A prospective, randomized study will be performed investigating the effects of a pumpless extracorporeal interventional lung assist [iLA] on the implementation of a lung-protective ventilatory strategy in patients with acute respiratory distress syndrome [ARDS] with a PaO2/FiO2 ratio < 200. The duration of ventilation, intensive care and hospital stay and in-hospital mortality will be investigated.

Evaluation group:

Implantation of the iLA - adaptation of the ventilation strategy, explantation of the iLA after corresponding improvement (see treatment plan for details) - weaning from the ventilation and extubation according to specified criteria.

Control group:

Ventilation strategy based on the concept of lung-protective ventilation without extracorporeal support, weaning from the ventilation and extubation according to specified criteria (see treatment plan for details).

Inclusion Criteria:

• The trial subjects are patients aged 18 years or older who have developed severe ARDS. Following the American-European Consensus Conference on ARDS, severe ARDS is defined as an oxygenation index (PaO2/FIO2) < 200 mmHg. These parameters must be present for a duration of at least 2 hours.

Exclusion Criteria:

• age < 18 years
• decompensated heart insufficiency
• acute coronary syndrome
• severe chronic obstructive pulmonary disease
• advanced tumour conditions with life expectancy < 6 months
• chronic dialysis treatment
• lung transplant patients
• proven Heparin-induced thrombocytopenia (HIT)
• morbid obesity (BMI >) 40
• Child Class B and C cirrhosis of the liver, acute fulminant hepatic failure
• severe peripheral arterial occlusive disease (pAVK III - IV), absence of limb doppler pulse
• brain injury (GCS < 9 + CT pathology)