2. Study characteristics.
| Zapol 1979 | Morris 1994 | Peek 2009 | Bein 2013 | |
| Study type | Multi‐centre | Single‐centre | Multi‐centre | Multi‐centre |
| Number of participants randomly assigned | 90 | 40 | 180 | 79 |
| Condition | ARDS | ARDS | ARDS | ARDS |
| ECMO type | VA | VV | VV | AV |
| Intervention group | ECMO + mechanical ventilation | ECCO2‐R + LFPPV | ECMO + mechanical ventilation | avECCO2‐R + mechanical ventilation |
| Control group | Mechanical ventilation | Mechanical ventilation | Mechanical ventilation | Mechanical ventilation |
| Protective lung ventilation* | No | No | Yes | Yes |
| Modern ECMO‡ | No | No | Yes | Yes |
ARDS = acute respiratory distress syndrome.
avECCO2‐R = arteriovenous extracorporeal membrane carbon dioxide removal.
LFPPV‐ECCO2 = low‐frequency positive‐pressure ventilation/extracorporeal carbon dioxide removal.
*Protective lung ventilation: Since the year 2000, significant changes in the treatment of ventilated patients known as protective lung ventilation with low tidal volumes have changed the standard of care for patients with acute respiratory distress syndrome (ARDS Network 2000).
‡Modern ECMO: usage of polymethylpentene oxygenators and heparin‐coated circuits (Terragni 2014; Zampieri 2013).