Hemodynamics during mechanical ventilation

Abstract

Hemodynamic and respiratory studies were carried out in patients with neurogenic respiratory paralysis or chronic pulmonary emphysema (some of them with “cor pulmonale” in congestive failure) who were subjected to artificial mechanical ventilation. Cardiac output generally decreased in patients with chronic respiratory paralysis and in all patients with “cor pulmonale” in congestive failure. In patients with chronic pulmonary emphysema, blood flow did not change. Mean circulation time was increased in almost all cases, whereas changes in “central” blood volume took the same direction as the modifications in cardiac output. Transmural pulmonary arterial pressure decreased in the 3 patients with chronic respiratory paralysis in whom it was measured, and in the only patient with chronic “cor pulmonale” in congestive failure in whom it was determined. A patient with myasthenia gravis in paralytic crisis was subjected successively to artificial ventilation with the iron lung and with positive pressure apparatus, showing minor changes in the variables studied.