Gas exchange efficiency was evaluated by measuring PaO2 and PaCO2 after discontinuing mechanical ventilation and simultaneously initiating circulatory support. PaO2 and PaCO2 were 23.0 ± 1.5/62.1 ± 2.8, 50.6 ± 5.2/46.1 ± 2.3, and 110.7 ± 29.8/38.9 ± 2.8 mmHg at flow rates of 1–3 L/min, respectively. Sufficient gas exchange was achieved at flow rates of 3 L/min and above.