The Journal of Thoracic and Cardiovascular Surgery, Vol 93, 823-831, Copyright © 1987 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Positive end-expiratory pressure and the damaged right ventricle. An experimental open versus closed chest study
HH Metzler, W Stenzl, PH Rehak, KH Tscheliessnigg and WF List
Hemodynamic changes after isolated impairment of right ventricular function
(produced by increasing afterload by temporary banding of the pulmonary
artery) were studied in 22 ventilated pigs during increased levels of
positive end-expiratory pressure (4, 8, 12, and 16 cm H2O). In the open
chest group, application of positive end-expiratory pressure produced only
a slight decrease of cardiac index. After right ventricular damage a
decrease of cardiac index of more than 25% occurred only when higher levels
of positive end-expiratory pressure were applied. In contrast to the open
chest group, the closed chest group showed more distinct cardiovascular
responses after positive end- expiratory pressure. In the damaged right
ventricle with a positive end- expiratory pressure of 16 cm H2O, right
ventricular end-diastolic pressure increased more than 100%. With positive
end-expiratory pressure, cardiac index decreased 34% before and 47% after
right ventricular damage. We conclude that positive end-expiratory pressure
induces a more pronounced decrease in cardiac index if right ventricular
function is impaired. During open chest conditions with lower levels of
positive end-expiratory pressure, these changes are only small, however,
and probably irrelevant. During closed chest conditions, the hemodynamic
changes are much more pronounced. High right ventricular end-diastolic
pressures resulting from impaired right ventricular contractility as well
as from high levels of positive end- expiratory pressure may have an impact
on biventricular function and right ventricular coronary driving pressure.
