A 52-year-old man is ventilated for ARDS. He has been on VV-ECMO for 7 days with improving native lung function. The ECMO team plans a 'sweep trial' to assess readiness for decannulation. During the trial, sweep gas is reduced to 0 L/min. Blood flow remains at 4 L/min. After 30 minutes, ABG shows: pH 7.38, PaO2 9.5 kPa, PaCO2 5.8 kPa on ventilator settings of PCV Pinsp 14, PEEP 8, FiO2 0.4, RR 14. What do these results suggest?