CONCISE PUBLICATIONS An Efficient Optimization Technique for Recovering Ventilation-Perfusion Distributions from Inert Gas Data EFFECTS OF RANDOM EXPERIMENTAL ERROR

of numerical analysis has been used to recover known distributions of intrapulmonary ventilation-perfusion ratios from inert gas data. Hypothetical lungs were simulated and corresponding inert gas retentions cal-culated. By using error-free retentions for seven gases and a 50-compartment model, it was possible to recover distributions containing up to three modes accurately and with greater efficiency than with other numerical meth-ods. When random error of a magnitude consistent with present analytical techniques was introduced into reten-tion data, the recovered distributions differed qualita-tively from the original ones. This resulted from the ill-conditioned nature of the mathematical problem, which makes a recovered distribution extremely sensitive to small errors in retention. Thus, present levels of mea-surement error represent an important limitation in cur-rent techniques for deriving distributions from inert gas measurements