature and evolution have endowed the lungs with more than one mechanism to accomplish it.