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Updated: Jun 24, 2026

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
07:09

Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise

Published on: February 20, 2017

Ventilation-perfusion relationships during exercise-induced asthma in children

U Freyschuss, G Hedlin, G Hedenstierna

    The American Review of Respiratory Disease
    |November 1, 1984
    PubMed

    Insights

    Exercise-induced asthma (EIA) causes hypoxemia by altering ventilation-perfusion (VA/Q) relationships. Studies show EIA in children leads to bimodal VA/Q distributions, impacting oxygen levels.

    Area of Science:

    • Pulmonary Physiology
    • Pediatric Respiratory Medicine
    • Exercise Physiology

    Background:

    • Exercise-induced asthma (EIA) is a common condition in children, often associated with hypoxemia.
    • The precise mechanisms linking EIA to reduced blood oxygen levels remain incompletely understood.

    Purpose of the Study:

    • To investigate the ventilation-perfusion (VA/Q) relationships during exercise in children with a history of EIA.
    • To elucidate the physiological basis of hypoxemia in EIA.

    Main Methods:

    • Utilized the multiple inert gas elimination technique to measure VA/Q distributions in 11 children with EIA.
    • VA/Q distributions were assessed at rest and after an exercise challenge designed to provoke EIA symptoms.

    Main Results:

    • Children who developed EIA post-exercise showed a shift from unimodal to bimodal VA/Q distributions.
    • A significant correlation was observed between hypoxemia and increased perfusion in low VA/Q regions (0.1-1).
    • High VA/Q regions correlated with reduced forced expiratory volume in 1 second (FEV1) and partial pressure of oxygen (PaO2), suggesting increased intrathoracic pressure impacting blood flow.

    Conclusions:

    • EIA in children is characterized by abnormal VA/Q distributions, specifically a bimodal pattern.
    • These VA/Q alterations, particularly increased perfusion in low VA/Q areas and high VA/Q regions, directly contribute to exercise-induced hypoxemia.
    • Increased intrathoracic pressure during EIA may impede regional blood flow, exacerbating gas exchange abnormalities.

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