[High oxygen breathing improves inhomogeneities of ventilation-perfusion distributions in acutely injured lungs].

Using twenty-five mongrel dogs either with or without alveolar flooding induced by oleic acid administration, the effects of high oxygen breathing (60% O2) on ventilation--perfusion (VA/Q) distributions in the lungs were systematically investigated. VA/Q distributions were examined by multiple inert gas elimination technique, from which the VA/Q values describing mean positions of perfusion (Q) and ventilation (VA) distributions against the VA/Q axis were calculated (mean Q and mean VA). As the first measure of dispersion for VA/Q distribution, the log standard deviation was estimated (log SD (Q) and logSD (VA)). As the second measure of dispersion, the area under the curve, constructed by plotting inert gas arterial-to-alveolar partial pressure differences as a function of blood-gas partition coefficient, was calculated (aAD area). High oxygen breathing slightly enhanced the dispersion of VA/Q distributions in the normal dogs but decreased that in the dogs injured with oleic acid. Therefore, we concluded that high oxygen breathing worsened the inhomogenieties of VA/Q distributions in normal lungs but did improve those in acutely injured lungs.