Dosage of epidural morphine analgesia after lower abdominal cancer surgery: a randomized clinical trial among the older adults.

BACKGROUND

Epidural morphine is considered one of the most potent drugs used for postoperative analgesia; however, its side effects are dose-related and exaggerated in elderly people. In this study, we aimed to determine which of three doses within that range (1.5 mg, 3 mg, or 4.5 mg) can provide adequate pain relief.

METHODS

A total of 102 patients were assessed for allocation into one of four groups to receive either placebo (group Morphine 0, N = 22), 1.5 mg of epidural morphine (Morphine 1.5, N = 22), 3 mg of epidural morphine (Morphine 3, N = 22), or 4.5 mg of epidural morphine (Morphine 4.5, N = 22) before skin incision, 24 h after surgery and 48 h after surgery. Cumulative intravenous IV-PCA morphine consumption, VAS pain scores, modified Ramsay Sedation Scores, nausea, vomiting, and pruritus were evaluated.

RESULTS

The VAS pain scores at activity of patients who received epidural morphine at doses of 3 mg and 4.5 mg were significantly lower than the placebo and 1.5 mg groups, VAS Score at 72 h was (2 ± 0.8) and (1.7 ± 1) vs (4.3 ± 1.1) and (4 ± 1) respectively, p value = 0.000. The mean total IV-PCA morphine consumption (mg) was significantly higher in patients who received received epidural 0.9% sodium chloride alone compared to 1.5 mg, 3 mg and 4.5 mg epidural morphine groups (38.1 ± 4.8 mg vs 27.2 ± 5.6 mg, 9.2 ± 3.5 mg, and 6.3 ± 3.3 mg respectively), p value = 0.000). However, the difference between the 3 mg and the 4.5 mg groups was not statistically significant in both of VAS scores and IV-PCA morphine consumption (P value > 0.05 for 3 mg vs. 4.5 mg). Patients who received 4.5 mg of epidural morphine experienced a significant increase in the level of sedation, measured by the Ramsay sedation scale, in comparison with 1.5 mg, 3 mg and placebo epidural morphine groups in the first 24 h, the Scale for this group was (2.5 ± 0.5) vs (2.1 ± 0.2, 2.1 ± 0.2, and 2.2 ± 0.5 respectively); p value = 0.000. No relationship between postoperative nausea and the dosage of epidural morphine was found.

CONCLUSION

Epidural morphine 3 mg as a bolus every 24 h with add on IV patient control analgesia (PCA) morphine, set to deliver 1.5 mg boluses on demand without background infusion with a lockout period of 45 min, could achieve effective and adequate analgesia lasting up to 72 h postoperatively without increasing in the level of sedation or other side effects in older adults after a lower abdominal cancer surgery.