Results will be reported as M(SD), median (interquartile) or numbers (percentages). A p value of < 0.05 was considered significant in all analyses. All data will be analyzed with the SPSS statistical software (version 9.0, SPP, Chicago, IL). ANOVA for repeated measurements will be used to compare baseline values (preoperative, POD0 and POD1) followed by Bonferroni post-hoc tests. Paired and unpaired Student t tests will be used to assess and to compare the effects of bronchodilators. Furthermore, the correlation between changes in EVLWI, CI, ITBVI and PaO2/FIO2 will be analyzed by linear regression.