Predicting Survival After Extracorporeal Membrane Oxygenation for ARDS: An External Validation of RESP and PRESERVE Scores

Abstract

Background: We aimed to test the performance of PRESERVE and RESP scores to predict death in patients with severe ARDS receiving extracorporeal membrane oxygenation (ECMO) with different case mixes.

Methods: All consecutive patients treated with ECMO for refractory ARDS, regardless of cause, in the Caen University Hospital in northwestern France over the last decade were included in a retrospective cohort study. The receiver operating characteristic curves of each score were plotted, and the area under the curve was computed to assess their performance in predicting mortality (c-index).

Results: Forty-one subjects were included. Pre-ECMO ventilator settings were: mean V_T, 6.1 ± 0.9 mL/kg; breathing frequency, 32 ± 4 breaths/min; PEEP, 11 ± 4 cm H₂O; peak inspiratory pressure, 48 ± 9 cm H₂O; plateau pressure, 30.4 ± 4.4 cm H₂O. At ECMO initiation, blood gas results were: pH 7.22 ± 0.17, P_aO2 /F_IO2 = 63 ± 22 mm Hg; P_aCO2 = 56 ± 18 mm Hg; F_IO2 = 99 ± 2%. Pre-ECMO data were available in 35 and 27 subjects for calculation of the PRESERVE score and RESP score, respectively. Pre-ECMO scoring system results were: median PRESERVE score, 4 (interquartile range 2-5), and median RESP score, 0 (interquartile range -2 to 2). Twenty-three subjects (56%) died, including 19 receiving ECMO. In univariate analysis, plateau pressure (P = .031), driving pressure (P = <.001), and compliance (P = .02) recorded at the time of ECMO initiation as well as the PRESERVE score (P = .032) were significantly associated with mortality. With a c-index of 0.69 (95% CI 0.53-0.87), the PRESERVE score had better discrimination than the RESP score (c-index of 0.60 [95% CI 0.41-0.78]) for predicting mortality.

Conclusions: The use of these scores in helping physicians to determine the patients with ARDS most likely to benefit from ECMO should be limited in clinical practice because of their relatively poor performance in predicting death in subjects with severe ARDS receiving ECMO support. Before widespread use is initiated, these scoring systems should be tested in large prospective studies of subjects with severe ARDS undergoing ECMO treatment.

Keywords: ARDS; extracorporeal membrane oxygenation; outcome.