Relationship of Essential Hypertension and Its Treatments on the Postoperative Pain Management: a Prospective, Observational, Cross-sectional Study

Numbers of postoperative PCA related side effects among three groups will be determined by comparing and analyzing frequency distributions. To determine whether the patients with hypertension require less post operative opiate analgesics than others, multivariate analysis with repeated measures will be performed to identify the major and the minor factors predicting the use of postoperative pain therapy. The major aim of the study is to test the hypothesis that the morphine comsumpted by the hypertension group is less than those of the normotension group. The minor aims for the study are the difference related to pain intensity, or the incidence of side effects among groups.