Fig. 4
Survival analysis in different PCO2 groups of patients with a P/F ratio ≥ 200. In the population with a P/F ratio ≥ 200, survival analysis showed that the survival rate of the group with VR ≥ 0.9 was higher than that of VR < 0.9 (p = 0.000) (a). Supgroup analysis revealed a similar trend in patients with PCO2 < 35 mmHg as that in total population (p = 0.018) (b). However, no significant differences existed in the overall survival for the subgroup with PCO2 35–45 mmHg (p = 0.493) (c) and PCO2 > 45 mmHg (p = 0.170) (d)