METHODS: In this prospective study, 48 patients scheduled for elective laparotomy were randomized to two groups of preemptive analgesia, namely, group K-P, in which anestheologists administered a combination of 0.3 mg/kg IV ketamine and 40.0 mg IV parecoxib, or group K, in which ones gave 0.3 mg/kg IV ketamine alone. Patients from both groups underwent surgery under general anesthesia, and total intraoperative opioid requirement was recorded. After surgery, morphine administered by automated patient-controlled analgesia (PCA) infusion device was initiated in all patients. Pain score was assessed using the visual analogue scale (VAS), and postoperative opioid requirement was recorded at 1 and 4 hours, and subsequently from 4-hour intervals up to 24 hours after surgery.
RESULTS: Compared to group K, group K-P required significantly lower rescue IV fentanyl in the recovery bay (0.10 ± 0.28 vs. 0.35 ± 0.46 μg/kg; P = 0.031), showing prolonged time-to-first analgesic request recorded by PCA device (70.8 ± 40.0 vs. 22.2 ± 15.8 mins; P ＜ 0.001), lower total morphine requirement delivered by PCA device (8.0 ± 4.6 vs. 16.8 ± 6.5 mg; P ＜ 0.001), and lower VAS values measured at all time points. There was no significant difference in intraoperative total opioid requirement between the groups.
CONCLUSIONS: Among laparotomy patients, multimodal preemptive analgesia by the use of a combination of low-dose IV ketamine and IV parecoxib was more effective than IV ketamine alone in reducing pain scores and postoperative analgesia requirement (e.g., PCA-administered morphine).