Table 11. Effectiveness of venous extracorporeal membrane oxygenation in treating patients with acute respiratory distress syndrome.

MV: mechanical ventilation; PaO₂: partial pressure of oxygen; FiO₂: fraction of inspired oxygen; PaCO₂: partial pressure of carbon dioxide; BMI: body mass index; VA-ECMO: venoarterial-extracorporeal membrane oxygenation; HIT: heparin-induced thrombocytopenia; RR: relative risk; CI: confidence interval; IS: ischemic stroke; PIP: peak inspiratory pressure; PEEP: positive end-expiratory pressure; PWP: pulmonary wedge pressure; ARDS: acute respiratory distress syndrome

*Defined by the presence of a positive end-expiratory pressure ≥ 10 cmH2O and a tidal volume of 6 mL/kg of predicted weight

Author	No.'s	Design	Inclusion Criteria	Exclusion Criteria	Primary Outcome	Main Findings	Considerations
Combes et al. [130]	249	International multicenter, randomized, controlled clinical trial	1. Patient intubated on MV < 7 days 2. PaO2/FiO2 < 50mmHg for > 3 hours OR PaO2/FiO2< 80mmHg for > 6 hours OR Arterial pH < 7.25 with PaCO2 ≥ 60mmHg > 6 hours 3. Optimized MV* 4. Age >18 years	1. Pregnant women 2. BMI > 45 3. Chronic respiratory failure 4. Indication for VA-ECMO 5. History of HIT 6. Advanced cancer 7. Dying patients 8. Coma after cardiac arrest 9. Nonreversible neurologic injury 10. Palliative patients	60-day mortality of 35% (44/124 patients) in the ECMO group and 46% (57/125 patients) in the control group (RR: 0.76; 95%CI 0.55 -1.04; p = 0.09)	Serious thrombocytopenia and bleeding that required transfusions were more common in the ECMO group. The incidence of IS, the requirement for renal replacement therapy, and the reduction of tidal volume, plateau pressure, and drive pressure were all lower in the ECMO group	Early interruption of the study due to futility Slow recruitment rate Due to refractory hypoxemia, the crossover rate was high (28%) as we switched from the control group to the ECMO group. At 60 days, the control group experienced a greater rate of treatment failure
Peek et al. [131]	180	Multicenter, randomized, controlled clinical trial	1. Age from 18 - 65 years 2. Severe but potentially reversible respiratory failure 3. Murray score ≥ 3.0 4. Uncompensated hypercapnia 5. Optimized MV.	1. PIP > 30cmH2O 2. FiO2 > 80% 3. Time of MV ≥ 7 days 4. Intracranial bleeding 5. Contraindication to heparinization 6. Limitation of support	6-month mortality after randomization or before hospital discharge of 37% (33/90) in the ECMO group and 53% (46/87) in the control group (RR: 0.69; 95%CI 0.05-0.97, p = 0.03)	The transfer of patients with severe but potentially reversible respiratory failure to a reference center in ECMO proved to be cost-effective and reduced mortality	Control group does not have standardization of MV parameters 22 patients did not use the device of the 90 patients who were randomized to receive ECMO
Morris et al. [133]	40	Dual-center, randomized, controlled clinical trial	1. PaO2 < 50mmHg for 2 hours with FiO2 = 100%, PEEP > 5 and PaCO2 of 30 - 45 or PaO2 < 50mmHg for 12 hours with FiO2 = 60%, PEEP ≥ 5cmH2O and PaCO2of 30 - 45 2. Optimized MV	1. Contraindication to anticoagulants 2. POAP > 25mmHg 3. Time of MV> 21 days 4. Severe, irreversible, and without treatment prospective systemic disease	30-day survival of 33% (7/21) in the ECMO group and 42% (8/19) in the control group (p = 0.8)	Does not advocate the use of ECMO in ARDS patients.	Small sample size High mortality rate (62% of patients died) Technical limitations inherent to the clinical trial period Non-protective MV in both groups
Zapol et al. [132]	90	Multicenter, randomized, controlled clinical trial	1. PaO2 < 50 mm Hg, for more than 2 hours with FiO2100% and PEEP ≥ 5cmH2O OR PaO2 < 50 mm Hg, for more than 12 hours with FiO2 = 60% and PEEP ≥ 5cmH2O	1. Age from 12 to 65 years old 2. Pulmonary lesion time > 21 days 3. PWP > 25mmHg 4. Severe, irreversible, and incurable systemic disease	30-day survival of 9.5% (4/42) in the ECMO group and 8.3% (4/48) in the control group (no significant difference)	The survival rate of patients with severe ARDS was not improved by ECMO, but it was able to support the respiratory system.	Mortality in both groups is greater than 90%. Technical limitations were inherent to the clinical trial period. Nonprotective MV in both groups.