In our research, the amount of morphine required by the patient was higher than that of the author Nguyen Trung Kien [8] (57.8 ± 11.3mg) and the age of the author's study of 69.2 ± 6.6 was higher than our study of 56.23 ± 13.21. In addition, in Nguyen Trung Kien's study, there were patients with laparoscopic surgery, so the demand for morphine may be lower than that of open surgery patients [8].