A Clinical Study on the Distribution of VA/Q in the Acute Respiratory Failure

Abstract

It has been speculated that in acute respiratory failure the main pathophysiological mechanism in the disrurbance of pulmonary oxygenation will be due to the formation of shunt and venilation-perfusion inequality. However there has been a little investigation which clarified such a disorder in distribution of ventilation-perfusion ratio on the cases of acute respiratory failure. In this paper the distribution of ventilationperfusion ratio was observed in the cases of acute respiratory failure using 6 inert gas method by which the distribution of ventilation-perfusion ratio is able to be serially measured dividing ventilation-perfusion ratio into 50 compartments. As the results, spread distribution of blood flow over wide ventilation-perfusion area, twice as wide dispersion as that in normal lung, and the formation of markedly increased shunt were observed in all the cases investigated. Furthermore significant correlation (r=0.97) was obtained between measured PaO₂ and PaO₂ which was calculated by computer simulation on the measured distribution pattern of ventilation-perfusion ratio.