Relationship between total intraoperative remifentanil consumption and cumulative 0- to 12-h postoperative morphine consumption. Each pointrepresents a patient. Black squares represent patients from the pupillometry group and white squares represent patients from the standard group. After testing for homogeneity of covariance, the solid line represents the correlation between intraoperative remifentanil consumption and cumulative 0- to 12-h postoperative morphine consumption in both groups. ANCOVA r = 0.38; P = 0.005.