THE EFFECTS OF VARIATIONS IN END-EXPIRATORY INFLATION PRESSURE ON CARDIORESPIRATORY FUNCTION IN NORMO-, HYPO AND HYPERVOLAEMIC DOGS

Abstract

The effects of altering end-expiratory inflation pressure were studied in mechanically ventilated dogs in the normo-, hypo- and hypervolaemic state. The mean fall in cardiac output resulting from an increase in end-expiratory pressure was smaller in the hypervolaemic group than in the other two groups. A positive end-expiratory pressure increased the mean deadspace/tidal volume ratio in all groups. A negative end-expiratory pressure increased venous admixture, particularly in the over-transfused animals, but the increase was not significant in the hypovolaemic group. A negative end-expiratory pressure did not affect deadspace/tidal volume ratio.