Determinants of patient-controlled epidural analgesia requirements: a prospective analysis of 1753 patients

Patient-controlled epidural analgesia (PCEA) has been widely used in postoperative pain management. Many factors may correlate with PCEA requirements but no previous study has ever investigated this subject. Therefore, we conducted this study to explore the relationship among patients' characteristics and total PCEA consumption during the 3-day postoperative course.

This prospective study was conducted with surgical patients receiving postoperative PCEA and completing the 3-day course. The PCEA regimen was prepared as 0.0625% bupivacaine with fentanyl (l microg/mL). Patients' characteristics including demographic data and surgical procedures were collected. The total doses were recorded after the course terminated. Stepwise regression analyses were conducted to select significant variables, which could determine total PCEA demand. Subgroup analyses were also performed to investigate whether differences exist among distinct surgical sites.

There were 1753 patients (1094 men and 659 women) included in the analysis. Weight, age, height, body mass index, sex distribution, and total PCEA consumption were significantly different among various surgical sites (all P<0.001). Operational sites, procedures involving malignant disease, weight, and age are the most significant factors in sequence to determine total PCEA requirements. Height and sex have no impact on PCEA demand. The multiple correlation coefficient of our model is 0.688 and the predictive formula of the 3-day postoperative PCEA requirement was 240.1+(130.5xsite)+(66.6xmalignancy)+(1.7xweight)-(0.4xage).

Our study demonstrated the association between patients' characteristics and total PCEA requirements from a large-scaled clinical data. Surgical procedures have more influence on PCEA consumption than demographic variables. Background infusion rate of PCEA could be determined from our predictive model.