The predictors of
postoperative pain and
analgesic consumption were previously found to include preoperative
pain, anxiety, age, type of surgery, and genotype, but remaining unclear was whether intraoperative factors could predict
postoperative pain. In the present study, we investigated the time-course of
fentanyl consumption using intravenous
patient-controlled analgesia records from patients who underwent
orthognathic surgery for mandibular
prognathism and analyzed the influence of
anesthesia methods and surgical methods together with sex on the time course. A significant difference in the time course of
fentanyl administration was found (P<0.001). No significant difference in the time course of
fentanyl administration was found between males and females (P = 0.653), with no interaction between time course and sex (P = 0.567). No significant difference in the time course of
fentanyl administration was found among
anesthesia methods, such as
fentanyl induction followed by
fentanyl maintenance,
fentanyl induction followed by
remifentanil maintenance, and
remifentanil induction followed by
remifentanil maintenance (P = 0.512), but an interaction between time course and
anesthesia method was observed (P = 0.004). A significant difference in the time course of
fentanyl administration was found between surgical methods, such as bilateral mandibular
sagittal split ramus osteotomy (BSSRO) and BSSRO combined with Le Fort I
osteotomy (bimaxillary; P = 0.008), with no interaction between time course and surgical method (P = 0.535). Total postoperative 24 h consumption associated with the bimaxillary procedure was significantly higher than with BSSRO (P = 0.008). The present results indicate that administration patterns and total 24 h consumption were different among the three groups of
anesthesia methods and between the two groups of surgical methods, respectively. Although more research on
patient-controlled analgesia patterns and consumption is necessary, the present study will contribute to adequately relieving individual patients from
postoperative pain.