Abstract: Objective  To study and analyze the effects of lung recruitment with different oxygen concentrations combined with positive end-expiratory pressure(PEEP) on stress response in patients with lung cancer and related factors of postoperative pulmonary complications. 
Methods  A total of 208 patients with non-small cell lung cancer (NSCLC) who underwent unilateral radical resection of lung cancer in our hospital were selected as the research subjects for retrospective analysis. According to the different oxygen concentrations, they were divided into the observation group ［fraction of inspiration O2 (FiO2) adjusted to 30%, n=124］ and the control group (FiO2 adjusted to 80%, n=84). Clinical indications, complications and influencing factors of complications were observed in two groups. "The number of types of pulmonary complications in a single individual" was applied to distinguish the previous "total number of single complications in a single individual", and "the influential factors of the number of types of pulmonary complications explored by Poisson probability regression analysis"was used to distinguish "the influential factors of complications or prognosis by binary logisitc regression analysis". 
Results  The dose of remifentanil (1.26±0.32) mg and rocuronium bromide (78.39±10.59) mg, duration of operation (125.92±24.18) min, duration of anesthesia (152.42±31.23) min, and length of hospital stay (5.29±0.72) d in the control group were higher or longer than those in the observation group ［(1.15±0.35) mg, ( 71.38±10.35) mg, (113.35±23.67) min, (132.88±28.67) min, and (4.45±0.72) d］ in the observation group (P＜0.05). The number of cases ［8(6.45%)］ with pleural effusion and the number of types of complications in the observation group ［17 cases (13.71%) of 1 type, 3 cases (2.42%) of 2 types］ were lower than those in the control group ［33 cases (39.29%) of 1 type, 16 cases (19.05%) of 2 types, 1 case (1.19%) of 3 types］, and the difference was statistically significant (P＜0.05). The factors influencing the number of types of pulmonary complications were grouping (different oxygen concentrations), smoking history, drinking history, hypertension, operation site, diabetes, pulmonary function status, American Society of Anesthesiologists(ASA) classification, age, duration of operation, intraoperative blood volume, cortisol, adrenocorticotropichormone(ACTH), dosage of remifentanil, forced expiratory volume in one second (FEV1), maximum ventilatory volume/minute(MVV), and oxygenation index. 
Conclusion  Lung recruitment with low concentration of oxygen is superior to that with high concentration, which can improve pulmonary function, promote oxygenation, and reduce complications. It should be noted that the occurrence of pulmonary complications is affected by various indicators, such as treatment conditions, basic conditions, anesthesia conditions and stress response, so as to optimize treatment and nursing measures.

Key words: lung neoplasms, different oxygen concentration, postoperative pulmonary complications