This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
4.1 In a multicentre randomised controlled trial (RCT) of 79 patients treated by low ventilation (about 3 ml/kg) combined with arteriovenous (AV) extracorporeal carbon dioxide removal (ECCO2R; n=40) or an acute respiratory distress syndrome network strategy without ECCO2R (about 6 ml/kg; n=39), 18% (7/40) of patients in the AV‑ECCO2R group died in hospital compared with 15% (6/39) in the control group (the difference between the 2 groups was not statistically significant). In an RCT of 40 patients treated by low‑frequency positive-pressure ventilation and venovenous (VV) ECCO2R (n=21) or continuous positive-pressure ventilation alone (n=19), survival rate at 30 days was 33% (7/21) in the group treated by VV‑ECCO2R compared with 42% (8/19) in the control group (p=0.56). In a systematic review including the 2 RCTs listed above and 12 observational studies, mortality rates of patients treated by VV- or AV‑ECCO2R ranged from 27% to 75% (mean 55.5%, standard deviations 74.2 to 60.3). In an analysis of UK patients on the Extracorporeal Life Support Organization register, the survival to discharge rate was 45% (27/60). Of those discharged, 48% (13/27) were discharged to home, and 41% (9/22) of patients receiving AV‑ECCO2R and 47% (18/38) receiving VV‑ECCO2R were discharged alive (the difference between the groups was not statistically significant). In an analysis of the Regensburg extracorporeal membrane oxygenation register data comparing the efficacy of different systems used to deliver ECCO2R, 32% (196/317) of patients overall were discharged from hospital (range across devices 60% to 78%).
4.2 Three case series of patients treated by AV‑ECCO2R reported a statistically significant reduction in the partial pressure of CO2 in arterial blood (PaCO2) within 24 hours of initiating ECCO2R support, compared with baseline. In the first case series of 90 patients, PaCO2 decreased from a median of 60 mmHg to 34 mmHg at 24 hours (p<0.05). In the second case series of 159 patients, PaCO2 decreased from 67 mmHg to 35 mmHg at 24 hours (p=0.001). In the third case series of 51 patients, PaCO2 decreased from 73 mmHg at baseline to 41 mmHg at 24 hours (p<0.01).
4.3 In the case series of 90 patients, there was a statistically significant increase in partial pressure of oxygen (PaO2) to fraction of inspired oxygen (FiO2) ratio from 58 mmHg at baseline to 101 mmHg at 24 hours (p<0.05). In the case series of 51 patients, there was a statistically significant increase in PaO2/FiO2 from 75 mmHg at baseline to 110 mmHg at 24 hours (p<0.05).
4.4 In the case series of 90 patients, median minute ventilation (MV) statistically significantly decreased from 13.0 litres/min at baseline to 9.9 litres/min at 24 hours (p<0.05). In the case series of 159 patients, mean MV decreased from 13.8 litres/min to 11.6 litres/min (p value not stated). In the case series of 51 patients, median MV statistically significantly decreased from 11.5 litres/min to 6.6 litres/min (p<0.01).
4.5 In the case series of 90 patients, median respiratory frequency statistically significantly decreased from 27 breaths/min at baseline to 23 breaths/min at 24 hours (p<0.05). In the case series of 159 patients, there was a decrease from 32 breaths/min at baseline to 29 breaths/min at 24 hours (p value not stated). In the case series of 51 patients, there was a decrease from 25 breaths/min to 21 breaths/min at 24 hours (p value not stated). In a multicentre retrospective matched comparison study of 42 patients treated by pumpless extracorporeal lung assist (PECLA; n=21) or invasive mechanical ventilation (n=21), there was a decrease from a median number of 28 breaths/min (interquartile range [IQR] 25–31) at baseline to a median number of 21 breaths/min (IQR 17–25) at 21–24 hours for the PECLA group (p value not stated).
4.6 The specialist advisers listed the following key efficacy outcomes: mortality, ventilator-free days, length of stay in intensive care, intubation avoidance and lowering of CO2 in the blood.