Evaluation of right ventricular function and driving pressure with blood gas analysis could better select patients eligible for VV ECMO in severe ARDS

Abstract

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. To the Editor, The Acute Respiratory Distress Syndrome (ARDS) is still associated with high mortality [1], despite application of recent guidelines [2, 3]. The EOLIA study suggested that ExtraCorporeal Membrane Oxygenation (ECMO) could be effective in some of the most severe patients, but failed to demonstrate a 20% increase in survival [4]. One reason could be that criteria for selecting patients were only based on blood gas analysis. Our hypothesis is that adding other factors could allow a better selection of patients who could benefit from ECMO. We took advantages to have a large multicentric cohort of patients under protective ventilation for moderate-tosevere ARDS [5] to determine the incidence, characteristics and outcome of patients eligible for ECMO according to EOLIA-based criteria and to identify patients who would benefit the most of the technique. ECMO was only used in these centers as a recue therapy. Mechanical ventilation was applied in the volumeassist control mode, with a target tidal volume (TV) of 6–8 mL/kg (predicted body weight) and a plateau pressure < 30 cmH2O. Respiratory rate could be increased in case of high arterial carbon dioxide partial pressure (PaCO2). Prone positioning was left to the discretion of the attending physician, but was typically performed in patients with a PaO2/FiO2 < 100 mmHg and/or an acute core pulmonale (ACP) [6]. Patients eligible for ECMO according to EOLIA-based criteria were identified as follows: PaO2/FiO2 < 80 mmHg with optimal PEEP, or a pH < 7.25 and PaCO2 > 60 mmHg with a respiratory rate ≥ 35 cycles/min, despite the use of prone positioning or nitric oxide inhalation. Statistical analysis was performed with R.4.0.4. Patients eligible for ECMO were compared to the rest of the cohort. Continuous data, expressed as medians (interquartile ranges), were compared with Mann–Whitney test. Categorical variables, expressed as numbers and percentages, were compared using the chi-square test or Fisher exact test. To evaluate independent factors associated with ICU mortality in this identified subgroup of patients, significant or marginally significant (p < 0.10) bivariate risk factors were examined using univariate and multivariable backward stepwise mixed logistic regression stratified on the center. SAPS II was forced in the model. 752 patients were studied. Characteristics and outcome are given in the Table 1. 67 (9%) patients were potentially eligible for ECMO. They had lower PaO2/ FiO2 (62 [55–72] versus 114 [90–120] mmHg: p < 0.01) and higher incidence of ACP (42% versus 20%, p < 0.001). Only 8 of them underwent the procedure. Open Access