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Perfusion redistribution after alveolar flooding: vasoconstriction vs. vascular compression
1Department of Internal Medicine, Washington University Medical School, St. Louis, Missouri 63110.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1991
Summary
Alveolar hypoxia and edema in the left caudal lobe (LCL) reduce pulmonary blood flow (PBF). Blocking vasoconstriction prevents these PBF changes, indicating it
Area of Science:
- Pulmonary Physiology
- Respiratory Medicine
Background:
- Alveolar hypoxia and edema are known to affect pulmonary blood flow (PBF).
- The precise mechanisms and the role of oncotic pressure in edema-induced PBF changes remain under investigation.
Purpose of the Study:
- To compare the effects of left caudal lobe (LCL) alveolar hypoxia on regional PBF with those of plasma-induced alveolar edema.
- To investigate the role of vasoconstriction and mechanical compression in mediating these PBF changes.
Main Methods:
- Regional PBF measurements using positron emission tomography in 16 dogs.
- Induction of LCL alveolar hypoxia and alveolar edema via plasma instillation.
- Assessment of PBF changes before and after endotoxin administration to block vasoconstriction.
Main Results:
- LCL alveolar hypoxia significantly reduced the LCL-to-right caudal lobe (L/R) PBF ratio.
- Plasma-induced alveolar edema (isooncotic or hypooncotic) similarly reduced the L/R PBF ratio.
- Prior endotoxin administration completely prevented the PBF changes induced by both hypoxia and edema.
Conclusions:
- Perfusion redistribution occurs in alveolar edema irrespective of oncotic pressure.
- Blocking regional vasoconstriction prevents alterations in regional PBF, suggesting mechanical compression is not the primary factor.
- Regional vasoconstriction is the key mechanism driving PBF changes in response to alveolar hypoxia and edema.