“…Therefore, the peripheral administration of opioid agonists may, theoretically, inhibit the chronic pain of infl ammation under ischemic conditions in PVD. Locally administered opioids have been shown to elicit effective analgesic effects in various acute and chronic clinical pain syndromes, including burn pain [27], infl ammatory pain [28], osteoarthritis [7], and rheumatoid arthritis [29], as well as after dental [11], urinary bladder [30], and knee surgery [31], too. In the present study we used morphine as an adjunct to bupivacaine through a popliteal catheter in chronic pain due to PVD, based on the interaction between opioids and infl ammatory conditions and also based on clinical trials as mentioned above.…”