An Evaluation of the Nitrous Oxide Method for the Quantification of Left-to-Right Shunts

Abstract

Extensive clinical use has now been made of the nitrous oxide test for the detection and localization of left-to-right circulatory shunts. On theoretical grounds the magnitude of such a shunt should be related to the systemic and pulmonary arteriovenous differences in nitrous oxide content measured early in the period of inhalation. In order to determine the validity of the nitrous oxide method for the quantification of a left-to-right shunt, total pulmonary and shunt flows were directly measured in experimental animals as nitrous oxide tests were performed simultaneously.