Continuous positive-pressure ventilation does not alter ventricular pressure-volume relationship.
To determine whether alterations in the mechanical properties (i.e., stiffening) of the right and left ventricles contribute to the decrease in right and left ventricular end-diastolic volumes during continuous positive-pressure ventilation (CPPV), we studied six dogs anesthetized with chloralose urethane and ventilated with a volume ventilator. We varied ventricular volumes by withdrawing or infusing blood. Pressure-volume curves, constructed by plotting transmural ventricular end-diastolic pressures against ventricular end-diastolic volumes, did not change during CPPV (12 cmH2O positive end-expiratory pressure) compared to intermittent positive-pressure ventilation (IPPV, 0 cmH2O end-expiratory pressure). We conclude that decreased ventricular end-diastolic volumes during CPPV result primarily from a decrease in venous return. Alterations in the mechanical properties of the ventricles do not play a significant role in this response.
D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D004285:Dogs; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D009200:Myocardial Contraction; D011312:Pressure; D013499:Surface Properties; D016276:Ventricular Function