The effect of regional lung injury or alveolar hypoxia on pulmonary blood flow and lung water measured by positron emission tomography.

We measured regional pulmonary blood flow (rPBF) and extravascular lung water (rEVLW) with positron emission tomography (PET) before and after a lobar lung injury induced by oleic acid in dogs. Changes in rPBF after injury were also compared with those observed after alveolar hypoxia limited to a similar volume of lung. Positron emission tomography techniques for measuring rPBF correlated well with microsphere methods, even in areas of low blood flow (R2 = 0.88). After lung injury, rPBF decreased by 54% from its control value, compared with a 36% decrease in response to alveolar hypoxia. This difference was significant (p less than 0.05). Changes in oxygenation after injury correlated significantly with residual blood flow in the injured area (R2 = 0.69) but not with rEVLW. These data suggest that mechanisms other than hypoxic vasoconstriction may affect rPBF after lung injury, and that individual variation in rPBF to the injured area will have an important influence on oxygenation.