Mortality rates of severe COVID-19-related respiratory failure with and without extracorporeal membrane oxygenation in the Middle Ruhr Region of Germany

Abstract

The use of extracorporeal membrane oxygenation (ECMO) is discussed to improve patients' outcome in severe COVID-19 with respiratory failure, but data on ECMO remains controversial. The aim of the study was to determine the characteristics of patients under invasive mechanical ventilation (IMV) with or without veno-venous ECMO support and to evaluate outcome parameters. Ventilated patients with COVID-19 with and without additional ECMO support were analyzed in a retrospective multicenter study regarding clinical characteristics, respiratory and laboratory parameters in day-to-day follow-up. Recruitment of patients was conducted during the first three COVID-19 waves at four German university hospitals of the Ruhr University Bochum, located in the Middle Ruhr Region. From March 1, 2020 to August 31, 2021, the charts of 149 patients who were ventilated for COVID-19 infection, were included (63.8% male, median age 67 years). Fifty patients (33.6%) received additional ECMO support. On average, ECMO therapy was initiated 15.6 ± 9.4 days after symptom onset, 10.6 ± 7.1 days after hospital admission, and 4.8 ± 6.4 days after the start of IMV. Male sex and higher SOFA and RESP scores were observed significantly more often in the high-volume ECMO center. Pre-medication with antidepressants was more often detected in survivors (22.0% vs. 6.5%; p = 0.006). ECMO patients were 14 years younger and presented a lower rate of concomitant cardiovascular diseases (18.0% vs. 47.5%; p = 0.0004). Additionally, cytokine-adsorption (46.0% vs. 13.1%; p < 0.0001) and renal replacement therapy (76.0% vs. 43.4%; p = 0.0001) were carried out more frequently; in ECMO patients thrombocytes were transfused 12-fold more often related to more than fourfold higher bleeding complications. Undulating C-reactive protein (CRP) and massive increase in bilirubin levels (at terminal stage) could be observed in deceased ECMO patients. In-hospital mortality was high (Overall: 72.5%, ECMO: 80.0%, ns). Regardless of ECMO therapy half of the study population deceased within 30 days after hospital admission. Despite being younger and with less comorbidities ECMO therapy did not improve survival in severely ill COVID-19 patients. Undulating CRP levels, a massive increase of bilirubin level and a high use of cytokine-adsorption were associated with worse outcomes. In conclusion, ECMO support might be helpful in selected severe cases of COVID-19.

Figure 1

Enrollment flowchart ICU: intensive care unit, ECMO: extracorporeal membrane oxygenation.

Figure 2

Days are shown as mean intervals for each group (ECMO survivors, ECMO deaths, Non-ECMO survivors, Non-ECMO deaths). (A) Intervals from symptom onset to hospital admission and hospital admission to ICU admission. (B) Intervals from hospital admission to intubation and hospital admission to ECMO cannulation. (C) Period of intubation (interval of intubation to extubation) and ECMO period (interval of ECMO cannulation to decannulation). (D) Intervals of hospital admission to death or discharge.

Figure 3

Kaplan Meier survival curve for hospital length, ECMO as explanatory variable and alive as censor variable with Burr fit and Cox proportional regression hazards model. p value = 0.91.

Figure 4

Survivors and deaths related to age groups are shown for the whole patient cohort (A) and especially for patients with ECMO support (B).

Figure 5

(A–F): some laboratory parameters over time (mean) (G): daily change of CRP at day t_i-1 against day t_i as Poincaré plot.