Differential effects of positive end expiratory pressure and cardiac tamponade on left-right ventricular mechanical function in the dog.
OBJECTIVE
The aim was to examine the hypothesis that an increased coupling occurs between the ventricles during tamponade via a ventricular-pericardial-ventricular interaction, but that ventricular coupling would be unaltered or reduced with positive end expiratory pressure (PEEP).


METHODS
An in situ arrested, canine heart preparation was used. Changes in left and right ventricular pressure (dPl, dPr) and volume (dVl, dVr) caused by increasing the volume of the other ventricle were measured at normal and at matched levels of raised pericardial pressures (Pp) caused by 20 cm H2O PEEP and by tamponade.


RESULTS
With PEEP, the coupling between the ventricles was unaltered when compared to control. With tamponade, dPl/dPr, dVl/dPr, dPr/dPl, and dVr/dPl increased significantly (p less than 0.05) by 0.21 (SEM 0.03, unitless), 0.45(0.04) ml.mm Hg-1, 0.18(0.03), and 0.28(0.04) ml.mm Hg-1 respectively.


CONCLUSIONS
Augmented ventricular interdependence occurs during tamponade but not with PEEP, which may help to explain the different haemodynamic patterns observed under these conditions.
Nakamoto
T
T
Philadelphia Heart Institute, Presbyterian Medical Center, PA 19104.
Li
K S
KS
Johnston
W E
WE
Santamore
W P
WP
D000818:Animals; D002305:Cardiac Tamponade / Q000503:physiopathology*; D004285:Dogs; D011175:Positive-Pressure Respiration; D016276:Ventricular Function / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology