Intravenous analgesics for pain management in postoperative patients: a comparative study of their efficacy and adverse effects

Purpose: To compare the effectiveness of post-operative pain management and associated adverse effects of ketamine and nefopam.
Methods: In total, 78 American Society of Anesthesiologists (ASA) grade 1 and 2 patients who had undergone abdominal surgery were given 3 mg of intravenous (IV) morphine as post-operative analgesia. Patients who still had pain were randomly selected (n = 48) and separated into three groups, and infused with isotonic saline (n = 15), 3 mg/kg/h ketamine (n = 17), or 3 mg/kg nefopam (n = 16), respectively. Verbal rating scale (VRS), visual analogue scale (VAS), satisfactory scores, and total morphine consumption, as well as several adverse events were determined.
Results: VRS and VAS scores, and morphine consumption were significantly lower (p < 0.05) in the entire analgesic group than in the saline group. However, ketamine appeared to provide better (p < 0.05) analgesic activity. The satisfactory score was concomitantly elevated (p < 0.05) in the ketamine group. Moreover, the occurrence of adverse events was substantially lower (p < 0.05) in the ketamine group and was equivalent to nefopam group except sedation.
Conclusions: The combination of ketamine with morphine provides optimal pain relief in abdominal surgery patients and show fewer adverse effects than nefopam, thus achieving overall better satisfaction.

Keywords
Post-operative pain; Abdominal surgery; Adverse effects; Morphine; Ketamine; Nefopam