CARDIORESPIRATORY EFFECTS OF EXPERIMENTAL LUNG EMBOLISM*

Abstract

Experimental pulmonary embolism was produced in sheep by means of graded amounts of barium sulfate emulsion. Ventilation, lung mechanics and circulation ere simultaneously measured. The effect of various neuroplegic pro cedures, oxygen breathing, the administration of antihistaminic and anti-serotonin drugs, and continuous epinephrine and isoproterenol infusions was assessed. In addition to the already known consequences of pulmonary embolism a gross fall in lung compliance was shown to occur, unrelated to lung edema. All but one of the procedures used in these experiments were ineffective in altering the onset of severity of hyperventilation, pulmonary hypertension, bronchoconstriction or fall in compliance but the effect of a smaller dose of embolic material was completely prevented by the administration of isoproterenol. It is concluded that postembolic pulmonary hypertension and compliance fall after a small dose of embolic material are predominantly functional and probably caused by the release of an unknown substance as a response to embolism.