Acute respiratory failure: pulmonary thromboembolism.

This seminar is concemed mainly with the mechanisms of gas exchange impairment in pulmonary thromboembolism. Studies of gas exchange in pulmonary embolism are stili not numerous. A few have been performed in experirnental anirnals [1]. The methods employed comprise the determination of gas ex- change parameters [2], including the physiological dead space [3], and the multiple inert gas elimina- tion technique [4-6]. Furthermore, little effort has been made to relate topographical alterations of ventilation and blood flow, detected by extemal counting of radioactive tracers, to the ventilationlperfusion (V'A/Q') disturbances responsible for impaired gas exchange in pulmonary embolism. This presentation reports data on pulmonary gas exchange, V'A/Q' distribution assessed by inert gas elimination, and regional lung function by ventilation and perfusion scan in human pulmonary embolism.