Can VA/Q distributions in the lung be recovered from inert gas retention data?

It has been suggested that the true distribution of ventilation-perfusion ratios can be determined from measurements made during the excretion of six different inert gases. This report shows that a number of considerably different distribution patterns will yield the same retention data, even in the absence of analytical error. Therefore, although analysis of inert gas retention data will allow one to arrive at a VA/Q distribution, it will not necessarily be the correct distribution.