Fig. 4

Relationship between oxygenation and respiratory effort. A: relationship between PaO₂ during VM, and the change in respiratory effort from VM to NRB (n = 15): only in patients with PaO₂ < 60 mmHg (n = 8, red dots), a strong, significant relationship was found. B: relationship between PaO₂ and respiratory effort with oxygen masks (NRB and, when available, VM); PaO₂: arterial oxygen tension. NRB Non-rebreather mask, VM Venturi mask, AIC Akaike information criterion