[A method of estimating alveolo-arterial gradient and arterial pressure of CO2, without analysis of blood].

In 31 normal and 378 patients suffering from various bronchopulmonary diseases, a relation was established experimentally between TCO and the alveolo-arterial gradient of CO2. From TCO and CO2 output, this relation allows to obtain a reproducible estimation of the alveolo-arterial gradient and of the arterial pressure of CO2 by a non-bloody method with sufficient clinical accuracy. Moreover, this methods permits to interpret TCO steady state more easily and especially so under unusual ventilatory conditions.