Background and objectives: Morphine may elicit potent antinociceptive effects by binding and activating peripheral opioid receptors. However, the results in clinical studies have varied. We examined the postoperative analgesic effects of incisional morphine in patients undergoing lumpectomies and axillary node dissections for breast cancer. For this purpose, a concentration of morphine within the range (0.25-0.6%) of those utilized in previous studies for postarthroscopy analgesia was chosen (0.6%).
Methods: Forty-five patients scheduled to undergo a lumpectomy and axillary node dissections for breast cancer were enrolled in this study after receiving Ethics Committee approval and patient consent. Patients were randomized to undergo irrigation of the surgical sites for 5 minutes prior to skin closure with 6 mg morphine diluted in 100 mL 0.9% normal saline (NS) and placebo intramuscular (i.m.) (peripheral MS group), 100 mL of 0.9% NS alone and placebo i.m. (placebo group), or 100 mL of 0.9% NS and 6 mg morphine i.m. in the deltoid muscle (i.m. MS group) in a double-blind fashion. In the postanesthesia care unit, patients received fentanyl via a patient-controlled analgesia (PCA) device programmed to deliver 25 microg every 10 minutes to a maximum dose of 150 microg/h. Patients were evaluated for pain using a visual analog scale card from 0-10, opioid consumption, and incidences of side effects at 2, 6, 12, 18, and 24 hours after surgery.
Results: All patients had adequate analgesia at rest and during arm movement with visual analog pain scores (VAPS) <3/10 throughout the study period. There were no significant differences in demographics, total fentanyl consumption (500 vs. 475 vs 933 microg, respectively; P = .2), VAPS at rest and during arm movement as well as fentanyl consumption at the different evaluation points among the three groups.
Conclusions: These results suggest that under the conditions of the study protocol, there is no value in utilizing morphine in solution at the surgical site for postoperative lumpectomy and axillary node dissection analgesia.