. 2015 Jan 22;2015(1):CD010381. doi: 10.1002/14651858.CD010381.pub2

1. Results reported from included studies.

Outcome	Zapol 1979^*	Morris 1994^*†	Peek 2009^‡	Bein 2013^§
Intervention/Population	VA ECMO + ventilation/ARDS patients	VV ECCO₂‐R + ventilation/ARDS patients	VV ECMO + ventilation/ARDS patients	AV ECCO₂‐R + ventilation/ARDS patients
All‐cause mortality (number (%)) Intervention group (IG) vs control group (CG)	38 of 42 (91) vs 44 of 48 (92)	14 of 21 (66) vs 11 of 19 (57)	33 of 90 (37) vs 45 of 90 (50)	7 of 40 (17.5) vs 6 of 39 (15.4)
All‐cause mortality difference IG vs CG  (RR, 95% CI)	RR 0.99, 95% CI 0.87 to 1.12 Not statistically significant	RR 1.15, 95% CI 0.71 to 1.88 Not statistically significant	RR 0.73, 95% CI 0.52 to 1.03 Not statistically significant	RR 1.14, 95% CI 0.42 to 3.08 Not statistically significant
Length of hospital stay (LOS) days (± SD)^a IG vs CG	Not reported	26.9 (4.9) vs 28.8 (5.7) Not statistically significant	35 (15.6 ‐74) vs 17 (4.8 ‐45.3)^b	46.7 (33) vs 35.1 (17) Not statistically significant
Survival to discharge (number (%)) IG vs CG	Not reported	7 (33)^c vs 8 (42)^c Not statistically significant	Not reported	33 (82.5) vs 33 (84.6) Not statistically significant
Disability as reported by study authors	Normal lung function: 7 of 8 (both groups) No limitations in daily activities for all survivors	Not reported	No severe disability^d at 6 months: IG: 57 of 90 (63%) CG: 41 of 87 (47%) Statistically significant^‡	Not reported
Adverse outcomes	IG and CG: septicaemia (20%), pneumothorax (45%) Not statistically significant IG: lower blood platelet and white blood cell concentration and greater blood/ plasma infusion reported with 1 to 2.5 liters Statistically significant	Major complications^e IG = 34 vs CG = 16 Not statistically significant Non‐brain haemorrhage IG = 21 vs CG = 0 Statistically significant IG: transfusion exceeded 0.8 L/d in 10 patients and led to bypass disconnection in 7 patients	IG = 2 vs CG = 0 1 was death due to mechanical failure of oxygen supply during ambulance Vessel perforation during cannulation	IG = 3 (7.5%) vs CG =0 1 had transient ischaemia of the lower limb 2 patients developed a "false" aneurysm from arterial cannulation Transfusion of blood units^f IG = 3.7 units vs CG = 1.5 Statistically significant

ARDS = acute respiratory distress syndrome.

AV ECCO₂‐R = arteriovenous extracorporeal membrane carbon dioxide removal.

VV ECCO₂‐R = veno‐venous extracorporeal membrane carbon dioxide removal.

^aSD = Standard deviation.

^b LOS days (interquartile range (IQR)).

^cSurvival at 30 days after randomization.

^dSevere disability was determined by the first 2 items of the EQ‐5D survey (item Mobility = unable to walk around, in addition to item Personal Care = unable to wash or dress).

^eCentral nervous system (CNS), peripheral vascular and other.

^fRed blood cell units until day 10.

^*The ECMO configuration and respirator settings in the ECMO group and/or the control group are outdated.

^†The trial was stopped after 40 participants.

^‡3 patients in the control group had unknown disability status. If the 3 patients were severely disabled, RR of the primary outcome (death or severe disability) was 0.67 (95% CI 0.48 to 0.94; P value 0.017); it was 0.72 (95% CI 0.51 to 1.01; P value 0.051) if they were not severely disabled. Only 68 (75%) of participants randomly assigned to the intervention group actually received ECMO.

^§Feasability study that used pump‐free avECCO₂‐R to achieve very low tidal volume (3 mL/kg) in established ARDS compared with standard mechanical ventilation (6 mg/kg).