[Hemodynamics in right heart damage under continuous positive pressure respiration. An experimental study of the open...

The haemodynamic effects of isolated right ventricular damage (produced by pressure overloading from temporary banding of the pulmonary artery) under increased positive end-expiratory pressure were investigated in 12 pigs. Under controlled ventilation and anaesthesia with fentanyl and pancuronium bromide the experimental study was performed with an open chest and pericardium; under these circumstances high levels of PEEP resulted primarily in an increase of right ventricular afterload. RAP (+30,2%, p less than 0.05) and RVEDP (+196%, p less than 0,01) of the damaged right ventricle were increased markedly, dRVp/dt is decreased (-18%, p less than 0,05) with a corresponding endsystolic pressure-volume relationship. The decrease of CI after moderate right ventricular lesion is more distinct under PEEP (-27%, p less than 0,01) than previously (-13%). Because of an elevation of TPR-I (+24%) there was no significant fall of systemic arterial pressure (-6,6%); heart rate also remained constant (+3%). Accordingly, with the open chest, haemodynamic changes related to increased positive end-expiratory pressure are very discrete, both in intact and damaged right ventricles; only with high levels of PEEP, elevation of pulmonary vascular resistance--under open chest conditions the predominant factor--limits myocardial performance of the damaged right ventricle and results in a significant reduction of cardiac output.