Journal of Applied Physiology, Vol 50, Issue 5 1071-1078, Copyright © 1981 by American Physiological Society
Evaluation of alveolar amplitude response technique for determination of lung perfusion in exercise
S. C. Luijendijk, A. Zwart, A. M. van der Kooij and W. R. de Vries
We investigated the influence of tracer gas venous return on the
determination of pulmonary perfusion (Qp) using the alveolar amplitude
response technique (AART) to evaluate the applicability of this technique
at rest and during exercise. The venous return influence was calculated by
a computer simulation applied to a simplified body compartment model. Using
the AART method, which neglects the influence of venous return, a
simulation based on acetylene as a tracer gas predicted an overestimation
of the actual value of Qp ranging from 0 to 10% for all work loads
investigated. These theoretical results were compared with experimental
results. Experiments with human subjects with acetylene as the tracer gas
yielded an underestimation of Qp of about 20% at rest and an overestimation
of about 7% under different exercise conditions. Experiments with
anesthetized dogs showed an underestimation of Qp of about 12% for
acetylene and about 6% for halothane. The theoretical and experimental
results related to exercise conditions are thus in good quantitative
agreement. The experimental data obtained for acetylene with human subjects
at rest and with anesthetized dogs are also in good quantitative agreement.
However, they deviate considerably from theoretical predictions. This
discrepancy may be due to the simplified body compartment model used in the
calculations, which can considerably influence the calculated results,
especially for conditions at rest. The main conclusion of this paper is
that recirculating tracer gas does not unduly influence results for Qp
obtained with the AART method when halothane is used as the tracer gas.
