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

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.