Fig. 2

Arterial blood gas analysis of both groups at four time points. *Was statistically significant compared with Group H, P < 0.05; ^aWas statistically significant compared with T1 in the group H, P < 0.05; ^bWas statistically significant compared with T2 in the group H, P < 0.05; ^cWas statistically significant compared with T3 in the group H, P < 0.05; ^dWas statistically significant compared with T1 in the group L, P < 0.05; ^eWas statistically significant compared with T2 in the group L, P < 0.05; ^fWas statistically significant compared with T3 in the group L, P < 0.05; T1, before anesthesia induction; T2, before left lung lavage; T3, at the end of operation when bilateral lung ventilation recovery; T4, six hours after operation