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Total amount of fentanyl use and frequency to push the button of PCA
Values are expressed as mean±SD, or median (interquartile range) [95% confidence interval]. *Mann-Whitney U test is used and expressed as median (interquartile range) [95% confidence interval] because of abnormal distribution; †P<0.05 compared with Group C. PCA, Patient-controlled analgesia machine; FPB, frequency to push the button of PCA.
