| Popis: |
To differentiate between the mechanisms which have been proposed to account for the hypotensive effect of pulmonary insufflation, cyclic volume changes of the right ventricle were qualitatively monitored by means of a variable resistance strain gauge sutured to the right ventricular wall. Artificially created decreases in venous return as well as cardiac tamponade of a degree sufficient to produce hypotension for brief periods were found to decrease the volume of the right ventricle. Increased right ventricular outflow resistance, however, produced a marked increase in right ventricular volume. With brief periods of hypotensive levels of pulmonary insufflation, right ventricular volume was found to increase in the animal with a wide-open chest; the volume decreased with the chest closed. It is concluded that in the open-chest condition the hypotensive mechanism of pulmonary insufflation is an increase in pulmonary vascular resistance, whereas in the closed-chest condition decreased venous return, cardiac tamponade, or both are predominantly responsible for the hypotension. |
