Our main finding was that patients who received long-term treatment with SL-BUP had high opioid requirements through the first postoperative day, regardless of type of anesthesia used or whether SL-BUP was preoperatively continued or discontinued. Use of opioids increased substantially after discharge from the PACU, and by 24 h after PACU discharge, no differences in opioid requirements were noted between patients who underwent surgical procedures with general anesthesia only versus combined general/regional anesthesia. Because our case series describes a heterogeneous surgical population with variable use of SL-BUP, we cannot provide suggestions regarding the best opioid management practices for patients on SL-BUP undergoing surgery.
Importantly, the naloxone component of SL-BUP is clinically insignificant when taken sublingually; equianalgesic opioid doses formulated as SL-BUP versus other forms of buprenorphine only (eg, transdermal) are clinically similar. Therefore, this study evaluated the opioid requirements of individual patients and specific anesthesia management modalities related to buprenorphine use. Because buprenorphine tightly binds to opioid receptors and has an analgesic ceiling effect, management of more intense postoperative pain with buprenorphine may be difficult [11]. This difficulty may be further complicated by the long half-life of buprenorphine because the time needed for complete buprenorphine elimination may exceed the hospital stay. Thus, an individualized perioperative analgesic plan should be instituted for a patient receiving buprenorphine. Three regimens have been proposed: withhold buprenorphine for a period before surgery, continue buprenorphine use through the perioperative period, or increase the preoperative buprenorphine dose to a maximum of 32 mg/d [15].
To date, no unified guidelines exist regarding perioperative care of patients receiving buprenorphine. The rationale for withholding buprenorphine before surgery is based on the premise that buprenorphine levels on opioid receptors decrease over several days to the point at which high-affinity, pure μ-opioid receptor agonists (eg, fentanyl, alfentanil, morphine) exert clinical effects [11]. However, the optimal withholding time is difficult to determine primarily because buprenorphine elimination half-life varies from 16.4 to 42 h [11]. Given the expected drug-elimination rule (typically 5 half-lives), it would take 7.7 days for buprenorphine to be entirely eliminated from the body [11]. The additional difficulty of individualizing recommendations results from interpatient variability in buprenorphine elimination. However, even partial elimination, which could be achieved by withholding buprenorphine for 72 to 120 h, could allow for approximately 2 to 3 half-lives to pass and, in turn, improve the effects of full opioid agonists [15]. It has been suggested that patients should be offered full opioid agonists (eg, fentanyl patch or other traditional opioids) during the preoperative withholding period, if needed [15], which was the case for 7 of our patients. We have shown that patients who undergo surgery while receiving SL-BUP have high 24-h postoperative opioid requirements regardless of whether they preoperatively continued or discontinued SL-BUP. In the present study, we do not have a comparison group of opioid-naïve patients. However, we recently reported, in a case matched study, that patients not receiving long-term preoperative opioids received less opioid IV-MEq following discharge from the PACU compared to patients who underwent surgery while being on uninterrupted transdermal buprenorphine therapy (median [IQR] opioid dose of 15 [3–35] vs 54 [38–90] mg IV) [16]. Although patients included in the present study underwent different surgeries than those in our previous publication, and represent a mix of SL-BUP use (uninterrupted vs interrupted with varying time since last dose), the amount of opioids administered for these patients likely exceeds that expected for patients undergoing similar procedures and not receiving long-term opioids. In our case series, the use of the “single-shot” regional technique was not associated with reduced 24-h opioid requirements. Intuitively, regional techniques that use continuous infusion (eg, via indwelling catheters) may be more beneficial, but further studies are needed to confirm or refute this notion. Multimodal pain management (ie, nonsteroidal anti-inflammatory drugs, gabapentinoids, acetaminophen, clonidine, ketamine, and dexmedetomidine) may benefit patients receiving SL-BUP. However, postoperatively, multimodal pain management was rarely used in the present case series: ketorolac in 1 regional anesthetic, 4 combined anesthetics, and 4 general anesthetics; ketamine in 4 general anesthetics; and both ketamine and ketorolac in 1 patients in the combined anesthesia group. Doses of ketorolac ranged from 15 to 30 mg in the first 24 h, and ketamine doses ranged from 20 to 60 mg. Therefore, the role of multimodal pain management for patients receiving SL-BUP cannot be evaluated in the present study.
The rate of anesthesiology pain service interventions in the present series was 47% for patients who received general anesthesia and 40% for those who received combined general/regional anesthesia. These high rates are similar to that seen in our recent case-control study, where we demonstrated that patients on uninterrupted transdermal buprenorphine had a rate of 32% requiring pain consults, compared to 0% in the control group (no buprenorphine) [16].
The limitations of the study are related to its retrospective design. First, the small number of patients who underwent various surgical procedures, received different types of anesthesia, and received different doses of SL-BUP (which were either continued up to the day of surgery or discontinued 1–30 days before surgery) is a limitation that precludes generalization of our findings and observations toward the best practices for patients receiving SL-BUP. Second, intraoperative opioid use may be affected by knowledge that the patient is receiving SL-BUP, and therefore providers may preemptively increase opioid load to counteract postoperative pain. However, postoperative opioid needs are clearly guided by patient reports of pain, and therefore a high opioid load administered during the postoperative period truly reflects the increased opioid requirement of a patient receiving long-term SL-BUP. The number of patients in the regional anesthesia group is too small to make conclusions regarding the role of these techniques in reducing opioid requirements, especially since regional anesthesia management was not protocolized. In our practice, preemptive pain service management applies to patients with continuous regional anesthesia catheters (the anesthesia pain management team manages infusion rates and adjuvant analgesic therapies); and for those with single-shot regional block and those receiving general anesthesia only, the surgical service is primarily responsible for prescribing postoperative pain medications, and the anesthesia pain service is consulted on an as-needed basis only (ie, in cases with inability to control pain by primary service). However, retrospectively, we could not clarify whether pain consults were scheduled proactively under the assumption that patients were on SL-BUP, and therefore would require additional postoperative pain management, or if the consult was triggered postoperatively due to a true need for elevated pain management expertise.
