Prediction of outcome in patients with ARDS: A prospective cohort study comparing ARDS-definitions and other ARDS-associated parameters, ratios and scores at intubation and over time

Abstract

Background Early recognition of high-risk-patients with acute respiratory distress syndrome (ARDS) might improve their outcome by less protracted allocation to intensified therapy including extracorporeal membrane oxygenation (ECMO). Among numerous predictors and classifications, the American European Consensus Conferenece (AECC)-and Berlin-definitions as well as the oxygenation index (OI) and the Murray-/Lung Injury Score are the most common. Most studies compared the prediction of mortality by these parameters on the day of intubation and/or diagnosis of ARDS. However, only few studies investigated prediction over time, in particular for more than three days. Objective Therefore, our study aimed at characterization of the best predictor and the best day(s) to predict 28-days-mortality within four days after intubation of patients with ARDS. Methods In 100 consecutive patients with ARDS severity according to OI (mean airway pressure*-F i O 2 /p a O 2), modified Murray-score without radiological points (Murray_mod), AECC-and Berlin-definition, were daily documented for four days after intubation. In the subgroup of 49 patients with transpulmonary thermodilution (TPTD) monitoring (PiCCO), extravascular lung water index (EVLWI) was measured daily.

Increased extravascular lung water index (EVLWI) reflects rapid inflammatory oedema and mortality in COVID-19 associated ARDS

“…14 ’ 19 A recent study in a non-COVID-19 cohort with ARDS patients suggests an improved and earlier prediction of 28-days-mortality compared to traditional scores of ARDS severity. 20 Furthermore, TPTD-monitoring of critically ill non-COVID-19 patients was independently associated with a lower mortality in this study.…”

“…Comparison of EVLWI in COVID-19-ARDS-patients with a recent non-COVID-19- cohort with ARDS. 20 The non-COVID-19-cohort comprised 49 consecutive patients with TPTD-monitoring and ARDS. 21 All patients of this cohort were treated in the same ICU as the COVID-19-patients and had been treated before 2019 (see Clinical Study Registration No.…”

“…Based on two independent study groups, a continuous endpoint (EVLWI with a mean of 12.5±4.9mL/kg in the control cohort p-value and an estimated EVLWI of 18±7mL/kg in the COVID-19-cohort, a number of 49 controls and 25 COVID-19-patients would result in a statistical power of >90% with a p-value of p<0.05. 20…”

Novel criteria to classify ARDS severity using a machine learning approach

“…Moreover, a definition of ARDS is required for clinicians to initiate treatments that would improve clinical outcomes [ 11 ], although stratification of ARDS—as defined by Berlin criteria—has been shown not very useful for assessing lung severity [ 8 , 12 ]. The empirical PaO 2 /FiO 2 cut-offs for “severity” of 100, 200, and 300 mmHg are arbitrary and poorly validated [ 13 ]. A recently published Reevaluation of Systemic Early Neuromuscular Blockade (ROSE) trial emphasized the variability of these PaO 2 /FiO 2 cut-offs as the investigators did not enroll patients based on the PaO 2 /FiO 2 at the time of ARDS onset, but based on a PaO 2 /FiO 2 < 150 mmHg within the first 48-h after ARDS diagnosis [ 14 , 15 ].…”

“…A recently published Reevaluation of Systemic Early Neuromuscular Blockade (ROSE) trial emphasized the variability of these PaO 2 /FiO 2 cut-offs as the investigators did not enroll patients based on the PaO 2 /FiO 2 at the time of ARDS onset, but based on a PaO 2 /FiO 2 < 150 mmHg within the first 48-h after ARDS diagnosis [ 14 , 15 ]. The PaO 2 /FiO 2 ratio strongly depends on ventilator settings, including positive end-expiratory pressure (PEEP), inspiratory/expiratory time (I:E) ratio, and FiO 2 , and the requirement of a minimum PEEP of 5 cmH 2 O did not substantially improve Berlin prediction compared to AECC [ 13 , 16 ]. Besides, Berlin definition does not account for the nonlinear relationship of PaO 2 and FiO 2 [ 17 ] and has a limited predictive accuracy in recent trials [ 18 – 21 ].…”