Response by Kremer et al to Letter Regarding Article, "Acute Impact of Prone Positioning on the Right Ventricle in COVID-19-Associated Acute Respiratory Distress Syndrome".

Abstract

HomeCirculation: Heart FailureVol. 15, No. 5Response by Kremer et al to Letter Regarding Article, “Acute Impact of Prone Positioning on the Right Ventricle in COVID-19–Associated Acute Respiratory Distress Syndrome” Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessLetterPDF/EPUBResponse by Kremer et al to Letter Regarding Article, “Acute Impact of Prone Positioning on the Right Ventricle in COVID-19–Associated Acute Respiratory Distress Syndrome” Nils Kremer, MD, Manuel J. Richter, MD and Khodr Tello, MD Nils KremerNils Kremer https://orcid.org/0000-0002-5615-0214 Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center, Germany. Search for more papers by this author , Manuel J. RichterManuel J. Richter Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center, Germany. Search for more papers by this author and Khodr TelloKhodr Tello https://orcid.org/0000-0002-5557-623X Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center, Germany. Search for more papers by this author Originally published22 Feb 2022https://doi.org/10.1161/CIRCHEARTFAILURE.121.009371Circulation: Heart Failure. 2022;15Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: February 22, 2022: Ahead of Print In Response:We thank our colleagues Hussain and Bernardo for their comment on our article, “Acute Impact of Prone Positioning on the Right Ventricle in COVID-19–Associated Acute Respiratory Distress Syndrome.”1There is no doubt that prone positioning is associated with improved lung mechanics and a long-term improvement in gas exchange. This is not only supported by various published data2 but also by our daily clinical observations in the treatment of patients, especially those with COVID-19–associated acute respiratory distress syndrome (ARDS). However, in our single case, we found that after prone positioning, right ventricular (RV) end-systolic and end-diastolic pressures and volumes were increased, accompanied by decreases in RV stroke volume and RV ejection fraction and worsening of pulmonary arterial pressures. The concept of mass effects by surrounding tissue compressing the RV outlined by Hussain and Bernardo is rational and may be a good explanation for the phenomenon, especially in obese patients. However, it is likely that the RV protective effects occur later on when the consolidated lung areas have been recruited again by prone positioning and reduced afterload. We agree with Hussain and Bernardo that the role of the RV in the context of mechanical ventilation in ARDS is not yet understood and deserves further investigation, especially since the prevalence of pulmonary hypertension and cor pulmonale is high in patients with ARDS and mortality is commonly associated with circulatory compromise. One of the landmark therapeutic modalities in ARDS is positive end-expiratory pressure (PEEP) adjustment up to >20 cm H2O depending on the fraction of inspired oxygen. It is known that invasive mechanical ventilation, primarily by changing the intrathoracic pressure, has a significant effect on RV function. However, the underlying mechanisms have not yet been examined in detail using pressure-volume loops, which are considered the gold standard for assessing RV physiological function. We are convinced that this technique can make a valuable contribution to our understanding of the behavior of the RV in ventilated patients, especially those with ARDS. Pressure-volume loops might sensitively reflect changes in the RV facing different afterload conditions. For example, in a patient experiencing end-stage pulmonary destruction and pulmonary hypertension due to COVID-19 ARDS, we were able to measure changes in RV function during a PEEP maneuver, with clear differentiation of inspiratory and expiratory pressure-volume loops (Figure). With increasing PEEP, we observed an increase in afterload (arterial elastance) and a small, clinically insignificant change in contractility (end-systolic elastance). Thus, as expected, there was less favorable RV–pulmonary arterial coupling (end-systolic elastance/arterial elastance) with increasing PEEP. This was also reflected in a decreasing RV ejection fraction.Download figureDownload PowerPointFigure. Right ventricular pressure volume loops with different values of positive end expiratory pressure in a patient with COVID-19–acute respiratory distress syndrome. A, Change in end-systolic elastance (Ees) and arterial elastance (Ea) with different positive end-expiratory pressures (PEEPs) in a patient with COVID-19–associated acute respiratory distress syndrome. Dashed lines indicate expiratory pressure-volume (PV) loops, and solid lines indicate inspiratory PV loops. Figure indicates changes of Ea (B), Ees (C), Ees/Ea (D), and right ventricular ejection fraction (RVEF; E) with different PEEP values. EF indicates ejection fraction.In conclusion, evidence prevails and until we measure RV function with the best possible method concerning pressure and volume, we will not be able to detect the real reaction of the RV to interventions such as prone positioning and PEEP.Article InformationDisclosures Dr Richter has received support from United Therapeutics and Bayer; speaker fees from Bayer, Actelion, Mundipharma, and Roche; and consultancy fees from Bayer. Dr Tello has received speaking fees from Actelion and Bayer. The other author reports no conflicts.FootnotesFor Disclosures, see page 535.