Influence of PEEP Ventilation Immediately after Cardiopulmonary Bypass on Right Ventricular Function: Outcome

We have chosen PEEP of 15 cmH20 because Metzler et al found that only high levels of PEEP elevating pulmonary vascular resistance limit myocardial performance of the right ventricle resulting in a significant reduction of CO. PEEP was found to be associated with a large decrease in left and right ventricular end-diastolic volumes. Right ventricular volume and performance, however, have been difficult to obtain because of the functional anatomy and complex geometry The correlation between the new thermodilution technique used in this study for estimation of RVEF and other methods such as first pass technique or equilibrium gated techniques is significant. Traditionally monitored hemodynamic parameters such as RAP or RVP, however, have failed to be representative for right ventricular function. RVEDR too, shows considerable individual variations and does not have a close relationship to ejection fraction or clinical evidence of right heart decompensation. zaditor eye drops

In our patients without RCA stenosis, RVEDV and RVESV were reduced significantly by PEEP ventilation which is in accordance with other studies. In the group with RCA-stenosis, however, right ventricular volume was not decreased significantly, thus showing that the right ventricle was insufficient and not able to transport blood adequately through the pulmonary vessels, although blood supply to the right chamber is reduced by PEEP; RVEF was decreased in these patients demonstrating that the right ventricle was unable to make the adaptations required.
MAP was significantly reduced only in the “with-RCA-group” and the resulting decrease in right coronary perfusion is contributing to the vicious circle. A critical decrease in right ventricular 02 supply/demand ratio may have developed and resulted in right ventricular ischemia and further deterioration of its function.
In agreement with our results, Skarvan et al demonstrated that surgical revascularization of the RCA may frequently be associated with right ventricular dysfunction. Results from Priebe indicate that severe right ventricular myocardial dysfunction may develop during moderate pulmonary hypertension only when right coronary artery (RCA) stenosis is present. It is stressed that patients not exhibiting clinical symptoms of coronary insufficiency at rest may develop severe myocardial dysfunction during only mild increases in pulmonary artery pressure. In the normal right ventricle, however, a mean PAP as high as 40 mm Hg may be sustained without reduction in CO.

Category: Cardiopulmonary Bypass

Tags: cardiopulmonary bypass, coronary artery, ventricular function