An alternative way of managing acute pain in patients who are in buprenorphine opioid substitution therapy programs

Abstract

Editor, We read with great interest the review article by Stromer et al.1 on the perioperative management of pain in patients who abuse opioids. It adds much to the knowledge base on which we rely to manage such a complex patient group. However, in our experience, there is an alternative and perhaps simpler and more effective way of managing patients who are in buprenorphine opioid substitution therapy (BOST) programs. This is of growing relevance as in many countries the number of such patients is increasing due to the perceived greater safety profile of buprenorphine compared with methadone. We acknowledge that the management of acute perioperative pain in a patient prescribed BOST is controversial.2 We agree that concerns about buprenorphine's long half-life, partial μ-agonist and κ-antagonist effects,1 in addition to its high opioid receptor affinity and slow dissociation from the μ-opioid receptor,3 have led many experts to recommend that it be ceased preoperatively and replaced with methadone or a pure μ-opioid agonist to ensure adequate intraoperative and postoperative pain relief.1,4,5 However, we believe that such concerns are unfounded. Contrary to the management plan suggested by Stromer et al., some authors have recommended that the buprenorphine, even in the high doses of 4 to 32 mg often used in BOST, be continued throughout the perioperative period.2 We, therefore, recently undertook a retrospective cohort study comparing pain relief and patient-controlled analgesia (PCA) opioid requirements in the first 24 h after surgery in 51 patients in methadone opioid substitution therapy (MOST; 29 patients) and BOST (22 patients) programs.3 The patients were further subgrouped into those whose methadone or buprenorphine was given or withheld on the first postoperative day. We found no statistically significant differences in the pain scores (rest and movement) or PCA morphine equivalents used between the MOST and BOST patients, suggesting that even for planned major surgery, adequate intraoperative and postoperative analgesia can be equally achieved for patients taking methadone and buprenorphine. Thus, changing preoperatively from buprenorphine to methadone seems to offer no advantage. Of special interest was that BOST patients who were not given their buprenorphine the day after surgery had statistically significantly higher PCA morphine equivalent requirements in the first 24 h after surgery (though similar pain scores) compared with those who were given their usual dose. As a result, concerns about the ability of high doses of buprenorphine to limit the access of full μ-opioid agonists to opioid receptors and reduce their analgesic efficacy would seem to be unwarranted.3 We also found that the BOST and MOST patients had a higher incidence of increased sedation (a better clinical indicator of early respiratory depression than a decrease in respiratory rate)6 than our opioid-naive patients. Although the reason for this is unclear, it is a finding also noted by Rapp et al.7 in opioid-tolerant patients in general. Thus, when opioid doses are rapidly and significantly escalated to deal with new acute pain in the opioid-tolerant patient2 as recommended by Stromer et al.,1 monitoring for respiratory depression, including using sedation scores, must still be mandated, as these patients may, perhaps counterintuitively, be at greater risk of respiratory depression than the opioid-naive patient. We routinely continue buprenorphine (or any other opioid the patient may be taking in the long-term) throughout the perioperative period, irrespective of its dose or the perceived size of the surgical insult. We manage additional acute pain with a full-agonist PCA opioid in higher-than-usual doses, adjuvant nonopioid analgesic agents including ketamine, and regional analgesia, whenever possible. Acknowledgements relating to this article Assistance with the letter: none. Financial support and sponsorship: none. Conflicts of interest: none. Presentation: none.